Articles parus en 2017 - Agrobonsens

Cette veille bibliographique est réalisée par Nathalie Roullé et Nicolas Chatel-Launay, Pôle d’excellence en lutte intégrée (PELI).

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Veille d’informations sur le thrips de l’oignon (Thrips tabaci)

Ce document présente une liste d’articles et de rapports de recherches réalisés au Québec

ou en dehors du Québec. Dernière mise à jour : 07 février 2017.

Table des matières

Articles parus en 2017 .................................................................................................................................................. 1

Articles parus en 2016 .................................................................................................................................................. 2

Articles parus en 2015 ................................................................................................................................................16

Articles parus en 2014 ................................................................................................................................................26

Articles parus avant 2014 ...........................................................................................................................................36

Articles parus en 2017

Gawande, S. J., Anandhan, S., Ingle, A. A., Jacobson, A., & Asokan, R. (2017). Heteroplasmy due to coexistence of mtCOI

haplotypes from different lineages of the Thrips tabaci cryptic species group. Bulletin of Entomological Research, 1-9.

Heteroplasmy is the existence of multiple mitochondrial DNA haplotypes within the cell. Although the number of

reports of heteroplasmy is increasing for arthropods, the occurrence, number of variants, and origins are not well

studied. In this research, the occurrence of heteroplasmy was investigated in Thrips tabaci, a putative species complex

whose lineages can be distinguished by their mitochondrial DNA haplotypes. The results from this study showed that

heteroplasmy was due to the occurrence of mitochondrial cytochrome oxydase I (mtCOI) haplotypes from two different

T. tabaci lineages. An assay using flow cytometry and quantitative real-time PCR was then used to quantify the per cell

copy number of the two mtCOI haplotypes present in individuals exhibiting heteroplasmy from nine geographically

distant populations in India. All of the T. tabaci individuals in this study were found to exhibit heteroplasmy, and in

every individual the per cell copy number of mtCOI from lineage 3 comprised 75–98% of the haplotypes detected and

was variable among individuals tested. There was no evidence to suggest that the presense of lineage-specific

haplotypes was due to nuclear introgression; however, further studies are needed to investigate nuclear introgression

and paternal leakage during rare interbreeding between individuals from lineages 2 and 3.

Zhao, X., Reitz, S. R., Yuan, H., Lei, Z., Paini, D. R., & Gao, Y. (2017). Pesticide-mediated interspecific competition between local

and invasive thrips pests. Scientific Reports, 7.

Competitive interactions between species can be mitigated or even reversed in the presence of anthropogenic

influences. The thrips species Frankliniella occidentalis and Thrips tabaci are highly invasive and damaging agricultural

pests throughout the world. Where the species co-occur, one species tends to eventually predominate over the other.

Avermectin and beta-cypermethrin are commonly used insecticides to manage thrips in China, and laboratory

bioassays demonstrated that F. occidentalis is significantly less susceptible than T. tabaci to these insecticides. In

laboratory cage trials in which both species were exposed to insecticide treated cabbage plants, F. occidentalis became

the predominant species. In contrast, T. tabaci completely displaced F. occidentalis on plants that were not treated with

insecticides. In field trials, the species co-existed on cabbage before insecticide treatments began, but with T. tabaci



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being the predominant species. Following application of avermectin or beta-cypermethrin, F. occidentalis became the

predominant species, while in plots not treated with insecticides, T. tabaci remained the predominant species. These

results indicate that T. tabaci is an intrinsically superior competitor to F. occidentalis, but its competitive advantage can

be counteracted through differential susceptibilities of the species to insecticides. These results further demonstrate the

importance of external factors, such as insecticide applications, in mediating the outcome of interspecific interactions

and produce rapid unanticipated shifts in the demographics of pest complexes.


Aizawa, M., Watanabe, T., Kumano, A., Miyatake, T., & Sonoda, S. (2016). Cypermethrin resistance and reproductive types in

onion thrips, Thrips tabaci (Thysanoptera: Thripidae). Journal of Pesticide Science, 41(4), 167-170.

Cypermethrin resistance and reproductive types were examined for T. tabaci strains. Some arrhenotokous and

thelytokous strains encoded the sodium channel mutation (T929I) involved in cypermethrin resistance. However, the

resistance levels varied to some degree among the strains. A cytochrome P450 inhibitor, piperonyl butoxide, showed

different synergistic effects on the strains examined. These results suggest that fundamental and additional levels of

cypermethrin resistance in T. tabaci are conferred respectively by reduced sensitivity of the sodium channel and by

cytochrome P450-mediated detoxification.

Almási, A., Tóbiás, I., Bujdos, L., & Jenser, G. (2016). Molecular characterisation of Thrips tabaci Lindeman, 1889 (Thysanoptera:

Thripidae) populations in Hungary based on the ITS2 sequences. Acta Zoologica Academiae Scientiarum Hungaricae, 62(2), 157-

164.

Thrips tabaci is comprised of morphologically indistinguishable ‘biotypes’or cryptic species with various host ranges,

populations propagating by distinct modes and with different virus vector ability. T. tabaci ‘communis-type’ has wide

host range while T. tabaci ‘tabaci-type’ is associated only with tobacco. Since tobacco was introduced to Europe only

500 years ago, we supposed that the differentiation of the T. tabaci ‘tabaci-type’ population had to begin on another

host species that is native to the Palaearctic region. To observe the interaction between host plant preference and

molecular characteristics, maximum likelihood tree based on the sequences of the internal transcribed spacer 2 region

of the rDNA (ITS2) of Thrips tabaci specimens collected on tobacco, onion, cabbage and distinct weed plants from

various locations of Hungary was analysed. According to the results of the phylogenetic study the only common host

for Thrips tabaci ‘tabaci-type’ and Thrips tabaci ‘communis-type’ was Solanum nigrum. This finding supported our

hypothesis that the splitting process of the two main molecular clades could have happened on this solanaceous host

species. To compare our results to that of the literature based on cytochrome oxidase I (COI) sequences further

investigations with these markers (mitochondrial DNA markers) still needed.

Annamalai, M., Kaushik, H. D., & Selvaraj, K. (2016). Bioefficacy of Beauveria bassiana. Proceedings of the National Academy of

Sciences, India Section B: Biological Sciences, 86(2), 505-511.

Bioefficacy of Beauveria bassiana (Balsamo) Vuillemin and Lecanicillium lecanii Zimmerman in comparison with their

commercial formulations along with standard check insecticide, Fenvalerate 20 EC were evaluated against onion thrips,

Thrips tabaci Lindeman under greenhouse as well as field conditions. The results revealed that the standard check

fenvalerate 20 EC @ 0.0075 % showed significantly the highest cumulative corrected mortality of 97.84 % followed by

commercial formulation of B. bassiana, Myco-Jaal @ 1 × 108 spores/mL which showed 80.90 % mortality. The

laboratory cultured B. bassiana showed percent mortalities of 74.11, 71.69 and 78.48 % for the concentrations of 1.23 ×

107, 1.23 × 106 and 1.23 × 108 spores/mL, respectively. However, these concentrations were statistically at par on all

the days of observation. Thrips mortality gradually increased with the increase in concentrations of fungal preparations

and days of observations. Similar trend was also observed in L. lecanii experiment. Under field conditions, Fenvalerate

20 EC @ 0.0075 % recorded highest mortality of T. tabaci (90.10 %) followed by commercial formulation of V. lecanii

(Phule Bugicide @ 2 × 108 cfu/g) with 74.90 % mortality. All the concentrations of fungal concentrations gave low



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mortality ranging from 9.40 to 10.10 % and 7.10 to 7.40 % at 2 days after treatment (DAT) of B. bassiana and L. lecanii,

respectively. The standard check of Fenvalerate 20 EC @ 0.0075 % was highly toxic and showed significantly maximum

percent reduction (90.50 %) of T. tabaci population in both the experiments. The present study clearly shows that these

entomopathogens may be integrated with existing integrated pest management (IPM) practices for management of T.

tabaci.

Asiye, U. Z. U. N., & DEMİRÖZER, O. (2016). Effective factors on host choice of phytophagous thrips and possibilities of use for

control. Turkish Bulletin of Entomology, 6(4), 327-338.

Thrips are cause directly damage by laying egg and feeding, indirectly by transmitting tospoviruses on plants. Many

factors depending host have important role in plant selection for nutrition, shelter and reproductive. It is known that

the first stimulant is host colour and as to second is host odors in host selection. Factors such as the nutrient content

and morphological characteristic, different plant parts and also infection status by different organisms indicate changes

according to the thrips species which can be influence on the choice of host. The stimulants which effective on host

choice are important in determining the strategy of monitoring and control of pest thrips populations. Considering of

stimulants that depending on host and combining of them are make more efficient combat with thrips. Specific

behavioral features of the thrips reveals necessity of alternative methods and supportive strategies in control of the

thrips. In this study, factors that effective on host choice of phytophagous thrips were discussed and evaluated use

status of this factors in control of thrips.

Babar, T. K. (2016). FIELD EVALUATION OF NEW INSECTICIDES AGAINST COTTON THRIPS (THRIPS TABACI LIND.) IN DISTRICT

MULTAN.

The studies were conducted at farmer's field in Tehsil Shujabad of Multan district. The efficacy of following insecticides

viz. Hicap 20 SL(imidacloprid) @ 500 ml/ha, Pirate 360 SC (chlorofenapyr) @ 250 ml/ha, Tracer 240 SC (spinosad) @ 125

ml/ha, Movento 50 WDG (spirotetramat) @ 500 gm/ha, Karate 2.5EC (lambda cyhalothrin) @ 825 ml/ha, Acephate 70

WP(acephate) @ 625 gm/ha, Imidacloprid 25 WP(imidacloprid) @ 185 gm/ha, Momentum 50 WDG (chlorofenapyr +

nitenpyram) @ 375 gm/ha, Confidor 70 WG (imidacloprid) @ 58 gm/ha were evaluated on transgenic cotton (Bt-886)

against adult thrips. Maximum mortality of thrips was recorded in Acephate 75SP i.e .86.91% and 75.47% after 24 and

72 hours of spray while Pirate 360 SC @ 250 ml/ha exhibited maximum percentage of mortality i.e. 58.18% after 168

hours of insecticides application.

Baker, M. A., Makhdum, A. H., Nasir, M., Imran, A., Ahmad, A., & Tufail, F. (2016). COMPARATIVE EFFICACY OF SYNTHETIC AND

BOTANICAL INSECTICIDES AGAINST SUCKING INSECT PEST AND THEIR NATURAL ENEMIES ON COTTON CROP. Journal of

Mountain Area Research, 1, 1-4.

The Synthetic and botanical insecticides are relatively safer for environment and beneficial insects. The study was

conducted in Rahim Yar Khan during the cotton cropping season 2014 to evaluate the comparative efficacy of two

Synthetic insecticides i.e. Nitenpyram (Jasper 10% SL) and Pyriproxyfen (Bruce 10.8% EC) and two botanical extracts of

Calotropic procera and Azadirachta indica, against sucking insect pest complex of cotton and their natural enemies.

Upon reaching economic thresholds, the recommended field doses of all the insecticides were applied on cotton

cultivar MNH-886. Data against sucking pests and their natural enemies was recorded 24 hours prior to insecticidal

application and then 24, 48, 72 and 96 hours after insecticidal application. Results revealed that Nitenpyram was much

toxic against sucking pests followed by Pyriproxyfen as compared to two botanical extracts. On the other hand, the

synthetic insecticides did not prove safer for natural enemies as compared to botanical extracts. It was concluded that

as an Integrated Pest Management (IPM) strategy, botanical extracts can be used at low infestation levels so that

ecosystem service of biological control may be sustained.

Begum, K., Patil, S., & Mohite, P. (2016). Evaluation of newer molecules of insecticides against Sucking pests complex Infesting

okra. Indian Journal of Applied Research, 6(2).

The studies on the efficacy of newer insecticides as foliar revealed that imidacloprid 17.8 SL @ 40 g a.i./ha was the most

effective treatment indicatingreduction in population of leafhoppers, aphids, whiteflies and thrips was 89.9, 93.1 , 91.0

and 90.65 per cent , respectively and recorded maximum fruit yield of 52.2 q/ha with 97.72 per cent increase in fruit

yield over untreated control. It was followed by imidacloprid 17.8 SL @ 15 g a.i./ha, thiamethoxam 25 WG, acetamiprid



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20 SP and fipronil 5 % SC. All the treatments, except spinosad 45 SC were effective in controlling sucking pest

population in okra and all the treatments were observed to be significantly superior over untreated control.

Carrillo, C. I. C., Funderburk, J., & Snyder, W. E. (2016). Thrips (Thysanoptera) Collected from S olanum dulcamara (Solanales:

Solanaceae) in Washington and Idaho. Florida Entomologist, 99(2), 306-307.

Bittersweet nightshade, Solanum dulcamara L. (Solanales: Solanaceae), was sampled at numerous locations in

Washington and Idaho. Adults of 8 species of thrips (Thysanoptera) from 3 families were collected, including the

worldwide plant pests Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman (Thripidae), which are vectors of

the serious plant viruses in the genus Tospovirus. Aeolothrips fasciatus Hinds (Aeolothripidae), a predator of small

insects, also was collected.

Chandra, S., Arora, A., Kumar, A., Jain, R., Marwaha, S., & Misra, T. (2016, March). Online software for forewarning of onion thrips.

In Computing for Sustainable Global Development (INDIACom), 2016 3rd International Conference on (pp. 1898-1900). IEEE.

Onion, Allium cepa, contribution is significant in foreign exchange under vegetables in India. Onion thrips, Thrips tabaci

Lindeman, is a potential pest of onion and causes considerable losses in the yield. Onion production as well as

infestation of crop pests and diseases is highly related to weather. These losses can be reduced to a considerable extent

if their occurrence and severity is known in advance. Indian Agricultural Statistical Research Institute (IASRI) have

developed weather based forewarning models on the data taken from Directorate of Onion and Garlic Research

(DOGR), Pune. Models have been developed for thirteen dates of sowing for the forewarning of crop age at first

appearance of thrips, crop age at peak population of thrips and maximum thrips population. To disseminate the

information in effective manner, online software has been developed based on these weather models. Online system

has been developed using three-tier architecture. Client layer in implemented using Hypertext Markup Language

(HTML), Cascading Style Sheet (CSS) and Java script. Application layer is implemented using Java Server Pages (JSP) and

database layer is implemented in Microsoft SQL Server. The models developed were tested with observed and

predicted value and percentage deviation was computed.

De Grazia, A., Marullo, R., & Moritz, G. (2016). Molecular diagnosis of native and quarantine pest thrips of southern European

citrus orchards. Bulletin of Insectology, 69(1), 1-6.

The ITS-RFLP technique of the amplified internal transcribed spacer regions of ribosomal DNA has been used to

establish the molecular identification of the most common pest thrips species of citrus orchards. Both native and

quarantine thrips species have been tested and molecular keys are proposed through ITS-RFLP techniques. The

restriction enzymes produced patterns that allowed unambiguous identification of seven thrips species examined

(visual key). The sequences of species can also be verified using a molecular key that permits identification of a species

through such parameters as primer pair used, restriction enzyme, length of PCR-product, fragments obtained. This

study has shown that the use of genetic markers can be a valid alternative for quarantine workers and for

epidemiological researchers, to whom the correct identification of pest species through classic morphological methods

could be either very difficult and time-consuming or visually impossible.

de Sousa Almeida, A. E. C., Nogueira, L., de Sousa Netto, M. I., de Azevedo Pereira, A. I., & de Jesus, F. A. G. (2016). Relationship

on the incidence of Thrips tabacci and spacing of garlic plantation. African Journal of Agricultural Research, 11(9), 755-759.

Thrips, Thrips tabaci Lind. (Thysanoptera: Thripidae), is a key pest of garlic in Brazil. This study aimed to evaluate the

influence of spacing on T. tabaci infestation of a garlic crop. The experiment was conducted at the experimental farm of

the Goiano Federal Institute (Instituto Federal Goiano – IF Goiano) - Campus Urutaí. The experimental design was a

randomized block with nine treatments and spacing in single rows (0.20 × 0.10 m, 0.25 × 0.10 m and 0.30 × 0.10 m)

and double rows (0.20 × 0.10 × 0.10 m; 0.20 × 0.15 × 0.08 m; 0.25 × 0.10 × 0.10 m; 0.25 × 0.15 × 0.08 m; 0.30 × 0.10 ×

0.10 m; and 0.30 × 0.15 × 0.08 m). The Chonan 15 genotype was used in three replicates. At 30, 50 and 70 days after

emergence (DAE), evaluations on the following features were carried out: leaf length, number of leaves, angle between

the two central leaves, damage and number of thrips per plant. At the end of the crop cycle, the plants were harvested.

Individual cured bulb mass, estimated commercial yield, number of cloves per bulb and bulb diameter were also

evaluated. Spacing influenced the angle between the central leaves, with spacing of 0.30 × 0.15 × 0.08 m, among the

least dense spacing, producing the widest angle (26.96o), suffered one of the highest degrees of insect damage. A



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spacing of 0.25 × 0.10 m had the highest number of thrips per plant (2.99). Spacing influenced production, with the

highest yield occurring with a spacing of 0.25 × 0.15 × 0.08 and 0.30 × 0.10 × 0.10 m (14.37 and 13.51 t/ha,

respectively). The least dense spacing produced the largest bulb diameter (42.80 mm) and mass (30.66 g).

Din, N., Ashraf, M., & Hussain, S. (2016). Effect of different non-chemical and chemical measures against onion thrips.

The effect of insecticides (Imidacloprid 200SL, 250 ml/acre; Imidacloprid + Fipronil 80 WG, 60 gm/acre, Chlorfenapyr

36SC, 50WDG, 100ml/acre and leaf extracts of (Nerium indicum, Calotropis procera and Datura stramonium seed

extract of each at 5%) were evaluated against Thrips tabaci in farmer’s field. Data recording intervals were 24, 48, 72-

hours and 7-days. The results revealed that maximum population reduction was observed in Imidacloprid + Fipronil

80WG (94.28%) followed by Chlorfenapyr 50WDG (93.37%), Chlorfenapyr 36SC (91.26%) and Imidacloprid 200SL

(85.06%) and where mean population of thrips per five plants were recorded 2.33, 2.33, 2.73 and 6.26, respectively.

After 24-hours of data recording interval among the botanicals,D. stramonium gave significantly lower population of

thrips (9.700 per five plants) and highest reduction percentage (82.36) after 48-h of intervals followed by C. procera and

N. indicum with mean population 11.36, 13.90 showing reduction percentage 79.33 and 74.76, respectively.

Driutti, A. (2016). Control biológico natural de trips, Thrips tabaci Lindeman 1888 (Thysanoptera: Thripidae) por sírfidos

predadores en cultivo de cebolla i>(Allium cepa L.) por el cultivo de borduras y/o entrelineas. Agrotecnia, (5), 3-15.

La cebolla (Allium cepa L.) es el cultivo más importante de la región del Alto Valle de ltajaí, Santa Catarina, Brasil. Este

cultivo tiene una elevada dependencia de los insumos químicos, siendo el trips (Thrips tabaci Lind.) la plaga más

importante. En la búsqueda del desarrollo de métodos agroecológicos de producción, los objetivos del presente

trabajo fueron: 1) verificar la influencia de la introducción de algunas especies de plantas en las borduras y en líneas

intercaladas en el cultivo, en el control biológico natural de T. tabaci, y 2) evaluar el potencial del control biológico

natural de T. tabaci por larvas de sírfidos (Diptera:Syrphidae). Los experimentos fueron conducidos en ltuporanga, SC,

en los años 1996 y 1997. El cultivo se desarrolló sin utilización de fertilizantes químicos y o productos de síntesis

química. En los experimentos 1y11 se ensayó la introducción de una mezcla de especies en las borduras, a saber: trigo

sarraceno, maíz, girasol, repollo y nabo forrajero. En el experimento 111 se ensayó el efecto de la siembra de nabo

forrajero en las borduras y en líneas paralelas entre las líneas del cultivo de cebolla. Se constató que la siembra de

especies atractivas para los predatores en las borduras, y de líneas en el interior del cultivo, reduce la densidad

poblacional de T. tabaci en las plantas de cebolla. No se encontró una relación de dependencia entre las poblaciones

de T. tabaci y larvas de sírfidos. Concluimos que en condiciones de cultivo agroecológico de cebolla, se verificó un

efecto favorable en el control biológico natural de este insecto, y que este proceso se efectúa por varias especies

antagonistas, no conocidas en su totalidad.

Fail, J. (2016). Speciation in Thrips tabaci Lindeman, 1889 (Thysanoptera): the current state of knowledge and its consequences.

Polish Journal of Entomology, 85(1), 93-104.

Based on DNA sequences of the mitochondrial COI gene, Thrips tabaci has been divided into three lineages: a tobacco-

associated (T) and two leek-associated types (L1, L2). It is believed that the arrhenotokous leek-associated type (L1) is

the ancient form of T. tabaci and that the T type diverged from it and adapted to solanaceous host plants. The third

lineage of T. tabaci, the so-called thelytokous leek-associated type (L2) and the L1 form share many host plants.

According to a recent study, the L2 form of T. tabaci could outcompete the L1 type on cabbage plants; it might

therefore be more accurate to identify it as the thelytokous cabbage-associated type.

Farkas, P., Bagi, N., Szabó, Á., Ladányi, M., Kis, K., Sojnóczki, A., ... & Fail, J. (2016). Biological control of thrips pests (Thysanoptera:

Thripidae) in a commercial greenhouse in Hungary. Polish Journal of Entomology, 85(4), 437-451.

Polyphagous thrips, like western flower thrips Frankliniella occidentalis and onion thrips Thrips tabaci, are major pests in

various ornamental and vegetable crops in greenhouses throughout the world. In Hungary, both of these polyphagous

thrips species frequently cause severe damage in many greenhouse crops, especially in commercial sweet pepper.

Chemical control is not always feasible because of certain ecological characteristics of these thrips species. The

commercially available phytoseiid predatory mites like Amblyseius swirskii and anthocorid flower bugs like Orius

laevigatus are often used simultaneously for the biological control of severe thrips infestation in sweet pepper

cultivation in Hungary. Our observations demonstrated that the polyphagous thrips assemblages were effectively



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controlled by the combined release of natural enemies, despite the fact that the establishment of O. laevigatus did not

seem to be successful in the first year. Overall, the thrips population density remained below the economic threshold in

both years. However, the low infestation level of thrips suggests that a single predator release strategy could be applied

effectively and still maintain the thrips below the damage threshold in greenhouse sweet pepper.

Iftikhar, R., Ashfaq, M., Rasool, A., & Hebert, P. D. (2016). DNA barcode analysis of thrips (Thysanoptera) diversity in Pakistan

reveals cryptic species complexes. PloS one, 11(1), e0146014.

Although thrips are globally important crop pests and vectors of viral disease, species identifications are difficult

because of their small size and inconspicuous morphological differences. Sequence variation in the mitochondrial COI-

5ʹ (DNA barcode) region has proven effective for the identification of species in many groups of insect pests. We

analyzed barcode sequence variation among 471 thrips from various plant hosts in north-central Pakistan. The Barcode

Index Number (BIN) system assigned these sequences to 55 BINs, while the Automatic Barcode Gap Discovery detected

56 partitions, a count that coincided with the number of monophyletic lineages recognized by Neighbor-Joining

analysis and Bayesian inference. Congeneric species showed an average of 19% sequence divergence (range = 5.6% -

27%) at COI, while intraspecific distances averaged 0.6% (range = 0.0% - 7.6%). BIN analysis suggested that all

intraspecific divergence >3.0% actually involved a species complex. In fact, sequences for three major pest species

(Haplothrips reuteri, Thrips palmi, Thrips tabaci), and one predatory thrips (Aeolothrips intermedius) showed deep

intraspecific divergences, providing evidence that each is a cryptic species complex. The study compiles the first

barcode reference library for the thrips of Pakistan, and examines global haplotype diversity in four important pest

thrips.

Jacobson, A. L., Nault, B. A., Vargo, E. L., & Kennedy, G. G. (2016). Restricted gene flow among lineages of Thrips tabaci supports

genetic divergence among cryptic species groups. PloS one, 11(9), e0163882.

Knowledge of the relative influence of population- versus species-level genetic variation is important to understand

patterns of phenotypic variation and ecological relationships that exist among and within morphologically

indistinguishable cryptic species and subspecies. In the case of cryptic species groups that are pests, such knowledge is

also essential for devising effective population management strategies. The globally important crop pest Thrips tabaci

is a taxonomically difficult group of putatively cryptic species. This study examines population genetic structure of T.

tabaci and reproductive isolation among lineages of this species complex using microsatellite markers and

mitochondrial COI sequences. Overall, genetic structure supports T. tabaci as a cryptic species complex, although

limited interbreeding occurs between different clonal groups from the same lineage as well as between individuals

from different lineages. These results also provide evidence that thelytoky and arrhenotoky are not fixed phenotypes

among members of different T. tabaci lineages that have been generally associated with either reproductive mode.

Possible biological and ecological factors contributing to these observations are discussed.

Karavina, C., Ibaba, J. D., Gubba, A., & Pappu, H. R. (2016). First report of Iris yellow spot virus infecting garlic and leek in

Zimbabwe. Plant Disease.

In Zimbabwe, garlic (Allium sativum L.) and leek (Allium ampeloprasum L.) are minor crops grown as herbs and spices

by a few farmers. Annual output is estimated at 200 tonnes for garlic and 160 tonnes for leek. Since both crops are

considered resistant to pests and diseases, most farmers do not implement crop protection measures during

production. Iris yellow spot virus (IYSV; genus Tospovirus, family Bunyaviridae) is an important emerging pathogen of

Alliums worldwide (Bag et al. 2015; Pappu et al. 2009). During a tospovirus disease survey in July 2015, garlic and leek

plants displaying suspected IYSV symptoms were found at three farms in Goromonzi, Mutasa, and Nyanga districts of

Zimbabwe. The symptoms consisted of straw-colored, spindle-shaped spots with poorly defined ends on leeks, and

diamond-shaped lesions with green chlorotic islands on garlic. These coalesced to form large, brown, necrotic patches

on the leaves. Disease incidence estimated by visual observations was 25% in leek and up to 60% in garlic. There was

high incidence of Thrips tabaci on all farms surveyed. Fifteen symptomatic and six healthy samples from the basal and

middle portions of young leaves collected at each farm were preserved in RNAlater solution (Ambion, Foster City, CA,

USA). IYSV presence was confirmed by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA)

using an IYSV kit (Loewe Biochemica GmbH, Sauerlach, Germany). All symptomatic samples tested were IYSV-positive,

while the healthy samples were negative. The pathogen was further confirmed by reverse transcription polymerase

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chain reaction (RT-PCR) using the nucleocapsid protein (N) gene-specific primers IYSV-NCP2_F (5′-

GGCGGTCCTCTCATCTTACTG-3′) and IYSV-NCP2_R (5′-GAAGTTCCAGGAGTGCATTTAGTC-3′) (Lee et al. 2011). Firstly,

total RNA was extracted using Quick-RNA MiniPrep Kit (Zymo Research, Irvine, CA, USA) according to manufacturer’s

instructions. Then, first strand cDNA was synthesized using the RevertAid First Strand cDNA Synthesis Kit (Thermo

Scientific, Waltham, MA, USA), followed by PCR using KAPA2G Fast HotStart ReadyMix Kit (KAPA Biosystems, Roche,

Basel, Switzerland), and the primers IYSV-NCP2_F and IYSV-NCP2_R. Amplicons of 236 bp, obtained in IYSV-positive

samples and not in healthy controls, were excised and purified from agarose gel using Qiagen Gel Extraction Kit

(Hilden, Germany) prior to cloning into the pCR2.1 vector of TOPO-TA Cloning kit (Invitrogen, Carlsbad, CA, USA). Three

positive clones were sequenced using M13 forward and reverse primers at Inqaba Biotechnical Industries (Pty) Ltd

(Pretoria, South Africa). The consensus sequence of the Zimbabwean IYSV garlic isolate (GenBank Accession No.

KT732272) shared 97% nucleotide identity with the corresponding region of onion-infecting isolates originating from

South Australia (KJ769188), Mexico (JX946658) and western USA (DQ233475), while the Zimbabwean leek isolate

(KT732273) shared 99% nucleotide identity with the onion-infecting IYSV isolate from Zimbabwe (KT271469). To our

knowledge, this is the first report of natural infection of garlic and leek by IYSV in Zimbabwe. Despite garlic and leek

being minor crops, IYSV occurrence on these crops shows the expanding host range of the pathogen in Zimbabwe.

Both garlic and leek are commonly intercropped with other vegetables and ornamental plants and could provide a

“green bridge” for IYSV survival. There is need to monitor IYSV disease impact on Allium spp. in the country.

Khaliq, A., Afzal, M., Khan, A. A., Raza, A. M., Kamran, M., Tahir, H. M., ... & Ullah, M. I. (2016). Management of Thrips tabaci

(Thysanoptera: Thripidae) Through Agronomic Practices in Onion Field Plots. Pakistan J. Zool, 48(6), 1675-1680.

Onion, Allium cepa (L.) is very important and highly valuable vegetable crop all over the world. Amongst the insect

pests, onion thrips, Thrips tabaci Linedman (Thysanoptera: Thripidae) has been proved to be the most important factor

for onion yield reduction. In the present study effects of intercropping and plant spacing were recorded in onion field

plots as a management tool against T. tabaci. For this purpose, four intercrops (chili, tomato, okra and cotton) and five

plant spacings (10, 15, 20, 25 and 30 cm) were used in onion field crop. Minimum thrips density per plant was recorded

in onion plots intercropped with cotton during the study period of two years. The maximum thrips density was

recorded in control plots (26.19±5.67), F4,250= 7.79; P<0.001. Onion plots intercropped with cotton gained the highest

bulb weight and yielded maximum onion/plot followed by tomato, chilli and okra, respectively. No difference in mean

bulb weight of control and onion plot intercropped with okra was recorded in the current study. However, bulb weight

of onion in both of these plots was significantly lower as compared to onion plots intercropped with cotton. Minimum

thrips density per plant was recorded in onion plots in which plant to plant space was 30 cm followed by 25 cm, 20 cm,

15 cm and 10 cm plant spacing during both experimental years. The thrips density was increased with the decrease of

plant to plant spacing. Further, single bulb weight with 30 cm plant spacing was significantly higher as compared to

lowest plant spacing (10 cm). In both years, onion plots with minimum plant spacing (10 cm) produced more yield/plot

but with lowest bulb weight and vice versa. Therefore, it was concluded that cotton should be intercropped with onion

as a trap crop and medium onion plant spacing should be practiced for reducing thrips infestation and suitable bulb

size with optimum yield.

Kliot, A., Kontsedalov, S., Lebedev, G., & Ghanim, M. (2016). Advances in Whiteflies and Thrips Management. In Advances in

Insect Control and Resistance Management (pp. 205-218). Springer International Publishing.

The sweetpotato whitefly Bemisia tabaci and thrips species such as the tobacco thrips, Thrips tabaci and the western

flower thrips Frankliniella occidentalis are major agricultural pests in various vegetable, ornamental and field crops.

These pests cause extensive damage by a direct feeding on plants, reducing quality of the produce, secreting

honeydew and transmitting economically important viruses. Management programs of both whitefly and thrips species

rely on using chemical insecticides, resulting thereby in developing resistance to all major insecticide classes makes

them a continuous problem in many cropping systems. Resistance monitoring is a major approach for the management

and reducing resistance, and thus during the last decade B. tabaci, T. tabaci and F. occidentalis populations in Israel

have been monitored for resistance to major insecticide classes. Monitoring results show that many T. tabaci and F.

occidentalis populations were found to be resistant to major insecticides used for controlling thrips species, primarily

spinosad, while whitefly populations were found to exhibit varying levels of resistance to neonicotinoids and other



8

classes, depending on the whitefly biotype and other agricultural practices. The long-term monitoring results and their

integration into resistance management programs will be presented in this review.

Kobayashi, K., & Hasegawa, E. (2016). A female-biased sex ratio reduces the twofold cost of sex. Scientific reports, 6.

The evolution of sexual reproduction remains a fascinating enigma in biology. Theoretically, populations of sexual

organisms investing half of their resources into producing male offspring that don’t contribute to reproduction should

grow at only half the rate of their asexual counterparts. This demographic disadvantage due to male production is

known as the twofold cost of sex. However, the question of whether this cost is truly twofold for sexual females remains

unanswered. The cost of producing males should decrease when the number of male offspring is reduced. Here, we

report a case where the cost of males is actually less than twofold. By measuring the numbers of sexual strain coexisting

with asexual strain among thrips, our survey revealed that the sexual strain showed female-biased sex ratios and that

the relative frequency of sexual strain is negatively correlated with the proportion of males in the sexual strain. Using

computer simulations, we confirmed that a female-biased sex ratio evolves in sexual individuals due to the coexistence

of asexual individuals. Our results demonstrate that there is a cost of producing males that depends on the number of

males. We therefore conclude that sexual reproduction can evolve with far fewer benefits than previously assumed.

Kumar, A. (2016). EVALUATION OF ONION GENOTYPES AGAINST ONION THRIPS, Thrips tabaci LINDEMAN AND ITS

MANAGEMENT THROUGH BOTANICALS (Doctoral dissertation, Indirra Gandhi Krishi Vishwavidyalaya Raipur).

Kumar, V. R., Prasad, N. V. V. S. D., & Madhumathi, T. (2016). Relative Toxicity of Different Insecticides against Thrips tabaci

Lindeman on Coton.

Eight insecticides were evaluated to find out their relative toxicity against thrips on cotton. Among the insecticides

evaluated, flonicamid 10 WG (15 g a.i./ha) had shown greater control against thrips throughout the crop period.

Diafenthiuron 50 WP (300 g a.i./ha) was found to be effective after flonicamid 10 WG where as fipronil 5 SC (50 g

a.i./ha) and acephate 75 SP (562.5 g a.i./ha) had shown satisfactory results in controlling thrips. Imidacloprid 17.8 SL

(35.6 g a.i./ha) and bifenthrin 10 EC (75 g a.i./ha) were less effective against thrips at all stages of the crop. Highest

number of bolls and seed cotton yield was observed in flonicamid 10 WG treated plot which had shown significantly

better performance over all other treatments.

Mandal, T., Ghosh, S. K., & Chakraborty, K. SEASONAL INCIDENCE OF THRIPS (THRIPS TABACI L.) INFESTING SOM PLANT LEAVES

(MACHILUS BOMBYCINA KING) AND THEIR MANAGEMENT USING BIOPESTICIDES.

Som plant (Machilus bombycina King) is an important forest tree cultivated as community forestry, useful for rearing of

muga silk worm (Antheraea assama Ww). Nutritional value of leaves plays an important role in larval growth and silk

productivity. The plant also has timber values. The plant is susceptible to various insect pests of which Thrips (Thrips

tabaci L.) causes heavy damage to tender leaves of the plant. Thrips was active all throughout the year. Lower

population level was recorded during 3rd week of March to last week of June and higher population level was

maintained during last week of November to 3rd week of January. Peak population (12.77/3 leaves) was recorded on

49th standard week that on 1st week of December. Thrips population had a significant positive correlation with

temperature ifference and relative humidity (maximum) while significant negative correlation with temperature

(maximum, minimum and average). This indicates that activity of thrips population increase with the rise of relative

humidity and population decrease with the rise of temperature. Imidaclorprid was found to be most effective against

thrips however extracts of Garlic gave a moderate thrips control. But Imidaclorprid is a highly toxic synthetic insecticide,

so there is every possibility to contaminate som plant leaf with the toxic chemicals, as som leaf is the major food

component of muga silk worm rearing. Plant extracts are of biological origin having low or no hazardous effect on

health and environment and so can be incorporated in IPM programme against thrips on som plant.

Miyazaki, J., Stiller, W. N., & Wilson, L. J. (2016). Sources of plant resistance to thrips: a potential core component in cotton IPM.

Entomologia Experimentalis et Applicata.

Thrips (Thysanoptera: Thripidae) are important pests of seedling cotton and their damage can delay crop maturity

and/or reduce yield. Plant resistance to thrips in cotton would reduce the need to treat crops with insecticides for their



9

control. This would support integrated pest management strategies by reducing the risk of selecting insecticide

resistance in concomitant pests and of disrupting the natural enemy complex. Traits that reduce thrips abundance in

cotton are poorly understood, but dense leaf hairs and high gossypol content are implicated to negatively affect thrips.

Furthermore, some diploid cottons are resistant against thrips. Thrips abundance and damage on a range of Gossypium

(Malvaceae) genotypes including hairy leaf, smooth leaf (glabrous), okra leaf shape, and diploid species was evaluated

over four crop seasons. Thrips were significantly less abundant and they caused less damage on diploid cotton

genotypes from Gossypium arboreum L. (BM13H, Roseum A256), Gossypium thurberi Tod. (GOS5310), and Gossypium

trilobum (Moc. & Sess. ex DC.) Skov. (GOS5332) than on the standard commercial Gossypium hirsutum L. cv. Sicot 71.

There was no significant relationship between thrips abundance or damage and leaf hairiness, leaf hardness, or leaf

shape, though conclusions about the value of these traits must be made cautiously as they are confounded across

genotypes that differ in a range of traits simultaneously. The diploid cottons had a lower damage per thrips ratio,

indicating that they are more tolerant of thrips feeding damage and thus could be valuable sources of host plant

resistance to thrips.

Manju, K. P., Giraddi, R. S., Mantur, S. M., & Kamanna, B. C. (2016). Role of Biorationals in Management of Thrips (Thrips Tabaci

(Linderman) on Carnation.

Studies on efficacy of biorationals against carnation thrips were conducted during 2013 in an naturally ventilated

polyhouse at Hi-tech horticulture unit, Saidapur Farm, MARS, UAS, Dharwad. L. lecanii @ 2 g/l emerged as the best

treatment by providing the highest percent protection over control followed by B. bassiana @ 2 g/l and NSKE @ 5%.

Lowest per cent protection was shown by P. lilacinus @ 2 g/l. L. lecanii @ 2 g/l recorded maximum yield,highest net

return and cost-benefit ratio followed by NSKE @ 5%.

Nadeem, M., Shah, M. A., & Iqbal, J. (2016). MANAGEMENT OF THRIPS IN MUNGBEAN CROP USING NEEM OIL (AZADIRACHTA

INDICA A. JUSS) AND DIFFERENT INSECTICIDES. Gomal University Journal of Research, 32(1).

A field study to test the comparative efficacy of synthetic insecticides (Confidar 200 SL @ 250 ml acre-1, Mospilan 20 SP

@ 250 ml acre-1, Actara 25 WG @ 48 gm acre-1) and neem oil concentrations (Neem oil 1%, Neem oil 2% and Neem

oil 3%) against thrips in mungbean crop was conducted at Arid Zone Research Institute (AZRI), Bhakkar (Punjab) during

the kharif season 2011. The Experiment was laid out in randomized complete block design (RCBD) with three replicates.

Mospilan 20 SP treated plot comparatively showed least per infloresence population of thrips (5.08) followed but not

significantly different to Actara 25 WG with 5.75 thrips per infloresence. Among neem oil concentrations tested,

although, all the concentrations (1, 2 and 3%) showed comparatively low per infloresence population of thrips than

control plot but neem oil 3% showed comparatively least per infloresence population of thrips (10.83). In case of

percent population reduction of thrips over control, maximum population reduction of thrips (65.06%) was found in

plots treated with Mospilan 20 SP followed but not significantly different to Actara 25 WG treated plot with 60.57%

population reduction of thrips. Among neem oil concentrations tested, neem oil 3% showed comparatively more

population reduction (25.51%) of thrips than other tested concentrations of neem oil.

Nahiyoon, S. A., Bukero, A., Lanjar, A. G., Rajput, L. B., & Qureshi, N. A. (2016). REPORTING VARIETAL PREFERENCE OF THRIPS

THRIPS TABACI LIND ON COTTON. Science International, 28(2).

ABSTRACT: The experiment was carried out at the Nahiyoon Agricultural Farm, village Haji Darya Khan Nahiyoon

Khesana morri District Hyderabad during the kharif cotton growing season during-2014. In this trial five cultivars of

cotton viz., BH-95, MNH-554, MNH-552, RH-400, and IAB-78 were sown in a dibbling method in rows of 10 meters and

each cultivars replicated three times. Observations were taken at 15 days after crop germination by counting the

nymph and adults of thrips on five leaves per plant i.e., two from bottom, two from middle and one leaf from the top of

each plant. The data revealed that thrips attacked all the cotton cultivars from germination till harvesting. The

maximum mean thrips population per plant was recorded RH-400 cultivar (6.21), followed by MNH-554 (5.33), MNH-

552 (5.23), BH-95 (5.08) and NIAB-8 (3.80). Among all varieties, NIAB-78 was comparatively more resistant than others.

The RH-400 variety was more susceptible than the others. It is therefore suggested that NIAB-78 variety may be sown

to avoid the attack of thrips on cotton.

10

Nataraja, M. V., Harish, G., Holajjer, P., & Savaliya, S. D. (2016). Efficacy of imidacloprid seed treatment for the control of

leafhoppers and thrips in groundnut. Legume Research: An International Journal, 39(2).

The bio-efficacy of imidacloprid seed treatment against leafhopper and thrips of groundnut was studied during kharif

(23rd to 42nd standard week) and summer (5th to 23rd standard week) cropping seasons of 2010 and 2011. The six

different concentrations viz., 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 g a. i. kg-1 were tested for their bio-efficacy. A

modified sweep net method was followed to record the leafhopper and thrips populations. Seed treatments with

imidacloprid @ 2.0 to 5.0 g a. i. kg-1 were found most effective in reducing the insect population.

However, seed treatment with imidacloprid @ 2.0 g a. i. kg-1 may be included in integrated pest

management (IPM) package for groundnut from environmental safety point.

Natwick, E. T., & Lopez, M. I. (2016). Thrips Control Onion 2014. Arthropod Management Tests, 41(1), tsw029.

https://academic.oup.com/amt/article/41/1/tsw029/2658030/Thrips-Control-Onion-2014

Nault, B. A., & Huseth, A. S. (2016). Evaluating an action threshold-based insecticide program on onion cultivars varying in

resistance to onion thrips (Thysanoptera: Thripidae). Journal of Economic Entomology, tow112.

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a highly destructive pest of onion, Allium cepa L., and

its management relies on multiple applications of foliar insecticides. Development of insecticide resistance is common

in T. tabaci populations, and new strategies are needed to relax existing levels of insecticide use, but still provide

protection against T. tabaci without compromising marketable onion yield. An action threshold-based insecticide

program combined with or without a thrips-resistant onion cultivar was investigated as an improved approach for

managing T. tabaci infestations in commercial onion fields. Regardless of cultivar type, the average number of

insecticide applications needed to manage T. tabaci infestations in the action-threshold based program was 4.3, while

the average number of sprays in the standard weekly program was 7.2 (a 40% reduction). The mean percent reduction

in numbers of applications following the action threshold treatment in the thrips-resistant onion cultivar, ‘Advantage’,

was 46.7% (range 40–50%) compared with the standard program, whereas the percentage reduction in applications in

action threshold treatments in the thrips-susceptible onion cultivar, ‘Santana’, was 34.3% (range 13–50%) compared

with the standard program, suggesting a benefit of the thrips-resistant cultivar. Marketable bulb yields for both

‘Advantage’ and ‘Santana’ in the action threshold-based program were nearly identical to those in the standard

program, indicating that commercially acceptable bulb yields will be generated with fewer insecticide sprays following

an action threshold-based program, saving money, time and benefiting the environment.

Nazemi, A., Khajehali, J., & Van Leeuwen, T. (2016). Incidence and characterization of resistance to pyrethroid and

organophosphorus insecticides in Thrips tabaci (Thysanoptera: Thripidae) in onion fields in Isfahan, Iran. Pesticide biochemistry

and physiology, 129, 28-35.

Onion thrips, Thrips tabaci Lindeman, is the main pest of onion-growing fields in Isfahan and is mainly controlled by

frequently spraying several insecticides. To investigate the resistance status and mechanisms, the susceptibility of ten

field populations collected from Isfahan onion-growing regions were tested to several currently used pesticides.

Resistance to the tested insecticides was observed in most populations when compared with the susceptible reference

population. Enhanced detoxification, implicated by the use of inhibitors of major metabolic detoxification enzymes, was

observed in the populations resistant to profenofos and chlorpyrifos. In the deltamethrin resistant populations, the

amino acid substitution T929I was detected in the voltage gated sodium channel, which is known to confer pyrethroid

resistance. These data are a first step towards more efficient resistance management tactics through early detection of

resistant onion thrips in Iran.

Panse, R. K., Sasode, D. S., Rajak, S. K., Sharma, S., Verma, N., & Mandloi, R. (2016). Development and Evaluation of Pest

Management Modules against Thrips tabaci (Lindeman) in Onion. Ecological Perspectives, 832.

Introduction: Productivity of onion (Allium cepa L.) is affected by many insect pests namely thrips (Thrips tabaci L.),

cutworm (Spodoptera litura F.), head borer (Helicoverpa armigera Hub.) and onion fly (Delia sp. L.), of which onion

thrips is one of the most important pests. Adult thrips migrate from exiting onion field to neighboring newly sown

onion crop. Therefore, barrier the adult thrips to reach onion crop may be greatly helpful in reducing the initial pest

load and subsequent multiplication of pest (Srinivas and Lawande, 2006). Keeping these points in view, four pest



11

management modules were evaluated against thrips in onion crop. Materials and Methods: The field trial was

conducted at College of Agriculture Jabalpur. Four pests management modules) outer row of Zea mays and 2 inner row

of Triticum aestivum (M1) chemical based module consist of 1st spray monocrotophos 36 SL, 0.04%, 2nd spray

profenofos 0 EC, 0.2%, 3rd spray lambda-cyhalothrin 25 EC, 0.2% (M2) botanical and consist of 1st spray Neem oil 1%,

2nd spray karanj oil 1% (M3) and iv) control (M4) against thrips. Five plants were randomly tagged for counting of

thrips at one day prior, 5, 10 and 14 days after each spray. Results and Discussion: The thrips population was recorded

lowest in M2 module and highest in M4 module during both the year of studies after 5, 10 and 14 days after spray,

which may be due to the fact that monocrotophos, 36 SL, 0.04%, profenofos 50 EC, 0.2% and lambda-cyhelothrin 25 EC,

0.02%, has long lasting protection period and high insecticidal potency than the others. Sollam & Hosseny (2003)

reported that profenofos gave significantly better control of thrips. Malik et al. (2003) observed monocrotophos 40 SL

was superior for effective control of Thrips tabaci in onion. The barrier crop of maize and wheat effectively blocked the

mean nymphs and adults thrips by 13.60/plant at 10 days after spray in comparison to control (28.85 thrips/plant at 10

days after spray). Similarly, Srinivas and Lawande (2006) reported maize barrier as cultural method for management of

thrips in onion. The perusal of data (Table 1) revealed that minimum pooled damage rating 2.33 was recorded in Pest

management module M2.

Pappu, H. R., & Rauf, A. (2016). First report of Iris yellow spot virus infecting green onion in Indonesia. Plant Disease, 100(12),

2539-2539.

Green onion (Allium fistulosum L.) is an important vegetable crop for small-holder farmers for domestic consumption in

Indonesia. Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) transmitted by Thrips tabaci is an

economically important viral pathogen of bulb and seed onion crops in many onion-growing areas of the world (1,3). In

Asia, IYSV has been reported in India and Sri Lanka (2,4). In April 2013, symptoms suspected to be caused by IYSV were

observed on a 1-month-old green onion crop grown for their leaves in a farmer's field in Cipendawa, Pacet, Cianjur

District, West Java. Symptoms consisted of elliptical to spindle-shaped, straw colored, irregular, chlorotic lesions with

occasional green islands on the leaves. Approximately 25% of the field had plants with these symptoms. The presence

of the virus was confirmed with an IYSV-specific Agdia Flash kit. IYSV infection was confirmed by RT-PCR with primers

specific to the nucleoprotein (N) gene of IYSV. Primers 465c: 5′-AGCAAAGTGAGAGGACCACC-3′ and IYSV-239f: 5′

TGAGCCCCAATCAAGACG3′ (3) were used as forward and reverse primers, respectively, using total nucleic acids eluted

from FTA cards that were previously coated with freshly prepared sap extracts from field samples. Amplicons of

approximately 240 bp were obtained from four symptomatic plants tested but not from healthy and water controls. The

amplicons were cloned and sequenced. Consensus sequence was derived from three clones. Comparison with IYSV N

gene sequences available in GenBank showed sequence identity of 95 to 99% confirming the identity of the virus as

IYSV. To our knowledge, this is the first report of IYSV infecting onion in Indonesia. The finding in Java underscores the

need for conducting surveys in Java as well as other onion-growing regions of Indonesia to gain a better understanding

of its incidence, distribution, and potential impact.

Patel, M. L., Patel, R. K., Sheth, D. B., & Patel, P. R. (2016). Influence of Abiotic Factors on Population Dynamics of Sucking Insect

Pests in Transgenic Cotton. Advances in Life Sciences, 5(5), 1871-1875.

A field experiment was conducted to investigate the impact of abiotic factors on population dynamics of sucking insect

pests in transgenic cotton cv. RCH138 Bt viz., aphid (Aphis gossypii Glover), jassid (Amrasca biguttula biguttula Ishida),

whitefly (Bemisia tabaci Gennadius), thrips (Thrips tabaci Lindeman) and mealybug (Phenaccocus solenopsis Tinsley)

under unprotected condition. The results of the field study revealed that the sucking pest population was found

throughout the year from first fortnight of August to end of January. The peak population of aphid, jassid, whitefly,

thrips and mealybug were 4.38, 4.39, 3.98, 1.53 and 4 grade infestation in 50th, 37th, 46th, 40th and 41st-42nd standard

week, respectively. Correlation analysis with the weather parameters viz., temperature, relative humidity, wind velocity,

sunshine hours and rainfall revealed that maximum temperature showed significant positive effect on all the sucking

insect pests. The minimum temperature showed negative effect on aphid population and non significant effect on

whitefly and thrips population. The relative humidity has non-significant effect, whereas precipitation has negative

effect on all the sucking pests.



12

Patil, V. V., Kabre, G. B., Dixit, S. S., & Desale, S. B. (2016). Evaluation of entomophathogenic fungi against onion thrips, Thrips

tabaci (Lindeman). International Journal of Plant Protection, 9(1), 168-171.

Different entophathogenic fungi were evaluated in field trials at the instructional farm of Agril. Entomology Section,

College of Agriculture, Dhule for the management of Onion thrips (Thrips tabaci L.) in onion during late Kharif season

of 2014-15. All the treatments were observed to be effective in reducing thrips infestation on onion crop. Among the

evaluated insecticide and biopesticides the treatment with profenophos 50 EC was recorded significantly lowest thrips

population and was at par with Metarhizium anisopliae 7.5 g. The next best treatments in order of their efficacy was

Verticillium lecanii 7.5 g, Metarhizium anisopliae 5 g, Metarhizium anisopliae 2.5 g and Verticillium lecanii 5 g,

respectively. This was followed by Verticillium lecanii 2.5 g, Beauveria bassiana 7.5 g, Beauveria bassiana 5 g and

Beauveria bassiana 2.5 g and were found effective to control onion thrips.

Pobożniak, M., Leśniak, M., Chuda, A., & Adamus, A. (2016). Field assessment of the susceptibility of onion cultivars to thrips

attack–preliminary results. Polish Journal of Entomology, 85(1), 121-133.

Field experiments on the susceptibility of onion to thrips infestation were carried out in 2012 and 2013. The

investigation used 18 cultivars and 5 breeding lines of Allium cepa, and the species A. fistulosum and A. roylei. In 2012

A. fistulosum was one of the most infested plants, whereas in 2013 infestation was no more than average. The most

infested cultivars of A. cepa were ‘Efekt’, ‘Alonso F1’, ‘Alibaba’ and ‘Wama’ and the ‘NOE5’ breeding line. In 2012 the

extent of damage ranged from 12 to 55%, in 2013 from 20 to 30%. The ‘NOE2’, ‘NOE3’ and ‘Wama’ cultivars were the

most seriously damaged by thrips. Leaf damage to A. fistulosum was minimal. No damage was caused to the wild

species A. roylei by feeding onion thrips.

Rahmani, H., Hoseini, M., Saboori, A., & Walzer, A. (2016). Prey preference of the predatory mite Neoseiulus californicus

(Mesostigmata: Phytoseiidae) when offered two major pest species, the two spotted spider mite and the onion thrips.

International Journal of Acarology, 42(6), 319-323.

Two prominent pest species, the Onion thrips, Thrips tabaci Lindeman and the two-spotted spider mite Tetranychus

urticae Koch frequently co-occur in greenhouse crops. The generalist predator, Neoseiulus californicus (McGregor), is

able to prey on both pest species; however, the presence of both T. tabaci and T. urticae may result in a preference of

one prey species releasing the other prey species from predation. Thus, N. californicus protonmyphs, deutonymphs and

females were simultaneously offered 1st T. tabaci instar larvae and different T. urticae developmental stages (larvae,

protonymphs, deutonymphs, and adult females) to evaluate the prey preference and prey consumption rates of N.

californicus and the body size ratios of predator and prey. Neoseiulus californicus preferred to prey on T. urticae

immatures. In contrast, all N. californicus developmental stages switched from T. urticae to T. tabaci, when T. urticae

females were present, although T. urticae females were smaller than 1st T. tabaci instar larvae. Our results showed that

N. californicus predators mainly prefer T. urticae as prey and consumptive effects of N. californicus on T. tabaci in the

presence of T. urticae should be very low.

Rezaie, M., & Javan Nezhad, R. (2016). Influence of diet on life table and population growth parameters of predatory mite

Neoseiulus barkeri (Hughes)(Acari: Phytoseiidae). International Research Journal of Applied and Basic Science, 10(5), 467-472.

ABSTRACT: The predatory mite Neoseiulus barkeri (Hughes) is the most important and wide distributed phytoseiid

mite. This predatory mite fed on plant injurious mite and small insect pests. Neoseiulus barkeri has been collected from

cucumber infested with two-spotted spider mite. Life tables of this predatory mite were studied on onion thrips (Thrips

tabaci Lind (Thysanoptera: Thripidae)), two-spotted spider mite (Tetranychus urticae Koch (Acari: Tetranychidae)) and

corn pollen, first larvae of onion thrips and egg mites were used as prey. This research was investigated in the

13

laboratory by using the mulberry excised leaf method in petri dishes at 2 1 C, 16L: 8D photoperiod and 70-80% RH.

Data were analyzed based on the age-stage, two-sex life table theory. Adult longevity (male) on three diets did

notshow any significant difference, but adult longevity (female) on corn pollen were significantly shorter than those

reared on T. tabaci and T. urticae. Preimaginal developmental time showed a significant difference in the mentuioned

treatments. The lifetime fecundities were 23.58, 48.67 and 26.40 offspring on T. tabaci, T. urticae and corn pollen

respectively. The intrinsic rate of increase (rm) on T. tabaci, T. urticae and corn pollen were 0.162d-1, 0.171d-1and

0.103d-1 respectively and show a significant difference. Net reproduction rate (R0) and Finite rate of increase (λ) on

three diets were not different. The mean generation time on T. tabaci, T. urticae and corn pollen showed a significant

difference. With attention to observed results, N. barkeri is a general predator and can play an important role in the

biological control of T. urticae and T. tabaci. Corn pollen was suitable alternative food for this predator.

Rosales-Escobar, O. E., Terán-Vargas, A. P., Guizar-Guzmán, L., Azuara-Domínguez, A., & Sánchez-Peña, S. R. (2016). Field

Application of the Generalist Entomopathogenic Fungus Metarhizium brunneum1 Did Not Affect Beneficial Orius cf. insidiosus2

on Maize. Southwestern Entomologist.

http://www.bioone.org/doi/abs/10.3958/059.041.0125?journalCode=swen

Rőth, F., Galli, Z., Tóth, M., Fail, J., & Jenser, G. (2016). The hypothesized visual system of Thrips tabaci (Lindeman) and

Frankliniella occidentalis (Pergande) based on different coloured traps’ catches. North-Western Journal of Zoology, 12(1), 40-49.

Thrips tabaci Lindeman and Frankliniella occidentalis (Pergande) are the most studied members of Thysanoptera:

Thripidae, since these thrips species have already become worldwide spread pests causing serious yield losses. Thrips

damage host plants directly through the feeding process and indirectly by transmitting plant viruses. Biological

characteristics of these species make them difficult to manage and prevent the damage they cause. This study is aimed

to find the most attractive colour of the commonly used sticky traps for mass trapping of these two species, and

generate information about the vision system of both specimens by investigating the reflectance spectrum of these

traps. The attractiveness of white, yellow, blue and fluorescent yellow sticky traps for T. tabaci was investigated in a

white cabbage field during summer production. The order of attractiveness of yellow, blue and fluorescent yellow traps

was also investigated for F. occidentalis in a greenhouse during the pollination season of selected cauliflower plants. In

this study number of captured thrips specimens was significantly affected by trap’s colour in open field for T.tabaci

(χ2(3)=14 ,4; p<0,001) and also in the greenhouse for F.occidentalis (χ2(2)=45 ,8; p<0,001). No significant differences

were found between the numbers of the specimens of T. tabaci caught by the yellow (average 36,03 specimens per

trap) and white (average 33,25 specimens per trap) coloured traps (Mean dif. 2,06; SE 3,79; Bonferroni sig. p=1,000),

while the blue colour (average 18,1 specimens per trap) proved to be the least attractive. Fluorescent yellow coloured

traps caught the highest number of the specimens (average 82,88 specimens per trap) of T. tabaci. The highest

numbers of F. occidentalis were also caught with fluorescent yellow sticky traps (average 47,88 specimens per trap),

followed by blue (average 21,67 specimens per trap) and yellow (average 9,29 specimens per trap). Thereby,

fluorescent yellow traps proved to be the most effective in this study for monitoring thrips species both in the field and

in the greenhouse. The light reflectance of the coloured sticky traps used in this study and the petals of cauliflower

flowers were also measured both in the UV and visible light ranges. The proportion of captured thrips specimens of the

two species (T. tabaci and F. occidentalis) and the light reflectance spectrum of the most preferred coloured traps

suggest that these thrips species might have different photoreceptor systems. Results of this study also suggest that

light reflectance in the yellow region and in the UV range has the most important effect on host plant selection of T.

tabaci and F. occidentalis.



14

Sathe, T. V., Pranoti, M., Patil, S. S., & Desai, A. S. (2016). Diversity, Economic Importance And Control Strategies of Thrips

(Thysanoptera) on Crop Plants. Indian Journal of Applied Research, 5(8).

Small, slender and fringe winged Thrips (Thysanoptera) caused damage to economic plants by sucking cell sap and

affecting growth and yield of the crops. A total of 29 species of thrips belonging to 20 genera have been reported

damaging agricultural crops like wheat, paddy, maize, sorghum, pulses, oil seeds, vegetables and forest plants.

Important genera refer to Thrips, Scirtothrips, Caliothrips, Taeniothrips, Anaphothrips, Chloethrips, Haplothrips,

Sorghithrips, Heliothrips, Panchaetothrips, Frankliniella, Dolichothrips, Meghaleurothrips, etc. The thrips were controlled

by spraying the crops with 0.03% Malathion/ Azadirachtin or 0.02%Phosphamidon/ 0.15 Carbaryl

Shichen, H., Xiangguo, L., & Dayong, J. (2016). Occurrence Characteristics and Control of Thrips tabaci in Yanji City. Plant

Diseases & Pests, 7(2).

With the increasing plant area of welsh onion, onion and Chinese onion, the damage of Thrips tabaci in Yanji City is

aggravating day by day. Through preliminary investigation and literature reading, we summarized occurrence status,

morphological characteristics, damage characteristics, occurrence regularity, living habit, outbreak cause and integrated

control technology of T. tabaci in Yanji City, in order to control the hazard of T. tabaci effectively.

Shrirame, P. H., Sawant, C. G., & Patil, R. V. (2016). Effect of Different Spacings and Fertilizer Levels on Incidence of Thrips (Thrips

Tabacilindman) and Whitefly (Bemisia Tabaci) on BT Cotton. BIOINFOLET-A Quarterly Journal of Life Sciences, 13(2b), 375-378.

Field experiments were conducted to study effect of different spacing and fertilizer levels on incidence of sucking pest

viz. Thrips (Thrips tabaci Lindman) and whitefly (Bemisia tabaci) in Bt cotton. Results indicated that the lowest incidence

of Thrips (Thrips tabaci Lindman) was observed in S4 180×30 cm (18518 plants/ha) plant spacing at 30 DAS (3.22). As

regards to the fertilizer levels, lowest incidence of thrips was observed under the influence of F1–120: 60: 60 NPK kg/ha

at 30 DAS (5.85). Lowest incidence of whitefly (Bemisia tabaci) was recorded under the plant spacing of S5 150×30 cm

(22222 plants/ha) plant spacing at 30 DAS (3.54). The effect of fertilizer levels showed that lowest incidence of whitefly

was recorded in F1–120: 60: 60 NPK kg/ha. At 30 DAS (6.62).

Smith, E. (2016). Patterns Of Dispersal Activity Of Onion Thrips, Thrips Tabaci Lindeman, In Onion Ecosystems.

Onion thrips, Thrips tabaci Lindeman, is an important agricultural pest worldwide. T. tabaci damages crops by feeding

on leaves and by transmitting plant pathogens, including Iris yellow spot virus (Bunyaviridae: Tospovirus) (IYSV). T.

tabaci and IYSV are perennial problems for New York's onion industry, and research is needed to improve our

understanding about T. tabaci biology, ecology and IYSV epidemiology for developing better management programs.

This dissertation examines the patterns of T. tabaci dispersal and colonization of onion crops. Clear sticky card traps

and trap-equipped unmanned aerial vehicles (UAVs) were used to monitor the seasonal dispersal patterns of T. tabaci

and IYSV. Most T. tabaci were captured below 2 m, while an average of 4% were captured above 2 m. Viruliferous T.

tabaci were captured with both card traps and UAVs, and proportions increased through the growing season each year.

T. tabaci dispersal activity below 6 m was observed to effectively cease at nightfall, while highest densities were

observed during the evening crepuscular period. T. tabaci dispersal activity and temperature tended to be positively

correlated, while negative correlations were observed with wind speed. Commercial onion fields were sampled in three

onion growing regions to identify the effect of adjacent habitat on patterns of T. tabaci colonization of onion fields.

Early-season densities of adult T. tabaci were not affected by adjacent habitat in 7 of 9 cases, while edge effects were

observed in 4 of 9 cases. Late-season densities were greater in onion fields adjacent to senescing onion fields, and

densities in these fields were observed to decrease with increasing distance into the onion fields. These results strongly

suggest that T. tabaci engage in both short- and longrange dispersal during the onion growing season, and that late-

season dispersal likely contributes to the spread of IYSV. Abiotic factors such as daylight, diel cycle, temperature, wind



15

speed and atmospheric pressure determine when T. tabaci flight is likely to occur. Early-season colonization of onion

fields occurs relatively uniformly in onion crops, while senescing crops are likely the source of adult T. tabaci colonizing

adjacent, non-senescing fields late in the season, prior to harvest.

Smith, E. A., Shields, E. J., & Nault, B. A. (2016). Impact of Abiotic Factors on Onion Thrips (Thysanoptera: Thripidae) Aerial

Dispersal in an Onion Ecosystem. Environmental Entomology, nvw089.

Onion thrips, Thrips tabaci Lindeman, is a significant pest of onion crops worldwide, but little is known about its

patterns of aerial dispersal in the context of abiotic environmental factors. Thrips tabaci adults were passively collected

from the air column above onion fields in western New York using clear sticky cards over a series of sampling periods in

2012, 2013, and 2014 while on-site weather conditions were recorded. Results indicated that T. tabaci adult densities on

aerial traps during daylight averaged 279 times greater per hour than densities on similar traps at night. Adult dispersal

also tended to spike during presunset, indicating that thrips initiated flight diurnally and within 1 h before sunset.

Densities of T. tabaci on aerial traps increased significantly as temperature increased above 17 °C and 90% of the thrips

were captured between 20.8 and 27.7 °C; no thrips were captured above 30.6 °C. Densities of T. tabaci on aerial traps

decreased significantly as wind speed increased, with no thrips captured at winds exceeding 3.8 m/s (13.7 kph). In 2013

and 2014, T. tabaci densities on aerial traps prior to the passage of a cold front (relatively high atmospheric pressure

and temperature with low wind speed) were significantly greater than densities after passage of the front, suggesting

that T. tabaci disperses on synoptic weather systems.

Subba, B., & SK, G. (2016). Population Dynamics of Thrips (Thrips Tabaci L.) Infesting Tomato (Lycopersicon Esculentum (L.) and

Their Sustainable Management.

Population dynamics of thrips (Thrips tabaci L.) in relation to abiotic factors and its botanical management in tomato

was assessed by Randomized Block Design for two consecutive seasons (2011-2013) at Uttar Banga Krishi

Viswavidhyalaya, Pundibari, Cooch Behar, West Bengal. Minimum number of thrips (0.42-53/leaf) population was

recorded during 38th to 44th standard week and maximum level of population was observed during 45th to 2nd (1.05-

1.89/leaf) and again during 6th to 20th (1.00-2.22/leaf) standard week. Correlation coefficient values worked out for

thrips incidence and weather parameters revealed that temperature difference had significant positive influence on

thrips while significant negative correlation with temperature (minimum and average), relative humidity (minimum,

average) and weekly total rainfall. In case of maximum relative humidity and maximum temperature non significant

negative influence was observed. The efficacy of botanicals extract and synthetic insecticides viz., tobacco 7.5%(75ml/L),

garlic 5%(50ml/L), Polygonum 5%(50ml/L), Spilanthes 5%(50ml/L), neem spilanthes (1.5ml 40ml/L), neem pesticide

(2.5ml/L), acetamiprid (1g/3L) were evaluated for the control of thrips. Result show that acetamiprid was most

efficacious against thrips providing 84.15% suppression. However neem Spilanthes gave satisfactory result provoding

72.27% suppression. The individual mean percent suppression of neem pesticides, extract of Spilanthes, Polygonum,

tobacco, garlic were 60.73%, 53.21%, 50.70% and 42.10%, and 41.52% respectively. The lowest yield was recorded from

control plots i.e. 18.32 t/ha and highest yield, 30.15 t/ha were recorded from acetamiprid treated plot followed by neem

Spilanthes (27.55 t/ha), Spilanthes (26.67 t/ha) and Polygonum (26.32 t/ha) which are significantly different from yield of

other treated plots. Other than control plots the lowest yield were recorded from garlic treated (23.11 t/ha) plots closely

followed by tobacco extract (24.02 t/ha) treated plots.

Wagh, K. D., Pawar, S. A., Datkhile, R. V., & Bhalekar, M. N. (2016). Management of Onion Thrips (Thrips Tabaci L.) Through Newer

Insecticides. BIOINFOLET-A Quarterly Journal of Life Sciences, 13(2a), 282-285.

Evaluation of insecticides against onion thrips [Thrips tabaci Lindeman (Thysanoptera: Thripidae)] revealed that

treatment with fipronil @ 0.0075% was most effective as it recorded least (4.00–6.00 thrips/plant) and maximum (25.67



16

t/ha) yield of onion bulbs, followed by spinosad @ 0.018%, acetamiprid @ 0.005% and clothianidin @ 0.0075%, among

different insecticides tested. The treatments with carbosulfan @ 0.025%, thiamethoxam @ 0.0075% and lambda

cyhalothrin @ 0.005% were equally effective and recorded less number of thrips and good yields.

Waqar, M. Q. (2016). Efficacy of Different Insecticides against Cotton Thrips (Thrips Tabaci Lind.)(Thripidae: Thysonoptera) in

Ecological Zone of Bahawalnagar. International Journal, 15.

A field experiment was conducted during summer seasons 2014 and 2015 to determine the efficacy of different

insecticides against cotton thrips (Thrips tabaci) at farmer’s field of Adaptive Research station Bahawalnagar. Six

different insecticides Spinosad 240SC @100ml/ha, Acephate 75SP@875g/ha, Dimethoate 40EC @1000ml/ha,

Chlorpenpyre 360GL @250ml/ha, Spintoram 120SC @150ml/ha and Acetamaprid 20SP @375g/ha were evaluated in a

three replicated RCBD method including an unchecked. Before application of insecticides, the pre treatment

observations were taken on thrips, while post treatment observations were taken after 24, 72 and 168 hours of

application of insecticides. However, Spinosad 240SC (87%) showed its effectiveness up to 7th day of the spray during

both years. The mortality percentage of thrips on cotton was observed in case of Spintoram 120SC (83%) and

Dimethoate 40EC (75%). This attained its effectiveness up to 7th day after application. Least controlled was observed

when applied Acetamaprid 20SP (47%) during both years 2014-15.

Yeturu, S. P. (2016). First report of Iris yellow spot virus infecting onion in the Pichincha and Tungurahua provinces of Ecuador.

Onion (Allium cepa) is one of the most important vegetable crops and is widely cultivated throughout the world. In

Ecuador onion is grown on an area of 16,000 ha with a production of 103,316 tonnes (Ministerio de Agricultura,

Ganadería, Acuacultura y Pesca, 2012). Iris yellow spot virus (IYSV) was first reported in Idaho, United States of America

in 1993 and has since spread to many other onion-producing areas in the world (Gent et al., 2006). IYSV is an emerging

virus and belongs to the family Bunyaviridae, genus Tospovirus. IYSV infects monocotyledonous and dicotyledonous

plants (Kritzman et al., 2000) and can be transmitted by mechanical inoculation and by Thrips tabaci in a persistent

manner (Cortêz et al., 1998). During April 2015, straw-coloured, irregularly shaped, chlorotic or necrotic lesions on

leaves were observed (Fig. 1) in two onion fields, one in the province of Pichincha and the other in Tungurahua in

Ecuador. The disease incidence observed in both fields was 10-15% and plants were heavily infested with thrips. Based

on symptomatology, a tospovirus infection was suspected.

저작권, 안내, 해외, 등재, & 카드큐. (2016). A Key to Four Thrips (Thysanoptera: Thripidae) of Agricultural Importance in Korea.

Morphological features of four species of thrips (Thysanoptera: Thripidae) of agricultural importance in Korea are

investigated and examined. Detailed descriptions of each species are provided with photographs. Four species of thrips

collected from agricultural fields are included: Frankliniella intonsa, Frankliniella occidentalis, Thrips palmi, and Thrips

tabaci. The genera Frankliniella Karny and Thrips Linnaeus can be distinguished by number of antennal segments (8-

segmented vs. 7-segmented), number of setae on pronotum (5 pairs vs. 2 pairs), and veinal setae of front wing

(complete vs. incomplete).


Aizawa, M., T. Watanabe and K. Yamamura (2015). "Estimation of the Dispersal Distance of the Onion Thrips, Thrips tabaci Using

Traps." Japanese Journal of Applied Entomology and Zoology 59(1): 31-40.

We investigated the dispersal distance of the onion thrips, Thrips tabaci Lindeman, using traps. In a greenhouse,

fourteen hours after releasing thrips, we found insects at sticky traps up to 54m from the release point. The estimated



17

mean dispersal distance (+/- SE) was 7.4 +/- 0.25m at thirty-nine hours after releasing thrips. In a field, forty-eight

hours after releasing thrips applied with the fluorescent brightening agent, we found insects at traps up to 119m from

the release point. The estimated mean dispersal distance (+/- SE) was 66.6 +/- 10.7m.

Bag, S., Schwartz, H. F., Cramer, C. S., Havey, M. J., & Pappu, H. R. (2015). Iris yellow spot virus (Tospovirus: Bunyaviridae): from

obscurity to research priority. Molecular plant pathology, 16(3), 224-237.

Taxonomy: Iris yellow spot virus (IYSV) is in the genus Tospovirus, family Bunyaviridae, with a single-stranded, tri-

segmented RNA genome with an ambisense genome organization. Members of the other genera in the family infect

predominantly vertebrates and insects. Geographical distribution: IYSV is present in most Allium-growing regions of the

world. Physical properties: Virions are pleomorphic particles of 80–120 nm in size. The particle consists of RNA, protein,

glycoprotein and lipids. Genome: IYSV shares the genomic features of other tospoviruses: a segmented RNA genome of

three RNAs, referred to as large (L), medium (M) and small (S). The L RNA codes for the RNA-dependent RNA

polymerase (RdRp) in negative sense. The M RNA uses an ambisense coding strategy and codes for the precursor for

the GN/GC glycoprotein in the viral complementary (vc) sense and a non-structural protein (NSm) in the viral (v) sense.

The S RNA also uses an ambisense coding strategy with the coat protein (N) in vc sense and a non-structural protein

(NSs) in the v sense. Transmission: The virus is transmitted by Thrips tabaci Lindeman (Order: Thysanoptera; Family:

Thripidae; onion thrips) and with less efficiency by Frankliniella fusca Hinds (tobacco thrips). Host: IYSV has a relatively

broad host range, including cultivated and wild onions, garlic, chives, leeks and several ornamentals. Some weeds are

naturally infected by IYSV and may serve as alternative hosts for the virus. Symptoms: IYSV symptoms in Allium spp. are

yellow- to straw-coloured, diamond-shaped lesions on leaves and flowering scapes. Diamond-shaped lesions are

particularly pronounced on scapes. As the disease progresses, the lesions coalesce, leading to lodging of the scapes. In

seed crops, this could lead to a reduction in yield and quality. Early to mid-season infection in bulb crops results in

reduced vigour and bulb size. Control: Resistant varieties are not available, but a limited number of accessions with field

tolerance have been identified. Integrated disease management tactics, including sanitation, crop rotation, thrips

management, maintenance of optimal plant vigour, soil fertility, irrigation and physical separation of bulb and seed

crops, can mitigate the effect of the disease. Virus code: 00.011.0.85.009

Bharani, G. N., Kohilambal, H., Sivasubramanian, P., & Banuprathap, G. (2015). Comparative efficacy of biopesticides and

insecticides against tomato thrips (Thrips tabaci Lind.) and their impact on coccinellid predators. The Bioscan, 10(1), 207-210.

Field studies were carried out to evaluate efficacy of biopesticides viz., Beauveria bassiana (2.5 kg ha-1) and Verticillium

lecani (2.5 kg ha-1) and novel insecticides viz., Imidacloprid 30.5 SC (100mL ha-1) and Thiomithoxam25 WG (75g.a.i. ha-

1) against the thrips, Thrips tabaci Lind. and predatory coccinellids in tomato ecosystem.Significantly lowest thrips

population was recorded in insecticidal treatments Imidacloprid 30.5 SC +Thiomithoxam 25 WG (1.15 nymphs plant-1)

followed by Thiomithoxam 25 WG (1.35 nymphs plant-1) andImidacloprid 30.5 SC (1.37 nymphs plant-1) compared to

bio pesticides Beauveria bassiana + Verticillium lecani(2.01 nymphs plant-1) followed by Beauveria bassiana, Verticillium

lecani (2.12 and 2.33 nymphs plant-1respectively) compared to control treatment recorded 6.27 nymphs plant-1.

Against coccinellids bio pesticide treatments Beauveria bassiana, Verticillium lecani (3.26 and 3.12 coccinellids plant

respectively) were found safer following insecticides Imidacloprid 30.5 SC and Thiomithoxam 25 WG (2.64, 2.79

coccinellids plant respectively) showed lower toxic compared to control treatment (3.53 coccinellids plant) in tomato

ecosystem. The use of bio pesticides and neonicotinoids can be used in compatible manner in future IPM programmes

for controlling thrips and reducing effect on natural enemies.

Blatt, S., A. Ryan, S. Adams and J. Driscoll (2015). "Onion thrips (Thrips tabaci (Thysanoptera: Thripidae)) in cabbage on Prince

Edward Island: observations on planting date and variety choice." Springerplus 4.

Onion thrips (Thrips tabaci Lindeman (Thysanoptera: Thripidae)) can be a pest in organic onion production on Prince

Edward Island. This study was to examine the effect of planting time and variety on infestation levels and damage by

onion thrips on cabbage (Brassicae oleracea capitala (L.)). A field site was planted with 2 main and 8 lesser varieties of

cabbage over 4 planting dates. Some varieties were short season and harvested on July 31 with longer season varieties

harvested on September 2. Blue sticky traps were used to capture thrips migrating into the field site from July 22-

September 2. Traps were counted weekly and cabbage heads within the field site were visually surveyed for thrips. At

harvest, heads were weighed and measured, thrips damage was assessed then the head was dissected and thrips



18

counted on the first four layers of the head. Thrips exhibited a preference for Lennox over Bronco throughout the

season although thrips populations were not high enough to effect economic damage in 2014. Planting date influenced

cabbage head weight and size with later plantings yielding the largest heads. Use of planting date and variety to avoid

thrips populations is discussed.

Chitturi, A., D. Riley, C. Nischwitz, R. Gitaitis and R. Srinivasan (2015). "Thrips Settling, Oviposition and IYSV Distribution on Onion

Foliage." Journal of Economic Entomology 108(3): 1164-1175.

Thrips tabaci Lindeman (Thysanoptera: Thripidae) adult and larval settling and oviposition on onion (Allium cepa L.)

foliage were investigated in relation to leaf position and leaf length at prebulb plant growth stages under controlled

conditions. In the laboratory, four and six adult females of T. tabaci were released on onion plants at three-leaf stage

and six- to eight-leaf stage, respectively, and thrips egg, nymph, and adult count data were collected on each of the

three inner most leaves at every 2-cm leaf segment. Thrips settling and oviposition parameters were quantified during

the light period on the above ground portion of onion plants from the distal end of the bulb or leaf sheath "neck"

through the tips of the foliage. Results from studies confirmed that distribution of thrips adults, nymphs, and eggs were

skewed toward the base of the plant. The settling distributions of thrips adults and nymphs differed slightly from the

egg distribution in that oviposition occurred all the way to the tip of the leaf while adults and nymphs were typically

not observed near the tip. In a field study, the foliage was divided into three equal partitions, i.e., top, middle, basal

thirds, and thrips adults by species, primarily Frankliniella fusca (Hinds) and T. tabaci, were collected from each partition

to determine if there was a similar bias of all adult thrips toward the base of the plant. The results suggested that adults

of different species appear to segregate along leaf length. Finally, thrips oviposition on 2-cm segments and Iris yellow

spot virus positive leaf segments were quantified in the field, irrespective of thrips species. Both variables demonstrated

a very similar pattern of bias toward the base of the plant and were significantly correlated.

Fekrat, L., M. Z. Aghl and V. Tahan (2015). "Application of the LAMP Assay as a Diagnostic Technique for Rapid Identification of

Thrips tabaci (Thysanoptera: Thripidae)." Journal of Economic Entomology 108(3): 1337-1343.

Rapid and accurate identification of potentially invasive taxa that may cause high economic losses or environmental

damage is of critical importance. The onion thrips, Thrips tabaci Lindeman, ranks as one of the world's most destructive

agricultural pests and commonly found in imported agricultural products and field samples, but is prone to undetected

transport because of its minute size as well as cryptic behavior. Although traditional taxonomic methods are pretty

useful in straightforward assignment of specimens to the genus Thrips, identification in the species level is much more

difficult and requires expertise, knowledge, and experience. Furthermore, it is often difficult or impossible to identify or

distinguish this species from other thrips by using material from other stages of development. Based on the foregoings,

use of a molecular technique known as loop-mediated isothermal amplification (LAMP) as a rapid and robust

alternative species diagnostic tool would be valuable. In this study, a relatively quick and simple method was used to

detect the presence of onion thrips DNA rapidly and discriminate it from other species, by using material from different

stages of development. Not only LAMP itself required less than 1 h to complete but also amounts of DNA as little as

that recovered from a single specimen were adequate for the detection. Another advantage of this identification system

is that nonspecialists will be able to make faster and cheaper identifications.

Fuji, S., Zen, S., Sato, I., Kishi, H., Furuya, H., & Okuda, M. (2015). Population dynamics of iris yellow spot virus in onion fields and

lisianthus greenhouses in Japan. Plant Pathology, 64(4), 808-816.

Iris yellow spot virus (IYSV, genus Tospovirus) mainly occurs on onion and lisianthus plants (Eustoma grandiflorum) in

Japan. The virus is genetically diverse and is classified based on its nucleocapsid protein sequence into two genotypes,

IYSVNL (NL) and IYSVBR (BR), first isolated in the Netherlands and Brazil, respectively. Both genotypes are present in

Japan, and they are sometimes found in the same field. Furthermore, the two genotypes are occasionally detected in a

single necrotic lesion of an infected plant (designated as a ‘mosaic’ genotype). In this study, the population structures

of these two genotypes and their dynamics in onion fields and lisianthus greenhouses from 2004 to 2006 were analysed

using reverse transcription-PCR-restriction length polymorphism analysis (RT-PCR-RFLP). In onion fields the two

genotypes were detected in all three years, and the BR genotype predominated within a year. On the other hand, both

genotypes were detected at the first outbreak each year in almost all lisianthus greenhouses; however, the BR genotype

was more widespread than the NL genotype. These results suggest that the incidence of IYSV disease in lisianthus



19

during each year was triggered by the invasion of viruliferous Thrips tabaci that have acquired one or both genotypes

from nearby onion fields. Although the BR genotype predominated in the last stages of cultivation, IYSV disease might

be expanded by monocyclic patterns but may occasionally spread secondarily in lisianthus greenhouses.

Gill, H. K., Garg, H., Gill, A. K., Gillett-Kaufman, J. L., & Nault, B. A. (2015). Onion thrips (Thysanoptera: Thripidae) biology, ecology,

and management in onion production systems. Journal of Integrated Pest Management, 6(1), 6.

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a well-known onion pest worldwide. Onion thrips

cause both direct and indirect damage to onion by feeding and ovipositing on leaves that may cause green onions

(scallions) to be unmarketable and dry bulb onion size to be reduced. Onion thrips can also transmit several plant

pathogens that reduce onion bulb size and quality. One of the most economically damaging onion pathogens

transmitted by onion thrips is Iris yellow spot virus (Bunyaviridae: Tospovirus). In this article, we discuss onion thrips

geographical distribution, host range, biology, damage, monitoring, economic thresholds, and management in onion

production.

Gupta, M., & Kumar, V. (2015). Effect of Some Species of Thrips, Thysanoptera: Thripidae on Chilli Crop of District Aligarh. Nature

& Environment, 20(2), 59-60.

A biological monitoring survey was carried out of Western Uttar Pradesh in district Aligarh on favorable growing season

to provide information on infestation and abundance of thrips species on the crop of chilli Capsicum annuum. A total of

five localities participated in our study. These localities are Tappal, Jalalli, Talib Nagar, Sumera and Kayamganj. Data was

collected from these localities on the basis of infestation level caused by thrips populations. Results indicated that a

total of four thrips species present such as; Scirtothrips dorsalis, Thrips tabaci, Frankiniella occidentalis and Frankniella

schultzei in those regions. The majority of the thrips species were recorded in the young stages (leaves, flowers and

fruits) of crop development appears young ball formation, necrosis of tissues, wilted growth of flowers and fruits and

finally yields loss.

Hurej, M., Kucharczyk, H., Twardowski, J. P., & Kotecki, A. (2015). Thrips (Thysanoptera) associated with two morphological forms

of Andean lupin (Lupinus mutabilis). Biologia, 70(7), 935-942.

The aim of this study was to determine thrips abundance, species composition, sex ratio and seasonal dynamics of

these insects on two morphological forms of Andean lupin (epigonal and semiepigonal). Thrips were studied in the

lupine plants sown at two dates at the Experimental Research Station at Pawłowice, near Wrocław, Lower Silesia,

Poland, during two growing seasons (2011-2012). The experiment was designed as a split-plot with four replicates for

each morphological form and time of sowing. For the determination of thrips species’ composition, plants were

collected from the central part of each plot when lupin was at the full blooming stage. In the laboratory, plants were

shaken over a sheet of white paper. Once in each season thrips were also collected with a sweep net. In the laboratory

larvae and adults were identified to species level and separated into males and females. During the whole lupin

growing season, insects were also counted weekly on 10 consecutive plants in the middle row of each plot. Frankliniella

intonsa, Thrips major and Aeolothrips intermedius were the dominant species in the full blooming stage of both

semiepigonal and epigonal forms of Andean lupin. Thrips tabaci also occurred in greater numbers. There were no

significant differences between numbers of thrips and number of species occurring on semiepigonal and epigonal

plants sown at the same time. In the most numerous species, like F. intonsa and T. major, mainly females occurred in

their population. In the population of A. intermedius males were abundant. Thrips occurring in Lupinus mutabilis,

irrespective of the used form of lupin or sowing time, had one peak of abundance, i.e., the last ten days of June and the

first ten days of July, when plants were at the blooming stage.

Iqbal, J., Ali, H., Hassan, M. W., & Jamil, M. (2015). Evaluation of indigenous plant extracts against sucking insect pests of okra

crop. Pakistan Entomologist, 37(1), 39-44.

Okra (Abelmoschus esculentus L.) is an important vegetable in Pakistan. Insect pests are the major threat for poor

production of the okra crop. The present study investigated the botanicals as an alternative approach to control

sucking insect pests of okra crop. The plant extracts of eight indigenous plants viz., tumha (Citrullus colosynthis L.),

datura (Datura innoxia M.), neem (Azadirachta indica A.), castor (Ricinus communis L.), hing (Ferula asafetida L.),

eucalyptus (Eucalyptus spp.) bitter gourd (Memordica chrantia L.) and garlic (Allium sativum L.) were tested for their



20

potential insecticidal efficacy against sucking insect pests, jassid (Amrasca bigutulla bigutulla I.), whitefly (Bemisia tabaci

G.) and thrips (Thrips tabaci L.). The mean sucking insect population and fruit damage caused by the chewing borers

was monitored to evaluate the efficacy of targeted plant extracts. It was revealed that, neem followed by garlic

significantly reduce the mean population of jassid (6.31, 6.86), whitefly (7.41, 8.21) and thrips (11.99, 12.43), respectively.

Neem also showed minimum fruit damage percentage (3.38%) followed by garlic (6.67%). The maximum pod yield

(3178.7 kg/ha) was observed in neem treated plots. It was concluded that the plants could be the possible alternate

option in insect pest management program.

Khalil, H., Raza, A. B. M., Afzal, M., Aqueel, M. A., Khalil, M. S., & Mansoor, M. M. (2015). Effects of plant morphology on the

incidence of sucking insect pests complex in few genotypes of cotton. Journal of the Saudi Society of Agricultural Sciences.

The study was conducted to find the role of physico-morphic plant factors viz., number of gossypol glands, hair density,

length of hair, plant height and thickness of leaf lamina per plant in fluctuating the population of thrips (Thrips tabaci

Lind.), jassid (Amrasca bigutella Dist.) and whitefly (Bemisia tabaci Genn.) on six genotypes of cotton viz., BT-703, CIM-

557, CIM-608, CIM-573, BT-3701 and FH-113. All the genotypes showed significant differences against sucking insect

pest population. Whitefly adult population exhibited negative response with gossypol glands on leaf lamina, midrib and

vein and also with plant height. Whitefly adult and nymphal population correlated positively with hair density on leaf

lamina and vein and length of hair on leaf midrib. The nymphal and adult population of jassid showed positive

correlation with gossypol glands on leaf lamina, vein and length of hair on leaf lamina, midrib and vein. Adult and

nymph population of jassid revealed negative response with hair density on leaf lamina and midrib and also with plant

height and leaf lamina thickness. Thrips population showed negative correlation with gossypol glands on leaf midrib,

vein, length of hair on leaf lamina and vein. Thrips population correlated positively with hair density on leaf midrib,

thickness of leaf lamina and plant height. The genotypes CIM-608 (3.70/leaf), CIM-608 (5.67 /leaf), BT-703(0.86/leaf),

BT-703 (1.14/leaf) and FH-113 (0.34/leaf) were found to be susceptible, whereas FH-113 (2.85/leaf), CIM-557 (3.46/leaf),

CIM-573 (0.40/leaf), CIM-557 (0.48/leaf) and BT-703 (0.08/leaf) were resistant to whitefly adult, whitefly nymph, jassid

adult, jassid nymph and thrips population respectively.

Kiraly, K. D., D. Reiter, P. Farkas, A. Sojnoczki and J. Fail (2015). "THE ONION THRIPS (THRIPS TABACI LINDEMAN, 1889) SPECIES

COMPLEX." Novenyvdelem 51(7): 317-324.

The onion thrips (Thrips tabaci Lindeman, 1889) is a major pest of agricultural crops worldwide. Based on recent

studies, onion thrips must be considered as a cryptic (sub)species complex, and the types within the complex differ

from each other in numerous attributes. There are three distinct T tabaci groups: two of them are associated with leek

(L1, L2) and the third with tobacco (T). Although the host range of the types are not precisely known, it is probable that

the L1 and L2 clades are polyphagous groups, while the T type has a narrower host range. Also, the types have different

reproductive modes: the L1 and T forms are arrhenotokous, and the L2 group is thelytokous. It is assumed, that there is

no complete reproductive isolation within the species complex. Every type could transmit TSWV, but the most efficient

vector is likely the T form. There are possible differences between the types in their pesticide resistance as well.

Laamari, M. and S. Houamel (2015). "First observation of Thrips tabaci and Frankliniella occidentalis on greenhouse crops in

Algeria." Bulletin OEPP 45(2): 205-206.

First observation of Thrips tabaci and Frankliniella occidentalis on greenhouse crops in Algeria This study was

conducted in the Biskra region (Southern Algeria) during the crop year 2010/2011 and provides the first observation of

Thrips tabaci and Frankliniella occidentalis (Thysanoptera, Thripidae) on greenhouse crops in Algeria. Tomato is

relatively highly infested compared to chilli and sweet pepper. Population levels of T. tabaci are higher than those of

F.occidentalis on the three crops.

Li, X.-W., J. Fail and A. M. Shelton (2015). "Female multiple matings and male harassment and their effects on fitness of

arrhenotokous Thrips tabaci (Thysanoptera: Thripidae)." Behavioral Ecology and Sociobiology 69(10): 1585-1595.

Although it is generally assumed that one or a few matings are sufficient to maximize female fitness and that mating is

generally assumed to be costly to females, multiple matings of females have been reported across a wide and

taxonomically diverse set of animals. Here, we investigated female mating frequency and male harassment rate in

arrhenotokous Thrips tabaci. In addition, the cost to females of mating, multiple matings, and male harassment to



21

females was evaluated. We found that T. tabaci females mated multiple times during their lifetime and were subjected

to a high rate of male harassment at all the ages we tested. Mating was costly to females in terms of reducing longevity

and delaying the initiation of egg laying, although mating did not affect the survivorship and longevity of males.

Furthermore, continual exposure to males also resulted in a fitness cost to mated females in terms of delayed egg

production and reduced fecundity. Virgin females of arrhenotokous thrips produce only male progeny whereas mated

females of arrhenotokous thrips produce males from unfertilized eggs and females from fertilized eggs. However,

multiple matings did not allow females to fertilize a larger proportion of their eggs to increase the female offspring

ratio. Our study demonstrates the conflicts between the occurrence of multiple matings and the cost of sexual activities.

This raises questions about the evolution of multiple matings and polyandry in this species. Furthermore, these findings

suggest that such phenomena may occur in other animal species and influence the evolution of their mating systems.

Li, X.-W., P. Wang, J. Fail and A. M. Shelton (2015). "Detection of Gene Flow from Sexual to Asexual Lineages in Thrips tabaci

(Thysanoptera: Thripidae)." Plos One 10(9).

Populations of Thrips tabaci are known to have two sympatric but genetically isolated reproductive modes, arrhenotoky

(sexual reproduction) and thelytoky (asexual reproduction). Herein, we report behavioral, ecological and genetic studies

to determine whether there is gene flow between arrhenotokous and thelytokous T. tabaci. We did not detect

significant preference by arrhenotokous males to mate with females of a particular reproductive mode, nor did we

detect significant behavioral differences between arrhenotokous males mated with arrhenotokous or thelytokous

females in their pre-copulation, copulation duration and mating frequency. Productive gene transfer resulting from the

mating between the two modes was experimentally confirmed. Gene transfer from arrhenotokous T. tabaci to

thelytokous T. tabaci was further validated by confirmation of the passage of the arrhenotokous male-originated

nuclear gene (histone H3 gene) allele to the F-2 generation. These behavioral, ecological and genetic studies confirmed

gene transfer from the sexual arrhenotokous mode to the asexual thelytokous mode of T. tabaci in the laboratory.

These results demonstrate that asexual T. tabaci populations may acquire genetic variability from sexual populations,

which could offset the long-term disadvantage of asexual reproduction.

Macharia, I., Backhouse, D., Skilton, R., Ateka, E., Wu, S. B., Njahira, M., ... & Harvey, J. (2015). Diversity of thrips species and

vectors of tomato spotted wilt virus in tomato production systems in Kenya. Journal of economic entomology, 108(1), 20-28.

Thrips have been recognized as primary vectors of tomato spotted wilt virus (TSWV) with Frankliniella occidentalis

(Pergande) reported as the most important and efficient vector, while other species such as Thrips tabaci Lindeman also

include populations that can vector the virus. A study was undertaken to establish the diversity of thrips and presence

of vectors for TSWV in four major tomato production areas in Kenya. The cytochrome oxidase 1 (CO1) gene was used

to generate sequences from thrips samples collected from tomatoes and weeds, and phylogenetic analysis done to

establish the variation within potential vector populations. Ceratothripoides brunneus Bagnall was the predominant

species of thrips in all areas. F. occidentalis and T. tabaci were abundant in Nakuru, Kirinyaga, and Loitokitok but not

detected at Bungoma. Other vectors of tospoviruses identified in low numbers were Frankliniella schultzei (Trybom) and

Scirtothrips dorsalis Hood. Variation was observed in T. tabaci, F. occidentalis, and F. schultzei. Kenyan specimens of T.

tabaci from tomato belonged to the arrhenotokous group, while those of F. occidentalis clustered with the Western

flower thrips G group. The detection of RNA of TSWV in both of these species of thrips supported the role they play as

vectors. The study has demonstrated the high diversity of thrips species in tomato production and the occurrence of

important vectors of TSWV and other tospoviruses.

Macharia, R. W., F. L. Ombura and E. O. Aroko (2015). "Insects' RNA Profiling Reveals Absence of "Hidden Break" in 28S

Ribosomal RNA Molecule of Onion Thrips, Thrips tabaci." Journal of nucleic acids 2015: 965294-965294.

With an exception of aphids, insects' 28S rRNA is thought to harbor a "hidden break" which cleaves under denaturing

conditions to comigrate with 18S rRNA band to exhibit a degraded appearance on native agarose gels. The degraded

appearance confounds determination of RNA integrity in laboratories that rely on gel electrophoresis. To provide

guidelines for RNA profiles, RNA from five major insect orders, namely, Diptera, Hemiptera, Thysanoptera,

Hymenoptera, and Lepidoptera, was compared under denaturing and nondenaturing conditions. This study confirmed

that although present in most of insect's RNA, the "hidden break" is absent in the 28S rRNA of onion thrips, Thrips

tabaci. On the other hand, presence of "hidden break" was depicted in whiteflies' 28S rRNA despite their evolutionary



22

grouping under same order with aphids. Divergence of 28S rRNA sequences confirms variation of both size and

composition of gap region among insect species. However, phylogeny reconstruction does not support speciation as a

possible source of the hidden break in insect's 28S rRNA. In conclusion, we show that RNA from a given insect order

does not conform to a particular banding profile and therefore this approach cannot be reliably used to characterize

newly discovered species.

Martin, N. A. (2015). "Onion thrips, Thrips tabaci (Thysanoptera: Thripidae), overwintering in South Auckland, New Zealand: the

importance of the local bionomic data/temperature model and biosecurity implications." New Zealand Entomologist 38(1): 17-

27.

Onion thrips flights in winter and early spring 1999 were monitored in South Auckland using sticky traps and trap

plants. A pair of yellow sticky traps and 10 'thrips-free' onion pot plants per site were changed every 2 weeks. Thrips

epicuticular waxes, and stomata on the surface of leaves accounted for resistance. For the cultivars BR 29 and Sirius, the

resistance was likely due to the presence of resistance-conferring substances or high amounts of some component in

the chemical composition of plants.

Mortazavi, N., & Aleosfoor, M. (2015). Efficiency of Thrips tabaci and Frankliniella occidentalis populations in transmission of

Tomato yellow ring virus. Zoology and Ecology, 25(3), 241-246.

The Tomato yellow ring virus (TYRV, family Bunyaviridae, genus Tospovirus) was found for the first time in greenhouses

of Shiraz in the southern province of Fars, Iran, in 2007. TYRV, like other tospoviruses, is transmitted by thrips. Many

factors affect the transmission efficiency of thrips-borne viruses such as thrips species or belonging to different

populations. In this study, we evaluated the transmission efficiency of TYRV by different populations of two thrips

species, Frankliniella occidentalis (Pergande) and Thrips tabaci (Lindeman) on different host plants. Transmission

experiments were made setting newly hatched larvae (≤4 h) for acquisition on systemically infected leaves of Petunia

hybrida, Nicotiana tabacum and Lycopersicon esculentum. The capacity of thrips to transmit the virus was assessed by

use of the petunia leaf disc technique. Results by the double antibody sandwich enzyme-linked immunosorbent assay

showed that different populations of both species could transmit this isolate to an indicator plant but in different

efficiency. Compared to F. occidentalis, T. tabaci populations had a higher efficiency of TYRV transmission. Among the

studied plants, tomato was the most susceptible in terms of virus infection. It is worth mentioning that the virus was

more efficiently acquired from tomato by thrips larval stage.

Muvea, A. M., Meyhöfer, R., Maniania, N. K., Poehling, H. M., Ekesi, S., & Subramanian, S. (2015). Behavioral responses of Thrips

tabaci Lindeman to endophyte-inoculated onion plants. Journal of pest science, 88(3), 555-562.

Endophytic fungi colonize healthy plant tissues and can in some cases induce systemic resistance to the host against

biotic and abiotic stresses. In our previous study, Hypocrea lixii isolate F3ST1 was able to colonize onion plants

endophytically and conferred resistance to them against onion thrips, Thrips tabaci. To further elucidate the mechanism

of resistance, we examined the behavioral response of adult and larval stages of T. tabaci to endophyte-inoculated (E+)

and endophyte-free (E−) onion plants/sections. In choice experiments, female T. tabaci preferred E− over E+ plants. The

number of feeding punctures and eggs was more on E− than on E+ plants. Oviposition was reduced sixfold on E+

plants within a 72-h experimental period. In the Y-tube olfactometer assay, thrips showed a 3.3-fold preference for E−

plants. In individual larval choice experiments, significantly more first and second instars were found on the leaf

sections of E− as compared to the E+ plants. In the settlement preference assay with groups of second instars, more

larvae preferred leaf sections from E− over E+ plants with incremental time. Our findings suggest that endophyte-

colonized onion plants may trigger antixenotic repellence of T. tabaci, impacting their biology. This repellence could be

exploited in thrips control programs by using endophyte-inoculated plants in the field.

Nazemi, A., Khajehali, J., & Van Leeuwen, T. (2015). Incidence and characterization of resistance to pyrethroid and

organophosphorus insecticides in Thrips tabaci (Thysanoptera: Thripidae) in onion fields in Isfahan, Iran. Pestic. Biochem. Physiol.

Onion thrips, Thrips tabaci Lindeman, is the main pest of onion-growing fields in Isfahan and is mainly controlled by

frequently spraying several insecticides. To investigate the resistance status and mechanisms, the susceptibility of ten

field populations collected from Isfahan onion-growing regions were tested to several currently used pesticides.

Resistance to the tested insecticides was observed in most populations when compared with the susceptible reference



23

population. Enhanced detoxification, implicated by the use of inhibitors of major metabolic detoxification enzymes, was

observed in the populations resistant to profenofos and chlorpyrifos. In the deltamethrin resistant populations, the

amino acid substitution T929I was detected in the voltage gated sodium channel, which is known to confer pyrethroid

resistance. These data are a first step towards more efficient resistance management tactics through early detection of

resistant onion thrips in Iran.

Palomo, L. A. T., Martinez, N. B., Johansen-Naime, R., Napoles, J. R., Leon, O. S., Arroyo, H. S., & Graziano, J. V. (2015). Population

fluctuations of thrips (Thysanoptera) and their relationship to the phenology of vegetable crops in the central region of Mexico.

Florida Entomologist, 98(2), 430-438.

The presence of thrips in vegetable crops has become an important phytosanitary issue in Mexico. Their direct injuries

to plants are the result of the feeding by their immature and adult stages, whereas their indirect injuries are caused by

the transmission of various viruses. The objective of this study was to identify the species of thrips associated with 6

vegetable crops in order to determine their population fluctuations and to ascertain the effects of temperature and

rainfall on their populations. Samples were collected from zucchini, onion, pepper, cucumber, tomato, and tomatillo in

Puebla and Morelos from Feb 2010 to Feb 2011. Three species were identified: Frankliniella occidentalis (Pergande)

(Thysanoptera: Thripidae) on all vegetables, Frankliniella fortissima (Priesner) on zucchini and cucumber, and Thrips

tabaci (Lindeman) (Thysanoptera: Thripidae) on onion and pepper. The highest population level for thrips coincided

with the presence of flowers on the crops, except in the case of onion. In general, 2 to 6 generations of thrips were

present in each crop cycle, and the levels of populations decreased when the plants were near senescence. The main

suppressive effect of weather on thrips populations was caused by rainfall.

Panwar, T. S., S. B. Singh and V. K. Garg (2015). "Influence of meteorological parameters on population dynamics of thrips (Thrips

tabaci Lindeman) and aphid (Aphis gossypii Glover) in Bt and non Bt cotton at Malwa region of Madhya Pradesh." Journal of

Agrometeorology 17(1): 136-138.

Rotenberg, D., Jacobson, A. L., Schneweis, D. J., & Whitfield, A. E. (2015). Thrips transmission of tospoviruses. Current opinion in

virology, 15, 80-89.

One hundred years ago, the disease tomato spotted wilt was first described in Australia. Since that time, knowledge of

this disease caused by Tomato spotted wilt virus (TSWV) and transmitted by thrips (insects in the order Thysanoptera)

has revealed a complex relationship between the virus, vector, plant host, and environment. Numerous tospoviruses

and thrips vectors have been described, revealing diversity in plant host range and geographical distributions.

Advances in characterization of the tripartite interaction between the virus, vector, and plant host have provided insight

into molecular and ecological relationships. Comparison to animal-infecting viruses in the family Bunyaviridae has

enabled the identification of commonalities between tospoviruses and other bunyaviruses in transmission by arthropod

vectors and molecular interactions with hosts. This review provides a special emphasis on TSWV and Frankliniella

occidentalis, the model tospovirus–thrips pathosystem. However, other virus–vector combinations are also of

importance and where possible, comparisons are made between different viruses and thrips vectors.

Shaikh, R. R., M. F. Acharya and N. S. Rode (2015). "BIONOMICS OF THRIPS TABACI LINDEMAN ON ONION." Journal of

Experimental Zoology India 18(1): 457-459.

Studies on bionomics of Thrips tabaci was made at constant temperature of 25 +/- 1 degrees C. There were two larval

instmrs. The total larval and pupal period was 5.68 +/- 1.49 and 5.32 +/- 1.30 days, respectively. The average longevity

of female was 20.36 +/- 4.24 days. The duration of total life slian (egg to death of adult) for male wa 37.50 +/- 3.54

days while, for female it was 45.96 +/- 4.24 days. The pre-oviposition, oviposition and post-oviposition period were 3.56

+/- 0.71, 20.36 +/- 4.24 and 3.52 +/- 1.41 days, respectively.

Shaikh, R. R., M. F. Acharya and N. S. Rode (2015). "EFFICACY AND RELATIVE PERSISTENCY OF DIFFERENT INSECTICIDES

AGAINST THRIPS TABACI L. ON ONION." Journal of Experimental Zoology India 18(1): 473-477.

Efficacy and relative persistency of different insecticides studied under field as well as labrarotary condition. Among

them cypermethrin (0.025%) emerged as most effective by recording significantly higher thrips Mortality and bulb yield

followed by profenofos (0.05%). Economics of various insecticides showed that acetamiprid (0.004%) registered the

24

highest cost benefit ratio and found effective and most economical treatment whereas, spinosad (0.014%) and

difenthiuron (0.1%), showed comparatively low cost: benefit ratio. All the insecticides under investigation gave

complete control tip to 6 days and then after the effect were decreased with increase in time. However, profenofos

(0.05%), chlorpyriphos (0.05%) and spinosad (0.014%) showed longer persistence up to 14 days.

Silva, R., Walter, G. H., Wilson, L. J., & Furlong, M. J. (2015). Effect of the postfeeding interval on olfactory responses of thrips to

herbivore‐induced cotton plants. Insect science.

We investigated the responses of 3 thrips species, Frankliniella schultzei Trybom, F. occidentalis Pergrande, and Thrips

tabaci Lindeman (Thysanoptera: Thripidae) to herbivore-damaged and undamaged cotton seedlings (Gossypium

hirsutum L. [Malvales: Malvaceae]) at a range of time intervals following damage by adult Tetranychus urticae (Koch),

adult T. ludeni (Zacher) (Acari: Tetranychidae) or Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) larvae in

olfactometer assays. The intensity/frequency of the response of thrips to herbivore-induced plants decreased with time

and ultimately disappeared in all cases; however, the rate at which the response declined was related to the herbivore

species that inflicted the damage. All 3 species of thrips were attracted to plants damaged by T. urticae for longer than

they were to plants damaged by T. ludeni. The duration for which damaged plants remained attractive was also affected

by the degree of damage inflicted on cotton seedlings. For example, F. schultzei was attracted to plants damaged by a

higher density of two-spotted spider mites (100/plant) for much longer than to plants damaged by a lower density of

these mites (50/plant). The results reinforce previous studies that demonstrate that arrangement of variables influences

the responses of thrips to their herbivore-induced cotton host plants. Results also show that these responses are

variable in time following herbivore damage to cotton plants, which further demonstrates how difficult it is to

generalize about the functional significance of these interactions.

Smith, E. A., M. Fuchs, E. J. Shields and B. A. Nault (2015). "Long-Distance Dispersal Potential for Onion Thrips (Thysanoptera:

Thripidae) and Iris yellow spot virus (Bunyaviridae: Tospovirus) in an Onion Ecosystem." Environmental Entomology 44(4): 921-

930.

Onion thrips, Thrips tabaci Lindeman, is a worldwide pest of onion whose feeding damage and transmission of Iris

yellow spot virus (IYSV) may reduce onion yields. Little is known about the seasonal dynamics of T. tabaci dispersal, the

distance of dispersal, or the movement of thrips infected with IYSV during the onion-growing season. To address these

questions, T. tabaci adults were collected using transparent sticky card traps in commercial onion fields three times

during the onion-growing season (June, July, and late August) at varying heights above the canopy (0.5-6m above soil

surface) and with trap-equipped unmanned aircraft (UAVs) flying 50-60m above onion fields during August sampling

periods in 2012 and 2013. Randomly selected subsamples of captured T. tabaci were tested for IYSV using RT-PCR.

Most T. tabaci adults were captured in late August and near the onion canopy (<2m) throughout the season. However,

4% of T. tabaci adults captured on sticky cards were at altitudes >= 2m, and T. tabaci were also captured on UAV-

mounted traps. These data strongly suggest that long-distance dispersal occurs. More T. tabaci captured on sticky cards

tested positive for IYSV in August (53.6%) than earlier in the season (2.3 to 21.5% in June and July, respectively), and 20

and 15% of T. tabaci captured on UAV-mounted traps tested positive for IYSV in 2012 and 2013, respectively. Our

results indicate that T. tabaci adults, including viruliferous individuals, engage in long-distance dispersal late in the

season and likely contribute to the spread of IYSV.

Sogo, K., K. Miura, M. Aizawa, T. Watanabe and R. Stouthamer (2015). "Genetic structure in relation to reproduction mode in

Thrips tabaci (Insecta: Thysanoptera)." Applied Entomology and Zoology 50(1): 73-77.

In agriculture, although it is important to identify species of pest insects, their morphological identification is often

difficult. DNA genotyping is useful for identifying morphologically indiscriminable species. Thrips tabaci Lindeman has

two reproductive modes (arrhenotoky and thelytoky), which differ in their pesticide resistance, but morphological

discrimination is not possible. Studies have established a simple method of discriminating the strains by using their

mitochondrial DNA sequences. Previous studies have placed so-called arrhenotokous individuals into a "polyphagous

thelytokous clade." We made the discovery of new arrhenotokous strains that place them in the thelytokous

monophyletic group. We show that this polyphagous thelytokous clade is not a monophyletic group. Therefore, the

methods currently used to distinguish thelytokous and arrhenotokous individuals need to be updated, and we need to

detect another region of DNA that will enable us to discriminate between the two types.



25

Szostek, S. and H. F. Schwartz (2015). "Overwintering Sites of Iris yellow spot virus and Thrips tabaci (Thysanoptera: Thripidae) in

Colorado." Southwestern Entomologist 40(2): 273-290.

Iris yellow spot virus (family Bunyaviridae, genus Tospovirus) and its insect vector, onion thrips, Thrips tabaci Lindeman,

are of economic concern worldwide in regions where onions (Allium cepa L.) are grown. Several weed species have

been described as additional hosts and likely green bridges for survival of Iris yellow spot virus, however, there is little

work regarding the overwintering habits and potential of onion thrips as a source of inoculum during the following

season. The results of this work confirm onion thrips and Iris yellow spot virus presence near three Colorado onion

fields throughout the winter, onion thrips reproduction on six non-allium plant species, and larval acquisition of Iris

yellow spot virus from two non-allium plant species. Thrips were monitored by sticky traps during the winter months

from 2011 to 2013. Thrips activity seemed to cease when the average temperature was cooler than 0 degrees C and

resumed once the average temperature warmed above 0 degrees C. Onion cull piles were constructed and were

apparently conducive to survival of thrips, but no live thrips were collected from the piles after onion bulbs began to

decay. Iris yellow spot virus was detected by RTPCR in live adult and larval thrips from onion; common mallow, Malva

neglecta Wallr.; dandelion, Taraxacum officinale Weber in Wiggers; flixweed, Descurainia sophia (L.) Webb. Ex Prantl;

prickly lettuce, Lactuca serriola L.; and salsify, Tragopogon dubius Scop. during the winters from 2010 to 2013. Iris

yellow spot virus was detected in prickly lettuce and flixweed. The five weed species were grown from seed in a

greenhouse and exposed to viruliferous thrips to elucidate their potential as green bridges. Of the five weeds, Iris

yellow spot virus was detected in eight of 15 salsify leaf samples and in three of six thrips larval samples reared on the

plant. Winter annuals play a role in overwintering survival of onion thrips and Iris yellow spot virus, providing inoculum

the next growing season, and weed management during the winter might be warranted.

ud Din, M., Nadeem, M. K., Ali, M., Waqar, M. Q., Ali, M. A., & Masood, N. (2015). Efficacy of some insecticides against cotton

thrips (Thrips tabaci Lind.) under natural field conditions. Journal of Environmental& Agricultural Sciences.(5), 1-3.

The Cotton (Gossypium hirsutum L.) is the most important cash crop of Pakistan. The thrips, (Thrips tabaci Lind) sucking

insect pest of cotton crop which create a big problem at the early stages of crop to its maturity. The efficacy of seven

common insecticides in use for its control, are, viz., Tracer 240SC (Spinosad), Orthene 75SP (Acephate), Sanitox 40EC

(Dimethioate), Pirate 360SC (Chlorfenapyr), Radiant125SC (Spinetoram), Mospilan 20SP (Acetamaprid) and Confidor

200SL (Imidacloprid) were evaluated for their effectiveness against thrips. on cotton crop under natural field conditions

during the year 2013. Results showed that Tracer and Radiant were less effective (34.52 and 31.58% mortality) for 24-

hours, but their efficacy increased after 2-hours (68.64 and 73.42 % mortality) and recorded with maximum mortality at

168 hours (83.67 and 84.33%) among all the tested insecticides. Santox and Orthene were found as most effective at

24hours (62.33 and 48.50% mortality), whereas their residual effect decreased gradually from 72 hours up to 168 hours

against population of thrips. Confidor and Mospilan were resulted as least effective on thrips population after 24, 72

and 168 hours post application time. Conclusions of our findings are that among the tested insecticides, Tracer 240SC

and Radiant 125SC were more effective for the control of thrips on cotton crop.

Uppar, V. and B. S. Nandihalli (2015). "SCREENING OF Bt COTTON GENOTYPES AGAINST COTTON THRIPS, THRIPS TABACI

(LINDEMAN) UNDER FIELD CONDITION." Journal of Experimental Zoology India 18(1): 181-184.

The field experiments on screening of 25 Bt cotton along with non-Bt DCH-32 cotton genotypes against the thrips,

Thrips tabaci (Lindeman) was carried out at the Agricultural Research Station, Dharwad during kharif 2012-13 and 2013-

14 seasons. The interactions of cotton genotypes were grouped based on the mean and standard-deviation. Out of 25

Bt cotton genotypes including inter and intra specific hybrids, one genotype was categorized as resistant (MRC-7351); 3

as moderately resistant (Chiranjivi, MRC-7918 and Bunny Bt); 10 as moderately susceptible; 6 as susceptible and 5 as

highly susceptible to thrips. Chiranjivi was significantly superior in recording maximum seed cotton yield of 29.37 q/ha,

followed by MRC-7918 (26.47 q/ha).

Wilson, R. G., S. B. Orloff and A. G. Taylor (2015). "Evaluation of insecticides and application methods to protect onions from

onion maggot, Delia antiqua, and seedcorn maggot, Delia platura, damage." Crop Protection 67: 102-108.

Onion maggot, Delia antiqua (Meigen), and seedcorn maggot, Delia platura (Meigen), are important pests of spring-

sown onions, Allium cepa L Larvae of both species feed on developing epicotyls and roots of young onion plants often



26

resulting in seedling mortality. Cultural controls used in combination with the insecticide chlorpyrifos are currently the

standard practice for maggot control in the western USA. However, cultural controls are only partially effective and

reliance on chlorpyrifos has several potential problems including future availability and development of resistance.

Insecticides including clothianidin, imidacloprid, spinosad, and thiamethoxam were evaluated in California, USA in

2011-2013 to identify efficacious alternatives to chlorpyrifos. Some insecticides were applied in multiple ways including

seed treatment, in-furrow application at planting, and rototiller incorporation prior to planting. Onion plant population,

vigor, and yield were measured to assess insecticide efficacy. Maggots reduced onion plant populations by more than

65% of the seeding rate in the untreated controls. Seed treatments with spinosad or clothianidin imidacloprid were the

best alternative to chlorpyrifos for minimizing onion mortality from maggot feeding. Onions treated with both seed

treatments had similar or higher plant populations and bulb yields compared to chlorpyrifos. The efficacy of spinosad

was greatly improved when applied as a seed treatment compared to an in-furrow application at planting or when

incorporated into the soil with a rototiller prior to planting. Spinosad seed treatment increased onion plant populations

by 256%, 76%, and 853% compared to untreated controls in 2011, 2012, and 2013, respectively. Conversely, in-furrow

and rototill-incorporated applications of spinosad were similar to the untreated control in terms of onion plant

population and yield. Seed treatments with newer chemistries could provide an efficacious alternative to chlorpyrifos

for protecting onions from maggot damage in western onion production systems. Published by Elsevier Ltd.

Xia, C., Chon, T. S., Ren, Z., & Lee, J. M. (2015). Automatic identification and counting of small size pests in greenhouse conditions

with low computational cost. Ecological Informatics, 29, 139-146.

We propose an automatic pest identification method suitable for large scale, long term monitoring for mobile or

embedded devices in situ with less computational cost. A procedure of segmentation and image separation was

devised to identify common greenhouse pests, whiteflies, aphid and thrips. Initially, the watershed algorithm was used

to segment insects from the background (i.e., sticky trap) images. Color feature of the insects were subsequently

extracted by Mahalanobis distance for identification of pest species. Accuracy and computational costs were evaluated

across different image resolutions. The correlation of determination (R2) between the proposed identification scheme

and manual identification were high, showing 0.934 for whitefly, 0.925 for thrips, and 0.945 for aphids even with low

resolution images. Comparing with the conventional methods, pests were efficiently identified with low computational

cost. Optimal image resolution for species identification regarding long-term survey was discussed in practical aspect

with less computational complexity.

Yeh, W. B., Tseng, M. J., Chang, N. T., Wu, S. Y., & Tsai, Y. S. (2015). Agronomically important thrips: development of species-

specific primers in multiplex PCR and microarray assay using internal transcribed spacer 1 (ITS1) sequences for identification.

Bulletin of entomological research, 105(01), 52-59.

Thrips, the sole vector of plant Tospovirus, are major pests of many agricultural crops throughout the world. Molecular

approaches have been applied in recent decades to identify these minute and morphologically difficult to distinguish

insects. In this study, sequences of internal transcribed spacer 1 (ITS1) region of 15 agronomically important thrips,

including several virus transmission species, have been analyzed in order to design species-specific primers for

multiplex PCR and probes for microarray assay. That the ITS1 sequence distances within species were smaller than

those among species suggests that the ITS1 fragment can be used for thrips species identification. The specificity and

stability of these primers, combined with universal paired primers, were tested and verified in multiplex PCR. Using

these specific primers as probes, microarray assay showed that PCR products of all thrips species hybridized

consistently to their corresponding probes, though some signals were weak. We have demonstrated that multiplex PCR

using specific primers based on ITS1 sequences is a simple, reliable, and cost-effective diagnostic tool for thrips species

identification. Moreover, the DNA microarray assay is expected to extend into a reliable high-throughput screening tool

for the vast numbers of thrips.




27

Bag, S., S. I. Rondon, K. L. Druffel, D. G. Riley and H. R. Pappu (2014). "Seasonal Dynamics of Thrips (Thrips tabaci) (Thysanoptera:

Thripidae) Transmitters of Iris Yellow Spot Virus: A Serious Viral Pathogen of Onion Bulb and Seed Crops." Journal of Economic

Entomology 107(1): 75-82.

Thrips-transmitted Iris yellow spot virus (IYSV) is an important economic constraint to the production of bulb and seed

onion crops in the United States and many other parts of the world. Because the virus is exclusively spread by thrips,

the ability to rapidly detect the virus in thrips vectors would facilitate studies on the role of thrips in virus epidemiology,

and thus formulation of better vector management strategies. Using a polyclonal antiserum produced against the

recombinant, Escherichia coli-expressed nonstructural protein coded by the small (S) RNA of IYSV, an enzyme linked

immunosorbent assay was developed for detecting IYSV in individual as well as groups of adult thrips. The approach

enabled estimating the proportion of potential thrips transmitters in a large number of field-collected thrips collected

from field-grown onion plants. Availability of a practical and inexpensive test to identify viruliferous thrips would be

useful in epidemiological studies to better understand the role of thrips vectors in outbreaks of this economically

important virus of onion.

Ben-Yakir, D., M. Chen, S. Pivonia, M. Amichai and D. Silverman (2014). "Solar Heating of Chives for Controlling Thrips."

International Cipa Conference 2012 on Plasticulture for a Green Planet 1015: 123-128.

Chives are herbaceous perennial plants grown all year around in walk in tunnels covered by polyethylene films and

screens. The leaves of chives are used fresh as a flavoring herb and are harvested once a month. The onion thrips,

Thrips tabaci, is an important pest of chives causing silver spots on the leaves that make them unfit for marketing. Only

a few pesticides are permitted for the control of thrips in chives and they are frequently ineffective due to the

development of resistant thrips populations. A two treatments procedure was developed for controlling thrips in chives

by solar heat. Plants were cut to a height of 3-5 cm and then covered with a transparent polyethylene film in the

morning. The polyethylene film was removed few hours later, after the temperature inside the plants' canopy was

above 40 degrees C for about 2 hrs. This treatment caused only minor heat damage to the chives plants while killing

most of the thrips. Because the pupal stage of thrips develops in the ground and it has a low metabolic rate, it was not

controlled efficiently by a single heat treatment. Therefore, a second heat treatment was given 3-5 days after the first

one, when most adults emerged from the pupae. In Israel, this procedure can be used during clear days from spring to

autumn, in most regions that chives is grown. Covering chives with polyethylene film that prevent water condensation

(anti-drip) increased temperatures by 3-4 degrees C over the temperatures under standard polyethylene film.

Therefore, anti-drip polyethylene film may be useful for solar heat treatments during cooler or cloudy days.

Birithia, R. K., S. Subramanian, J. W. Muthomi and R. D. Narla (2014). "Resistance to Iris yellow spot virus and onion thrips among

onion varieties grown in Kenya." International Journal of Tropical Insect Science 34(2): 73-79.

Iris yellow spot virus (IYSV) vectored by Thrips tabaci threatens profitable onion production in eastern Africa. Host plant

resistance is considered to be the first line of defence against insect-transmitted virus diseases. Hence, information on

resistance to IYSV and T. tabaci among common onion cultivars in Kenya is crucial for the development of integrated

pest management strategies. This study evaluated the resistance to thrips and IYSV among widely grown onion

cultivars in Kenya, viz. Red Pinoy, Red Creole, Bombay Red, Green Bunching and Texas Grano, over two growing

seasons. Straw-coloured, diamond-shaped necrotic lesions typical of IYSV infection were observed 2 weeks after

transplantation. Observations on thrips numbers per plant, IYSV disease incidence and severity, and virus intensity were

undertaken to assess the resistance. Varieties differed significantly with respect to both IYSV disease incidence and

thrips numbers per plant from fourth week to physiological maturity. Red Pinoy, Green Bunching and Red Creole were

highly susceptible to the virus and thrips, while Texas Grano and Bombay Red were moderately resistant. There were

significant differences among the varieties with regard to IYSV intensity, with the highest and the least virus intensity

positively correlated with disease severity being recorded in Red Pinoy and Texas Grano, respectively. Among the

varieties, Texas Grano produced the highest yield in both seasons, while Red Pinoy produced the least. Hence, Texas

Grano and Bombay Red could be recommended as moderately resistant cultivars to thrips and IYSV to be grown in

Kenya for markets where pungency is not preferred and preferred, respectively. Regions with high levels of thrips

population and IYSV infestation are not suitable for the cultivation of Red Pinoy.

28

Boateng, C. O., H. F. Schwartz, M. J. Havey and K. Otto (2014). "Evaluation of Onion Germplasm for Resistance to Iris Yellow Spot

(Iris Yellow Spot Virus) and Onion Thrips, Thrips tabaci." Southwestern Entomologist 39(2): 237-260.

Onion (Allium cepa L.) is the most economically important monocot besides grasses. The crop suffers severe damage

from onion thrips, Thrips tabaci Lindeman, a cosmopolitan and polyphagous insect pest. In addition to causing direct

feeding damage, onion thrips is the principal vector of the economically important Iris yellow spot virus (Tospovirus sp.,

family Bunyaviridae). Any attempt to manage this pathosystem will require a multifaceted approach based on

integrated pest management. Host plant resistance is an important foundation to the success of such approaches. A

multi-state, multi-disciplinary research project was established to identify, validate, and deliver resistance to this

pathosystem for use by the onion industry. As part of the project, diverse onion plant introduction (PI) accessions from

the USDA germplasm collection, advanced breeding lines, and commercial cultivars were evaluated from 2009 through

2011 in fields in Colorado. Sixteen, 15, and 10 better performing onion genotypes were selected in 2009, 2010, and

2011, respectively. Of these, PI 264320 (Grano), PI 546140 (San Joaquin), and PI 546192 (Yellow Sweet Spanish) were

selected in both 2009 and 2010, and PI 258956 (Calderana 1028) and PI 546188 (Yellow Sweet Spanish Winegar) were

selected in all 3 years. These genotypes should be useful to improve commercial cultivars to reduce losses by the two

pests.

Cramer, C. S., N. Singh, N. Kamal and H. R. Pappu (2014). "Screening Onion Plant Introduction Accessions for Tolerance to Onion

Thrips and Iris Yellow Spot." Hortscience 49(10): 1253-1261.

Iris yellow spot is an economically important disease of onion that reduces bulb size and yield and is difficult to control.

The disease is spread by Thrips tabaci (onion thrips) and disease symptoms are exacerbated by hot, dry climatic

conditions that also favor rapid thrips multiplication and make control programs less effective. Currently, no onion

cultivar is resistant to the disease and/or thrips. Certain onion foliar characteristics have shown nonpreferential feeding

activity by thrips and may be the first step in developing Iris yellow spot (IYS)-tolerant onion cultivars. Seventy-five

onion PI accessions from the U.S. germplasm collection were evaluated for leaf color, waxiness (bloom), and axil

pattern; thrips number per plant; and IYS disease severity under conditions that favored thrips and disease buildup.

Plants of PI 289689 were less attractive to thrips and had a lower number of thrips per plant than plants of most other

accessions. These plants were rated as having light green to green-colored foliage and a relatively low amount of

epicuticular leaf wax. Plants of Pls 239633 and 546192 generally exhibited less severe IYS disease symptoms than those

of other accessions. Individual plants, that exhibited less leaf area exhibiting IYS disease symptoms, were selected at

bulb maturity from 22 different accessions with PI 546140 producing the largest number of selected bulbs.

Physiological plant development, environmental conditions, and tolerance to plant stress may influence the degree of

disease symptom expression. Further work that examines the role of plant maturity and host plant tolerance to stress

with respect to disease expression is needed.

Damon, S. J., R. L. Groves and M. J. Havey (2014). "Variation for Epicuticular Waxes on Onion Foliage and Impacts on Numbers of

Onion Thrips." Journal of the American Society for Horticultural Science 139(4): 495-501.

Natural variation exists in onion (Allium cepa L.) for amounts of epicuticular waxes on foliage, and plants with lower

amounts of these waxes suffer less feeding damage from onion thrips (Thrips tabaci Lind.). Wild-type onion possesses

copious amounts of epicuticular waxes and is often referred to as "waxy." The recessively inherited "glossy" phenotype

has significantly less wax relative to waxy types and shows resistance to onion thrips but is vulnerable to spray damage,

foliar pathogens, and excessive transpiration. Phenotypes visually intermediate between waxy and glossy also exist in

onion, which we refer to as "semiglossy." Epicuticular waxes on the leaves of glossy, semiglossy, and waxy onions were

evaluated for appearance using scanning electron microscopy (SEM) and amounts and types were analyzed using gas

chromatography/mass spectrometry. Wax crystals were clearly visible on the surface of waxy foliage with decreasing

amounts on semiglossy and none on glossy leaves. The ketone hentriacontanone-16 was the most prevalent wax on

leaves of waxy onion and was significantly (P < 0.01) less on semiglossy relative to waxy plants and on glossy relative to

waxy and semiglossy plants. Numbers of adult and immature onion thrips were significantly reduced (P < 0.05) on

glossy and/or semiglossy accessions relative to waxy in field and greenhouse cage experiments. These results indicate

that semiglossy plants possess intermediate amounts of epicuticular waxes that may protect leaves from diseases or

environmental stresses while still conferring resistance to onion thrips. Therefore, the semiglossy phenotype should be

useful in integrated programs managing this important onion pest.



29

Damon, S. J. and M. J. Havey (2014). "Quantitative Trait Loci Controlling Amounts and Types of Epicuticular Waxes in Onion."

Journal of the American Society for Horticultural Science 139(5): 597-602.

Natural variation exists in onion (A Ilium cepa L.) for amounts and types of epicuticular waxes on leaves. Wild-type waxy

onion possesses copious amounts of these waxes, whereas the foliage of semiglossy and glossy phenotypes

accumulates significantly less wax. Reduced amounts of epicuticular waxes have been associated with resistance to

onion thrips (Thrips tabaci Lindeman), an important insect pest of onion. A segregating family from the cross of waxy

and semiglossy onions was used to map single nucleotide polymorphisms (SNPs) and identify chromosome regions

affecting amounts and types of epicuticular waxes as measured by gas chromatography mass spectrometry. The

amount of the primary epicuticular wax on onion leaves, hentriacontanone-16, was controlled by one region on

chromosome 5. One region on chromosome 2 affected concentrations of several primary fatty alcohols. Results indicate

that the region on chromosome 2 may be associated with the acyl reduction pathway, and the region on chromosome

5 may affect the decarbonylation pathway of epicuticular wax biosynthesis. Because lower amounts of epicuticular

waxes are recessively inherited, SNPs tagging regions on chromosomes 2 and 5 will be useful for marker-assisted

breeding to vary amounts and types of epicuticular waxes on onion foliage with the goal to develop cultivars resistant

to onion thrips.

Dutta, B., A. K. Barman, R. Srinivasan, U. Avci, D. E. Ullman, D. B. Langston and R. D. Gitaitis (2014). "Transmission of Pantoea

ananatis and P-agglomerans, Causal Agents of Center Rot of Onion (Allium cepa), by Onion Thrips (Thrips tabaci) Through

Feces." Phytopathology 104(8): 812-819.

Frankliniella fusca, the tobacco thrips, has been shown to acquire and transmit Pantoea ananatis, one of the causal

agents of the center rot of onion. Although Thrips tabaci, the onion thrips, is a common pest of onions, its role as a

vector of P. ananatis has been unknown. The bacterium, P. agglomerans, is also associated with the center rot of onion,

but its transmission by thrips has not been previously investigated. In this study, we investigated the relationship of T.

tabaci with P. ananatis and P. agglomerans. Surface-sterilized T. tabaci were provided with various acquisition access

periods (AAP) on onion leaves inoculated with either P. ananatis or P. agglomerans. A positive exponential relationship

was observed between thrips AAP duration and P. ananatis (R-2 = 0.967; P = 0.023) or P. agglomerans acquisition (R-2

= 0.958; P = 0.017). Transmission experiments conducted with T. tabaci adults indicated that 70% of the seedlings

developed center rot symptoms 15 days after inoculation. Immunofluorescence microscopy with antibodies specific to

P. ananatis revealed that the bacterium was localized only in the gut of T. tabaci adults. Mechanical inoculation of onion

seedlings with fecal rinsates alone produced center rot but not with salivary secretions. Together these results

suggested that T. tabaci could efficiently transmit P. ananatis and P. agglomerans.

Fekrat, L., S. Manzari and P. Shishehbor (2014). "Morphometric and Molecular Variation in Thrips tabaci Lindeman (Thysanoptera:

Thripidae) Populations on Onion and Tobacco in Iran." Journal of Agricultural Science and Technology 16: 1505-1516.

Onion thrips, Thrips tabaci Lindeman, is a broadly distributed pest that attacks a wide range of crops. To investigate the

intra-specific morphometric variation and the genetic diversity of the species in Iran, four populations from tobacco

plus 18 populations from onion were studied in some 17 provinces of Iran. Morphological analysis, using principal

components and canonical discriminant analyses indicated that the populations living on tobacco were significantly

different from those living on onion. DNA sequence data for the COI gene was obtained for all the populations

including some other 21 population sequences retrieved from the GenBank database. Maximum parsimony analyses

revealed the distinct clades of T. tabaci on tobacco and on onion with the exception of one population collected from

tobacco grown in Golestan Province. The results were identical for maximum likelihood and neighbor-joining analyses.

Both molecular and morphometric analyses show heterogenecity of T. tabaci populations representing at least two

different biotypes on tobacco and on onion.

Fok, E. J., J. D. Petersen and B. A. Nault (2014). "Relationships between insect predator populations and their prey, Thrips tabaci,

in onion fields grown in large-scale and small-scale cropping systems." Biocontrol 59(6): 739-748.

Onion thrips, Thrips tabaci Lindeman, is the primary pest of onion, which is grown in either large-scale, monoculture

systems surrounded by other onion fields, or in small-scale systems surrounded by multiple vegetable crops. In 2011

and 2012, populations of insect predators and their prey, T. tabaci, were assessed weekly in onion fields in both



30

cropping systems. Insect predator taxa (eight species representing five families) were similar in onions grown in both

systems and the most commonly occurring predators were from the family Aeolothripidae. Seasonal population

dynamics of predators and T. tabaci followed similar trends within both cropping systems and tended to peak in late

July and early August. Predator abundance was low in both systems, but predator abundance was nearly 2.5 to 13 times

greater in onion fields in the small-scale system. T. tabaci abundance often positively predicted predator abundance in

both cropping systems.

Gombac, P. and S. Trdan (2014). "The efficacy of intercropping with birdsfoot trefoil and summer savoury in reducing damage

inflicted by onion thrips (Thrips tabaci, Thysanoptera, Thripidae) on four leek cultivars." Journal of Plant Diseases and Protection

121(3): 117-124.

Onion thrips, Thrips tabaci (Thysanoptera, Thripidae), are an important pest of leek (Allium porrum) in Slovenia, and

their control is becoming increasingly difficult for several reasons (e.g., increased resistance, specific life cycle).

Therefore, intercropping, whereby the seeds of a different plant species are sown amidst the primary crop, represents a

promising method to prevent pest damage. Our field experiments were conducted in 2009 and 2011, during which we

studied the suitability of two different intercrops for reducing the extent of the damage inflicted by onion thrips on the

leaves of four different leek cultivars. For the first time, birdsfoot trefoil (Lotus corniculatus, Fabaceae) and summer

savoury (Satureja hortensis, Lamiaceae) were chosen as intercrops. Both intercrops significantly reduced the extent of

damage in both years when compared to the control plots, in which an intercrop was not sown. We found no

noteworthy differences among the cultivars regarding the extent of damage. We also studied the effect of these

intercrops on the leek yield. Consistent with previous studies, when grown with these intercrops, the leek yield was

lower than that of the control plots; however, we conclude that this reduction is acceptable in light of the advantages of

intercropping, especially when utilizing birdsfoot trefoil.

Huang, J. H., S. Freed, L. S. Wang, W. J. Qin, H. F. Chen and H. G. Qin (2014). "Effect of temperature on development and

reproduction of Proprioseiopsis asetus (Acari: Phytoseiidae) fed on asparagus thrips, Thrips tabaci." Experimental and Applied

Acarology 64(2): 235-244.

Thrips tabaci Lindeman (Thysanoptera: Thripidae) is one of the most important pests of asparagus in China. In this

study the effects of five constant temperatures (15, 20, 25, 30 and 35 A degrees C) on the growth, survivorship and

reproduction of Proprioseiopsis asetus (Chant) (Acari: Phytoseiidae) fed on T. tabaci was examined under laboratory

conditions. Development time of immatures decreased with increasing temperature. The lower egg-to-adult

developmental threshold (T (0)) and thermal constant (K) of P. asetus were estimated at 15.2 A degrees C and 75.8

degree days by means of a linear model. Fertilized females fed on T. tabaci produced offspring of both sexes, whereas

the offspring sex ratio [a (TM) Euro/(a (TM) EuroA + a (TM),)] of P. asetus at 20-35 A degrees C was female-biased (0.68-

0.78) and not significantly influenced by temperature. Survivorship during immature development was significantly

influenced by temperature, and was especially low at 15 A degrees C. Pre- and post-oviposition periods of fertilized

females shortened with the increase in temperature. The longest oviposition period was 20.4 days, at 25 A degrees C,

whereas at 15 A degrees C the mites did not reproduce. Maximum average life time fecundity and mean daily fecundity

was recorded at 25 and 35 A degrees C, respectively; the intrinsic rate of increase ranged from 0.05 (20 A degrees C) to

0.17 (35 A degrees C). The results indicate the capability of P. asetus to develop and reproduce at a broad range of

temperatures, especially above 25 A degrees C, which can be used for better management of T. tabaci in asparagus.

Khaliq, A., A. A. Khan, M. Afzal, H. M. Tahir, A. M. Raza and A. M. Khan (2014). "Field evaluation of selected botanicals and

commercial synthetic insecticides against Thrips tabaci Lindeman (Thysanoptera: Thripidae) populations and predators in onion

field plots." Crop Protection 62: 10-15.

The effectiveness of three botanical insecticides (neem, datura and bitter apple), and three new chemistry synthetic

insecticides (acephate, spirotetramat and spinetoram) against onion thrips (Thrips tabaci) was evaluated in experimental

field plots at university of Sargodha, Pakistan. The influence of these botanical and chemical insecticides on natural

predators and crop yield was simultaneously investigated.. All the botanicals and chemical insecticides tested caused

significant reductions (45-70%) in thrips populations; the botanicals gave more than 60% control of thrips, while among

chemical insecticides, acephate was found to be the most effective followed by spirotetramat and spinetoram,

respectively, and these insecticides gave better control than the botanicals. The adverse effects of the botanicals on



31

predator populations were negligible compared to the chemical insecticides. All chemical treatments resulted in a

significantly higher yield compared to the untreated control. The botanicals and chemical insecticides became less

effective by 7 days after treatment. Therefore, it is recommended that treatment with botanical or chemical insecticides

should be repeated weekly consecutively at least three times to keep thrips populations below economic injury levels

until crop maturity. (c) 2014 Elsevier Ltd. All rights reserved.

Khan, M. A., A. Ali, M. Aslam, Z. Tahir, M. M. Khan and I. Nadeem (2014). "THE ROLE OF MORPHOLOGICAL AND CHEMICAL

PLANT TRAITS IMPARTING RESISTANCE IN BT COTTON GENOTYPES AGAINST THRIPS, Thrips tabaci (Lind.)." Pakistan Journal of

Agricultural Sciences 51(3): 725-731.

A study was carried out in the experimental area of Ayub Agricultural Research Institute Faisalabad during (2012) to

determine the role of morphological and biochemical parameters of Bt cotton genotypes influencing resistance against

thrips Thrips tabaci (Lind). Six advance lines and one Bt cotton approved variety IR-NIBGE-5, SITARA 10-M, SITARA 11-

M, PB-38, SITARA-009, IR-NIBGE-4 and BT-121 respectively were planted in Randomized Complete Block Design with 3

replications. Varieties differ significantly in response to thrips population on per leaf basis. SITARA 10-M showed

maximum population of thrips (5.01/leaf) and did show significant difference with all other genotypes. Various

morphological and biochemical traits also differ significantly among seven genotypes of cotton. Gossypol glands on

Leaf lamina and phosphorus contents of leaves showed negative and highly significant correlation -0.447 and -0.490

respectively with the thrips population while hair density on veins and lamina and hair length on lamina showed

positive and significant correlation 0.806, 0.574 and 0.45 respectively with the thrips population. All others parameters

showed non-significant correlation with the thrips population. The R-2 values, computed together for multiple

regression analysis for thrips population indicated that hair density on vein was the most important factor which

contributed maximum i.e. 58.2% in pest population fluctuation of the pest. Gossypol gland on lamina was the second

important factor showing impact of 20%, Hair density on lamina and hair length on lamina showed 6.90% and 0.30%

impact in per unit change in pest population. Phosphorus contents showed 24% impact in per unit change in the pest

density. Principle component analysis of morphological and chemical factors revealed that gossypol gland on lamina

showed contrasting behavior having maximum variance value 95.159%. Hair density on vein also showed contrasting

behavior with variance values of 3.741%. Hair density on lamina, hair length of lamina and Phosphorus content was not

an important factor due to minimum variance value of 0.804%, 0.234% and 0.064%. Morphological and biochemical

take part in resistance against pest which can be used as important tool in integrated pest management model.

Kumar, R., J. C. Tian, S. E. Naranjo and A. M. Shelton (2014). "Effects of Bt Cotton on Thrips tabaci (Thysanoptera: Thripidae) and

Its Predator, Orius insidiosus (Hemiptera: Anthocoridae)." Journal of Economic Entomology 107(3): 927-932.

Laboratory studies were conducted to investigate tritrophic transfer of insecticidal Cry proteins from transgenic cotton

to an herbivore and its predator, and to examine effects of these proteins on the predator's development, survival, and

reproduction. Cry1Ac and Cry2Ab proteins from the bacterium Bacillus thuringiensis (Bt) produced in Bollgard-II (BG-II,

Event 15985) cotton plants were acquired by Thrips tabaci Lindeman (Thysanoptera: Thripidae), an important sucking

pest of cotton, and its generalist predator, Orius insidiosus (Say) (Hemiptera: Anthocoridae). The average protein titers

in BG-II cotton leaves were 1,256 and 43,637 ng Cry1Ac and Cry2Ab per gram fresh leaf tissue, respectively. At the

second trophic level, larvae of T. tabaci reared on BG-II cotton for 48-96 h had 22.1 and 2.1% of the Cry1Ac and Cry2Ab

levels expressed in leaves, respectively. At the third trophic level, O. insidiosus that fed on T. tabaci larvae had 4.4 and

0.3% of the Cry1Ac and Cry2Ab protein levels, respectively, expressed in BG-II plants. O. insidiosus survivorship, time of

nymphal development, adult weight, preoviposition and postoviposition periods, fecundity, and adult longevity were

not adversely affected owing to consumption of T. tabaci larvae that had fed on BG-II cotton compared with non-Bt

cotton. Our results indicate that O. insidiosus, a common predator of T. tabaci, is not harmed by BG-II cotton when

exposed to Bt proteins through its prey. Thus, O. insidiosus can continue to provide important biological control

services in the cotton ecosystem when BG-II cotton is used to control primary lepidopteran pests.

Li, X. W., J. Fail, P. Wang, J. N. Feng and A. M. Shelton (2014). "Performance of Arrhenotokous and Thelytokous Thrips tabaci

(Thysanoptera: Thripidae) on Onion and Cabbage and Its Implications on Evolution and Pest Management." Journal of Economic

Entomology 107(4): 1526-1534.



32

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is an important pest on onion and cabbage. Two

reproductive modes-arrhenotoky and thelytoky-are found in this species and co-occur in the field. We compared life

table traits between arrhenotokous and thelytokous T. tabaci on cabbage and onion. Experiments were conducted in

cages to determine which reproductive mode is more competitive. Additionally, host adaption of the arrhenotokous

and thelytokous T. tabaci between onion and cabbage was investigated. On onion, arrhenotokous T. tabaci performed

better than thelytokous T. tabaci, while on cabbage the opposite occurred. When comparing life table and

demographic growth parameters (net reproductive rates R-0, mean generation time T, the intrinsic rate of natural

increase r(m), finite rate of increase lambda, and population doubling time T-d) on different host plants, we found that

arrhenotokous T. tabaci performed better on onion than on cabbage, whereas thelytokous T. tabaci performed better

on cabbage than on onion. Host-related performance differences in this species suggest that the divergence between

two reproductive modes might be associated with host adaption. Pest management strategies for this global pest

should recognize that the two reproductive modes can impact population dynamics on different crops.

Makabe, T., T. Futamura, T. Noudomi, M. Wakakuwa and K. Arikawa (2014). "Phototaxis of Western Flower Thrips, Frankliniella

occidentalis and Onion Thrips, Thrips tabaci and the Possibility of Controlling Thrips Using Ultraviolet-emitting Trap in the

Greenhouse of Satsuma Mandarin (Citrus unshiu)." Japanese Journal of Applied Entomology and Zoology 58(3): 187-195.

The western flower thrips, Frankliniella occidentalis Pergande and the onion thrips, Thrips tabaci Lindeman are major

pests of Satsuma Mandarin (Citrus unshiu Marc.) fruits under greenhouse culture. To use thrips' phototactic behavior

for plant protection, we first determined the spectral sensitivity of the compound eyes of T. tabaci by recording

electroretinogram. We then measured the action spectrum of phototaxis in flight activity in both species. Also

measured the correlation between attractiveness of light and air temperature in both species. The compound eye

spectral sensitivity exhibited two large sensitivity bands each peaking at 362 nm and at 532 nm. Both F. occidentalis and

T tabaci were strongly attracted to wavelengths around 350 nm. The attractiveness of 350 nm light was much stronger

than that of 525 nm. The number of attracted individuals decreased as the air temperature dropped. We examined

whether ultraviolet-emitting traps reduced the damage to fruits due to the thrips in greenhouses. As a result,

ultraviolet-emitting traps were as effective as spraying of insecticides, Clothianidin and Acephate. Extensive browning

on peels was found in the fruits irradiated with the light whose wavelength was shorter than 300 nm.

Mautino, G. C., L. Bosco and L. Tavella (2014). "Impact of control strategies on Thrips tabaci and its predator Aeolothrips

intermedius on onion crops." Phytoparasitica 42(1): 41-52.

Thrips tabaci (Thysanoptera: Thripidae) is a major pest of onion worldwide. In 2011, research was conducted in a

commercial onion field in northwestern Italy to: (i) assess the presence of autochthonous onion thrips predators on the

crop; and (ii) evaluate the impact of the commonly used insecticides and alternative pest management strategies on

onion thrips and its autochthonous predators. Toxicity of the active ingredients on local populations of onion thrips and

its predatory thrips was also evaluated in laboratory bioassays. During field surveys, the highest and lowest thrips

infestations were observed in plots treated with lambda-cyhalothrin and spinosad, respectively. The effectiveness of

spinosad on T. tabaci was also confirmed in laboratory bioassays. The dominant zoophagous species Aeolothrips

intermedius (Thysanoptera: Aeolothripidae) was more adversely affected by treatment with lambda-cyhalothrin,

confirmed by a decrease in predator/prey ratios. The use of spinosad and acibenzolar-S-methyl is suggested as an

alternative to conventional insecticides for the preservation of A. intermedius, which proved to be a potential biological

control agent of T. tabaci.

Muvea, A. M., R. Meyhofer, S. Subramanian, H. M. Poehling, S. Ekesi and N. K. Maniania (2014). "Colonization of Onions by

Endophytic Fungi and Their Impacts on the Biology of Thrips tabaci." Plos One 9(9).

Endophytic fungi, which live within host plant tissues without causing any visible symptom of infection, are important

mutualists that mediate plant-herbivore interactions. Thrips tabaci (Lindeman) is one of the key pests of onion, Allium

cepa L., an economically important agricultural crop cultivated worldwide. However, information on endophyte

colonization of onions, and their impacts on the biology of thrips feeding on them, is lacking. We tested the

colonization of onion plants by selected fungal endophyte isolates using two inoculation methods. The effects of

inoculated endophytes on T. tabaci infesting onion were also examined. Seven fungal endophytes used in our study

were able to colonize onion plants either by the seed or seedling inoculation methods. Seed inoculation resulted in 1.47



33

times higher mean percentage post-inoculation recovery of all the endophytes tested as compared to seedling

inoculation. Fewer thrips were observed on plants inoculated with Clonostachys rosea ICIPE 707, Trichoderma

asperellum M2RT4, Trichoderma atroviride ICIPE 710, Trichoderma harzianum 709, Hypocrea lixii F3ST1 and Fusarium

sp. ICIPE 712 isolates as compared to those inoculated with Fusarium sp. ICIPE 717 and the control treatments. Onion

plants colonized by C. rosea ICIPE 707, T. asperellum M2RT4, T. atroviride ICIPE 710 and H. lixii F3ST1 had significantly

lower feeding punctures as compared to the other treatments. Among the isolates tested, the lowest numbers of eggs

were laid by T. tabaci on H. lixii F3ST1 and C. rosea ICIPE 707 inoculated plants. These results extend the knowledge on

colonization of onions by fungal endophytes and their effects on Thrips tabaci.

Nakao, S., C. Chikamori, A. Hori and S. Toda (2014). "Relationship between Pyrethroid Resistance and Attacking Persimmon in

the Onion Thrips, Thrips tabaci (Thysanoptera: Thripidae)." Japanese Journal of Applied Entomology and Zoology 58(3): 255-262.

To detect biological differences between pyrethroid-resistant strains and pyrethroid-susceptible strains of the onion

thrips, Thrips tabaci, developmental and ovipositional characteristics on the leaves of 5 varieties of persimmon and

green bean were investigated by rearing trials using isofemale lines. In addition, suitability of 2 varieties of persimmon

fruits as foods for thrips larvae was compared between a pyrethroid-resistant strain and a pyrethroid-susceptible strain

of onion thrips. Irrespective of susceptibility levels to pyrethroid, while T tabaci adults deposited eggs into persimmon

leaves, few individuals completed larval development on the leaves, suggesting that T tabaci does not develop on

persimmon leaf throughout reproductive seasons. Both strains of T. tabaci successfully molted into adults when they

fed on persimmon fruits, but survival rates in immature stages differed among varieties and developmental stages of

the fruits. These differences may cause inter-specific and seasonal variation in injury levels by thrips attacking

persimmon orchards. The pyrethroid-resistant strains showed lower fecundities compared to the pyrethroid-susceptible

strains of onion thrips on green bean leaf. In conclusion, there was no evidence that unique characteristics other than

susceptibility levels to pyrethroid insecticide contribute to pestilent levels of the onion thrips in commercial persimmon

orchards.

Nault, B. A., W. C. Kain and P. Wang (2014). "Seasonal Changes in Thrips tabaci Population Structure in Two Cultivated Hosts."

Plos One 9(7).

Thrips tabaci is a major pest of high-value vegetable crops and understanding its population genetics will advance our

knowledge about its ecology and management. Mitochondrial cytochrome oxidase subunit I (COI) gene sequence was

used as a molecular marker to analyze T. tabaci populations from onion and cabbage fields in New York. Eight COI

haplotypes were identified in 565 T. tabaci individuals collected from these fields. All T. tabaci were thelytokous and

genetically similar to those originating from hosts representing seven plant families spanning five continents. The most

dominant haplotype was NY-HT1, accounting for 92 and 88% of the total individuals collected from onion fields in mid-

summer in 2005 and 2007, respectively, and 100 and 96% of the total in early fall in 2005 and 2007, respectively. In

contrast, T. tabaci collected from cabbage fields showed a dynamic change in population structure from mid-summer

to early fall. In mid-summer, haplotype NY-HT2 was highly abundant, accounting for 58 and 52% of the total in 2005

and 2007, respectively, but in early fall it decreased drastically to 15 and 7% of the total in 2005 and 2007, respectively.

Haplotype NY-HT1 accounted for 12 and 46% of the total in cabbage fields in mid-summer of 2005 and 2007,

respectively, but became the dominant haplotype in early fall accounting for 81 and 66% of the total in 2005 and 2007,

respectively. Despite the relative proximity of onion and cabbage fields in the western New York landscape, T. tabaci

populations differed seasonally within each cropping system. Differences may have been attributed to better

establishment of certain genotypes on specific hosts or differing colonization patterns within these cropping systems.

Future studies investigating temporal changes in T. tabaci populations on their major hosts in these ecosystems are

needed to better understand host-plant utilization and implications for population management.

Pobozniak, M. and E. H. Koschier (2014). "Effects of pea (Pisum sativum L.) cultivars on Thrips tabaci Lindeman preference and

performance." Journal of Agricultural Science 152(6): 885-893.

The polyphagous onion thrips Thrips tabaci Lindeman (Thysanoptera: Thripidae) is a serious pest in many protected and

field crops and has recently been found to occur in high numbers in Pisum sativum L. crops. In the present study, the

abundance of T. tabaci was compared on two pea cultivars in the field. Data on sweep net catches at different sampling

times during the day suggest that peak activity of the thrips is at noon. Significantly more thrips larvae and adults were



34

caught on the early pea cultivar Cud Kelwedonu compared with the very early cultivar Pionier, particularly during and

after flowering of the peas. Analysis of primary plant compounds indicated that the higher leaf nitrogen and sucrose

contents in the leaves of cvar Cud Kelwedonu promote thrips population growth in pea. The preference of T. tabaci for

leaves of cvar Cud Kelwedonu was confirmed in experiments in the laboratory. Thrips tended to settle, caused

significantly more feeding damage and laid significantly more eggs on the leaves of Cud Kelwedonu. Knowledge on

abundance, activity patterns and host use of T. tabaci in pea may contribute to optimizing cultivar selection, monitoring

and timing of possible control measures in the future.

Reitz, S. R. (2014). "ONION THRIPS (THYSANOPTERA: THRIPIDAE) AND THEIR MANAGEMENT IN THE TREASURE VALLEY OF THE

PACIFIC NORTHWEST." Florida Entomologist 97(2): 349-354.

Onion thrips, Thrips tabaci Lindeman and thrips-transmitted Iris yellow spot virus are the most significant pest complex

affecting onion production in the Treasure Valley of eastern Oregon and southwestern Idaho. Thrips feeding damage

and virus infection significantly reduce onion bulb size and economic returns for this high value crop. The high

concentration of onion fields in the Treasure Valley and the long, hot, dry growing season present a number of

challenges for managing onion thrips and Iris yellow spot virus (IYSV). Insecticides are the primary tool that growers

have to manage this pest complex. With the long growing season, growers need to exercise good insecticide resistance

management programs to maintain the effectiveness of currently available insecticides. To do this, growers need to

rotate among available products and use as few applications as practical. A challenge for researchers is to determine

not only which insecticides are effective but also to determine when during the season different products may be most

effectively used. Techniques for analyzing field trial data are discussed, including comparing changes in pest

populations before and after various insecticide applications are made. These comparisons can be made through the

use of linear estimates and contrasts as part of analyses of variance, and they can aid in determining efficacy of

different treatments by accounting for pre-application populations. These techniques will help researchers in

developing sound sequence of insecticide applications for onion thrips management.

Riley, D. G., A. N. Sparks, Jr. and A. Chitturi (2014). "CURRENT STATUS OF THRIPS (THYSANOPTERA: THRIPIDAE) IN VIDALIA

ONIONS IN GEORGIA." Florida Entomologist 97(2): 355-361.

The Vidalia onion crop in Georgia is grown in the winter, and the key insect pests in Georgia are thrips (Thysanoptera:

Thripidae). The thrips complex consists predominantly of tobacco thrips, Frankliniella fusca (Hinds), with smaller

percentages of western flower thrips, F. occidentalis Pergande, eastern flower thrips, F. tritici (Fitch) and onion thrips,

Thrips tabaci Lindeman. Onion thrips has become a greater concern in the last 10 years likely due to the introduction of

a more aggressive biotype of T. tabaci on onions coming from Peru into the Vidalia region. A preliminary laboratory

bioassay at 25 degrees C suggested that this onion thrips biotype could out-compete tobacco thrips on onions.

Surveys were conducted from 2004 through 2013 in commercial Vidalia onion fields to determine if this increase in the

percentage of onion thrips would occur. Average seasonal temperatures were highly correlated (r = 0.811) with percent

T. tabaci and negatively correlated (r = -0.807) with F. fusca. The results suggest that temperature might regulate the

proportion of onion thrips to tobacco thrips in the field, with a higher percentage of tobacco thrips occurring during

cool winters and more onion thrips occurring in warm winters. Nevertheless, F. fusca continues to be the dominant

thrips species in the Vidalia onion winter growing region of Georgia averaging 78% of the adult thrips population from

2004 to 2013.

Schwartz, H. F., D. H. Gent, S. M. Fichtner, K. Otto, C. O. Boateng, S. Szostek, W. S. Cranshaw and L. A. Mahaffey (2014). "Thrips

tabaci (Thysanoptera: Thripidae) and Iris yellow spot virus Associated with Onion Transplants, Onion Volunteers, and Weeds in

Colorado." Southwestern Entomologist 39(4): 691-704.

Infestation by onion thrips, Thrips tabaci Lindeman, was determined on transplants of onion (Allium cepa L.) received in

Colorado during March and April from out-of-state sources (Imperial Valley, CA; near Phoenix, AZ; and southern Texas)

during 2004 to 2008. In the 5 years of the study, 50 to 100% of the transplant lots sampled arrived infested with thrips.

Among infested transplant lots, the overall number of thrips averaged 0.15 to 0.63 per plant, with as many as four per

plant in some lots. T. tabaci was the dominant thrips species in all seasons and locations of transplant origin. In

addition, 19 of 83 (23%) tested lots had plants positive for Iris yellow spot virus. Iris yellow spot virus and T. tabaci were

detected in volunteer onion plants as early as 1 May, a few weeks after the summer onion crop was planted, suggesting



35

a possible role of infected volunteer plants in perennation of the virus between onion crops. Iris yellow spot virus and T.

tabaci were detected in many common weeds including blue mustard (Chorispora tenella (Pall.) DC), common purslane

(Portulaca oleracea L.), field bindweed (Convolvulus arvensis L.), flixweed (Descurainia sophia Webb & Berth.), prickly

lettuce (Lactuca serriola L.), and redroot pigweed (Amaranthus retroflexus L.) in early spring near onion fields in

Colorado during 2006 to 2009. Confirmation that Iris yellow spot virus and Iris yellow spot virus-infective thrips

overwintered in volunteer onions and some common winter annual and perennial weeds emphasizes that managing

volunteer onions and weeds is important for management of iris yellow spot, in addition to planting transplants free of

thrips and the pathogen.

Silva, R., G. H. Walter, L. J. Wilson and M. J. Furlong (2014). "Responses of Thrips tabaci to odours of herbivore-induced cotton

seedlings." Entomologia Experimentalis Et Applicata 151(3): 239-246.

Herbivore-induced changes in plants have been widely viewed as defensive responses against further insect attack.

However, changes in plants as a consequence of herbivore feeding can elicit various responses in herbivores; these are

variable, context dependent, and often unpredictable. In this laboratory study, the responses of Thrips tabaci Lindeman

(Thysanoptera: Thripidae) to volatiles emitted by intact and herbivore-damaged or mechanically damaged cotton

seedlings [Gossypium hirsutum L. (Malvaceae)] were investigated in dual-choice olfactometer assays. Thrips tabaci

showed increased attraction to seedlings subject to foliar mechanical damage and those with foliar damage inflicted by

conspecifics or Tetranychus urticae Koch (Acari: Tetranychidae), upon which it preys. However, T.tabaci did not

discriminate between intact seedlings and those with foliar damage inflicted by Helicoverpa armigera Hubner

(Lepidoptera: Noctuidae), two other species of thrips, Frankliniella schultzei Trybom and Frankliniella occidentalis

Pergrande (Thysanoptera: Thripidae), or those with root damage inflicted by Tenebrio molitor L. (Coleoptera:

Tenebrionidae). Attraction of T.tabaci was also affected by herbivore density on damaged plants. That is, seedlings

damaged by higher densities of T.urticae or T.tabaci were more attractive than seedlings damaged by lower densities of

the corresponding arthropod. Although attracted to plants damaged by conspecifics or T.urticae, T.tabaci showed

greater attraction to seedlings damaged by T.urticae than to seedlings damaged by conspecifics. Results are discussed

in the context of the responses of F.schultzei and F.occidentalis to herbivore-induced cotton seedlings, highlighting the

complexity, variability, and unpredictability of the responses of even closely related species of insects to plants under

herbivore attack.

Teulon, D. A. J., C. Castane, M. C. Nielsen, A. M. El-Sayed, M. M. Davidson, R. Gardner-Gee, J. Poulton, A. M. Kean, C. Hall, R. C.

Butler, C. E. Sansom, D. M. Suckling and N. B. Perry (2014). "Evaluation of new volatile compounds as lures for western flower

thrips and onion thrips in New Zealand and Spain." New Zealand Plant Protection 67: 175-183.

Two glasshouse trials in a capsicum crop near Warkworth, New Zealand, in January 2011 and two field trials in a

nectarine orchard near Lleida, Spain, in July 2013 were undertaken to determine if trap capture of Frankliniella

occidentalis (western flower thrips, WFT) and Thrips tabaci (onion thrips, OT) could be increased by alternative volatile

compounds beyond the known thrips attractant, methyl isonicotinate (MI). On blue sticky board traps in the crop in

New Zealand, none of six alternative compounds tested caught more thrips (mostly WFT, OT and two other species)

than the Control traps. In contrast to MI, catches with the alternative lures were mostly significantly lower. For both

trials in the orchard in Spain using white water traps, the highest numbers of WFT and OT were caught in traps with MI,

significantly higher than the Control (up to 11 x for both species) and higher than most of the nine alternative odour

compounds tested.

Wang, J. C., B. Zhang, J. P. Wang, H. G. Li, S. F. Wang, L. J. Sun and C. Y. Zheng (2014). "Effects of Heat Stress on Survival of

Frankliniella occidentalis (Thysanoptera: Thripidae) and Thrips tabaci (Thysanoptera: Thripidae)." Journal of Economic

Entomology 107(4): 1426-1433.

Temperature is known to play a crucial role in the population dynamics of insects. Insects have evolved different

mechanisms to resist unfavorable extreme temperatures. In recent years, western flower thrips, Frankliniella occidentalis

(Pergande) (Thysanoptera: Thripidae), and onion thrips, Thrips tabaci (Lindeman) (Thysanoptera: Thripidae), have caused

significant damage to vegetable crops. Because of global warming and expanding areas of vegetable cultivation, a

study of the effects of heat stress on these thrips species is warranted. We exposed the various developmental stages of

western flower thrips and onion thrips to temperatures of 41, 43, or 45 degrees C for 2, 6, 12, 24, or 36 h to determine



36

the effects of heat stress on survival. Our results showed that the heat resistance of nonadult western flower thrips was

greater than that of the nonadult onion thrips, and that the natural heat resistant ability was the primary factor in heat

resistance in western flower thrips. In contrast, the heat resistance of adult onion thrips was greater than that of the

adult western flower thrips, which was primarily the result of the ability of searching suitable microenvironment that

enabled the onion thrips to mitigate the effects of high temperatures more efficiently than the western flower thrips.

Our analysis of the differences in heat resistance between western flower thrips and onion thrips provides important

information for the development of thermal treatments for controlling western flower thrips and onion thrips.

Wu, M. X., H. Gotoh, T. Waters, D. B. Walsh and L. C. Lavine (2014). "Identification of an alternative knockdown resistance ( kdr)-

like mutation, M918L, and a novelmutation, V1010A, in the Thrips tabaci voltage-gated sodium channel gene." Pest

Management Science 70(6): 977-981.

BACKGROUNDKnockdown resistance (kdr) has been identified as a main mechanism against pyrethroid insecticides in

many arthropod pests including in the onion thrips, Thrips tabaci. To characterize and identify pyrethroid-resistance in

onion thrips in Washington state, we conducted insecticide bioassays and sequenced a region of the voltage gated

sodium channel gene from several different T. tabaci populations. RESULTSField collected Thrips tabaci were found to

have large variations in resistance to the pyrethroid insecticide lambda-cyhalothrin. We identified two single nucleotide

substitutions in our analysis of a partial sequence of the T. tabaci voltage-gated sodium channel gene. One mutation

resulted in the non-synonymous substitution of methionine with leucine (M918L), which is well known to be

responsible for super knockdown resistance in some pest species. Another non-synonymous substitution, a valine (GTT)

to alanine (GCT) replacement at amino acid 1010 (V1010A) was identified in our study and was associated with lambda-

cyhalothrin resistance. CONCLUSIONWe have characterized a known kdr mutation and identified a novel mutation in

the voltage-gated sodium channel gene of Thrips tabaci associated with resistance to lambda-cyhalothrin. This gene

region and these mutations are expected to be useful in the development of a diagnostic test to detect kdr resistance

in many onion thrips populations. (c) 2013 Society of Chemical Industry

Wu, S. Y., Y. L. Gao, X. N. Xu, E. D. Wang, Y. J. Wang and Z. R. Lei (2014). "Evaluation of Stratiolaelaos scimitus and Neoseiulus

barkeri for biological control of thrips on greenhouse cucumbers." Biocontrol Science and Technology 24(10): 1110-1121.

Stratiolaelaos scimitus Berlese (Acari: Laelapidae) is an important soil-dwelling predatory mite used to control thrips

and it is necessary to explore its potential predation capacity. In the present study, the functional response for S.

scimitus on the pupae of Frankliniella occidentalis Pergande was examined. In addition, the effects of released S.

scimitus for the control of Thrips tabaci Lindeman and F. occidentalis on greenhouse cucumber were evaluated, and

compared with that of the common predator Neoseiulus barkeri Hughes (Acari: Phytoseiidae). The results showed that

S. scimitus exhibited a Holling type II functional response on thrips pupae. The greenhouse study indicated that the

release of N. barkeri and S. scimitus separately at the density of 250 mites/m(2) suppressed the population growth of

thrips. In comparison with control plots, N. barkeri and S. scimitus reduced the population of T. tabaci by 76% and 64%

in six weeks, respectively. Releases of N. barkeri and S. scimitus led to a reduction in F. occidentalis by 41% and 43%,

respectively. Significantly lower densities of both thrips species per leaf were recorded in treatments of individual

releases of N. barkeri or S. scimitus than that in the control plots. The findings highlight the potential for utilising N.

barkeri and S. scimitus as biological control agents of T. tabaci and F. occidentalis, respectively.

Articles parus avant 2014

Aguilar-Fenollosa, E. and J. A. Jacas (2013). "Effect of ground cover management on Thysanoptera (thrips) in clementine

mandarin orchards." Journal of Pest Science 86(3): 469-481.

Conservation biological control by means of ground cover offers an interesting alternative to chemical control. A

complex of Thysanoptera (thrips) species inhabits citrus, some of which are considered pests. This study investigated

the effect of ground cover management on thrips species composition, distribution, and seasonal abundance in four

commercial clementine mandarin (Citrus clementina Tanaka) orchards. Three soil management systems were compared:



37

resident vegetation, Festuca arundinacea Schreber (Poales: Poaceae), and bare soil. Cover management affected thrips

species diversity and abundance. Two of the main species causing fruit damage in Spanish citrus, Frankliniella

occidentalis (Pergande) and Thrips tabaci Lindeman, were abundant in the resident ground cover. However, their

abundance was strongly depressed in the F. arundinacea cover. The resident vegetation cover could provide a range of

suitable host plants supporting populations of potential thrips pest species beyond the citrus blooming period. The F.

arundinacea cover, which hosted Poaceae-specific thrips species, could also provide alternative food sources for

Phytoseiidae mites. These predatory mites could reduce populations of potential thrips and other citrus pests below

economic injury level. Our results confirm the suitability of F. arundinacea as a cover crop for clementine mandarins.

Akram, M., F. Hafeez, M. Farooq, M. Arshad, M. Hussain, S. Ahmed, K. Zia and H. A. A. Khan (2013). "A CASE TO STUDY

POPULATION DYNAMICS OF Bemisia tabaci AND Thrips tabaci ON Bt AND NON-Bt COTTON GENOTYPES." Pakistan Journal of


Studies were conducted to investigate the performance of eight Bt and five non-Bt cotton genotypes against whitefly

and thrips and impact of abiotic factors on the population fluctuation of these sucking pests, at Cotton Research

Station, Multan, during 2010 and 2011. The results exhibited that Bt genotypes found more susceptible host for the

whitefly and thirps than non-Bt genotypes, during the course of years of study. Among Bt genotypes, maximum and

minimum temperature showed significant and positive effect on whitefly population whereas relative humidity exerted

negative effect during 2010. During 2011, the effect of all the factors was non significant. On cumulative basis, there

was positive correlation between population of whitefly and minimum temperature. But in case of non-Bt, it has

negative with maximum temperature whereas relative humidity had a positive effect on whitefly population. Similar

trend was observed for thrips population on Bt varieties during both years but on non-Bt varieties only minimum

temperature exerted strong positive impact on thrips population. Hierarchical regression models for whitefly and thrips

revealed that minimum temperature was the most important factor ( Bt and non-Bt varieties). Maximum temperature

was the major contributing factor for whitefly fluctuation on Bt varieties during 2010.

Balint, J., N. Burghardt, M. Hohn, B. Penzes and J. Fail (2013). "Does Epidermal Thickness Influence White Cabbage Resistance

against Onion Thrips (Thrips tabaci)?" Notulae Botanicae Horti Agrobotanici Cluj-Napoca 41(2): 444-449.

Present studies were made to investigate the association between epidermal thickness and resistance of white cabbage

against onion thrips, Thrips tabaci Lindeman, 1889 (Thysanoptera: Thripidae). Six white cabbage varieties including

three susceptible (Green Gem; 'Hurricane' and 'Quisor') and three resistant to onion thrips ('Balashi', 'Bloktor' and

'Rand') were involved in the studies. Additionally, the extent of antixenotic resistance during head formation and the

level of thrips damage at harvest were also assessed and compared between varieties. A higher density of onion thrips

was observed on susceptible than on resistant varieties. The results indicate that the epidermis is of the same thickness

in susceptible white cabbage varieties as in resistant ones; therefore, we conclude that the thicknesses of either the

adaxial or the abaxial part of the epidermis of head-forming leaves is not responsible for cabbage resistance to thrips.

The study thus confirms that annxenotic resistance of white cabbage to thnps is not determined by epidermal

thickness.

Balint, J., B. V. Nagy and J. Fail (2013). "Correlations between Colonization of Onion Thrips and Leaf Reflectance Measures across

Six Cabbage Varieties." Plos One 8(9).

The main purpose of this study was to reveal if the UV-A, and visible light reflection of leaves of white cabbage varieties

is correlated to resistance against onion thrips. The antixenotic resistance (AR) against onion thrips and thrips damage

differed between varieties Balashi, Bloktor, Riana - considered resistant - and Green Gem, Hurricane, Quisor -

considered susceptible. The solar UV-A (340-400 nm) and visible (401-650 nm) light reflection of white cabbage leaves

were recorded. Correlation between AR against onion thrips and reflection of leaves in UV-A and visible range of the

studied white cabbage varieties were computed. According to the AR evaluation onion thrips density was always higher

on susceptible than on resistant varieties. The UV-A light reflection of head forming leaves and the contrast between

head and exterior leaves (H/E) was negatively correlated with onion thrips host preference at an early stage of cabbage

head formation. The visible light reflection of both head forming and exterior leaves was also negatively correlated with

onion thrips host preference. Susceptible varieties had greater damage ratings at harvest than resistant ones and

positive correlations were observed between AR and damage. AR against onion thrips may be affected by differences in



38

reflection of cabbage leaves at an early growth stage. It is suggested that more intensive reflection of leaves and/or

higher contrast values between the reflectance intensity of head versus outer leaves made the resistant varieties less

attractive to onion thrips. Our results reported here provide the first evidence of negative correlation between UV-A

and visible reflection of leaves and AR of white cabbage against a dangerous insect pest, opening new perspectives for

understanding the role of reflection by plant leaves in pest management.

Birithia, R., S. Subramanian, H. R. Pappu, J. Muthomi and R. D. Narla (2013). "Analysis of Iris yellow spot virus replication in vector

and non-vector thrips species." Plant Pathology 62(6): 1407-1414.

Iris yellow spot virus (IYSV, genus Tospovirus) is a viral disease of bulb and seed onion crops and is transmitted by

Thrips tabaci. Foliage damage of up to 75% has been reported in Kenya and Uganda. In this study, the rate of IYSV

replication in the larva, pupa and adult stages of T.tabaci and other non-vector thrips species and colour forms such as

Frankliniella occidentalis, F.schultzei (dark) and F.schultzei (pale) was evaluated by monitoring relative levels of

nucleocapsid (N) and non-structural (NSs) proteins using N- and NSs-specific antibodies. The effect of IYSV replication

on mortality of thrips was also determined. N protein levels increased in all three stages of IYSV-fed T.tabaci, indicating

replication of IYSV. In IYSV-fed non-vector thrips, the increase of N protein levels in the larval stage was lower than

IYSV-fed T.tabaci but higher than their healthy counterparts. The N protein levels did not increase at pupal and adult

stages. NSs protein was not detected in first instar of either vector or non-vector thrips species. After a 4h post-

acquisition period, a significant increase in NSs proteins was only observed in IYSV-fed T.tabaci, clearly differentiating

vectors and non-vectors of IYSV. IYSV replication did not influence the survival of the vector thrips species, T.tabaci

populations or the non-vector thrips species. This study indicates the effectiveness of monitoring non-structural

proteins such as NSs, compared to nucleocapsid proteins, for differentiating vectors and non-vectors of IYSV.

Buckland, K., J. R. Reeve, D. Alston, C. Nischwitz and D. Drost (2013). "Effects of nitrogen fertility and crop rotation on onion

growth and yield, thrips densities, Iris yellow spot virus and soil properties." Agriculture Ecosystems & Environment 177: 63-74.

Onion thrips and Iris yellow spot virus (IYSV) are two primary yield reducing factors in onion production worldwide.

Current management practices rely on heavy use of insecticides and fertilizers, threatening the sustainability of onion

systems. Little is known about how cultural practices such as reduced fertility, soil biostimulants, and crop rotation

affect onion yield, thrips densities, soil properties, and IYSV incidence. In a replicated field experiment, reduced nitrogen

(N) (134 kg N ha(-1), one-third the standard grower rate), slightly decreased yield and onion size. Adult thrips

populations were 23 to 31% lower in the reduced as compared to standard N (402 kg N ha(-1)) and biostimulant

treatment, respectively. Growing onions following a one year cycle in corn rather than wheat reduced onion thrips in

one of two years. The addition of a biostimulant had no effect on soil properties, but may have slightly increased yield,

attracted adult thrips, and increased thrips populations. lYSV incidence was not influenced by fertilizer rate or crop

rotation. Soil microbial biomass and readily mineralizable carbon were greater following wheat, while soil nitrate (NO3-)

accumulation was greater in standard N treatments. Soil microbial activity, as measured by dehydrogenase enzyme

potential, may have been adversely affected by high N rates. Results suggest that reduced N, without biostimulant,

sustained onion yields, decreased onion thrips densities and potential for IYSV incidence, created a more favorable soil

environment for microbial activity, and reduced the risk of NO3- leaching (c) 2013 Elsevier B.V. All rights reserved.

Fail, J., M. E. Deutschlander and A. M. Shelton (2013). "Antixenotic Resistance of Cabbage to Onion Thrips (Thysanoptera:

Thripidae). I. Light Reflectance." Journal of Economic Entomology 106(6): 2602-2612.

Onion thrips (Thrips tabaci Lindeman) has become a significant pest of cabbage (Brasssica oleracea L.) in regions with a

dry continental climate. Thrips-resistant cabbage varieties have been developed in breeding programs, but the

mechanisms of resistance remain largely unknown. Antixenosis, one of the three resistance mechanisms, may play a

role but no plant trait has been identified as a source of antixenosis. A series of studies were conducted to identify

resistance mechanisms in this insectDcrop interaction and to seek plant traits that were correlated to resistance. In this

first article of the series, the result of studying antixenosis and overall resistance of cabbage and the correlation

between antixenosis and light refiectance characteristics are reported. There were distinct differences in the overall

resistance to thrips between the six cabbage varieties studied. There were more pronounced differences between

varieties based on the number of damaged head leaves compared with the use of damage ratings as a measure of

overall resistance. Varieties also differed in their level of antixenosis; proportional abundance of thrips adults on head-



39

forming leaves was more closely correlated to overall resistance of cabbage than actual thrips numbers. Some of the

variables computed from the recorded reflectance spectra of cabbage were correlated to thrips abundance on head-

forming leaves only in the first but not in the second year of this study, suggesting that either spectral characteristics

do not affect antixenosis or other variables may affect thrips' responses to spectral cues. Furthermore, multiple spray

applications of a kaolin particle-based product significantly changed the light reflectance characteristics of cabbage,

but it did not reduce the actual thrips abundance on head-forming leaves.

Jacobson, A. L., W. Booth, E. L. Vargo and G. G. Kennedy (2013). "Thrips tabaci Population Genetic Structure and Polyploidy in

Relation to Competency as a Vector of Tomato Spotted Wilt Virus." Plos One 8(1).

Knowledge of population-level genetic differences can help explain variation among populations of insect vectors in

their role in the epidemiology of specific viruses. Variation in competency to transmit Tomato spotted wilt virus (TSWV)

that exists among populations of Thrips tabaci has been associated with the presence of cryptic species that exhibit

different modes of reproduction and host ranges. However, recent findings suggest that vector competency of T. tabaci

at any given location depends on the thrips and virus populations that are present. This study characterizes the

population genetic structure of T. tabaci collected from four locations in North Carolina and examines the relationship

between population genetic structure and variation in TSWV transmission by T. tabaci. Mitochondrial COI sequence

analysis revealed the presence of two genetically distinct groups with one characterized by thelytokous,

parthenogenetic reproduction and the other by arrhenotokous, sexual reproduction. Using a set of 11 microsatellite

markers that we developed to investigate T. tabaci population genetic structure, we identified 17 clonal groups and

found significant genetic structuring among the four NC populations that corresponded to the geographic locations

where the populations were collected. Application of microsatellite markers also led to the discovery of polyploidy in

this species. All four populations contained tetraploid individuals, and three contained both diploid and tetraploid

individuals. Analysis of variation in transmission ofTSWV among isofemale lines initiated with individuals used in this

study revealed that 'clone assignment,' 'virus isolate' and their interaction significantly influenced vector competency.

These results highlight the importance of interactions between specific T. tabaci clonal types and specific TSWV isolates

underlying transmission of TSWV by T. tabaci.

Jacobson, A. L. and G. G. Kennedy (2013). "Specific Insect-Virus Interactions Are Responsible for Variation in Competency of

Different Thrips tabaci Isolines to Transmit Different Tomato Spotted Wilt Virus Isolates." Plos One 8(1).

Local adaptation between sympatric host and parasite populations driven by vector genetics appears to be a factor that

influences dynamics of disease epidemics and evolution of insect-vectored viruses. Although T. tabaci is the primary

vector of Tomato spotted wilt virus (TSWV) in some areas of the world, it is not an important vector of this economically

important plant virus in many areas where it occurs. Previous studies suggest that genetic variation of thrips

populations, virus isolates, or both are important factors underlying the localized importance of this species as a vector

of TSWV. This study was undertaken to quantify variation in transmissibility of TSWV isolates by T. tabaci, in the ability

of T. tabaci to transmit isolates of TSWV, and to examine the possibility that genetic interactions and local adaptation

contribute to the localized nature of this species as a vector of TSWV. Isofemale lines of Thrips tabaci from multiple

locations were tested for their ability to transmit multiple TSWV isolates collected at the same and different locations as

the thrips. Results revealed that the probability of an isofemale line transmitting TSWV varied among virus isolates, and

the probability of an isolate being transmitted varied among isofemale lines. These results indicate that the interaction

of T. tabaci and TSWV isolate genetic determinants underlie successful transmission of TSWV by T. tabaci. Further

analysis revealed sympatric vector-virus pairing resulted in higher transmission than allopatric pairing, which suggests

that local adaptation is occurring between T. tabaci and TSWV isolates.

Jima, T. A., H. Tekie and G. Tikubet (2013). "Effects of manure application and host plant spacing on the infestation level and

damage of Thrips tabaci Lindeman (Thysanoptera: Thripidae) in onion (Allium cepa)." African Entomology 21(2): 316-323.

The effect of manure application and host plant spacing on the infestation level and damage of Thrips tabaci in onion

were investigated under field conditions and in cage experiments. Manure applications before and at transplanting

were used in a factorial combination with three levels of plant spacing as treatments. Plots with no manure application

were included as controls. In field experiments, significantly fewer number of adults and nymphs of T tabaci per plant

were recorded in plants grown in soil with manure applied before transplanting at a rate of 20 t/ha. Plants grown



40

without manure application harboured significantly higher numbers of T. tabaci at 45 days after transplanting and late

growth stages. Plots that received manure application before transplanting (20 t/ha) with 20 x 30 cm and 20 x 25 cm

spacing showed markedly reduced mean thrips counts per plant, and had significantly higher leaf size compared to

those transplanted with manure application (20 t/ha) and at 20 x 30 cm plant spacing. The extent of damage incurred

on onion plants by natural infestation of T tabaci was mostly mild at 15 and 30 days after transplanting and

intermediate damage was recorded on plants at 45 days and late growth stages. On the other hand, plants in plots

without manure application and 20 x 20 cm and 20 x 25 cm spacing showed markedly reduced leaf size and had

intermediate damage at 15 and 30 days after transplanting and sustained severe attack as the crop matures. In cage

experiments, significantly lower mean number of larvae and adults were recorded from pots with manure application

before transplanting followed by at transplanting manure application as compared to plots with no manure application.

This study illustrated that optimum organic manure application at the appropriate time had an effect on the infestation

level of onion thrips. Therefore, manure application three months before transplanting was found to be the critical

period for optimum plant growth and had the lowest onion thrips infestation.

Karar, H., G. Abbas, A. Hameed, M. F. Shahzad, G. Ahmad, A. Ali and M. Saleem (2013). "RELATIVE SUSCEPTIBILITY OF ONION

(Allium cepa) GENOTYPES OF PAKISTAN TO ONION THRIPS (Thrips tabaci) (THYSANOPTERA: THRIPIDAE)." Pakistan Journal of


The present studies were conducted during 2008-2010, to test the susceptibility of onion crop to a globally recognized

pest of onion Thrips tabaci Lindeman. The results revealed that genotype, VRIO-3'was highly susceptible one having

181.7 thrips per plant. The genotype 'Desi Large. was moderately resistant having 94.2 thrips per plant. Survey of

susceptibility of onion cultivars revealed that there is a scarcity of thrips resistant varieties in agro-ecosystem of Punjab,

Pakistan. So, thrips resistant varieties must be developed to combat the menace to thrips attack. This study provides a

guideline to the genetic engineers and conventional breeders.

Kijima, K., S. Ohno, T. Ganaha-Kikumura and T. Shimizu (2013). "Control of Flower Thrips, Flankliniella intonsa (Trybom) and

Sweetpotato Whitefly, Bemisia tabaci (Gennadius) on Sweet Pepper in Greenhouses in Okinawa, Southwestern Japan, by

Releasing Polyphagous Indigenous Predator, Campylomma chinensis Schuh (Hemiptera: Miridae)." Japanese Journal of Applied

Entomology and Zoology 57(3): 167-175.

Field experiments were replicated three times from 2008 to 2011 to evaluate the effectiveness of a polyphagous

indigenous predator, Campylomma chinensis, to control Frankliniella intonsa and Bemisia tabaci in sweet pepper

greenhouses in Okinawa, southwestern Japan. C. chinensis was released three or four times in each trial, with a density

of one adult per plant per release (0.5 adults/m(2)). The C. chinensis population was successfully established in the

greenhouse in all experiments. The density of F. intonsa in the greenhouse where C. chinensis was released was

consistently lower than that in the non-released greenhouse in all experiments. The density of B. tabaci in the

greenhouse where C. chinensis was released was lower than that in the non-released greenhouse except for one

experiment in which the density of B. tabaci did not increase in the non-released greenhouse. The percentage of fruit

damaged by F. intonsa and B. tabaci was also examined in two of the three experiments; the percentage in the C.

chinensis-released greenhouse was consistently lower than that in the non-released greenhouse in both experiments.

These results strongly suggest that C. chinensis is a promising biological control agent for F. intonsa and B. tabaci in

sweet pepper greenhouse cultivation.

Kobayashi, K. and E. Hasegawa (2013). "Isolation of microsatellite loci from the onion thrips, Thrips tabaci." Journal of Insect

Science 13.

Thrips tabaci Lindeman (Thysanoptera: Thripidae), a cosmopolitan pest insect, is subdivided into at least three genetic

lineages that have different biological characters, such as reproductive mode and resistibility to insecticides. Since the

lineages are discriminated only by mitochondrial DNA, there is a possibility of gene flow among lineages at the

genomic level. Nine polymorphic microsatellite loci were newly isolated from the taxon. Moderate to high levels of

polymorphism were observed, with numbers of alleles ranging from 6 to 12 in 51 individuals. The mean observed and

expected heterozygosities ranged from 0.1373 to 0.3725 and 0.5381 to 0.7748, respectively. Contrary to the expectation

under Hardy-Weinberg's equilibrium, six of the nine loci exhibited a reduction to homozygosities. However, we

41

confirmed that alleles in all the loci were inherited as Mendeilan characteristics. These new loci will be useful to explore

discrimination of lineages and population genetics in this species.

Kobayashi, K. and E. Hasegawa (2013). "Discrimination of reproductive forms of Thrips tabaci (Thysanoptera: Thripidae) by PCR

with sequence specific primers (vol 105, pg 555, 2012)." Journal of Economic Entomology 106(2): VI-VII.

Lebedev, G., F. Abo-Moch, G. Gafni, D. Ben-Yakir and M. Ghanim (2013). "High-level of resistance to spinosad, emamectin

benzoate and carbosulfan in populations of Thrips tabaci collected in Israel." Pest Management Science 69(2): 274-277.

BACKGROUND: The onion thrips, Thrips tabaci Lindeman, is a major pest of several crop plants in the genus Allium,

such as onions, garlic and chives. In Israel, these crops are grown in open fields and in protected housing. This thrips is

usually controlled by the application of chemical insecticides. In recent years, spinosad, emamectin benzoate and

carbosulfan have been the major insecticides used for the control of the onion thrips. In the last 4 years, growers of

chives and green onion from several regions of Israel have reported a significant decrease in the efficacy of insecticides

used to control the onion thrips. RESULTS: The susceptibility of 14 populations of the onion thrips, collected mainly

from chives between the years 2007 and 2011, to spinosad, emamectin benzoate and carbosulfan was tested using a

laboratory bioassay. The majority of the populations showed significant levels of resistance to at least one of the

insecticides. LC50 values calculated for two of the studied populations showed that the resistance factor for spinosad

compared with the susceptible population is 21 393, for carbosulfan 54 and for emamectin benzoate 36. Only two

populations, collected from organic farms, were susceptible to the insecticides tested. CONCLUSION: This is the first

report of a high resistance level to spinosad, the major insecticide used to control the onion thrips. Resistance cases to

spinosad were associated with failures to control the pest. Populations resistant to spinosad also had partial or

complete resistance to other insecticides used for controlling the onion thrips. Copyright (C) 2012 Society of Chemical

Industry

Nault, B. A., C. L. Hsu and C. A. Hoepting (2013). "Consequences of co-applying insecticides and fungicides for managing Thrips

tabaci (Thysanoptera: Thripidae) on onion." Pest Management Science 69(7): 841-849.

Background Insecticides and fungicides are commonly co-applied in a tank mix to protect onions from onion thrips,

Thrips tabaci Lindeman, and foliar pathogens. Co-applications reduce production costs, but past research shows that an

insecticide's performance can be reduced when co-applied with a fungicide. An evaluation was made of the effects of

co-applying spinetoram, abamectin and spirotetramat with commonly used fungicides, with and without the addition

of a penetrating surfactant, on onion thrips control in onion fields. Results Co-applications of insecticides with

chlorothalonil fungicides reduced thrips control by 25-48% compared with control levels provided by the insecticides

alone in three of five trials. Inclusion of a penetrating surfactant at recommended rates with the insecticide and

chlorothalonil fungicide did not consistently overcome this problem. Co-applications of insecticides with other

fungicides did not interfere with thrips control. Conclusion Co-applications of pesticides targeting multiple organisms

should be examined closely to ensure that control of each organism is not compromised. To manage onion thrips in

onion most effectively, insecticides should be applied with a penetrating surfactant, and should be applied separately

from chlorothalonil fungicides.(c) 2012 Society of Chemical Industry

Saleem, M. W., S. Ahmed, W. Wakil and S. T. Sahi (2013). "Resistance to Thrips (Thrips tabaci) in Bt Cotton Genotypes in Punjab,

Pakistan, Based on Population Dynamics and Plant Morpho-chemical Properties." International Journal of Agriculture and

Biology 15(2): 331-336.

The present study was conducted to evaluate twenty Bt-cotton genotypes for their resistance to thrips, Thrips tabaci

(Lind.) under field conditions in Faisalabad, Pakistan. Thrips population seedling(-1) and leaf(-1) was recorded from

each genotype in 2008 and from these data, six genotypes were selected for final screening trial in 2009. Thrips density

per leaf was correlated with abiotic factors, morphological and chemical characteristics to establish basis of resistance

mechanism. Results showed that AA-802 and VH-259 with 3.40 and 4.45 thrips per leaf were resistant and susceptible

genotypes, respectively and two had significant difference between each other (p<0.05). Weather factors were non-

significantly correlated with leaf thrips populations except relative humidity, which was positively and significantly

correlated (r=0.451; p = 0.014). Hair density on leaf midrib (r=0.850) and vein (r=0.762) were positively whereas

gossypol gland on leaf lamina (r=0.462) were positively correlated with leaf(-1) thrips population. Moisture contents,



42

total minerals, protein, lipids, reducing sugar, calcium, magnesium, and zinc were significantly correlated with thrips

population. These findings are discussed in comparison with basis of resistance on non-Bt-cotton varieties reported

earlier, in the study area. (C) 2013 Friends Science Publishers

Smith, H. A., C. M. Macvean, C. Bailey and J. M. Benavente (2013). "FABA BEANS ARE NOT A GOOD TRAP CROP FOR THRIPS

(THYSANOPTERA: THRIPIDAE) IN SNOW PEAS IN GUATEMALA." Florida Entomologist 96(4): 1603-1605.

Snow peas intercropped with faba beans in the Guatemalan highlands did not show a reduction in thrips densities

compared to snow peas in monoculture, and faba bean does not appear to function as a trap crop. Thrips species

composition differed markedly on each host, which may largely explain the results. Thrips tabaci was predominant on

snow peas, while Frankliniella occidentalis was the main species on faba beans.

Szostek, S. and H. Schwartz (2013). "Onion thrips (Thrips tabaci) and Iris yellow spot virus survival throughout Colorado winters."

Phytopathology 103(6): 142-142.

Westmore, G. C., F. S. Poke, G. R. Allen and C. R. Wilson (2013). "Genetic and host-associated differentiation within Thrips tabaci

Lindeman (Thysanoptera: Thripidae) and its links to Tomato spotted wilt virus-vector competence." Heredity 111(3): 210-215.

Of eight thelytokous populations of onion thrips (Thrips tabaci) collected from potato (three populations), onion (four)

or Chrysanthemum (one) hosts from various regions of Australia, only those from potato were capable of transmitting

Tomato spotted wilt virus (TSWV) in controlled transmission experiments. Genetic differentiation of seven of these eight

populations, and nine others not tested for TSWV vector competence, was examined by comparison of the DNA

sequences of mitochondrial cytochrome oxidase subunit 1 (COI) gene. All Australian populations of T. tabaci grouped

within the European 'L2' clade of Brunner et al. (2004). Within this clade the seven populations from potato, the three

from onion, and the four from other hosts (Chrysanthemum, Impatiens, lucerne, blackberry nightshade) clustered as

three distinct sub-groupings characterised by source host. Geographical source of thrips populations had no influence

on genetic diversity. These results link genetic differentiation of thelytokous T. tabaci to source host and to TSWV

vector capacity for the first time.

Wu, S. Y., Y. L. Gao, X. N. Xu, Y. P. Zhang, J. Wang, Z. R. Lei and G. Smagghe (2013). "Laboratory and greenhouse evaluation of a

new entomopathogenic strain of Beauveria bassiana for control of the onion thrips Thrips tabaci." Biocontrol Science and

Technology 23(7): 794-802.

The onion thrips Thrips tabaci is one of the most important pests of greenhouse and open-field broccoli, onion and

other crops. However, the current strategy of using synthetic pesticides for its control is inadequate and unsustainable,

leading to a growing interest in novel and effective biological control alternatives such as entomopathogenic fungi.

Among 20 isolates of Beauveria bassiana tested for virulence against T. tabaci in laboratory bioassays, we found strain

SZ-26 as the most potent, causing 83-100% mortality in adults at 1x10(7) mL(-1)conidia after 4-7 days. Further

experiments in greenhouses showed the strain SZ-26 significantly lowered the numbers of adult and larval stages.

Bag, S., S. I. Rondon and H. R. Pappu (2012). "Seasonal dynamics of Iris yellow spot virus transmitters among Thrips tabaci

populations from onion fields." Phytopathology 102(7): 8-8.

Broughton, S. and J. Harrison (2012). "Evaluation of monitoring methods for thrips and the effect of trap colour and

semiochemicals on sticky trap capture of thrips (Thysanoptera) and beneficial insects (Syrphidae, Hemerobiidae) in deciduous

fruit trees in Western Australia." Crop Protection 42: 156-163.

Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), plague thrips (Thrips imaginis

Bagnall), and onion thrips (Thrips tabaci Lindeman) are pests of deciduous fruit trees in Australia. Yellow sticky traps

and tapping buds and flowers for thrips are currently recommended for monitoring, but it is not known whether one

method is more efficient than the other, or if selectivity could be optimised by trap colour, or addition of

semiochemicals Thripline(ams)(R) or Lurem-TR lures to traps. The number and species of thrips caught by trapping and

tapping of flowers and leaves, on different trap colours (black, blue, green, red, yellow, white), including a control (clear)

and thrips semiochemicals, were evaluated in a series of trials in commercial deciduous fruit orchards in the Perth Hills,

Western Australia. There was poor correlation between thrips caught on traps and tapping samples (R-2 = 0.00 -0.05),



43

with tapping less likely to trigger the action threshold and yielding less than 1% of the number of thrips caught on

sticky traps. More thrips (E occidentalis, T. imaginis and T. tabaci) were caught on blue, yellow and white bases, than on

clear, red, green or black bases. On commercially available sticky traps, seven times more E occidentalis were caught on

'Seabright blue' traps than yellow. The addition of semiochemicals increased capture of E occidentalis by three times on

baited compared to unbaited traps, on yellow and 'Seabright' blue traps. Thripline(ams)(R) attracted E occidentalis, but

had no effect on the capture of T imaginis or T tabaci, whilst Lurem-TR attracted more E occidentalis and also increased

the capture of T. imaginis. More beneficial insects including brown lacewings (Micromus tasmaniae (Walker)) and

hoverflies (Melangyna viridiceps (Macquart)) were caught on blue trap bases (1.6 times more) than other trap base

colours. No beneficial insects were present during the Thripline(ams)(R) experiment, whilst Lurem-TR increased trap

capture of brown lacewings by 1.3 times. A monitoring system incorporating blue sticky traps in conjunction with

Thripline(ams)(R) would be more selective at detecting and monitoring E occidentalis in deciduous fruit in Australia.

Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.

Diaz-Montano, J., J. Fail, M. Deutschlander, B. A. Nault and A. M. Shelton (2012). "Characterization of Resistance, Evaluation of

the Attractiveness of Plant Odors, and Effect of Leaf Color on Different Onion Cultivars to Onion Thrips (Thysanoptera:

Thripidae)." Journal of Economic Entomology 105(2): 632-641.

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a worldwide pest of onion, Allium cepa L. In field

studies on onion resistance conducted in 2007 and 2008 using 49 cultivars, 11 showed low leaf damage by T. tabaci. In

laboratory studies, the 11 cultivars, along with two susceptible checks and four additional cultivars, were evaluated to

characterize resistance to T. tabaci and to determine if color and/or light reflectance were associated with resistance to

T. tabaci. No-choice tests were performed with adults and the numbers of eggs and larvae were counted on each

cultivar after three and 10 d, respectively. In choice tests in which all cultivars were planted together in a circle in a

single pot, 100 adults were released and the number of adults on each plant was evaluated 24 h later. The behavioral

response of walking T. tabaci adults to plant odors was studied in a glass Y-tube olfactometer. The reflectance spectrum

of leaves was measured using a UV-VIS spectrophotometer. Results indicate that resistant cultivars showed an

intermediate-high antibiotic effect to T. tabaci and all of them showed a very strong antixenotic effect. There were no

significant preferences in the response of walking T. tabaci adults to plant odors. The two susceptible cultivars had the

highest values of leaf reflectance for the first (275-375 nm) and second (310-410 nm) theoretical photopigment-system

of T. tabaci, and these values were significantly different from most resistant cultivars. These results suggest a strong

response of T. tabaci to onion cultivars with higher reflectance in the ultraviolet range (270-400 nm). Overall, these

results appear promising in helping to identify categories of resistance to T. tabaci in onions that can be used in

breeding programs.

Diaz-Montano, J., M. Fuchs, B. A. Nault and A. M. Shelton (2012). "RESISTANCE TO ONION THRIPS (THYSANOPTERA: THRIPIDAE)

IN ONION CULTIVARS DOES NOT PREVENT INFECTION BY IRIS YELLOW SPOT VIRUS FOLLOWING VECTOR-MEDIATED

TRANSMISSION." Florida Entomologist 95(1): 156-161.

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a global pest of onion, Allium cepa L., and the

principal vector of Iris yellow spot virus (IYSV) that can cause 100% crop losses. The purpose of this study was to

evaluate onion cultivars resistant to T tabaci feeding damage for their reaction to IYSV following exposure to

viruliferous T tabaci in both laboratory and field experiments. In the laboratory experiment, virus-free onion cultivars

grown in pots were infested with 32 T tabaci second instars collected from onions in an IYSV-infected field. In the

complementary field experiment, virus-free onion plants in pots were moved to an onion field where IYSV was present.

In both laboratory and field trials, plants were tested for IYSV by DAS-ELISA after 2 and 3 wk, respectively. Although

plants were exposed to T tabaci for a short period, IYSV was detected in all onion cultivars with the percentage of

infected plants varying from 3 to 25% and 37 to 70% in the laboratory and field experiments, respectively. IYSV

infection levels did not differ statistically between thrips-susceptible and thrips-resistant onion cultivars in laboratory

and field experiments.

Dutta, B., R. D. Gitaitis, R. Srinivasan, D. Langston and A. Barman (2012). "Acquisition and transmission of Pantoea ananatis and

Pantoea agglomerans (causal agents of center rot of onion) by onion thrips (Thrips tabaci)." Phytopathology 102(7): 33-33.



44

Fiaz, M., A. Hameed, M. ul Hasan and W. Wakil (2012). "Efficacy of Plant Extracts on Some Cotton (Gossypium hirsutum) Pests:

Amrasca bigutulla bigutulla Ishida and Thrips tabaci Lindeman." Pakistan Journal of Zoology 44(1): 277-283.

Jassids (Amrasca bigutulla bigutulla Ishida) and thrips (Thrips tabaci Lindeman) have become major pests

in,subcontinent due to invasion of Bt cotton. Insecticidal resistance by these pests is another threat, keeping in view

these facts five plants derivative viz., Lemon oil, Bittergourd (Momordica charantia L) extract, bakain (Melia azadarach)

leaf extract, Neem (Azadirachta indica) oil and Neem (A. indica) leaf extract, each at a 5% concentration were tested for

their repellency and phagodeterrent effects against jassid and thrips with three applications upon emergence of pest

population. The variety CIM-496 was sown during 2008 at experimental area of the department of Agriculture,

Entomology, University of Agriculture, Faisalabad. Six treatments including control were maintained following

Randomized Complete Block Design with three replications. The plant derivatives were applied three times at the

interval of 20 days. Data were recorded at 24, 48, 72 hrs, and 7 days intervals after application of each treatment.

Results revealed that lemon oil proved to be the most effective plant derivative against jassid followed by neem oil,

bakaine, bitter gourd and neem leaf extract in all three applications. In case of thrips all plant derivatives controlled

thrips,population significantly. Bakain leaf extract, neem oil and neem leaf extract. showed comparatively higher

mortality of the thrips as compared to other plant derivatives. Studies concluded that plant derivatives can be good

alternatives to chemical pesticides to control sucking pests complex especially jassids and thrips in Pakistan

Kobayashi, K. and E. Hasegawa (2012). "Discrimination of Reproductive Forms of Thrips tabaci (Thysanoptera: Thripidae) by PCR

With Sequence Specific Primers." Journal of Economic Entomology 105(2): 555-559.

In agriculture, although it is important to identify species of pest insects, the morphological identification is often

difficult. DNA genotyping is useful for the identification of species in morphologically indiscriminable species. Thrips

tabaci (Lindeman) can be divided into two reproductive forms (arrhenotoky and thelytoky, each of which different in

pesticide resistance) but morphological discrimination is not possible. Here, we establish a simple method to

discriminate the strains based on their mitochondrial DNA sequences. Phylogenetic analysis including the T. tabaci and

congeneric species provided ancestor sequences of each strain of T. tabaci. Based on the ancestor sequences, we

developed a primer set that include strain specific primers on sense strand and common primer on anti sense strand.

Using this primer set, the strains of 196 individuals of T. tabaci were successfully assigned to each of genotypic forms.

As the phylogeny and ancestor sequences were based on worldwide samples, this method will work well on most

populations around the world.

Lucas, M. R., J. D. Ehlers, P. A. Roberts and T. J. Close (2012). "Markers for Quantitative Inheritance of Resistance to Foliar Thrips

in Cowpea." Crop Science 52(5): 2075-2081.

Molecular assisted breeding is currently constrained by the lack of breeder-friendly trait-associated markers, especially

among lesser studied crops. Recent advances in genomic technology are being applied to many important crop

species, promoting the development of robust marker-trait associations. Regions of the cowpea [Vigna unguiculata (L.)

Walp.] genome controlling the quantitative resistance to feeding by foliar thrips (Thrips tabaci and Frankliniella

schultzei) were tagged by coupling phenotypic observations from two recombinant inbred line populations generated

from domesticated parents. Three regions (Thr-1, Thr-2, and Thr-3) explaining approximately 32, 24, and 9%,

respectively, of the phenotypic variation were tagged with several expressed sequence tag (EST)-derived single

nucleotide polymorphism (SNP) markers and are presented here as haplotypes composed of multiple SNP markers.

Regions within the soybean [Glycine max (L.) Merr.] genome that are syntenic to cowpea Thr-1, Thr-2, and Thr-3 are

also reported.

Mautino, G. C., L. Bosco and L. Tavella (2012). "Integrated management of Thrips tabaci (Thysanoptera: Thripidae) on onion in

north-western Italy: basic approaches for supervised control." Pest Management Science 68(2): 185-193.

BACKGROUND: Thrips tabaci Lindeman (Thysanoptera: Thripidae) is a major pest on onion, Allium cepa L., worldwide. In

2010, research was conducted in a commercial onion field in north-western Italy in order (i) to evaluate the efficacy of

different insecticides and of the SAR activator acibenzolar-S-methyl, (ii) to correlate thrips infestation levels with bulb

size and weight at harvest and (iii) to implement a reliable thrips sampling method. Efficacy of the three active

ingredients spinosad, lambda-cyhalothrin and acibenzolar-S-methyl on local thrips populations were also evaluated in

laboratory bioassays. RESULTS: During field surveys, the highest and the lowest thrips infestations were observed in



45

plots treated with lambdacyhalothrin and with spinosad and acibenzolar-S-methyl respectively. The effectiveness of

spinosad was also confirmed in laboratory bioassays. At harvest, bulb size and weight did not significantly differ

between treatments. A high correlation with visual inspection made plant beating a suitable sampling method for

routine practice, enabling a good estimate of thrips infestation. CONCLUSION: Damage caused by thrips is often not

severe enough to warrant the frequent pesticide applications the crops receive in north-western Italy. The use of

spinosad and acibenzolar-S-methyl is suggested as an alternative to conventional insecticides for the preservation of

natural enemies. (C) 2011 Society of Chemical Industry

Morishima, M., T. Fukuda and T. Waki (2012). "Seasonal Occurrence of Thrips tabaci (Lindeman) and the Incidence of Necrotic

Streak Disease Caused by Iris yellow spot virus (IYSV) on Chinese Chive Allium tuberosum." Japanese Journal of Applied

Entomology and Zoology 56(3): 95-101.

We investigated the seasonal occurrence of Thrips tabaci (Lindeman), transmitter and viruliferous thrips of Iris yellow

spot virus (IYSV), and the incidence of necrotic streak disease caused by IYSV in Chinese chive fields in Tochigi

Prefecture, to establish a control system for the disease. The seasonal occurrence of T. tabaci had two peaks. The higher

was in mid-June and the other was in mid-August to early September in 2007 and 2008. Transmitter and viruliferous

thrips gradually increased from June, peaked between July and October and declined to low levels from December to

May. The disease developed after the number of thrips increased, raising the incidence of transmitters and viruliferous

individuals in the field. In contrast, symptoms were only observed from July to October and did not develop in new

leaves or petioles after cutting plants off above the ground. Moreover, we found viruliferous individuals (1.9%) in the

Chinese chive nursery in May 2008, and symptomless infection in the field, based on the detection of IYSV by DAS-

ELISA. These results suggested that controlling the population density of thrips in mid-May prevented the development

of the disease in Tochigi Prefecture.

Nielsen, S. L., A. Enkegaard, M. Nicolaisen, P. Kryger, M. V. Marn, I. M. Plesko, A. Kahrer and R. A. Gottsberger (2012). "No

transmission of Potato spindle tuber viroid shown in experiments with thrips (Frankliniella occidentalis, Thrips tabaci), honey

bees (Apis mellifera) and bumblebees (Bombus terrestris)." European Journal of Plant Pathology 133(3): 505-509.

Experiments were carried out to investigate whether Potato spindle tuber viroid (PSTVd) can be transmitted intra- and

inter-species from infected Solanum jasminoides to non-infected S. jasminoides and S. esculentum and from infected

Brugmansia sp. to S. esculentum by Frankliniella occidentalis and Thrips tabaci by leaf sucking. The F. occidentalis

experiments also included feeding on pollen prior to feeding on PSTVd-infected leaf. No thrips-mediated transmission

of PSTVd was recorded. The possibility of PSTVd transmission by Apis mellifera and Bombus terrestris during their

feeding/pollinating activities within ornamentals and from ornamentals to S. esculentum was included, and no bee-

mediated transmission was recorded.

Pizzol, J., D. Nammour, P. Hervouet, C. Poncet, N. Desneux and P. Maignet (2012). "Population Dynamics of Thrips and

Development of an Integrated Pest Management Program Using the Predator Franklinothrips vespiformis." Xxviii International

Horticultural Congress on Science and Horticulture for People (Ihc2010): International Symposium on Greenhouse 2010 and

Soilless Cultivation 927: 219-226.

The thrips Frankliniella occidentalis (Pergande) and Thrips tabaci (Lindeman) (Thysanoptera: Thripidae) are among the

major pests in rose greenhouses in southern France. For integrated thrips management, the predator Neoseiulus

cucumeris (Oudemans) (Acarina: Phytoseiidae) is available as a biological control agent, but it is not always efficient

enough in case of heavy contamination of rose crops by the thrips. In this context, we tested the effectiveness of

another predator, Franklinothrips vespiformis (Crawford) (Thysanoptera: Aeolothripidae) against thrips. The experiments

were performed in an insect- proof rose greenhouse (576 m(2)). The efficiency of the predator F. vespiformis was tested

in combination with N. cucumeris and compared to N. cucumeris alone while the thrips population dynamics in the

rose greenhouse were monitored. The combined use of F. vespiformis (5 adults per m2) with releases of N. cucumeris

during the periods of heavy infestation gave better results than when using N. cucumeris alone; these results were

observed both against adult thrips and larvae. Our results point at the importance of combining various natural

enemies against thrips in rose greenhouses, and their implication for Integrated Pest Management on roses are

discussed.



46

Seki, M. and T. Murai (2012). "Insecticidal effect of high carbon dioxide atmospheres on thrips eggs oviposited in plant tissue."

Applied Entomology and Zoology 47(4): 433-436.

Thrips are damaging crop pests, but their eggs are difficult to detect for farmers and agricultural inspectors. We

investigated the insecticidal effects of an elevated carbon dioxide atmosphere on thrips eggs oviposited within plant

tissues. Percent mortality of Frankliniella occidentalis (Pergande), Frankliniella intonsa (Trybom), Thrips tabaci Lindeman,

and Thrips palmi Karny exposed to 60 % CO2 was evaluated at different temperatures (20, 25, 30, and 34 degrees C)

and durations. Egg mortality of all four species increased with CO2 exposure duration at each temperature, and the

time required to achieve 100 % mortality decreased as the temperature increased between 20-30 degrees C. Exposure

to 60 % CO2 at 30 degrees C for 12 h is considered to be 100 % lethal to most thrips pests of fresh agricultural

produce. Our findings suggested that CO2 treatment could be used to propagate thrips-free plants in horticultural

nurseries.

Seki, M. and T. Murai (2012). "Responses of five adult thrips species (Thysanoptera; Thripidae) to high-carbon dioxide

atmospheres at different temperatures." Applied Entomology and Zoology 47(2): 125-128.

The effect of high carbon dioxide atmospheres (60% CO2) at different temperatures (20, 25, 30 and 34A degrees C) on

adult female mortality in Frankliniella occidentalis (Pergande), Frankliniella intonsa (Trybom), Thrips tabaci Lindeman,

Thrips palmi Karny, and Thrips parvispinus Karny were tested. Mortality of the five thrips species increased with CO2

exposure duration at each temperature. Median lethal times (LT50) and times required to achieve 100% mortality due

to CO2 exposure decreased with increasing temperature, for all thrips species. Exposure to 60% CO2 atmospheres at

30A degrees C is considered to be 100% lethal within 24 h to most pests of fresh agricultural produce. Our findings

suggest that CO2 treatment could be used to propagate thrips-free plants in horticultural nurseries, and as a

quarantine tool for controlling insects in/on transported plants.

Srinivasan, R., S. Sundaraj, H. R. Pappu, S. Diffie, D. G. Riley and R. D. Gitaitis (2012). "Transmission of Iris Yellow Spot Virus by

Frankliniella fusca and Thrips tabaci (Thysanoptera: Thripidae)." Journal of Economic Entomology 105(1): 40-47.

Thrips-transmitted Iris yellow spot virus (IYSV) (Family Bunyaviridae, Genus Tospovirus) affects onion production in the

United States and worldwide. The presence of IYSV in Georgia was confirmed in 2003. Two important thrips species that

transmit tospoviruses, the onion thrips (Thrips tabaci (Lindeman)) and the tobacco thrips (Frankliniella fusca (Hinds)) are

known to infest onion in Georgia. However, T. tabaci is the only confirmed vector of IYSV. Experiments were conducted

to test the vector status of F. fusca in comparison with T. tabaci. F. fusca and T. tabaci larvae and adults reared on IYSV-

infected hosts were tested with antiserum specific to the nonstructural protein of IYSV through an antigen coated plate

ELISA. The detection rates for F. fusca larvae and adults were 4.5 and 5.1%, respectively, and for T. tabaci larvae and

adults they were 20.0 and 24.0%, respectively, indicating that both F. fusca and T. tabaci can transmit IYSV. Further,

transmission efficiencies of F. fusca and T. tabaci were evaluated by using an indicator host, lisianthus (Eustoma

russellianum (Salisbury)). Both F. fusca and T. tabaci transmitted IYSV at 18.3 and 76.6%, respectively. Results confirmed

that F. fusca also can transmit IYSV but at a lower efficiency than T. tabaci. To attest if low vector competency of our

laboratory-reared F. fusca population affected its IYSV transmission capability, a Tomato spotted wilt virus (Family

Bunyaviridae, Genus Tospovirus) transmission experiment was conducted. F. fusca transmitted Tomato spotted wilt

virus at a competent rate (90%) suggesting that the transmission efficiency of a competent thrips vector can widely vary

between two closely related viruses.

Su, J., Y. L. Guo, X. G. Ma and J. L. Wang (2012). The comparison of drug resistance between western flower thrips (WFT) and

thrips tabaci. Advances in Chemistry Research Ii, Pts 1-3. S. Chen, Z. T. Liu and Q. Z. Zeng. 554-556: 1812-1815.

Leaf dipping method is used in this paper to compare the drug resistance of the invasive species western flower thrips

and the native thrips tabaci to 6 kinds of insecticides: phoxim, chlorpyrifos, beta-cypermethrin, spinosad, emamectin-

benzoate and avermectin. The results showed that the western flower thrips had a higher drug resistance to phoxim,

chlorpyrifos and beta-cypermethrin than thrips tabaci, while beta-cypermethrin and avermectin had a good activity

against thrips tabaci. Spinosad had the best control effect, with a concentration of 0.5 mg/L, the corrected mortality of

these two thrips reached above 90%.



47

Szostek, S. (2012). "Overwintering onion thrips (Thrips tabaci) are a source of Iris yellow spot virus in Colorado." Phytopathology

102(7): 117-117.

Visalakshy, P. N. G. and A. Krishnamoorthy (2012). Comparative Field Efficacy of Various Entomopathogenic Fungi against Thrips

tabaci: Prospects for Organic Production of Onion in India. Xxviii International Horticultural Congress on Science and

Horticulture for People. I. Mourao and U. Aksoy. 933: 433-437.

India ranks first in world in export of Allium cepa. The crop production is subjected to stress by the sap sucking pest,

Thrips tabaci. There is an increasing demand for alternative non-toxic and eco-friendly management strategies such as

biological control of horticultural crop pests in the recent years, due to the varied disease effects of pesticides.

Preliminary studies at our institute indicated fungal pathogens isolated from thrips (institute isolates) as potential

biological control agents of T. tabaci in onion. This paper reports on the field efficacy of these microbial control agents

against Thrips tabaci in onion cultivar 'Arka Niketan' at the Indian Institute of Horticultural Research, Bangalore, India.

Four species of microbial pathogens (Metarrhizium anisopliae, Verticillium lecanii, Beauveria bassiana and entomophilic

nematode Steinernerma casrpocapsae; Bouncer (TM)) at different dosages (1x10(9) and 1x10(7) spores/ml) were

evaluated. Two criteria i.e., thrips density and marketable yield were selected to determine the effectiveness. Thrips

density/plant was estimated through a destructive sampling method and yield gain by recording marketable produce

that was subjected to t-test to determine the best treatment. Results indicated significant reduction in thrips

population/plant and corresponding yield increase in entomopathogen treatments that was on par to chemicals. A

mean population of 8.3 to 10.0 thrips/plant was recorded in entomopathogen treatments compared to 18.4 in control

and 5.5 thrips/plant in chemical check respectively. M. ansiopliae at a concentration of 1x10(9) spores/ml with adjuvant

(sunflower and Triton-X) recorded the lowest thrips/plant population contributing to 58% reduction and 49.12%

increase in yield over control. This study suggests that entomopathogens can substitute chemical pesticides in the

management of Thrips tabaci in onion.

Wakil, W., M. U. Ghazanfar, Y. J. Kwon, I. Shamas ul and K. Ali (2012). "Toxicity of Paecilomyces lilacinus blended with non-

conventional agents to control cotton thrips (Thrips tabaci Lind.) (Insecta: Thysanoptera: Thripidae)." African Journal of

Microbiology Research 6(3): 526-533.

The entomopathogenic fungus Paecilomyces lilacinus (2.3 x 10(9) conidia ml(-1)) was blended with other non-

conventional agents like Azadirachta indica (10 ml L-1) and diatomaceous earth formulation PyriSec (3 g L-1) for the

control of cotton thrips (Thrips tabaci Lind.) (Insecta: Thysanoptera: Thripidae) using leaf detached bioassay and under

semi-natural conditions. The bioassays were set at 25 +/- 1 degrees C and >70% relative humidity at 16L/8D

photoperiod and the data for mortality was taken after 2, 4, 6, 8 and 10-d. All the treatments showed significant control

of thrips population on cotton. Over all, the application of P. lilacinus blended with A. indica exhibited higher mortality

compared with its combination with PyriSec against T. tabaci. The results of the present study showed that P. lilacinus

may provide effective control of the insect pest when blended with other non-conventional safer control agents.

Diaz-Montano, J., M. Fuchs, B. A. Nault, J. Fail and A. M. Shelton (2011). "Onion Thrips (Thysanoptera: Thripidae): A Global Pest of

Increasing Concern in Onion." Journal of Economic Entomology 104(1): 1-13.

During the past two decades, onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), has become a global pest

of increasing concern in commercial onion (Allium cepa L.), because of its development of resistance to insecticides,

ability to transmit plant pathogens, and frequency of producing more generations at high temperatures. T. tabaci feeds

directly on leaves, causing blotches and premature senescence as well as distorted and undersized bulbs. T tabaci can

cause yield loss >50% but can be even more problematic when it transmits Iris yellow spot virus (family Bunyaviridae,

genus Tospovirus, IYSV). IYSV was identified in 1981 in Brazil and has spread to many important onion-producing

regions of the world, including several U.S. states. IYSV symptoms include straw-colored, dry, tan, spindle- or diamond-

shaped lesions on the leaves and scapes of onion plants and can cause yield loss up to 100%. Here, we review the

biology and ecology of T. tabaci and discuss current management strategies based on chemical, biological, and cultural

control as well as host resistance. Future directions for research in integrated pest management are examined and

discussed.

48

Fathi, S. A. A., F. Gholami, G. Nouri-Ganbalani and A. Mohiseni (2011). "Life history parameters of Thrips tabaci (Thysanoptera:

Thripidae) on six commercial cultivars of canola." Applied Entomology and Zoology 46(4): 505-510.

The onion thrips, Thrips tabaci Lind. (Thysanoptera: Thripidae), is an important pest of the canola crop, Brassica napus

L., in the Ardabil region. In this study, life history parameters of T. tabaci were investigated on six canola cultivars,

namely: Talayh, Zarfam, RGS003, Opera, Option500, and Hayola401. Experiments were performed in a climate chamber

set at 25 +/- A 1A degrees C and 55 +/- A 5% RH under 16L:8D. The results indicated that the development time of

immature stages was significantly longer on RGS003 than on Opera, Hyola401, Zarfam, Option500, and Talayh. The

onion thrips reared on RGS003 had the lowest number of eggs laid per female (15.5) and the lowest survival rate (40%)

among the tested cultivars. The lowest intrinsic rate of natural increase (r (m)) and population growth rate (lambda)

were observed on RGS003, and were the highest on Zarfam. The generation time (T) was shortest on Zarfam (21.5 days)

and longest on RGS003 (26.5 days). Similarly, the doubling time (DT) was shortest on Zarfam (4.5 days) and longest on

RGS003 (8.1 days). Considering the significant effect of the host plant on the life history parameters of onion thrips, it

was concluded that RGS003 is the least suitable cultivar among the other tested canola cultivars for integrated

management of onion thrips in canola fields.

Hendawy, A. S., S. K. M. El-Fakharany and S. A. A. Kassem (2011). "Ecological and Toxicological Studies on Thrips tabaci Lindeman

and Associated Spiders on Onion Plantations." Egyptian Journal of Biological Pest Control 21(2): 337-342.

Population fluctuation of Thrips tabaci Lind. and its associated spiders in onion plantations, as influenced by some

weather factors, was studied at El-Riad district, Kafr El-Sheikh Governorate, Egypt in two successive growing seasons

2008/09 and 2009/10. Toxicity of certain compounds; fenitrothion, etoxazole, super misrona, sour orange, acidless

orange, baladi mandarin and Bermectine in reducing the population density of T. tabaci were evaluated. Also, the side

effect of these compounds on spiders' population was assessed. The population density of T. tabaci and spiders peaked

in March and April in both seasons. Surveyed spiders were found belong to seven families; Araneidae, Dictynidae,

Lycosidae, Linyphiidae, Philodromidae, Theridiidae and Thomisidae. Temperature had highly significant positive

correlation, while the spiders were highly significant negative for T. tabaci in 2008/09 season. Combined effect of

spiders and weather factors on the density of thrips was high. All tested compounds under field conditions showed

reduction of infestation of T. tabaci. For the residual effect, all tested compounds gave significant reduction of thrips

infestation up to day 14th post treatment. Fenitrothion and Bermectine were the most effective, followed by etoxazole,

sour orange, super misrona and then, acidless orange and baladi mandarin which induced the lowest reduction in

thrips population. Concerning the side effect of these compounds on spiders; Bermectine and plant oil extracts (sour

orange, acidless orange and baladi mandarin) had slight effects, whereas etoxazole and super misrona were moderate.

Fenitrothion was the highly toxic compound against spiders.

Herron, G. A., B. J. Langfield, T. M. Tomlinson and J. H. Mo (2011). "Dose-response testing of Australian populations of onion

thrips Thrips tabaci Lindeman (Thysanoptera: Thripidae) further refines baseline data and detects methidathion and likely

imidacloprid resistance." Australian Journal of Entomology 50: 418-423.

Field strains of Thrips tabaci Lindeman were collected from bulb onion in New South Wales, Queensland and South

Australia and returned to the laboratory for culturing and subsequent bioassay to determine chemical specific

responses. Chemicals tested included diazinon, dimethoate, ?-cyhalothrin and methidathion with imidacloprid and

spinetoram evaluated to establish reliable susceptible baseline responses. Reference (susceptible) responses were

compared back with those previously published and for all insecticides more susceptible strains were found for

resistance comparison. Results for methidathion in particular were found to be significantly different from those

reported previously. These differences influenced resistance factor calculation considerably. A high 49-fold

methidathion resistance was detected, a result consistent with anecdotal grower concerns of poor product performance

against T. tabaci. Resistance to diazinon remains generally low with all strains tested showing <6-fold at the LC50 level.

LC50 dimethoate resistance peaked at 17-fold. Maximum (56-fold) ?-cyhalothrin resistance was significantly less than

previously found but responses were very heterogeneous implying resistance could very quickly increase. Worryingly,

the difference in imidacloprid responses between the least and most tolerant was 41-fold although the chemical is

neither used nor registered for use against T. tabaci. We consider such a high and significant difference in response to

imidacloprid is most likely caused by an unknown cross-resistance that may compromise any future development of

imidacloprid for use against T. tabaci. Thrips remain susceptible to spinetoram.



49

Hoedjes, K., J. T. J. Verhoeven, R. Goldbach and D. Peters (2011). "Iris Yellow Spot Virus in the Netherlands: Occurrence in Onion

and Confirmation of Transmission by Thrips tabaci." Xii International Symposium on Virus Diseases of Ornamental Plants(901):

199-206.

Since its first detection in the Netherlands in 1992, Iris yellow spot virus (IYSV, genus Tospovirus) has been reported

worldwide in Allium crops, in a few ornamentals and in a small number of weeds. After recent findings of IYSV in

Alstroemeria and Eustoma in the Netherlands, a number of neighbouring onion fields were surveyed. In 2005 and 2006,

only few infected plants were found with obvious symptoms of IYSV. In 2007, after sampling and testing small leaf

samples with various types of damage, including small brown-yellow colored spots and spots with thrips feeding

damage, a high percentage of plants were found with positive IYSV scores in ELISA. Infection by IYSV could be

confirmed in most ELISA-positive samples by RT-PCR. Under laboratory conditions, evidence was obtained that Thrips

tabaci acts as a vector for this virus. Acquisition of the IYSV from infected Datura stramonium plants resulted in virus

uptake and replication in over 60% of the thrips exposed, as determined by Western blotting and immunolocalisation

of the virus in the foregut, and in epithelial and midgut muscle cells using antibodies against both the viral N and NSs

proteins. Successful transmission of IYSV to seedlings of Emilia sonchifolia was observed, however, only at low

frequency under the laboratory conditions used.

Pobozniak, M. (2011). "The occurrence of thrips (Thysanoptera) on food legumes (Fabaceae)." Journal of Plant Diseases and

Protection 118(5): 185-193.

The occurrence, quantity and population fluctuations in thrips (Thysanoptera) on various food legume crops

(Leguminosae or Fabaceae) in southern Poland were investigated. Eighteen species of thrips have been described on

food legume vegetables, with Thrips tabaci, Frankliniella intonsa and Thrips fuscipennis being the most common. The

latter three species made up 90% or more of the total number of thrips collected during 2006 and 2007. Thrips

occurred on peas (Pisum sativum) and lentil (Lens culinaris) in May and June, and on beans (Phaseolus vulgaris) and

soya beans (Glycine max) in June and July. The number of T tabaci on (young) lentil and peas was significantly higher

than on beans and soya beans. Most were observed in the flowers and developing young pea pods. A large number of

Frankliniella intonsa was present during the flowering stage, but the insects were short-lived. T. fuscipennis was present

in all samples, with a peak in numbers during the flowering period.

Smith, E. A., A. Ditommaso, M. Fuchs, A. M. Shelton and B. A. Nault (2011). "Weed Hosts for Onion Thrips (Thysanoptera:

Thripidae) and Their Potential Role in the Epidemiology of Iris Yellow Spot Virus in an Onion Ecosystem." Environmental

Entomology 40(2): 194-203.

Onion thrips, Thrips tabaci Lindeman, is a key foliage-feeding pest of onion worldwide and the principal vector of a

serious onion pathogen, Iris yellow spot virus (IYSV). Long-term management of T. tabaci and IYSV will require an

understanding of T. tabaci ecology and IYSV epidemiology in onion ecosystems. This study focused on identifying

winter-annual, biennial and perennial weed species that host both T. tabaci and IYSV. Unlike summer-annual weeds,

weeds with these habits survive overwinter and could serve as a green bridge for IYSV to survive between onion-

growing seasons. T. tabaci larvae and adults were sampled every two weeks from 69 weed species in five areas located

adjacent to onion fields in western New York in 2008 and 2009. Twenty-five of the 69 weed species were identified as

hosts for T. tabaci larvae and populations were highest on the Brassicaceous weeds, Barbarea vulgaris Ait. f., Sinapis

arvensis L., and Thalspi arvense L. None of these species are hosts for IYSV. Four of the 25 weed species were hosts for

both T. tabaci larval populations and IYSV: common burdock, Arctium minus Bernh., dandelion, Taraxacum officinale G.

H. Weber ex Wiggers, curly dock, Rumex crispus L., and chicory, Cichorium intybus L. Of these four weed species, T.

officinale and A. minus may play an important role in the epidemiology of IYSV in New York onion fields because they

may survive between onion-growing seasons, they are relatively abundant in the landscape, and they support relatively

high densities of T. tabaci.

Sparks, A. N., S. Diffie and D. G. Riley (2011). "Thrips Species Composition on Onions in the Vidalia Production Region of

Georgia." Journal of Entomological Science 46(1): 40-45.

Thrips are the key arthropod pest of onions in Georgia. Historically, this pest complex has been reported to consist

primarily of tobacco thrips, Frankliniella fusca (Hinds), western flower thrips, F. occidentalis (Pergande), and onion thrips,

50

Thrips tabaci Lindeman, with < 1% reported as onion thrips. Onion thrips, however, has become a greater concern in

this region because this species is the primary vector of Iris Yellow Spot Virus (IYSV), which was detected in commercial

fields in 2003, and both onion thrips and IYSV were detected in culled onions imported from Peru into the Vidalia

region in 2003. Surveys were conducted from 2004 through 2010 in commercial onion fields in the 2 primary counties

where Vidalia onions are produced to determine whether onion thrips were becoming more prominent within this

region. From 2004 through 2006, F. fusca was the predominant pest species collected in this region. Onion thrips were

detected and were widely distributed at levels within historical indications. In 2007, onion thrips were detected in

commercial fields at levels well above historical levels, representing 49.4% of all pest thrips collected with samples

exceeding 90% in some fields. This percentage has steadily declined since 2007, with onion thrips only 1.4% of the total

pest thrips collected in 2010 and a maximum of 9.6% in any field. Several factors may have contributed to this shift in

species composition including introduction of a more competitive biotype of onion thrips and insecticide resistance

within the onion thrips.

Srinivasan, R., F. Z. Guo, D. Riley, S. Diffie, R. Gitaitis, A. Sparks and A. Jeyaprakash (2011). "Assessment of Variation Among Thrips

tabaci Populations from Georgia and Peru Based on Polymorphisms in Mitochondrial Cytochrome Oxidase I and Ribosomal ITS2

Sequences." Journal of Entomological Science 46(3): 191-203.

The onion thrips, Thrips tabaci (Lindeman), is the only known vector of Iris yellow spot virus (IYSV). IYSV was detected in

Georgia for the first time in 2003. Phylogenetic analysis using nucleotide sequences of the IYSV capsid gene indicated

that it may have been accidentally introduced from repackaging of imported Peruvian onions in the Vidalia onion-

growing region. The tobacco thrips, Frankliniella fusca (Hinds), has been the dominant thrips species on onions in

Georgia. However, in recent years the incidence of T. tabaci on onions has been consistently increasing. Laboratory

competition studies indicated that T. tabaci outcompeted F. fusca on onion foliage. This led to speculation that a new

biotype of T. tabaci may have been introduced along with IYSV through importation of Peruvian onions. This hypothesis

was tested by analyzing variations in the mitochondrial cytochrome oxidase I gene and internal transcribed spacer

region 2 of T. tabaci populations from Georgia and Peru. DNA was extracted from T. tabaci samples from Georgia and

Peru and subjected to PCR using specific primers. The resulting amplicons were sequenced. Parsimony and Bayesian

analysis of the COI sequences indicated that all the Peruvian taxa fell into a single clade along with one Georgia taxon.

All the other Georgia taxa were in a separate clade. ITS2 sequence comparisons indicated that Georgia and Peru taxa

were found in numerous clades. High variation among taxa from each region indicated that ITS2 may not be suitable to

assess intraspecific variation among T. tabaci populations.

Takeuchi, R. and S. Toda (2011). "Discrimination of Two Reproductive Forms of Thrips tabaci by PCR-RFLP, and Distribution of

Arrhenotokous T. tabaci in Tottori Prefecture." Japanese Journal of Applied Entomology and Zoology 55(4): 254-257.

To discriminate between arrhenotokous and thelytokous forms of the onion thrips (Thrips tabaci), we developed a

simple molecular diagnostic method that uses PCR-RFLP of the mitochondrial cytochrome c oxidase subunit I (COI)

gene. Digestion of 490-bp COI amplicons with EcoO1091 provided reproductive form-specific RFLP patterns. Using this

method, we surveyed the frequencies of the two reproductive forms in 9 Welsh onion fields in Tottori Prefecture.

Arrhenotoky dominated in the western area, although 100% of individuals were thelytokous in the eastern area. The

COI haplotype of the arrhenotokous individuals was haplotype 1 or 2, which has not previously been found in Japan.

Yousefi, M., A. Abasifar, A. F. Hafshejani and J. J. Sendi (2011). "Resistance of eight Iranian onion cultivars to onion thrips (Thrips

tabaci Lindeman) in the Markazi Province of Iran." African Journal of Agricultural Research 6(21): 4925-4930.

Thrips tabaci L. is one of the most important pests of onion in Iran. In this research, eight Iranian onion cultivars

(Ghermez-e-Azarshar, Sefid-e-Kashan, Sefid-e-Native Khomein, Sefid-e-Improved Khomein, Sefid-e-Qom, Sefid-e-

Kordestan, Sefid and Ghermez-e-Shahroud) were cultivated in a RCB design with four replications in Arak, between

2001 and 2003. The number of thrips on five plants was recorded every two weeks and ten days interval on non-

sprayed and sprayed plots, respectively. The symptoms of pest feeding, which includes chlorosis and necrosis were

rated based on a scale from 1 to 10 for usual damaging and leaf curling another symptom a 1 to 6 scale. The control

field was sprayed with current insecticides every 10 days in order to decrease the thrips population. In this study, the

highest number of thrips was observed on Ghermez-e-Azarshahr, Sefid-e-improved Khomein and Sefid-e-Shahroud

and the lowest number was recorded on non-prayed fields and then on Ghermez-e-Shahroud, Sefid-e-Kordestan. The



51

highest amount of damage was observed on Ghermez-e-Azarshahr while, the lowest one for Sefid-e-Kordestan and

Qom. In non-sprayed plots, the highest yield was recorded for Sefid-e-Kashan and Qom cultivars and the lowest yield

for Sefid-e-Kordestan cultivar. The results of the study over the three years showed Sefid-e-Kashan and Sefid-e-Qom as

the genotypes resistant to thrips, Sefid-e-improved onion of Khomein as a tolerant genotype and Ghermez-e-

Azarshahr having high level of thrips density (more than 25 thrips in each plant) and high level of damage, and leaf

curling is introduced as a genotype sensitive to thrips.

Zepa, C., V. Tabara, I. Petrescu and I. Palagesiu (2011). "CHEMICAL CONTROL OF THRIPS TABACI ATTACK ON THE CROP OF

CALENDULA OFFICINALIS." Romanian Agricultural Research 28: 243-247.

The attacked not treated crops of Calendula officinalis can be compromised; therefore it is very important to know the

number of specimens of Thrips tabaci on plants, in order to intervene with efficient treatments, which should reduce

the number of pest populations. The products Mospilan 20 SP 0.04%, Confidor Energy 0.08%, Fastac 10 EC 0.04%,

Actara 25 WG 0.02% and Calypso 480 SC 0.02% were tested for the control of common thrips (Thrips tabaci) on the

crop of Calendula officinalis decorative plants from the protected areas of the Didactical Station of Timisoara, where the

density of the thrips populations was on average 19.11 insects/flower, much higher than the accepted economical level

of damaging (1-2 adults/flower). The tested products proved good efficiency in controlling the population of

Thysanoptera from the flower glass houses. The most efficient in controlling the tobacco thrips were the products

Actara 25 VG and Confidor Energy, having an efficiency of over 97%, followed by Fastac 10 EC RV, with an efficiency of

over 86%. Seven days after the treatments in the marigold crop, the smallest number of living insects was collected

from the plots treated with Actara 25 VG (3.33 insects/plot), followed by the plots treated with Confidor Energy (4.33

insects/plot), these two products being indicated for controlling the thrips from the marigold crop.

Bosco, L. and L. Tavella (2010). "Population dynamics and integrated pest management of Thrips tabaci on leek under field

conditions in northwest Italy." Entomologia Experimentalis Et Applicata 135(3): 276-287.

Thrips tabaci Lindeman (Thysanoptera: Thripidae) is a major pest of leek, Allium porrum L. (Alliaceae), in Piedmont,

northwest Italy, and to control its infestation the leek crop is sprayed intensively with insecticides during the summer

period. In order to find the most efficient and environment-friendly method of thrips control, research was conducted

on six commercial farms during 20052006 to assess thrips population composition and infestation levels, and in an

experimental field during 2005-2007. Biological and chemical control were compared during 2005-2006, whereas

integrated pest management was adopted during 2007. During the growing season, thrips and natural enemy

populations were monitored at 14-day intervals by beating plants; new leaves of plants were also visually inspected for

thrips-feeding symptoms. Furthermore, in the experimental field at harvest-time, the level of thrips injury to plants was

assigned to one of five classes, depending on the percentage of leaf area damaged. Over 99% of phytophagous adult

thrips found were male and female T. tabaci. Infestations were very variable in the crops surveyed, partly due to broad-

spectrum chemical treatments against the leek pests, which often failed to control thrips. In general, populations

peaked in September, when they reached the maximum mean values ranging between 1.7 and 33.1 thrips per plant. At

harvest, none of the surveyed farms experienced quality losses due to thrips injuries. In the experimental field during

2005-2006, the mean number of thrips per plant was greater in the chemical than in the biological control treatment,

even though damage indices showed no significant differences between the two treatments. Predatory thrips of the

genus Aeolothrips (Thysanoptera: Thripidae) and predatory bugs of the genus Orius (Heteroptera: Anthocoridae),

mostly Orius majusculus Reuter, were particularly abundant during 2007, supporting the importance of management

with selective insecticides to encourage natural colonization by predators.

Costa, G. M., A. L. Boica, F. G. de Jesus and N. R. Chagas (2010). "EFFECTS OF THE USE OF PLANT OILS ASSOCIATED OR NOT TO

PESTICIDE, ON THE CONTROL OF Bemisia tabaci (GENNADIUS, 1889) AND Thrips tabaci (LINDEMAN, 1888), IN BEAN PLANTS

DURING THE WATERS SEASON." Bioscience Journal 26(1): 15-23.

The objective of this experiments was evaluate the control of Bemisia tabaci and Thrips tabaci, through the use of plant

oils associated or not to insecticide in bean plants, besides verifying the consequences on yield. The experiment was

carried out in the period of rainy seasons, by utilizing Carioca variety. The statistical design was the randomized blocks,

by employing a 6x2 factorial scheme ( plant oil versus insecticide), totalizing 12 treatments and four replications. It was

concluded thet application of plant oils without insecticide can be utilized on the control of the B. tabaci biotipo B,

52

since their population and the symptoms of golden mosaic was similar to the treatment plant oils plus insecticide;

among the plant oils Agrex (R) plant oil promoted a higher control of white fly. For T. tabaci the application of plant oil

associated to insecticide provide with a smaller population index when compared to the treatments without this

association. The yield was not affected by the population of B. tabaci biotipo B and T. tabaci when plant oils were

utilized, associated or not to the insecticide.

Diaz-Montano, J., M. Fuchs, B. A. Nault and A. M. Shelton (2010). "Evaluation of Onion Cultivars for Resistance to Onion Thrips

(Thysanoptera: Thripidae) and Iris Yellow Spot Virus." Journal of Economic Entomology 103(3): 925-937.

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), a worldwide pest of onion, Allium cepa L., can reduce

onion yield by >50% and be even more problematic when it transmits Iris yellow spot virus (family Bunyaviridae, genus

Tospovirus, IYSV). Because T. tabaci is difficult to control with insecticides and other strategies, field studies on onion,

Allium cepa L., resistance to T. tabaci and IYSV were conducted in 2007 and 2008 in two locations in New York state.

Forty-nine cultivars were evaluated for resistance by counting the number of larvae weekly and recording leaf damage.

In another experiment, the impact of T. tabaci and IYSV on plant growth and yield was examined by spraying half of the

plants with an insecticide. Eleven of the 49 cultivars had very little leaf damage and were considered resistant to T.

tabaci. Visual assessment indicated that all resistant cultivars had yellow-green-colored foliage, whereas the other 38

had blue-green-colored foliage. The visual assessment of color agreed with data on color taken with a HunterLab Ultra

Scan XE colorimeter. The onions 'Colorado 6' and 'NMSU 03-52-1' had the lowest numbers of T. tabaci, suggesting

strong antibiosis and/or antixenosis. The other nine cultivars had variable numbers of T. tabaci, indicating a possible

combination of categories of resistance. In the nonprotected treatments there were significant reductions in plant

height and plant weight in most of the resistant cultivars, but there were reductions in bulb weight only in a few of

them. The average of plants infected with IYSV was 10% in 2007 and 60% in 2008. Our findings indicate potential for

developing onion resistance to T. tabaci as part of an overall integrated pest management strategy but suggest

difficulties in identifying resistance to IYSV.

Foster, S. P., K. Gorman and I. Denholm (2010). "English field samples of Thrips tabaci show strong and ubiquitous resistance to

deltamethrin." Pest Management Science 66(8): 861-864.

BACKGROUND: Onion thrips, Thrips tabaci Lindeman, is a prevalent pest of glasshouse and field vegetables, such as

leeks and salad onions. Pesticides are the main option for control, but this approach risks the evolution and spread of

insecticide resistance. In the light of anecdotal reports in the United Kingdom of poor efficacy of pyrethroids against T.

tabaci, thought to be primarily a consequence of resistance, the responses to deltamethrin of ten English samples of T.

tabaci, collected from field leeks and salad onions in 2006, were measured to establish the level and prevalence of

potential resistance to this compound. RESULTS: All the samples showed significant deltamethrin resistance that was

comparable or slightly lower than the maximum level reported previously for T. tabaci from New Zealand.

CONCLUSION: The mechanism(s) conferring deltamethrin resistance remain unknown at present but are likely to

extend to other synthetic pyrethroids approved for use against this species. The findings suggest that these

compounds are unlikely to give satisfactory control of T. tabaci in England and have stimulated the recommendation to

use alternatives. (C) 2010 Society of Chemical Industry

Hsu, C. L., C. A. Hoepting, M. Fuchs, A. M. Shelton and B. A. Nault (2010). "Temporal Dynamics of Iris Yellow Spot Virus and Its

Vector, Thrips tabaci (Thysanoptera: Thripidae), in Seeded and Transplanted Onion Fields." Environmental Entomology 39(2):

266-277.

Onion thrips, Thrips tabaci (Lindeman) (Thysanoptera: Thripidae), can reduce onion bulb yield and transmit iris yellow

spot virus (IYSV) (Bunyaviridae: Tospovirus), which can cause additional yield losses. In New York, onions are planted

using seeds and imported transplants. IYSV is not seed transmitted, but infected transplants have been found in other

U.S. states. Transplants are also larger than seeded onions early in the season, and thrips, some of which may be

viruliferous, may preferentially colonize larger plants. Limited information is available on the temporal dynamics of IYSV

and its vector in onion fields. In 2007 and 2008, T. tabaci and IYSV levels were monitored in six seeded and six

transplanted fields. We found significantly more thrips in transplanted fields early in the season, but by the end of the

season seeded fields had higher levels of IYSV. The percentage of sample sites with IYSV-infected plants remained low

(<12%) until August, when infection levels increased dramatically in some fields. The densities of adult and larval thrips



53

in August and September were better predictors of final IYSV levels than early season thrips densities. For 2007 and

2008, the time onions were harvested may have been more important in determining IYSV levels than whether the

onions were seeded or transplanted. Viruliferous thrips emigrating from harvested onion fields into nonharvested ones

may be increasing the primary spread of IYSV in late-harvested onions. Managing T tabaci populations before harvest,

and manipulating the spatial arrangement of fields based on harvest date could mitigate the spread of IYSV.

Inoue, T., T. Murai and T. Natsuaki (2010). "An effective system for detecting Iris yellow spot virus transmission by Thrips tabaci."

Plant Pathology 59(3): 422-428.

A simple, effective and convenient laboratory leaf system was developed to detect transmission of Iris yellow spot virus

(IYSV) by thrips. It was shown that IYSV was transmitted highly efficiently by adults and also by larvae of five

thelytokous populations of Thripstabaci from distinct areas in Japan: over all these populations, transmission efficiency

of adults ranged from 20.4% (19/93) to 41.1% (76/185) and that of larvae from 17.3% (14/81) to 44.1% (67/152). Finally,

it was demonstrated that IYSV infection was not detrimental to the development and fecundity of thrips until early

adulthood. Larval mortalities of virus-exposed thrips were higher than in their unexposed counterparts in all three

populations, but the differences were not significant. The results demonstrated that T. tabaci populations have

considerable potential to cause outbreaks of IYSV and spread the disease because of their efficient transmission of the

virus.

Mahaffey, L. A. and W. S. Cranshaw (2010). "Thrips Species Associated with Onion in Colorado." Southwestern Entomologist

35(1): 45-50.

Surveys of onion, Allium cepa L., fields in Colorado during 2004-2005 found that a complex of thrips species, comprised

of onion thrips, Thrips tabaci Lindeman, and three Frankliniella species, were present in almost every location. Onion

thrips predominated, averaging between 82.6 and 84.9% of the thrips recovered during the two seasons. Second in

abundance was western flower thrips, F. occidentalis Pergande, that averaged 12.6 and 12.2% of the total thrips found

during the two years, respectively. Two additional plant-feeding species, F. tenuicornis (Uzel) and F. schultzei (Trybom),

also were recovered from the onion fields, and the latter comprised as much as 42% of the thrips in one southeastern

Colorado field survey. The relative proportion of the thrips species in fields varied between sites and during the season,

differences that might need to be considered when managing thrips on the onion crop. Three species, F. tenuicornis, F.

schultzei, and a predatory species, the vespiform thrips, Franklinothrips vespiformis (Crawford), recovered during this

study constitute new state records.

Muchero, W., J. D. Ehlers and P. A. Roberts (2010). "QTL analysis for resistance to foliar damage caused by Thrips tabaci and

Frankliniella schultzei (Thysanoptera: Thripidae) feeding in cowpea Vigna unguiculata (L.) Walp." Molecular Breeding 25(1): 47-

56.

Three quantitative trait loci (QTL) for resistance to Thrips tabaci and Frankliniella schultzei were identified using a

cowpea recombinant inbred population of 127 F(2:8) lines. An amplified fragment length polymorphism (AFLP) genetic

linkage map and foliar feeding damage ratings were used to identify genomic regions contributing toward resistance to

thrips damage. Based on Pearson correlation analysis, damage ratings were highly correlated (r a parts per thousand

yen 0.7463) across seven field experiments conducted in 2006, 2007, and 2008. Using the Kruskall-Wallis and Multiple-

QTL model mapping packages of MapQTL 4.0 software, three QTL, Thr-1, Thr-2, and Thr-3, were identified on linkage

groups 5 and 7 accounting for between 9.1 and 32.1% of the phenotypic variance. AFLP markers ACC-CAT7, ACG-CTC5,

and AGG-CAT1 co-located with QTL peaks for Thr-1, Thr-2, and Thr-3, respectively. Results of this study will provide a

resource for molecular marker development and the genetic characterization of foliar thrips resistance in cowpea.

Nault, B. A. and A. M. Shelton (2010). "Impact of Insecticide Efficacy on Developing Action Thresholds for Pest Management: A

Case Study of Onion Thrips (Thysanoptera: Thripidae) on Onion." Journal of Economic Entomology 103(4): 1315-1326.

An action threshold (AT) is one of the most important decision-making elements in integrated pest management.

Unlike economic thresholds, ATs are not typically derived from an economic injury level model, but they are more

commonly used. ATs may be identified from research-based, pest-crop relationships, but they also may be based on

experience. ATs may be adjusted depending on, e.g., weather and plant variety, but modifying ATs to accommodate

differences in insecticide efficacy has received little attention. To examine this point, several combinations of ATs and



54

insecticides were evaluated against onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), a major pest of

onion (Allium cepa L.). Studies were conducted in New York onion fields from 2006 to 2008 by using registered

insecticides for T. tabaci on onions. We hypothesized that the most efficacious insecticides would provide acceptable

control of thrips populations regardless of AT (one, three, and five thrips per leaf), whereas less effective products

would only control populations using the lowest AT (one thrips per leaf). Results indicated that T. tabaci infestations

were managed effectively when spinetoram was applied after a three larvae per leaf threshold, but not when using

lambda-cyhalothrin, methomyl or formetanate hydrochloride. However, T. tabaci infestations were managed well when

methomyl and formetanate hydrochloride were applied after a one larva per leaf threshold. T. tabaci infestations were

never controlled using lambda-cyhalothrin, regardless of the AT used. None of the products reduced T. tabaci

populations to an acceptable level when applied at a five larvae per leaf threshold. Implications of adjusting ATs based

on efficacy of different insecticides are discussed.

Pourian, H. R., R. Talaei-Hassanloui, A. A. Kosari and A. Ashouri (2010). "Effects of Metarhizium anisopliae on searching, feeding

and predation by Orius albidipennis (Hem., Anthocoridae) on Thrips tabaci (Thy., Thripidae) larvae." Biocontrol Science and

Technology 21(1): 15-21.

The generalist predator Orius albidipennis Reut. (Hem., Anthocoridae) and entomopathogenic fungus Metarhizium

anisopliae (Metchnikoff) Sorokin (Ascomycota: Clavicipitaceae) are important biocontrol agents of Thrips tabaci

Lindeman (Thys., Thripidae) in most greenhouses. In this study, we estimated searching time, feeding time and

predation rate in O. albidipennis feeding on untreated and treated thrips larvae which had been inoculated with three

concentrations of M. anisopliae V275 at four time intervals; 0, 24, 48 and 72 h after infestation. Applied concentrations

were 1x103, 2x104 and 2x105 conidia/mL which roughly correspond to the LC25, LC50 and LC75 for second instar-

larvae. O. albidipennis responded to the presence of the M. anisopliae on the treated hosts by increasing the searching

time and decreasing feeding time and predation rate levels. It was also able to detect and avoid treated patches.

Sedaratian, A., Y. Fathipour, A. A. Talebi and S. Farahani (2010). "Population Density and Spatial Distribution Pattern of Thrips

tabaci (Thysanoptera: Thripidae) on Different Soybean Varieties." Journal of Agricultural Science and Technology 12(3): 275-288.

Population density and spatial distribution of Thrips tabaci Lindeman on seven soybean varieties (Williams, Tellar, Sahar,

Dpx, L(17), Sari and Zane) and one genotype (Ks3494) were studied in Tehran region, during 2007. The highest

population density of the thrips per leaf was recorded on Dpx and on Ks3494 (0.81 +/- 0.05 and 0.80 +/- 0.05,

respectively). The lowest population density was observed on L(17) and Tellar (0.62 +/- 0.04 and 0.64 +/- 0.03,

respectively). To estimate the spatial distribution pattern of this pest, data were analyzed through index of dispersion,

Lloyd's mean crowding, Morisita's index as well as through regression models (Taylor and Iwao). The index of dispersion

and Lloyd's mean crowding indicated an aggregated pattern for the spatial distribution of this insect in all the varieties

and the genotype of soybean. Spatial distribution of T. tabaci using Morisita's index was aggregated in most of the

sampling dates. In Taylor's model, regression between log S(2) and log m was not significant for Dpx varieties (P> 0.05),

but the b values of Taylor's power law on Zane, Sahar, Williams and Tellar varieties exceeded 1, indicating aggregated

distribution. However, the other varieties had a b value equal to 1, indicating random distribution. Iwao's patchiness

regression indicated that the spatial distribution of T. tabaci on Sari, Zane, Williams and Tellar varieties as well as on

Ks3494 genotype was aggregated, but on the rest of varieties the pattern was of a random one. It is concluded that

soybean varieties affect the population density and spatial distribution of T. tabaci. Spatial distribution parameters of

this species can be employed to outline a sampling program as well as to estimate the population density of T. tabaci.

Shibao, M., Y. Inoue, S. Morikawa and H. Tanaka (2010). "Lethal High Temperatures of Onion Thrips, Thrips tabaci Lindeman

(Thysanoptera: Thripidae), and Control of the Thrips with Solar Radiation by Covering the Ground with Film." Japanese Journal of

Applied Entomology and Zoology 54(2): 71-76.

The lethal high temperature of onion thrips. Thrips tabaci Lindeman was evaluated at selected temperatures and

duration combinations under laboratory conditions. T. tabaci adults were killed by exposure to either 42 degrees C for

2h or 44-50 degrees C for 30 min. The soil temperatures attained under transparent polyvinylchloride film were

investigated in an open field at specific times in 2006 in Osaka Prefecture. Maximum temperatures of 44 degrees C or

higher were attained from early May to late October at a depth of 2cm beneath the soil surface. The effect of solar

radiation by covering the ground with transparent polyvinylchloride film during the emergence of T. tabaci was



55

investigated in an open field after harvesting the Welsh onions in June and July 2008. The numbers of T. tabaci

emergent adults were significantly lower in the solar radiation treatment plots than in the control plots. The results

suggests that T. tabaci can be killed with solar radiation by covering the ground with film, and that this control method

is effective during the period from early May to late October in Osaka Prefecture.

Simantara, P., D. Rees and A. Westby (2010). Potential Non-Chemical Methods for Use against Thrips (Thrips tabaci) in Green

Asparagus. Iii International Conference Postharvest Unlimited 2008. W. B. Herppich. 858: 325-328.

Alternative methods for disinfestation of asparagus against thrips (Thrips tabaci) need to be developed for the Thai

export trade, ensuring efficient thrips' mortality, while maintaining quality and environmental safety. Hot air/water using

temperatures of 40-60 degrees C and high CO2 treatments were studied at laboratory level. An appropriate treatment

involving hot water at 45 degrees C for 15 min, with or without high CO2 treatment, followed by hydro-cooling with

water at ambient temperature (similar to 20 degrees C) was identified. Methods to assess quality, such as objective tests

(% mass loss, force measurement, colour measurement) and subjective tests (appearance, decay, off-odour, snap-test

for texture) gave no indication of significant quality deterioration. Chlorophyll fluorescence and ion leakage

measurements were used to assess physiological stress. The F-v/F-m ratio which indicates the intactness of

photosystem II was shown to decrease immediately after all heat treatments tested, but recovered over 24h for non-

damaging heat treatments (42.5 and 45 degrees C). A rise in % K+ leakage was observed that increased with treatment

temperature but recovered over 24h following treatment at 45 degrees C. High CO2 showed neither significant

detrimental effect nor indication of physiological stress, and could kill thrips although not at a sufficiently high rate.

Confirmatory trials to demonstrate the efficacy of these treatments in Thailand using naturally infested asparagus were

carried out. The mortality rate of thrips was as high as when this method was tested in the UK. Adoption of the selected

disinfestation method into existing process lines in Thailand would not be too complicated.

Srinivasan, R., H. Pappu, D. G. Riley and R. D. Gitaitis (2010). "Evaluating Thrips tabaci and Frankliniella fusca (Thysanoptera:

Thripridae) as vectors of Iris yellow spot virus." Phytopathology 100(6): S122-S122.

Ullah, F., M. Maraj ul, A. Farid, M. Q. Saeed and S. Sattar (2010). "Population Dynamics and Chemical Control of Onion Thrips

(Thrips tabaci, Lindemann)." Pakistan Journal of Zoology 42(4): 401-406.

Population dynamic studies conducted at Peshawar, Pakistan showed that the activity of onion thirps (Thrips tabaci

Lindermann) was first recorded on 3rd February (1.20 thrips/plant) and reached to its peak (100 thrips/plant) during the

last week of April. Later, the population declined to 3.85 thrips/plant towards the end of May as the crop started to

mature. Population model using the meteorological data indicated that linear and quadratic components of average air

temperature were important in predicting the population development of T tabaci. However, the model accounted only

for 44% of total population variability. The insecticides; Thiodan (R), Confidor (R), Tracer (R), Megamos (R), and Actara

(R) were sprayed three times and data were taken at 24 hours, 72 hours, seven days and 10 days intervals. Except

Actara, all insecticides were significantly effective against the pest as compared to control. Maximum cost-benefit ratio

was recorded for Confidor (39.45) and the least was recorded for Actara (3.41) treated plots.

Voorrips, R. E., G. Steenhuis-Broers, M. Tiemens-Hulscher and E. T. L. van Bueren (2010). "Earliness, Leaf Surface Wax and Sugar

Content Predict Varietal Differences for Thrips Damage in Cabbage." V International Symposium on Brassicas and Xvi

International Crucifer Genetics Workshop, Brassica 2008 867: 127-131.

When cabbage is cultivated for storage in the Netherlands, it is usually harvested around mid-October. This type of

cabbage crop may be severely damaged by thrips (Thrips tabaci). The thrips population on the plants and the more

severe symptoms develop mostly during September and October. Also during cold storage symptoms continue to

develop. The damage caused by thrips is due to the symptoms that develop after feeding, which are small callus-like

growths that will turn brownish after some time and which may cover substantial amounts of leaf area. Large

differences exist between cabbage varieties in their susceptibility to thrips damage. It is not clear whether these

differences are due to resistance (affecting the thrips population in the plant) or to tolerance (affecting the

development of symptoms upon thrips feeding). Further, not much is known about plant traits affecting the resistance

or tolerance to thrips. In order to guide selection and breeding for resistance to thrips, this study aimed to identify

plant traits causing these differences. In the years 2005, 2006 and 2007 we performed field experiments with collections

56

of varieties differing in a number of plant traits, with earliness varying from moderately late to very late. In the field

experiments we relied upon natural infestation by thrips. Several times during the period August-October plants were

harvested and assessed for the amount of thrips damage and the number of thrips, as well as for several morphological

and physiological traits, including head circumference, leaf thickness, developmental stage, head compactness, leaf

surface wax, and Brix value as an indication of the content of soluble sugars. One factor affecting the amount of thrips

damage was the timing of the development of the head. Regression studies showed that more advanced plant

development at the end of August increased thrips damage at the final harvest. Other plant traits affecting thrips

damage were Brix and the amount of leaf surface wax. However no single plant trait explained more than 45% of the

variation in thrips damage at the final harvest. Optimal regression models, explaining up to 75% of the variation in

thrips damage included Brix and leaf surface wax late in the season, as well as an indicator of plant development earlier

in the season, and in 2005 also leaf thickness. The possible role of these plant traits in relation to thrips is discussed.

Wogin, M. J., R. C. Butler, D. A. J. Teulon and M. M. Davidson (2010). "Field response of onion thrips and New Zealand flower

thrips to single and binary blends of thrips lures." Canadian Entomologist 142(1): 75-79.

Tests were performed to determine whether combining two thrips lures, ethyl nicotinate (EN) and ethyl isonicotinate

(EI), in the same water trap increased the numbers of New Zealand flower thrips (NZFT), Thrips obscuratus Crawford,

and onion thrips, T. tabaci Lindeman (Thysanoptera: Terebrantia: Thripidae), caught in the field relative to traps with a

single lure. Traps with both lures (1:1 ratio; mixture or separate adjacent vials) caught 5-9 times more female onion

thrips (thelyotokous populations are the most prevalent in New Zealand) than traps with EN only (P < 0.001), but

caught similar numbers to traps with El only. Traps with both lures caught 2-3 times as many male and female NZFT

than traps with El only, but similar numbers to traps with EN only. Thus, a combination of the two lures in one trap

could be used to detect and monitor flying onion thrips and NZFT simultaneously.

Al-mazra'awi, M. S., A. Al-Abbadi, M. A. Shatnawi and M. Ateyyat (2009). "Effect of application method on the interaction

between Beauveria bassiana and neem tree extract when combined for Thrips tabaci (Thysanoptera: Thripidae) control." Journal

of Food Agriculture & Environment 7(2): 869-873.

The combined effect of the entomopathogen Beauveria bassiana and the neem tree extract were evaluated against the

onion thrips Thrips tabaci by two application approaches on potted tomato plants in a greenhouse. The first approach

was a topical application of a mixture of the two control agents while the second was a topical application of B.

bassiana and a drenching application of neem tree extract. In the mixture application, onion thrips adults treated with

B. bassiana and sub-lethal doses of neem tree extracts exhibited greater mortalities than insects treated with the fungus

alone but with no synergistic interaction. However, the two control agents interacted antagonistically when neem tree

extract was used at full field application rate. In the topical of B. bassiana and drenching application of neem tree

extract, the treated insects exhibited mortalities higher than using each control agent alone and the two control agents

interacted synergistically at sub-lethal doses of the neem tree extract. These results indicate that the application

method affected the interaction between B. bassiana and the neem tree extract because drenching neem tree extract

while applying B. bassiana topically enhanced the efficacy of the entomopathogen. Furthermore, using sub-lethal doses

of neem tree extract with B. bassiana improved the effectiveness of the control process while reducing the amount of

insecticide used. Consequently, better insect control is achieved with minimal impact on the environment.

Bag, S., S. Rondon and H. R. Pappu (2009). "Monitoring onion thrips (Thrips tabaci) and Iris yellow spot virus in bulb and seed

onion crops: A potential IPM component for mitigating IYSV epidemics." Phytopathology 99(6): S7-S7.

Dai, Y. J., M. M. Shao, D. Hannaway, L. L. Wang, J. P. Liang, L. Hu and H. Lu (2009). "Effect of Thrips tabaci on anatomical features,

photosynthetic characteristics and chlorophyll fluorescence of Hypericum sampsonii leaves." Crop Protection 28(4): 327-332.

Thrips tabaci damage can affect the anatomical features, photosynthetic characteristics and chlorophyll fluorescence of

Hypericum sampsonii. Anatomical observation found that T. tabaci damage changed the proportion of spongy tissue

thickness to the whole leaf thickness. Net photosynthetic rate (PN) of slightly, partially and severely infested leaves

decreased 16.49, 22.85 and 45.29%, respectively, compared to that of uninfected leaves. However, transpiration rate (E),

intercellular CO(2) concentration (C(i)) and stomatal resistance (G(s)) increased significantly with injury severity. T. tabaci

57

damage resulted in reduction of effective quantum yield, apparent electron transport rate, and photochemical and non-

photochemical quenching. (C) 2008 Elsevier Ltd. All rights reserved.

Davidson, M. M., R. C. Butler and D. A. J. Teulon (2009). "Pyridine Compounds Increase Thrips (Thysanoptera: Thripidae) Trap

Capture in an Onion Crop." Journal of Economic Entomology 102(4): 1468-1471.

The effect of the thrips (Thysanoptera: Thripidae) lures ethyl isonicotinate, methyl isonicotinate, and ethyl nicotinate on

numbers of thrips captured in white water traps in an onion (Allium. spp.) crop, in New Zealand, was examined. Female

onion thrips, Thrips tabaci Lindeman (69.0%), and Thrips obscuratus Crawford (27.8%) (males and females) were the

most common species found in traps in the onion crop. Ethyl isonicotinate, methyl isonicotinate, and ethyl nicotinate

caught 18, 12, and 4 X more onion thrips, respectively, than controls (no-lure). In contrast, traps with ethyl isonicotinate

set up in a grass field at the same time as the onion crop trial caught 84X more onion thrips than traps without this

lure. For T obscuratus, traps with ethyl isonicotinate, methyl isonicotinate, and ethyl nicotinate caught 10, 13, and 12X

more thrips, respectively, than controls in the onion crop.

Ibrahim, N. D. and A. A. Adesiyun (2009). "Effects of age and height of onion (Allium cepa L.) plants on infestation thrips, Thrips

tabaci Linderman ((Thysanoptera: Thripidae) in Sokoto, Nigeria." African Journal of Agricultural Research 4(2): 76-84.

Three sets of onion (Allium cepa L.) crops transplanted at 4 week intervals were exposed to thrips, Thrips tabaci

Lindeman (Thysanoptera, Thripidae) infestation at different times from February to May in 2001 - 2002 and 2002 - 2003.

Results indicated that at 4, 8 and 12 weeks after transplanting (WAT), the oldest (12 weeks) and tallest (60 cm) plants

had the highest thrips population of 240 thrips/plant and rose to 416 thrips/plant one week later. In the second and

third generations, the middle aged plants (second oldest) had the highest thrips population of 608 thrips/plant and this

was significantly different (P < 0.05) from the oldest and youngest, even though in some cases they were the second

tallest. This was maintained at 5, 9 and 13; 6, 10 and 14 and 7, 11 and 15 WAT (first generation only). Plants exposed to

thrips in March consistently had the highest thrips population. It was also observed that 40% of onion leaves constitute

inner leaves, 50% intermediate and 10% outer leaves. The percentages of thrips in those regions were 64, 33 and 3%,

respectively. Therefore, it was obvious that the oldest crop had the highest population of thrips early in the season and

later in the season. The second oldest crops continued to support the highest number of thrips irrespective of the

period of the year.

Ibrahim, N. D. and A. A. Adesiyun (2009). "Effects of staggered planting dates on the control of Thrips tabaci Lindeman and yield

of onion in Nigeria." African Journal of Agricultural Research 4(1): 33-39.

Eight-week old onion seedlings were transplanted from December to April in 2001-2002 and November to March in

2002-2003 growing seasons to assess the level of thrips damage and its effect on onion bulb yield. Results obtained

revealed that thrips started appearing from January but the number was very low until end of February when the

population reached 12 thrips/plant. November transplant was free of thrips up to 9 weeks after transplanting (WAT),

December transplant up to 8 WAT, January transplant up to 6 WAT, while February, March and April transplant had

population of > 5 thrips /plant at 4 WAT. There was a significant difference (P<0.05) between plantings from 4-14 WAT.

The peak of thrips incidence in the various transplants were as follows: November at 15 WAT (120), December at 12.5

WAT (234), January at 9.5 WAT (373), February at 8.5 WAT (217), March at 6 WAT (41.2) and April at 5 WAT (20). Onion

bulb yields were also found to differ in descending order as follows: November (48 t/ha), December (42 t/ha), January

(13.5 t/ha), February (5.5 t/ha) and March (1.5 t/ha).

Malik, M. F., M. Nawaz, J. Ellington, R. Sanderson and A. H. El-Heneidy (2009). "Effect of Different Nitrogen Regimes on Onion

Thrips, Thrips tabaci Lindemann, on Onions, Allium cepa L." Southwestern Entomologist 34(3): 219-225.

Six rates of nitrogen were evaluated on onion thrips, Thrips tabaci Lindemann, on onions, Allium cepa L., in Quetta,

Balochistan, Pakistan, in 2002 and 2003. Soil in the region is sandy loam, alkaline, moderate in calcium, and very low in

nitrogen, phosphorous, and potassium. Low (50 kg N/ha) and optimum (150 kg N/ha) amounts of nitrogen applied to

soil had no effect on abundance of thrips, although abundance of thrips (7.6 per plant) decreased at 150 kg of nitrogen

per hectare. The maximum abundance of thrips (13 per plant) was observed with high rates of nitrogen (200 and 250

kg/ha), which increased abundance of thrips as much as 73.9%. Onion yields increased with nitrogen to 200 kg/ha. A



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rapid decrease in yield occurred when 200-250 kg/ha of nitrogen was used. Maximum yield (15,250 kg/ha) had the best

cost-benefit ratio (1.43).

Mo, J., M. Stevens and D. L. Liu (2009). A temperature-driven daily process model for onion thrips populations in onions.

A temperature-driven process model was developed to describe the seasonal patterns of populations of onion thrips,

Thrips tabaci Lindeman, in onion crops. The model used daily cohorts (individuals of the same developmental stage and

daily age) as the population unit. After each day, individuals in a daily cohort either move to the next daily cohort in the

same developmental stage, advance to the first daily cohort of the next developmental stage, or be removed from the

population due to mortality and/or emigration. Stage transitions were modelled as a logistic function of accumulated

degree-days (DD) to account for variability in development rate among individuals. Daily survival was modelled as a

logistic function of daily mean temperature. Parameters for development, survival, and fecundity were estimated with

published data. A single invasion event was used to initiate the population process, starting at 1-100 days after onion

emergence (DAE) for 10-100 days at a daily rate of 0.001-0.9 adults/plant/day. The model was validated against five

observed seasonal patterns of onion thrips populations from two unsprayed sites in the Riverina, New South Wales,

Australia, during 2003-2006. Performance of the model was measured by a fit index based on the proportion of

variation in observed data explained by the model (R(2)) and the differences in total thrips-days between observed and

predicted populations. Satisfactory agreement between simulated and observed seasonal patterns was obtained within

the range of invasion parameters tested. Model best-fit was obtained at invasion starting dates of 6-98 DAE with a daily

invasion rate of 0.002-0.2 adults/plant/day and a duration of 30-100 days. Under the best-fit invasion scenarios, the

model closely reproduced the observed seasonal patterns, explaining 73-95% of variability in adult and larval densities

during population increase periods. The results showed that small invasions of adult thrips over a period of days with a

gradual population build-up of thrips within onion crops were sufficient to bring about the observed seasonal patterns

of onion thrips populations. Sudden mass invasions may reproduce well the rapid ascending phases of the population

build-up but these alone would fail to account for the low population periods. Support for small gradual invasions was

found in sticky traps data, which showed that onion thrips were moving into the onion field in small numbers long

before the first thrips were detected in onion, and in egg monitoring data, which revealed onion thrips eggs in newly

emerged onion leaves. According to the model, applications of contact insecticides are better timed before the

accumulated adult populations have reached 10% of total adult thrips-days during seasons of early to intermediate

invasions (160 days after onion emergence), and when accumulated adult populations are between 10% and 50%

during seasons of late invasions (> 60 days after onion emergence). Model simulations also suggest that management

practices that delay or reduce onion thrips invasions are critical in controlling peak infestation levels. Such practices

include removal of volunteer onions (sprouts from left-over bulbs from previous seasons) and weed control, which

reduce the source populations, and the application of a systemic insecticide at sowing, which protect onion plants from

onion thrips infestation during the early growth stages. Temperature driven, the model can be directly used to assess

the impact of climate change on onion thrips populations. After modifications of species-specific parameters, the

model can be easily adapted to describe the population dynamics of other insect species.

Mo, J. H., M. Stevens, D. L. Liu and G. Herron (2009). "Investigating the Effect of Invasion Characteristics on Onion Thrips

(Thysanoptera: Thripidae) Populations in Onions With a Temperature-Driven Process Model." Environmental Entomology 38(6):

1575-1584.

A temperature-driven process model was developed to describe the seasonal patterns of populations of onion thrips,

Thrips tabaci Lindeman, in onions. The model used daily cohorts (individuals of the same developmental stage and,

daily age) as the population unit. Stage transitions were modeled as a logistic function of accumulated degree-days to

account for variability in development rate among individuals. Daily survival was modeled as a logistic function of daily

mean temperature. Parameters for development, survival, and fecundity were estimated from published data. A single

invasion event was used to initiate the population process, starting at 1-100 d after onion emergence (DAE) for 10-100

d at the daily rate of 0.001-0.9 adults/plant/d. The model was validated against five observed seasonal patterns of

onion thrips populations from two unsprayed sites in the Riverina, New South Wales, Australia, during 2003-2006.

Performance of the model was measured by a fit index based on the proportion of variations in observed data

explained by the model (R(2)) and the differences in total thrips-days between observed and predicted populations.

Satisfactory matching between simulated and observed seasonal patterns was obtained within the ranges of invasion



59

parameters tested. Model best-fit was obtained at invasion starting dates of 6-98 DAE with a daily invasion rate of

0.002-0.2 adults/plant/d and an invasion duration of 30-100 d. Under the best-fit invasion scenarios, the model closely

reproduced the observed seasonal patterns, explaining 73-95% of variability in adult and larval densities during

population increase periods. The results showed that small invasions of adult thrips followed by a gradual population

build-up of thrips within onion crops were sufficient to bring about the observed seasonal patterns of onion thrips

populations in onion. Implications of the model on timing of chemical controls are discussed.

Multani, P. S., C. S. Cramer, R. L. Steiner and R. Creamer (2009). "Screening Winter-sown Onion Entries for Iris Yellow Spot Virus

Tolerance." Hortscience 44(3): 627-632.

Identification of resistant or tolerant onion (Allium cepa L.) cultivars is crucial for the development of integrated

management strategies for Iris yellow, spot virus (IYSV). Exclusively vectored by onion thrips (Thrips tabaci), IYSV is a

potentially devastating tospovirus of onion that has been confirmed to be present in 15 countries all over the world. In

this study, 18 winter-sown onion entries were screened for IYSV symptom expression over two seasons. Over the

growing season, straw-colored, necrotic lesions typical of IYSV infection were observed and rated for disease severity.

Entries, NMSU 03-52-1, NMSU 04-41, NMSU 04-44-1, and 'NuMex Jose Fernandez', exhibited fewer symptoms than

many other entries tested. 'Caballero', NMSU 04-57-1, NMSU 04-78-1, and 'Cimarron' exhibited more symptoms.

Disease progression over time was rapid for entries exhibiting more symptoms and slow for entries exhibiting fewer

symptoms. Enzyme-linked immunosorbent assay (ELISA) optical densities correlated poorly with the severity of disease

symptoms. Trends in the disease progression over time emphasize the importance of rating IYSV symptoms late in the

crop's development and to search for delayed disease progression rather than early symptom expression to determine

IYSV susceptibility.

Patil, J., A. Govardhan and V. D. Mytri (2009). An Intelligent System for Predicting Thrips Tabaci Linde Pest Population Dynamics

Allied To Cotton Crop.

The agricultural sector in India is up against a series of problems when it comes to increasing crop productivity. A

number of successful researches have been carried out to discover productive agricultural practices to improve crop

cultivation but despite their efforts, productivity achieved by most of the farmers has not been in upper-bound level.

The prime reason stated globally for crop loss is Insect pests. An efficient pest management technique can be devised if

we could predict in advance the occurrences of peak activities of a given pest. Researchers are undertaken to

understand the pest population dynamics by employing analytical and other techniques on pest surveillance data sets.

In this paper, we present an intelligent system for pest prediction in cotton crop with the aid of the data obtained from

College of Agriculture, Raichur, India. We make an effort to understand population dynamics of Thrips tabaci Linde

(Thrips) pest on cotton (Gossypium Arboreum) crop using neural networks by analyzing pest surveillance data. The

Multi-layer perceptron neural network with back-propagation training algorithm is utilized in the design of the

presented intelligent system. The results show that neural network system can be able to give results with a very high

degree of accuracy and is best suited to build a prediction system. With the aid of this pest prediction system, the

farming communities get more beneficiaries in crop productivity.

Ribeiro, P. J., D. N. Viola, C. G. B. Demetrio, B. F. Manly and O. A. Fernandes (2009). "SPATIAL PATTERN DETECTION MODELING

OF THRIPS (Thrips tabaci) ON ONION FIELDS." Scientia Agricola 66(1): 90-99.

Onion (Allium cepa) is one of the most cultivated and consumed vegetables in Brazil and its importance is due to the

large laborforce involved. One of the main pests that affect this crop is the Onion Thrips (Thrips tabaci), but the spatial

distribution of this insect, although important, has not been considered in crop management recommendations,

experimental planning or sampling procedures. Our purpose here is to consider statistical tools to detect and model

spatial patterns of the occurrence of the onion thrips. In order to characterize the spatial distribution pattern of the

Onion Thrips a survey was carried out to record the number of insects in each development phase on onion plant

leaves, on different dates and sample locations, in four rural properties with neighboring farms under different

infestation levels and planting methods. The Mantel randomization test proved to be a useful tool to test for spatial

correlation which, when detected, was described by a mixed spatial Poisson model with a geostatistical random

component and parameters allowing for a characterization of the spatial pattern, as well as the production of prediction

maps of susceptibility to levels of infestation throughout the area.



60

Riefler, J. and E. H. Koschier (2009). "Behaviour-modifying activity of eugenol on Thrips tabaci Lindeman." Journal of Pest Science

82(2): 115-121.

A series of observational bioassays were conducted to investigate the behavioural responses of the onion thrips, Thrips

tabaci Lindeman (Thysanoptera: Thripidae), to an application of a secondary plant compound to two different host

plants with dissimilar leaf surface characteristics. Eugenol, a phenylpropanoid compound known to deter feeding and

oviposition of the onion thrips, was applied to leek (Allium porrum L.) and cucumber (Cucumis sativus L.) at 1%

concentration. Using a video system and special software for computing observational data, influences of this plant

compound on the behaviour of T. tabaci females were evaluated. Eugenol treatment significantly prolonged the time

periods thrips spent being inactive and moving across the treated leek or cucumber surface. The feeding periods on

leek leaves treated with eugenol were clearly shorter compared to periods on untreated leek. The behaviours related to

oviposition on leaves from both host species treated with eugenol were slightly reduced. T. tabaci females avoided

direct contact with eugenol particularly when applied to leek, showing significantly lower contact duration compared to

an untreated surface. This shows that behaviour-modifying secondary compounds such as eugenol may be used in

various strategies and may contribute to the enhancement of current biological control measures and/or form novel

components of Integrated Pest Management strategies.

Riefler, J. and E. H. Koschier (2009). "Comparing Behavioural Patterns of Thrips tabaci Lindeman on Leek and Cucumber." Journal

of Insect Behavior 22(2): 111-120.

This study documents the behavioural repertoire of Thrips tabaci. Seventeen behavioural elements shown by adult

females were videotaped, described and classified into seven behavioural categories. The comparison of thrips

behaviour on leek and cucumber over 24 h (L:D = 16:8) revealed that on cucumber thrips spent significantly less time

being inactive, but significantly more time with feeding resulting in significantly higher feeding damage compared to

leek. Oviposition behaviour incidence and oviposition rate were somewhat, but not significantly lower on cucumber

compared to leek. Sequences of leaf surface exploration lasted significantly longer on cucumber than on leek. Thrips

females were as active during light as during dark periods. Our results show that T. tabaci females spend different

amounts of time with resting, feeding and explorative behaviours on leek and cucumber, thus indicating differences in

host use on these two crops.

Schwartz, H. F., D. H. Gent, S. M. Fichtner, R. Hammon, W. S. Cranshaw, L. Mahaffey, M. Camper, K. Otto and M. McMillan (2009).

"Straw Mulch and Reduced-Risk Pesticide Impacts on Thrips and Iris Yellow Spot Virus on Western-Grown Onions."

Southwestern Entomologist 34(1): 13-29.

Iris yellow spot virus and its vector the onion thrips, Thrips tabaci Lindeman, are yield-limiting pests of onion, Allium

cepa L., throughout the western U.S. In experiments in Colorado during 2005 to 2007, straw mulch applied to the center

of onion beds at the early to mid-bulb growth stage reduced abundance of thrips as much as 33% when compared to

nontreated plots of transplanted onions. Cumulative thrips-days indicated that straw mulch significantly reduced

season-long abundance by 10 to 20% compared with check plots in bare soil. The addition of conventional insecticides

(methomyl alternated with lambda-cyhalothrin) was associated with 12 to 27% greater cumulative thrips-days

compared to the nontreated check in two experiments. In contrast, a reduced-risk insecticide program (spinosad

alternated with azadirachtin) had fewer cumulative thrips-days on both bare soil (15%) and straw mulch (36%)

compared to nontreated checks. Enhanced thrips control generally persisted during mid-season and may have

contributed to reduced stress from damage by thrips feeding and reduced incidence and/or severity by Iris yellow spot

virus during the early to mid-bulb stages of plant growth. Total yield and yield of jumbo-sized onions were increased as

much as 13 and 18% by straw mulch compared to bare soil treatments among the individual experiments. Peak

abundance of thrips on commercial red onion plants evaluated during 2004 was positively correlated with the incidence

of iris yellow spot 40 days (R(2) = 0.5864, P = 0.0060) and 54 days (R(2) = 0.6086, P = 0.0046) later, indicating that

suppressing thrips might provide some control of the disease. Effective long-term management of thrips and iris yellow

spot in onion crop systems will depend on a multi-faceted approach that integrates host resistance, modified cultural

practices such as straw mulching and irrigation scheduling, and judicious use of reduced-risk insecticides.



61

Toda, S. and M. Morishita (2009). "Identification of Three Point Mutations on the Sodium Channel Gene in Pyrethroid-Resistant

Thrips tabaci (Thysanoptera: Thripidae)." Journal of Economic Entomology 102(6): 2296-2300.

In the onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), the development of resistance to pyrethroid

insecticides has become a problem worldwide. To identify this species' resistance mechanism, we analyzed partial

nucleotides and deduced the amino acid sequences of the para-orthologous sodium channel gene by using 10

Japanese strains of T tabaci that have a variety of susceptibility levels to pyrethroids. Six nucleotide substitutions were

found in their cDNA sequences. Three of these create amino acid substitutions, M918T, T929I, and L1014F, which are

well known to be associated with knockdown resistance in some pest insects. in the five highly resistant strains, two

mutations, M918T and L1014F, were always detected with wild-type sequences, suggesting that these strains have both

mutations heterozygously. A moderately resistant strain was homozygous for the T929I mutation. This is the first report

to identify these three major mutations within the same species.

Bosco, L., E. Giacometto and L. Tavella (2008). "Colonization and predation of thrips (Thysanoptera : Thripidae) by Orius spp.

(Heteroptera : Anthocoridae) in sweet pepper greenhouses in Northwest Italy." Biological Control 44(3): 331-340.

Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman (Thysanoptera: Thripidae) are major pests of sweet

pepper for direct damage and tospovirus transmission. To control their infestations, Orius laevigatus (Fieber)

(Heteroptera: Anthocoridae) is produced by many commercial insectaries and widely used on IPM vegetable crops of

Europe. This predator is naturally widespread along the Mediterranean and Atlantic coasts, and not in more continental

areas, where other Orius spp. are more common. Research was conducted in a continental area of Northwest Italy in

2002-2003 to assess the natural presence of anthocorids on pepper, and to compare their colonization and predatory

ability with those of the species artificially introduced. Experiments were conducted in 12 sweet pepper greenhouses, in

six of which O. laevigatus release was made. From late May to early October, thrips and anthocorids were sampled on

pepper by collecting flowers; Orius spp. were also collected on neighboring wild flora. Independently of the releases,

Orius specimens were found in all surveyed greenhouses, but O. niger Wolff, also captured on various wild plants, was

the most abundant species. It naturally colonized crops from late June and proved to be the most efficient predator on

sweet pepper in the surveyed area, if not disturbed by pesticide application. Contrarily, O. laevigatus was rarely found

and only in the greenhouses in which it had been released. However its introduction resulted in thrips control before

natural colonization by the native species occurred. (C) 2007 Elsevier Inc. All rights reserved.

Cabrera-Asencio, I. and A. L. Velez (2008). "Insecticides and populations of Thrips tabaci (Lindermann) and Liriomyza trifolii

(Burges) in onions." Journal of Agriculture of the University of Puerto Rico 92(1-2): 87-101.

The use of insecticides to decrease Thrips tabaci and Liriomyza trifolii population in onion (Allium cepa L.) was

evaluated for two consecutive years. The insecticides most frequently used by farmers were evaluated: cypermethrin,

avermectin, oxamyl, azadirachtin and dimetyl. A treatment with water only, plus the control, was also evaluated. It was

observed that the use of cypermethrin resulted in the least number of nymphs and adults of Thrips tabaci and the best

onion yield. As for Liriomyza trifolii, it was observed that the use of avermectin and cypermecthrin resulted in the least

numbers of larvae.

Chikte, P., S. M. Thakare and S. K. Bhalkare (2008). "Influence of various cotton-based intercropping systems on population

dynamics of thrips, Scircothrips dorsalis Hood and whitefly, Bemisia tabaci Genn." Research on Crops 9(3): 683-687.

Studies were carried out during 2004-05 in the field of Department of Entomology, Dr. Panjabrao Deshmukh Krishi

Vidyapeeth, Akola in randomized block design using eight intercrop system replicated three times including sole crop

of cotton with an objective to assess the potential of intercropping system in minimizing thrips and whiteflies on

cotton. Intercropping of cowpea in cotton proved the best in suppressing the population of thrips and whiteflies.

Moreover, the treatment of cotton+cowpea produced higher yield (251 kg/ha) and was at par with the treatment of

cotton+marigold (232 kg/ha) and cotton+sorghum (210 kg/ha).

De Vries, E. J., A. W. G. Van der Wurff, G. Jacobs and J. A. J. Breeuwer (2008). "Onion thrips, Thrips tabaci, have gut bacteria that

are closely related to the symbionts of the western flower thrips, Frankliniella occidentalis." Journal of Insect Science 8.

It has been shown that many insects have Enterobacteriaceae bacteria in their gut system. The western flower thrips,

Frankliniella occidentalis Pergande [Thysanoptera: Thripidae], has a symbiotic relation with Erwinia species gut bacteria.



62

To determine if other Thripidae species have similar bacterial symbionts, the onion thrips, Thrips tabaci, was studied

because, like F. occidentalis, it is phytophagous. Contrary to F. occidentalis, T. tabaci is endemic in Europe and biotypes

have been described. Bacteria were isolated from the majority of populations and biotypes of T. tabaci examined.

Bacteria were present in high numbers in most individuals of the populations studied. Like F. occidentalis, T. tabaci

contained one type of bacterium that clearly outnumbered all other types present in the gut. This bacterium was

identified as an Erwinia species, as was also the case for F. occidentalis. However, its biochemical characteristics and 16S

rDNA sequence differed from the bacteria present in F. occidentalis.

Downes, C. J., B. B. C. Page, C. W. van Epenhuijsen, P. C. M. Hoefakker and A. Carpenter (2008). "Response of the onion pests

Thrips tabaci (Lind.) (Insecta : Thysanoptera : Thripidae) and Aspergillus niger (van Tieghem) (Fungi : Hyphomycetes) to

controlled atmospheres." Postharvest Biology and Technology 48(1): 139-145.

The effects on onion thrips (Thrips tabaci) of controlled atmospheres (CAs) containing 15, 30,45 and 60% carbon

dioxide in air were determined by measuring the metabolic heat rates (MHRs) using inicrocalorimetry and compared

with previous conventional trials. Black mould (Aspergillus niger), Cultured in several different ways, was exposed to the

same CAs with the effects being determined by microcalorimetry and colony-growth measurements. The effect of

temperature on the MHR of black mould was measured from 5 to 45 degrees C. These results show CAs high in carbon

dioxide are a promising treatment for the postharvest control of thrips but are ineffective for the control of black mould

at ambient temperatures. Temperatures above 35 degrees C, in combination with CAs, may be an effective treatment

for black mould if onions are not damaged by these conditions. (c) 2007 Elsevier B.V. All rights reserved.

Herron, G. A., T. M. James, J. Rophail and J. H. Mo (2008). "Australian populations of onion thrips, Thrips tabaci Lindeman

(Thysanoptera: Thripidae), are resistant to some insecticides used for their control." Australian Journal of Entomology 47: 361-

364.

Onion thrips, Thrips tabaci Lindeman, is a major pest of Australian field onion Allium cepa Linnaeus with their control

heavily reliant on a few insecticides. An earlier study after grower complaints of control failures did not detect

resistance in three populations. After testing an additional nine populations via a Potter spray tower laboratory bioassay

unequally against alpha-cypermethrin, diazinon, dimethoate, lambda-cyhalothrin, malathion and methidathion, we

document resistance in T tabaci for the first time in Australia. The maximum difference in response (resistance) for each

insecticide was detected by dividing the most resistant LC50 response by the least resistant LC50 response. Comparison

of the most susceptible to the least susceptible population tested produced alpha-cypermethrin and lambda-

cyhalothrin resistance at 164- and 606-fold, respectively. Diazinon and dimethoate resistance was also detected at 27-

fold and 5.2-fold respectively although omethoate, malathion and methidathion resistance were not detected.

Larentzaki, E., J. Plate, B. A. Nault and A. M. Shelton (2008). "Impact of straw mulch on populations of onion thrips (Thysanoptera

: Thripidae) in onion." Journal of Economic Entomology 101(4): 1317-1324.

Development of insecticide resistance in Onion thrips, Thrips labaci Lindeman (Thysanoptera: Thripidae), populations in

onion (Allium spp.) fields and the incidence of the T. tabaci transmitted Iris yellow spot virus have stimulated interest in

evaluating alternative management tactics. Effects of straw mulch applied in commercial onion fields in muck areas of

western New York were assessed in 2006 and 2007 as a possible Onion thrips management strategy. In trials in which

no insecticides were applied for thrips control, straw mulch-treated plots supported significantly lower T tabaci

populations compared with control plots. In both years, the action thresholds of one or three larvae per leaf were

reached ill Straw mulch treatments between 7 and 14 d later than in the control. Ground predatory fauna, as evaluated

by pitfall trapping, was not increased by straw mulch in 2006; however, populations of the common predatory thrips

Aeolothrips fasciatus (L.) (Thysanoptera: Aeolothripidae) were significantly lower in straw mulch plots in both years.

Interference of straw mulch in the pupation and emergence of T. tabaci was investigated in the lab and their

emergence was reduced by 54% compared with bare soil. In the field the overall yield of onions was not affected by the

straw mulch treatment; however, the presence of,jumbo grade onions (>77 mm) was increased ill 2006, but not in 2007.

These results indicate that populations of T labaci adults and larvae call be significantly reduced by the use of straw

mulch without compromising overall Onion yield. The use of this cultural practice in an Onion integrated pest

management program seems promising.



63

Larentzaki, E., A. M. Shelton and J. Plate (2008). "Effect of kaolin particle film on Thrips tabaci (Thysanoptera : Thripidae),

oviposition, feeding and development on onions: A lab and field case study." Crop Protection 27(3-5): 727-734.

Laboratory studies were conducted to evaluate the effects of a kaolin-based particle film on biological characteristics of

the onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), on onions. Oviposition rate was significantly

reduced on kaolin-treated vs. water-treated onion leaves and plants, in choice and no-choice assays. Hatch rate was

reduced when kaolin particle film was applied over eggs on onion leaves. The time required for development of larval

stages was significantly increased and mortality was significantly higher on kaolin than on water-treated onion leaves.

Feeding choice was influenced by the presence of the kaolin treatment and in choice assays both larvae and adults fed

significantly less on kaolin-treated than on water-treated leaves. In a field study, significantly more adults were

captured in the beginning of the season on control than on kaolin-treated plots, and at population peaks significantly

more larvae and adults were harbored in control plots. The results indicate the potential of kaolin particle film against

onion thrips in an integrated pest management program. However, because of the importance of a continuous

coverage of plant material with kaolin particle film, better application methods and perhaps frequent applications will

be required to cover newly expanding foliage. (c) 2007 Elsevier Ltd. All rights reserved.

Martin, N. A., P. J. Workman, D. Hedderley and L. L. Fagan (2008). "Monitoring onion (Allium cepa) crops for onion thrips (Thrips

tabaci) (Thysanoptera : Thripidae): testing a commercial protocol." New Zealand Journal of Crop and Horticultural Science 36(2):

145-152.

Onion thrips (Thrips tabaci) is the main insect pest on New Zealand onions (Allium cepa). Insecticide applications are

triggered by thrips numbers exceeding action thresholds. A new crop monitoring protocol that involves sampling a

minimum of 100 plants (up to 4 ha) or 25 plants/ha, was tested in 10 young or mature onion crops. Two people

independently sampled each crop by zigzagging up and down groups of onion beds defined by pairs of sprayer wheel

tracks and selecting a plant at random at predetermined intervals along the crop beds. The number of thrips adults and

larvae per plant was recorded. A strong relationship was found between total numbers of thrips and the percentage of

plants infested. If the onion industry raised its spray action threshold from 0.1 thrips/plant to 2 or 3 thrips/plant (c. 50%

plants infested), it could adopt presence-absence sampling that would be faster than counting all thrips. The time to

monitor a crop was affected by field size,, and only increased slightly with higher levels of infestation. The new

guidelines could also be used for monitoring disease and weeds.

Mo, J. H., S. Munro, A. Boulton and M. Stevens (2008). "Within-plant distribution of onion thrips (Thysanoptera : Thripidae) in

onions." Journal of Economic Entomology 101(4): 1331-1336.

Two aspects of the within-plant distribution of Thrips tabaci Lindeman (Thysanoptera: Thripidae) on onion, Allium cepa

L., plants were investigated: 1) diurnal variations in the distribution of adults and larvae between basal and upper

sections of Onion leaves, and 2) between-leaf and within-leaf distribution of the eggs. The diurnal investigations

showed that higher proportions of larvae than Of adults congregated at the basal sections of plants, particularly when

plants were young and thrips density was low. As plants matured and thrips density increased, the larvae became more

dispersed. Regardless of plant size, there were always more adults in the Upper than basal plant sections. There were

no clear time-windows during the 24-h diurnal cycle when more thrips were in the upper plant parts. T. tabaci eggs

were laid everywhere in the plant. Leaves of intermediate ages had more eggs than older Or younger leaves. Within

leaves, the white leaf sheath received the least eggs and leaf tips received slightly more eggs than leaf sheaths. The

highest egg density was found between the green leaf base and the leaf tips. Regardless of plant size, more than half of

all eggs were laid above the basal sections. The percentage increased to >95% in mature plants. Except when plants

were small the Outer leaves were preferred over inner leaves and upper leaf sections preferred over lower leaf sections

as egg-laying sites by adults. Implications of the results in the management of T. tabaci are discussed.

Morishita, M. (2008). "Pyrethroid-resistant onion thrips, Thrips tabaci Lindeman (Thysanoptera : Thripidae), infesting persimmon

fruit." Applied Entomology and Zoology 43(1): 25-31.

A total of 53 strains of onion thrips, Thrips tabaci Lindeman, were established, of which 14 strains were collected from

persimmon fruit and 39 strains from a vetch weed, Vicia angustifolia, in commercial persimmon orchards in Wakayama

Prefecture. Susceptibility to insecticides was evaluated by the Petri dish-spraying tower method. Pyrethroid-resistant

strains and pyrethroid-susceptible strains of T tabaci were found in persimmon fruit. The LC50 values of cypermethrin



64

and fluvarinate of the pyrethroid-resistant strain were > 240ppm and > 800ppm, respectively, with resistance ratio of >

200; however, no significant differences were observed between the two strains in the susceptibility to the other five

insecticides, including organophosphates and neonycotinoids. There was a wide range of variability in mortality from

1.1 to 100% caused by cypermethrin at 60 ppm (LC50 values from 0.390 ppm to 177 ppm) in T tabaci collected from

vetch in 5 different persimmon orchards. Regional difference was detected in the proportion of the pyrethroid-resistant

strain: up to 67% of the strains collected from Naga where some orchards had been heavily applied with pyrethroids,

compared to 17% of the strains collected from Kawahara where organophosphates and neonycotinoids had been

applied.

Morsello, S. C., R. L. Groves, B. A. Nault and G. G. Kennedy (2008). "Temperature and precipitation affect seasonal patterns of

dispersing tobacco thrips, Frankliniella fusca, and onion thrips, Thrips tabaci (Thysanoptera : Thripidae) caught on sticky traps."

Environmental Entomology 37(1): 79-86.

Effects of temperature and precipitation on the temporal patterns of dispersing tobacco thrips, Frankliniella fusca, and

onion thrips, Thrips tabaci, caught on yellow sticky traps were estimated in central and eastern North Carolina and

eastern Virginia from 1997 through 2001. The impact that these environmental factors had on numbers of F fusca and T

tabaci caught on sticky traps during April and May was determined using stepwise regression analysis of 43 and 38

site-years of aerial trapping data from 21 and 18 different field locations, respectively. The independent variables used

in the regression models included degree-days, total precipitation, and the number of days in which precipitation

occurred during January through May. Each variable was significant in explaining variation for both thrips species and,

in all models, degree-days was the single best explanatory variable. Precipitation had a comparatively greater effect on

T tabaci than F fusca. The numbers of F. fusca and T tabaci captured in flight were positively related to degree-days and

the number of days with precipitation but negatively related to total precipitation. Combined in a single model, degree-

days, total precipitation, and the number of days with precipitation explained 70 and 55% of the total variation in the

number of F. fusca captured from 1 April through 10 May and from 1 April through 31 May, respectively. Regarding T

tabaci flights, degree-days, total precipitation, and the number of days with precipitation collectively explained 57 and

63% of the total variation in the number captured from 1 April through 10 May and from 1 April through 31 May,

respectively.

Pandey, A. K., S. K. Dwivedi, S. B. Ahmed and Z. Ahmed (2008). "Spatial distribution of thrips (Thrips tabaci) in onion (Allium cepa)

under cold arid region of Jammu and Kashmir." Indian Journal of Agricultural Sciences 78(1): 65-69.

A field study was carried out during 2003-04 at Ladakh at to study the spatial distribution of onion thrips (Thrips tabaci

Lindeman) in 'Brown Spanish' onion (Allium cepa L.). The various indices of dispersion, viz variance mean ratio,

exponent k and common k (Kc), Lloyd's indices of mean crowding (x*) and patchiness index (x*root x) and Taylor's

power law revealed that the onion thrips exhibited aggregated or contagious pattern of distribution in the field. The

value of Taylor's aggregation index (b) was 1.3778 and 1.4186 during 2003 and 2004 respectively. In study of Iwao's m*

- m relationship it was found that contagiousness coefficient value (a = 1.002 and 1.038 respectively) was > 1. This also

indicated that thrips population followed negative binomial distribution pattern as an alternative of poisson or random

distribution. The intercept also justified that the distribution of thrips was contagion in nature.

Pizzol, J., D. Nammour, J. P. Ziegler, S. Voisin, N. Olivier, B. Paris and P. Maignet (2008). Efficiency of Neoseiulus cucumeris and

Franklinothrips vespiformis for Controlling Thrips in Rose Greenhouses. Proceedings of the International Symposium on High

Technology for Greenhouse System Management, Vols 1 and 2. S. DePascale, G. S. Mugnozza, A. Maggio and E. Schettini: 1493-

1498.

The two thrips species Frankliniella occidentalis Pergande and Thrips tabaci Lindeman [Thysanoptera: Thripidae] are

serious pests of greenhouse roses in the Mediterranean region. The present study was undertaken in 2005 and 2006 in

two 130 m(2) greenhouses in the South of France (Nice), on three varieties of roses: 'Aubade', 'Miss Paris' and

'Sayonara'. Integrated pest control using Neoseiulus cucumeris Oudemans [Acarina: Phytoseiidae] supplemented by

Franklinothrips vespiformis Crawford [Thysanoptera: Aeolothripidae] successfully limited the populations of thrips and

kept them below the economic threshold. Under our experimental conditions, F. vespiformis did not become

established on the crop. Among the three varieties, 'Aubade' (cream) and 'Sayonara' (yellow) were more severely

attacked by the thrips than 'Miss Paris' (red), however the damage was especially visible on 'Aubade'.



65

Pourian, H., R. Talaei-Hassanloui, A. Kharazi-Pakdel and H. Allahyari (2008). "Functional response of Orius albidipennis preying on

healthy and Metarhizium anisopliae-infected larvae and adults of Thrips tabaci." Comparative Biochemistry and Physiology a-

Molecular & Integrative Physiology 150(3): S93-S93.

Pourian, H. R., R. Ezzati-Tabrizi and R. Talaei-Hassanloui (2008). "An improved cage system for the bioassay of Metarhizium

anisopliae on Thrips tabaci (Thysanoptera : Thripidae)." Biocontrol Science and Technology 18(7): 745-752.

The ability of thrips and other minute insects to escape from conventional assay cups led to development of a

successful assay chamber. In the present study, we evaluated three bioassay systems for thrips; Tashiro cage, microtube

assay and leaf sandwich assay and introduced an improved thrips entomopathogenic bioassay system (TEBS). Our

objective was to investigate the effect of Metarhizium anisopliae on Thrips tabaci using an easy-to-use and inexpensive

holding chamber that would produce bioassay results with acceptable levels of accuracy and precision. In our assays,

we found that escape of second-instar larvae from TEBS was significantly less than those of other methods which we

tested. Our results indicated that our assay system was more suitable than the other conventional assays for the

bioassay of entomopathogenic fungi on T. tabaci.

Reddy, P. V. R. and C. Aswath (2008). "Resistance of exotic collections of gerbera (Gerbera jamesonii) against whitefly (Bemisia

tabaci) and thrips (Thrips palmi) under polyhouse conditions." Indian Journal of Agricultural Sciences 78(5): 449-452.

An experiment was conducted during 2003-04 to study the resistance of 16 exotic collections of gerbera (Gerbera

jamesonii Bolus ex. Hooker R) against whitefly (Bemisia tabaci Genn.) and thrips (Thrips palmi Karney) under polyhouse

conditions at Bangalore. Of the 16 collections screened, 2 varieties 'Eva', and 'Carocci' showed combined resistance to

both whitefly and thrips while 3 varieties 'Alberino' 'Dil', and 'Cassiona' were highly susceptible to both the pests.

Varietal reactions were also studied in relation to flower structure type and colour. It was found that double types were

least susceptible (38.26%) to thrips damage compared to single (56.48%) and semi-double types (75.38%). Among

flower colours, red colour attracted highiest thrips incidence (77.89%), followed by yellow (59.61%) while pink varieties

had significantly less damage (34.37%).

Shelton, A. M., J. Plate and M. Chen (2008). "Advances in control of onion thrips (Thysanoptera : Thripidae) in cabbage." Journal

of Economic Entomology 101(2): 438-443.

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), feeding injury results in discoloration and a rough

texture on cabbage, Brassica oleracea capitata (L.), leaves, and damage may occur deep inside the head. It has become

a key pest of cabbage in the United States and many other countries. Previous studies have indicated poor control

using insecticides. The present study identified imidacloprid drenches and sprays of acetamiprid, dimethoate, spinosad,

and imidacloprid as insecticides that performed better than the industry standard, lambda-cyhalothrin. However,

additional tests with foliar sprays of dimethoate and acetamiprid indicated there was not an ideal crop stage

(precupping, cupping, or postcupping) at which either insecticide could be applied for reliable control of T. tabaci,

possibly because of multiple flights of thrips into the crop or the asynchrony of flights and susceptible crop stages. In

tests in a commercial field, a soil drench of imidacloprid 4 wk after transplanting reduced the number of damaged

leaves in the head by 32%, whereas five sprays of acetamiprid reduced damage by 51%. Combining both insecticide

regimes reduced damage by 85%, but resulted in a very costly management program. Cabbage varieties varied

considerably in susceptibility with some having negligible thrips injury, regardless of being treated with an insecticide.

Planting date affected susceptibility of cabbage to some degree, but not as much as other tactics. Overall, these studies

indicate that increased emphasis should be placed on breeding cabbages to be resistant to T. tabaci as the foundation

for its management.

Talaei-Hassanloui, R., H. Pourian and R. Ezzati-Tabrizi (2008). "A new cage system for the bioassay of entomopathogenic fungi on

Thrips tabaci (Thysanoptera : Thripidae)." Comparative Biochemistry and Physiology a-Molecular & Integrative Physiology 150(3):

S112-S112.

Tatemoto, S. and T. Shimoda (2008). "Olfactory responses of the predatory mites (Neoseiulus cucumeris) and insects (Orius

strigicollis) to two different plant species infested with onion thrips (Thrips tabaci)." Journal of Chemical Ecology 34(5): 605-613.



66

Responses of Neoseiulus cucumeris (a predatory mite) and the predatory insect Orius strigicollis to volatiles associated

with two different plant species infested with onion thrips, Thrips tabaci, were examined in a Y-tube olfactometer. Both

predators species showed a significant preference for volatiles from infested cucumber leaves without T. tabaci over

clean air. However, they were not attracted to volatiles from uninfested cucumber leaves, artificially damaged cucumber

leaves, or volatiles from T. tabaci plus their visible products collected from cucumber leaves. These results suggest that

both predator species are capable of exploiting herbivore-induced volatiles from T. tabaci-infested cucumber leaves as

a foraging cue. Neither predator was attracted to volatiles from uninfested spring onion leaves, infested spring onion

leaves without T. tabaci, or volatiles from T. tabaci plus their visible products collected from spring onion leaves.

Interestingly, they avoided volatiles from artificially damaged spring onion leaves. A possible explanation for the non-

significant olfactory responses of the predator species to spring onion plants with infestation damage of T. tabaci is

discussed.

Trdan, S., D. Znidarcic, M. Kac and M. Vidrih (2008). "Yield of early white cabbage grown under mulch and non-mulch conditions

with low populations of onion thrips (Thrips tabaci Lindeman)." International Journal of Pest Management 54(4): 309-318.

The damage caused by Thrips tabaci to a susceptible hybrid of early white cabbage was studied in field experiments

undertaken during 2004 and 2005. The three treatments tested were beds of cabbage mulched with: (1) barley straw,

(2) hay, and (3) black polyethylene (PE) sheeting. Bare-soil (un-mulched) beds were used as the control treatment. One

early and one late experiment were performed in both years. In the early experiments, the mulches were applied at the

start of the experiment, whereas in the late experiments the soil was first covered with black polyethylene for

approximately 1 month. In both years, the springs were cold and wet, and so the thrips appeared late and their

numbers were low. The highest mean actual weight and trimmed weight were recorded for cabbage grown in 2005

under PE mulch (actual early: 995g, actual late: 1184 g, trimmed early: 870g, trimmed late: 1056 g). Year 2004 gave

lower values (110g for both variables) under barley straw and hay mulch (165g and 160g, respectively). There was no

evidence of an allelopathic effect of water extracts of either barley straw or hay.

Voorrips, R. E., G. Steenhuis-Broers, M. Tiemens-Hulscher and E. T. L. van Bueren (2008). "Plant traits associated with resistance to

Thrips tabaci in cabbage (Brassica oleracea var capitata)." Euphytica 163(3): 409-415.

Thrips tabaci is a major problem in the cultivation of cabbage for storage, as this pest causes symptoms that

necessitate the removal of affected leaves from the product. Between cabbage varieties large differences in

susceptibility occur. This study aimed to identify plant traits associated with these differences, in field experiments with

natural infestation in 2005 and 2006. One factor affecting the amount of thrips damage was the timing of the

development of the head. In an experiment with different planting dates especially the early maturing, more susceptible

varieties were shown to benefit from later planting. In comparisons of multiple varieties in both years, regression

studies showed that more advanced plant development in August and early September increased thrips damage at the

final harvest. However, no single plant trait explained more than 25% (2005, Brix) or 48% (2006, compactness) of the

variation in thrips damage. Optimal regression models, explaining up to 75% of the variation in thrips damage included

Brix and leaf surface wax late in the season, as well as an indicator of plant development earlier in the season, and in

2005 also leaf thickness. The possible role of these plant traits in relation to thrips is discussed.

Waiganjo, M. M., J. M. Mueke and L. M. Gitonga (2008). Susceptible onion growth stages for selective and economic protection

from onion thrips infestation. Proceedings of the International Symposium on Sustainability through Integrated and Organic

Horticulture. R. K. Prange and S. D. Bishop: 193-199.

The growth of the bulb onion is subject to significant stress and yield reduction caused by sap feeding onion thrips. In

Kenya, the general control recommendation is to spray the crop with insecticides as soon as the pest appears and to

continue thereafter, throughout the crop season. The practice is expensive and environmentally hazardous. Two field

trials were conducted at the Kenya Agricultural Research Institute (KARI) Mwea-Tebere farm to identify the growth

stages most susceptible to onion thrips infestation that would provide the highest economic benefits to the onion

grower by managing thrips, with the aim of promoting need-based onion pesticide application. The trial design was

randomized complete blocks of 16 treatments replicated three times., The treatments constituted insecticide

treatments at different onion growth stages and frequencies. Thrips density/plant was estimated weekly through a

destructive cutting and bagging method. Yield gains due to the application of the protection regimes were calculated

67

and the marginal returns estimated as the income of yield gain divided by the cost of the control option. Thrips

infestation was significantly (p=0.05) higher in the unprotected plots than all the protected plots in the first and second

trial and resulted in significant yield losses of 59 and 29%, respectively. A significant onion yield response to thrips

infestation was observed during the 2(nd) month (bulb-formation) and 3(rd) month (bulb-enlargement) after

transplanting, but no significant response was observed in the 1(st) month (pre-bulbing) and 4(th) month (maturation)

respectively. Onion protection only during the bulb-formation stage resulted in higher marginal returns than full season

pesticide application. The studies suggested that control recommendations for onion thrips could be refined to

optimize selective pesticide use in Kenya.

Wimmer, D., D. Hoffmann and P. Schausberger (2008). "Prey suitability of western flower thrips, Frankliniella occidentalis, and

onion thrips, Thrips tabaci, for the predatory mite Amblyseius swirskii." Biocontrol Science and Technology 18(6): 533-542.

Western flower thrips, Frankliniella occidentalis, and onion thrips, Thrips tabaci, are both important polyphagous pests

of vegetables and ornamentals in greenhouses. Difficulties in biological control of these pests have prompted a search

for new natural enemies. Most recently, the predatory mite Amblyseius swirskii has been commercialised as biological

control agent of whiteflies and thrips. However, little is known about the suitability of thrips as prey for A. swirskii. We

therefore assessed prey acceptance and life history of A. swirskii when feeding on F. occidentalis and T. tabaci at 25 +/-

1 degrees C. Amblyseius swirskii juveniles preyed upon first larval instars of both F. occidentalis and T. tabaci but

suffered from high mortality (67 and 78%). Developmental time (egg to adult) of A. swirskii was 7.8 days with either

prey species. Adult A. swirskii females readily accepted first larval instars of both thrips species, which were attacked in

<20 min on a leaf and <10 min in an artificial cage. Oviposition rates (0.92 and 0.99 eggs/female/day) and offspring sex

ratios (63 and 70% females) were similar with F. occidentalis and T. tabaci as prey. Less than one-third of juveniles

reaching adulthood and oviposition rates below one egg/female per day resulted in relatively low intrinsic rates of

increase (r(m)) (0.056 and 0.024 per day with F. occidentalis and T. tabaci, respectively). Altogether, our study suggests

that the recently reported superiority of A. swirskii to the widely used Neoseiulus cucumeris in suppression of thrips is

due to other traits than its population growth capacity with thrips as prey.

Zen, S., M. Okuda, S. Fuji and T. Iwanami (2008). "THE SEASONAL OCCURRENCE OF VIRULIFEROUS THRIPS TABACI AND THE

INCIDENCE OF IRIS YELLOW SPOT VIRUS DISEASE ON LISIANTHUS." Journal of Plant Pathology 90(3): 511-515.

The occurrence of viruliferous onion thrips (Thrips tabaci) outside lisianthus greenhouses was examined from 2003 to

2005. Adults were captured using blue sticky traps placed outside the greenhouses, and viruliferous individuals were

identified using DAS-ELISA. While T tabaci appeared from April to July, viruliferous individuals were mainly detected

from the end of May to the middle of June. Leaf necrosis caused by Iris yellow spot virus (IYSV) developed soon after

the massive appearance of viruliferous T tabaci in the field. The disease appeared simultaneously in June on lisianthus

plants at different growth stages. These results suggest that the infection source of IYSV is located outside the

greenhouses. Surveys conducted in an onion field near the lisianthus greenhouses showed that viruliferous T tabaci

dispersed after harvesting of onions, suggesting that IYSV-infected onion plants are the inoculum sources in this area.

Asokan, R., N. K. K. Kumar, V. Kumar and H. R. Ranganath (2007). "Molecular differences in the mitochondrial cytochrome

oxidase I (mtCOI) gene and development of a species-specific marker for onion thrips, Thrips tabaci Lindeman, and melon thrips,

T-palmi Karny (Thysanoptera : Thripidae), vectors of tospoviruses (Bunyaviridae)." Bulletin of Entomological Research 97(5): 461-

470.

A quick and developmental-stage non-limiting method of the identification of vectors of tospoviruses, such as Thrips

tabaci and T. palmi, is important in the study of vector transmission, insecticide resistance, biological control, etc.

Morphological identification of these thrips vectors is often a stumbling block in the absence of a specialist and limited

by polymorphism, sex, stage of development, etc. Molecular identification, on the other hand, is not hampered by the

above factors and can easily be followed by a non-specialist with a little training. The mitochondrial cytochrome

oxidase I (mtCOI) exhibits reliable inter-species variations as compared to the other markers. In this communication, we

present the differences in the mtCOI partial sequence of morphologically identified specimens of T. tabaci and T. palmi

collected from onion and watermelon, respectively. Species-specific markers, identified in this study, could successfully

determine T. tabaci and T. palmi, which corroborated the morphological identification. Phylogenetic analyses showed

that both T. tabaci and T. palmi formed different clades as compared to the other NCBI accessions. The implication of



68

these variations in vector efficiency has to be investigated further. The result of this investigation is useful in the quick

identification of T. tabaci and T. palmi, a critical factor in understanding the epidemiology of the tospoviruses, their

management and also in quarantine.

Chatzivassiliou, E. K., D. Peters and N. I. Katis (2007). "The role of weeds in the spread of Tomato spotted wilt virus by Thrips

tabaci (Thysanoptera : Thripidae) in tobacco crops." Journal of Phytopathology 155(11-12): 699-705.

Oviposition of Thrips tabaci, larval development and their potential to acquire Tomato spotted wilt virus (TSWV) from

infected Amaranthus retroflexus, Datura stramonium, Lactuca serriola, Solanum nigrum and Sonchus oleraceus plants

and the ability of the adults to transmit this virus to these weeds and tobacco (Nicotiana tabacum cv. Basmas) were

studied. When a T. tabaci female was given an oviposition period of 4 days, an average of 21 larvae were produced on

leaves of D. stramonium, 17.5 on S. nigrum, 16.3 on L. serriola and 14.3 on S. oleraceus. Significantly higher numbers of

larvae were found on tobacco (29.5), and lower numbers on A. retroflexus (1.9). In a choice test, when females were

placed onto leaves of these weed species and tobacco in a Petri dish, D. stramonium was preferred over tobacco. Equal

numbers of larvae emerged on leaves of tobacco, of L. serriola and of S. nigrum. Oviposition was lower on A. retroflexus

and S. oleraceus in this test. After the transfer of newborn 24 h old larvae to leaf discs of tobacco or to one of the

weeds 87, 84, 82, 71, 64 and 17% became pupa on tobacco, D. stramonium, L. serriola, S. nigrum, A. retroflexus or S.

oleraceus respectively. After acquisition of virus by newborn-24 h old larvae from L. serriola, D. stramonium, S. nigrum

and A. retroflexus 69.5, 51.4, 32.6 and 22% of the adults became transmitters. No transmission could be recorded on S.

oleraceus due to a high larval mortality. Males appeared to be more efficient transmitters than females. Tobacco was

more susceptible to TSWV than petunia and the weed species, while among weeds, S. nigrum was the most and A.

retroflexus the least susceptible species.

de Borbon, C. M. (2007). "A key for the identification of second instar larvae of some common thrips (Thysanoptera : Thripidae).

Mendoza, Argentina." Revista De La Facultad De Ciencias Agrarias 39(1): 69-81.

There are few published identification key to thrips larvae. Nevertheless the subject is of basic interest for detection of

the host range of thrips. Some species are able to transmit Tospovirus, causal agents of spotted wilt and other diseases.

The insect acquires the virus only as larvae. A key to larvae is a useful tool for epide-miological studies. The

identification of larvae is difficult because they have fewer distinctive characters than adults, also individuals are

constantly growing. The larvae of the species included in this work were obtained from field on several weeds and

some cultivated and native plants. Also, they were reared on bean pods or pollen and diluted honey from identified

adults. In this paper a brief description of second instar larvae of Frankliniella australis Morgan, F. gemina Bagnall, F

occidentalis Pergande, F. schultzei Trybom, F. valdiviana Sakimura et O'Neil and Thrips tabaci Lindeman and a key to

separate them, are presented.

Inoue, T. and T. Sakurai (2007). "Factors in low transmissibility of Tomato spotted wilt virus (TSWV) in asexual onion thrips, Thrips

tabaci (Thysanoptera : Thripidae): effects of virus infection on longevity of thrips vector." Journal of Insect Science 7.

Karadjova, O. and V. Krumov (2007). "Overview of TSWV transmission by Thrips tabaci in Bulgarian tobacco fields." Journal of

Insect Science 7.

Larentzaki, E., A. M. Shelton, F. R. Musser, B. A. Nault and J. Plate (2007). "Overwintering locations and hosts for onion thrips

(Thysanoptera : Thripidae) in the onion cropping ecosystem in New York." Journal of Economic Entomology 100(4): 1194-1200.

Identifying locations where onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), overwinter and

subsequently disperse is important for designing control strategies. In upstate New York from 2003 through 2006,

potential overwintering sites in the commercial onion, Allium cepa L., cropping system were investigated early in the

spring before onion seedling emergence and again late in the season after onions were harvested. Onion thrips adults

were sampled directly from the soil and indirectly from the soil by using emergence cages. Sampling locations included

onion field interiors and edges and areas outside of these fields, including woods. Host material sampled included

onion culls; volunteer onions, which sprout from cull onions left behind after harvest; and weeds. Onion thrips adults

were found in all sections of onion fields and in locations outside of onion fields, with the fewest emerging from woods.

Emergence began in early May and extended into June. Peak emergence occurred during the last half of May, at which

69

time 50-75% of the population had emerged. Adults colonized volunteer onions as early as late March and as late as

mid-November. No adults were found overwintering in onion cull piles. Adults also colonized several weed species,

especially pigweed, Amaranthus hybridis L., and lambsquarters, Chenopodium album L., late in the fall. Our results

indicate that onion thrips adults overwinter in the soil within and near onion fields and that they probably colonize

volunteer onion plants before subsequent generations infest the onion crop in the spring. Volunteer onions and weeds

also provide onion thrips with a host after onions are harvested. Consequently, onion thrips management strategies

should include tactics that reduce volunteer onion and weed abundance.

Leite, G. L. D., V. G. M. de Sa, R. E. M. Guanabens, C. A. da Costa and F. W. S. Silva (2007). "Incidence of insects and diseases in

onion cultivars and populations." Horticultura Brasileira 25(1): 100-102.

Onion (Allium cepa L.) is one of the most important vegetable crops in Brazil. It is attacked by insects and diseases, such

as Thrips tabaci Lindeman (Thysanoptera: Thripidae), Botrytis squamosa (J.C. Walker), Alternariaporri (Ellis) and

Colletotrichum gloeosporioides f.sp. cepae Penz. This work evaluated the incidence of thrips, onion leaf blight, purple

blotch, and smudge in eight elite populations of the Embrapa's onion breeding program ("CNPH 6415", "CNPH 6074",

"CNPH 6244", "CNPH 6400 Chata", "CNPH 6400 Redonda", "Valencianita" x "Aurora", "Primavera" x "Pera Norte" and

"Pera Norte" x "Primavera") and eight commercial onion varieties ("Granex 429", "BRS Cascata", "Belem IPA 9", "Crioula

Alto Vale", "Bola Precoce", "Primavera", "Regia" and "1015 Y"). In regions of high incidence of C. gloeosporioides, the

recommended materials are "CNPH 6415", "CNPH 6074" and "CNPH 6244"; "CNPH 6415", "CNPH 6074", "CNPH 6244",

"BRS Cascata", "Valencianita" x "Aurora", "Primavera" x "Pera Norte", "Belem IPA 9", "Bola Precoce", "Primavera" and

"Regia" are recommended for A. porri. high incidence; and of T tabaci are "CNPH 6415", "CNPH 6074", "Granex 429",

"Bola Precoce", "Primavera" and "Regia". The onion populations "CNPH 6415" and "CNPH 6074" are resistant to those

two diseases and thrips. On the other hand, "CNPH 6400 Chata", "CNPH 6400 Redonda" and "1015 Y" are susceptible to

C. gloeosporioides, A. porri and T tabaci. All the studied materials were considered susceptible to B. squamosa.

Maclntyre-Allen, J. K., J. H. Tolman, C. D. Scott-Dupree and C. R. Harris (2007). "Confirmation by fluorescent tracer of coverage of

onion leaves for control of onion thrips using selected nozzles, surfactants and spray volumes." Crop Protection 26(11): 1625-

1633.

Track sprayer and field sprayer trials were completed to assess the effect of different nozzles, surfactants and carrier

volumes on product delivery to the inner leaves of onion plants using a fluorescent tracer. Track sprayer trials revealed

more tracer on the inner leaves of onions using either the Tee.Jet (R) XR8004 flat fan or D4/DC25 disc-core hollow cone

nozzles. In three of four experiments, more tracer was detected on onions sprayed alone or combined with Sylgard (R)

309 at 200 L/ha than plants sprayed with tracer+Companion (R). When the carrier volume was increased to 400 L/ha,

more tracer was detected on onions sprayed alone or combined with Companion. In field trials, the XR8004 delivered

more tracer than the D4/DC25 (F= 32.8; P < 0.00; d.f. = 1,77). The best coverage was observed on plants sprayed with

the flat fan combined with Agral (R) 90, sprayed at either 400 L/ha (29% coverage) or 600 L/ha (23% coverage). (c) 2007

Elsevier Ltd. All rights reserved.

Madadi, H., A. Enkegaard, H. F. Brodsgaard, A. Kharrazi-Pakdel, J. Mohaghegh and A. Ashouri (2007). "Host plant effects on the

functional response of Neoseiulus cucumeris to onion thrips larvae." Journal of Applied Entomology 131(9-10): 728-733.

The performance of herbivores, natural enemies and their interactions may be affected directly or indirectly by host

plant traits, e.g. the physical plant characteristics may influence the search pattern and the functional response of

predators. We studied the functional response of adult females of the predatory mite Neoseiulus cucumeris to first

instar larvae of Thrips tabaci on three host plants (sweet pepper, eggplant and cucumber). The 24-h leaf disc

experiments conducted at 25 +/- 1 degrees C, 60 +/- 10% relative humidity and 16 : 8 h (light : dark) showed that N.

cucumeris exhibited a type II functional response on all host plants. The following search rates and handling times were

estimated from fitting the data to the disc equation 0.043/h and 1.798 h (cucumber); 0.048/h and 1.030 h (sweet

pepper) and 0.0441/h and 2.294 h (eggplant) giving an estimated maximum predation of 13.35, 23.31 and 10.46 larvae

per day respectively. The data from sweet pepper could also be described by the random predator equation (a':

0.051/h; T-h: 0.472 h). The host plant species interacted significantly with prey density on the functional response of N.

cucumeris with the relative differences in the number of thrips eaten on each host plant increasing with density. It is

suggested that it is mainly the difference in trichome density between the three host plants that is responsible for the



70

observed differences in the functional response of N. cucumeris. These results emphasize the importance of the host

plant characteristics on the performance of natural enemies and for optimizing their use in biological control of pests.

Natwick, E. T., J. A. Byers, C. C. Chu, M. Lopez and T. J. Henneberry (2007). "Early detection and mass trapping of Frankliniella

occidentalls(1) and thrips tabaci(1) in vegetable crops." Southwestern Entomologist 32(4): 229-238.

Western flower thrips, Frankfiniella occidentalis (Pergande), and onion thrips, Thrips tabaci Lindeman, are economic

pest insects of head lettuce, Lactuca sativa L., and dehydrator onions, Allium cepa L., in the Imperial Valley, California,

Colored sticky traps were evaluated as potential detection and monitoring devices of the two thrip species over a two-

month period in 2006. Results showed that blue sticky card traps consistently captured more adult thrips of both

species compared to yellow sticky card traps, Numbers of thrips captured on blue sticky traps were positively correlated

to numbers captured on yellow sticky traps, Adult thrips were captured in much higher numbers on sticky card traps

than recovered from whole plant samples. Significant negative correlations between F. occidentalis numbers on plant

samples and colored sticky traps suggest that adults left lettuce plants and were attracted to nearby traps. In addition,

the numbers of thrips caught on traps relative to estimated plant populations support the hypothesis that mass

trapping was significant in the treated area. Spectroradiometric and RGB (red, green, blue) digital image color analysis

of the traps in sunlight showed the blue sticky cards reflected considerably more light in the 400-500 nm range (R = 49,

G = 187, B = 255) than the yellow sticky cards that reflected more light in the 550-700 nm range (R = 227, G = 234, B =

67). Because blue sticky card traps captured many times more adult thrips than recovered from whole plant samples,

blue traps may be more sensitive in detecting early presence of thrips in lettuce and onion fields.

Nault, B. A. (2007). "Reproductive biology of Thrips tabaci from New York onion fields." Journal of Insect Science 7.

Rosa, J. and G. G. Kennedy (2007). "Thrips tabaci and tomato spotted wilt virus: inheritance of vector competence." Entomologia

Experimentalis Et Applicata 124(2): 161-166.

Populations of onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), were shown to differ significantly in their

ability to transmit an isolate of tomato spotted wilt virus (Tospovirus: Bunyaviridae) (TSWV) collected from potato

[Solanum tuberosum L. (Solanaceac)]. To gain an understanding of the basis for this variation, we generated reciprocal

crosses between an efficient and an inefficient transmitting population. The resulting F, progeny and progeny from the

parental populations were tested for their ability to transmit TSWV. Our results indicate that the ability to transmit

TSWV efficiently by T tabaci is inherited as a recessive trait.

Rueda, A., F. R. Badenes-Perez and A. M. Shelton (2007). "Developing economic thresholds for onion thrips in Honduras." Crop

Protection 26(8): 1099-1107.

Seasonal abundance and effect on onion yield reduction were studied for onion thrips, Thrips tabaci Lindeman, for two

consecutive seasons (dry and rainy) to develop economic thresholds (ET) in Honduras. Overall, thrips populations were

highest during the dry season, with average thrips per leaf per day 5.2 times higher than during the rainy season. In the

two onion cultivars tested (Granex 429 (R) and Texas Grano 438 (R)) thrips densities were similar, but Texas Grano 430

(R) showed 30% more yield reduction as a result of thrips damage than Granex 429 (R). ETs were calculated using four

different methods based on the equilibrium between cost of thrips management and profits losses (based on either

thrips densities or an action threshold (AT)), maximizing net profits derived from thrips management. and maximizing

the rate of return of thrips management. Thrips infestations below 1.0 thrips per leaf per day did not appear to affect

yield and during the rainy season thrips populations were always below this economic injury level. However, during the

dry season our data indicate farmers should use an AT between 0.5 and 1.6 thrips per leaf, depending on the particular

agronomic, climatic and market conditions. (c) 2006 Elsevier Ltd. All rights reserved.

Sabbour, M. M. and M. H. Abbass (2007). "Efficacy of some microbial control agents against onion insect pests in Egypt."

Egyptian Journal of Biological Pest Control 17(1-2): 35-40.

The entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana were tested aganist onion insect pests.

Results showed that they significantly decreased the infestations with Thrips tabaci, Delia alfrii and Eumerus amoenus.

Under the laboratory conditions. 26 2 C and 70-80% RFI, the IC50 S recoded were 113, 87 and 71 spores/ml for the

respective pests species by M. anisopliae. Using, B. bassiana, the LC(50)s were I 10 98 and 66 for the same insect



71

species. respectively. Respective LC50 S of Verticillium lecanii were 161, 150 and 141 spores/ml. Under green house

conditions. results showed that: the LC(50)s of B. bassiana were 130, 87 mid 65 spores/ml oil T. taboci, D. alfrii and E.

amoenus while respective LC50 s of M. anisopliae were 121, 81 and 70 spores/ml. Under field conditions, the

infestation's percentages with T. tabaci were 72 +/- 2.5, 83 +/- 3.4 and 97 +/- 5.1 % in the untreated plot and

decreased to 3 1 4.7. 28 +/- 2.1 and 2 1 +/- 2.2% after 20, 50 and 90 days ill B. bassiana treated areas, respectively.

Lesser effects oil the target insect pests under the field conditions were achieved by V lecanii mid Bacillus thuringiensis.

Generally, relative yield loss significantly decreased when onion plants were treated with any of the B. bassiana, M.

anisopliae, V. lecanii and B. thuringiensis.

Teulon, D. A. J., M. M. Davidson, D. I. Hedderley, D. E. James, C. D. Fletcher, L. Larsen, V. C. Green and N. B. Perry (2007). "4-pyridyl

carbonyl and related compounds as thrips lures: Effectiveness for onion thrips and new zealand flower thrips in field

experiments." Journal of Agricultural and Food Chemistry 55(15): 6198-6205.

On the basis of structural and/or aroma analogies to known thrips (Thysanoptera: Thripidae) lures, 35 compounds (18

pyridine derivatives, 13 benzene derivatives, and 4 other compounds), consisting of both synthetic and naturally

occurring compounds, were screened for their ability to bring about increased thrips capture in field experiments using

water traps in Canterbury, New Zealand. Most of the thrips caught were New Zealand flower thrips (NZFT) (Thrips

obscuratus) or onion thrips (OT) (Thrips tabaci). The greatest increase in capture for NZFT (158 times for female cf. to

water control) was for the known lure ethyl nicotinate, a 3-pyridyl ester. Ethyl isonicotinate, the 4-pyridyl regioisomer of

ethyl nicotinate, not previously reported as a thrips lure, provided the greatest increases in capture for OT (31 times) of

any of the compounds tested, significantly more than ethyl nicotinate. Other 4-pyridyl carbonyl compounds, including

ethyl 4-pyridyl ketone, also increased OT capture significantly. The natural floral compound cis-jasmone, which

increased trap capture of NZFT (female 42 times, male 25 times) but not OT, is reported as a thrips lure for the first

time.

Toda, S. and T. Murai (2007). "Phylogenetic analysis based on mitochondrial COI gene sequences in Thrips tabaci Lindeman

(Thysanoptera : Thripidae) in relation to reproductive forms and geographic distribution." Applied Entomology and Zoology

42(2): 309-316.

Thrips tabaci Lindeman is an extensively distributed pest insect that injures a wide range of crops. To investigate the

intra-specific genetic diversity of this species, we analyzed an 8 10 bp region of the mitochondrial cytochrome oxidase

gene subunit I (COI). Eight populations from six foreign countries and 18 Japanese populations were tested, and 17

different haplotypes were identified. Apparent differences were found between arrhenotokous and thelytokous strains

in their COI sequences. A phylogenetic tree of the COI gene shows two distinct groups. We assume that these two

groups correspond respectively to the arrhenotokous strain and the thelytokous strain. Japanese thelytokous types

consisted of five haplotypes. Two haplotypes were identified from problematic populations in terms of the greater

amount of damage they caused and the development of insecticide resistance. Both haplotypes were also found

overseas, suggesting that some strains from overseas may have caused the above-mentioned problems in Japan.

Toda, S., T. Murai and M. Morishita (2007). "Intra-specific genetic variation in Thrips tabaci." Journal of Insect Science 7.

Trdan, S., N. Valib and D. Znidarcic (2007). "Field efficacy of deltamethrin in reducing damage caused by Thrips tabaci Lindeman

(Thysanoptera : Thripidae) on early white cabbage." Journal of Pest Science 80(4): 217-223.

Our research assessed how the number of sprayings with deltamethrin influenced the efficiency against onion thrips,

Thrips tabaci, on early white cabbage. The study was performed in 2002 and 2005 using the early white cabbage

cultivar Parel, which is very susceptible to the attack of onion thrips. The cabbages were planted in a block-design

experiment, with percentage of damage on the exterior leaves recorded according to the positions of the leaves (i.e.

outer to inner). Although the attack of thrips was much greater in 2002 than in 2005, nevertheless, control plants in

both years showed much more damage than plants with at least one insecticide spraying. In 2002, there was little

difference between one and two sprayings, but three sprayings showed a significantly improved result. However, three

sprayings of this insecticide is generally not permitted in farming practice. In 2005, no differences in efficacy among

one, two and three sprayings were recorded. We also assessed a high threshold (up to 10% damaged leaf surface) and

low threshold (up to 1% damaged leaf surface) for the removal of damaged leaves. In 2002, both thresholds were



72

exceeded for control plants, but in 2005, the attack of thrips was mild enough that neither threshold was exceeded. In

this case, one spraying was sufficient to reduce leaf damage below the higher (more tolerant) threshold, but three

sprayings were needed to reduce leaf damage below the lower (more stringent) threshold. Therefore, in Slovenia or

other parts of the world with similar climatic conditions, we recommend one spraying as broadly effective and

recommend the more tolerant threshold for leaf removal.

Trdan, S., N. Valic and D. Znidarcic (2007). "Efficacy testing of dDifferent IPM methods against Thrips tabaci Lindeman

(Thysanoptera : Thripidae) on cabbage and onion." Journal of Insect Science 7.

van Epenhuijsen, C. W., D. I. Hedderley, K. G. Somerfield and D. W. Brash (2007). "Efficacy of ethyl formate and ethyl acetate for

the control of onion thrips (Thrips tabaci)." New Zealand Journal of Crop and Horticultural Science 35(2): 267-274.

Both adult and juvenile thrips (Thrips tabaci) reared on leeks (Allium ampeloprasum) were very susceptible to the

effects of ethyl formate. Complete control was achieved at concentrations as low as 2.7 g/m(3) after 2 h. Treatment of

thrips-infested onions (Allium cepa) with 160 g/m(3) of an aerosol containing 16.7% ethyl formate by weight in carbon

dioxide killed nearly all adult thrips immediately after treatment. An assessment 9 days after treatment indicated that

eggs had not been killed by the treatment. No residues of ethyl formate were detected in onions collected 1-28 days

after treatment following application of two very high dose rates (236 and 756 g/m(3)). Ethyl formate had no effect on

skin colour, onion firmness, or incidence of rots, and no visual signs of phytotoxicity were evident on onions treated

with concentrations up to 324 g/m(3). The highest dose of ethyl formate tested on eggs (27 g/m(3) for 2 h) in small

pieces of leek gave marginally lower nymph counts than the untreated control. Ethyl acetate at rates of 94 and 120

g/m(3) significantly reduced the numbers of emerging nymphs compared with those emerging from an untreated

control. This fumigant is a similar compound to ethyl formate but may be less phytotoxic. When ethyl formate is used

for disinfestation of heavily infested onions, a second treatment is needed to control the egg stages.

van Tol, R., D. E. James, W. J. de Kogel and D. A. J. Teulon (2007). "Plant odours with potential for a push-pull strategy to control

the onion thrips, Thrips tabaci." Entomologia Experimentalis Et Applicata 122(1): 69-76.

We compared the efficacy of four plant essential oils to repel onion thrips, Thrips tabaci (Lindeman) (Thysanoptera:

Thripidae), in the presence of an attractive odour, ethyl iso-nicotinate in a pasture field. Four horizontal white sticky

plates were placed adjacent to (directions: N, S, E, W) a central horizontal white plate (C). After 24 h, in the treatment

combination where the four plates were sprayed with essential oil surrounding a central sticky plate sprayed with ethyl

iso-nicotinate, fewer onion thrips were found on the plates treated with sweet marjoram [Origanum majorana L.

(Labiatae)] or clove basil [Ocimum gratissimum L. (Labiatae)] (87 and 71% less, respectively) compared to the control

treatment of four water-sprayed plates surrounding a central plate with ethyl iso-nicotinate. We also compared the

distribution of onion thrips on the plates. Relative thrips numbers on each plate were compared with similar (N, S, E, W,

and C) plates in the control treatment. There were relatively lower thrips numbers on the south (23% reduction) and

west (26% reduction) O. majorana-treated plates and higher numbers (37% increase) on the central attractant-treated

plate indicating a short-distance push-pull effect. When four plates were sprayed with the thrips attractant surrounding

a central sticky plate sprayed with an essential oil or water (control), only O. majorana reduced the number of thrips on

the attractant-sprayed plates (62% reduction). The distribution of thrips on the different plates within this treatment

combination did not change substantially when compared to the distribution in the water-control treatment. Other

essential oils tested (wormwood [Artemisia arborescens L. (Compositae)]) and tea tree [Melaleuca alternifolia (Maiden.

& Betche.) Cheel. (Myrtaceae)]) were not effective in any of the treatments. It appears that O. majorana is a promising

thrips repellent which could be used for further testing in a push-pull system with the attractant ethyl iso-nicotinate.

The field setup used also proved to be a valuable tool for evaluating the potential of repellents to control onion thrips.

Bergant, K., L. K. Bogataj and S. Trdan (2006). "Uncertainties in modelling of climate change impact in future: An example of

onion thrips (Thrips Tabaci Lindeman) in Slovenia." Ecological Modelling 194(1-3): 244-255.

Uncertainties related to the climate impact studies are reviewed on the case of onion thrips in Slovenia. Paper illustrates

cumulative uncertainty introduced by future emission scenarios, general circulation models, downscaling procedures,

weather generators and impact (degree-day) models as common tools in climate impact studies. The result of

cumulative uncertainty is a wide range of expected warming in Slovenia in the 21st century. An expected increase of air



73

temperature, relative to 1990, is between 1.5 and 7 degrees C till the end of present century. Due to heterogeneity of

the present climate conditions in Slovenia, quite uniform air temperature increase on the entire area will have different

impact on the change of cumulative degree-days (DD) and related number of generations of onion thrips per year (N-

gen) in different regions. An example of Ljubljana and Bilje shows that larger increase of DD and related N-gen is

expected for regions with warmer climate. As a result, more damage will probably be caused in areas that are already

strongly exposed to the problem of onion thrips. Harmfulness of the pest in the areas, where it is not a serious threat at

present, will also increase. However, we have to be fully aware of a large amount of uncertainty related to studies of

climate change impact while interpreting their results. (c) 2005 Elsevier B.V. All rights reserved.

Cabrera-Asencio, I. and A. L. Velez (2006). "Companion crops and insecticides to control populations of Thrips tabaci L. and

Liriomyza trifolli B. in onion." Journal of Agriculture of the University of Puerto Rico 90(1-2): 115-123.

For three consecutive years, the companion crops Rosmarinus officinalis L., Ocimum, sanctus L., Ocimurn basilicum L.,

Uppia micronera B. and Plectranthus amboinicus L., and the insecticides cypermethrin and avermectin were evaluated

for controlling Thrips tabaci L. and Uriomyza trifolil B. in onion. Populations of T tabaci and L. trifolii were kept at low

levels in all treatments during the three-year study., Populations of T tabaci nymphs and adults decreased significantly

in the third year of treatments with companion crops and applications of cypermethrin plus avermectin. Similar trends

were observed the first year; however, this decrease was not observed for L. trifolii. Populations of L. trifolii did not

follow any particular pattern in response to the treatments.

Cabrera-Asencio, I. and A. L. Velez (2006). "Handling of populations of Thrips tabaci L. (Thysanoptera : Thripidae) and Liriomyza

Trifolii B. (Diptera : Agromyzidae) in onion with accompanying crops." Journal of Agriculture of the University of Puerto Rico

90(1-2): 125-128.

Cabrera-Asencio, I. and A. L. Velez (2006). "Population fluctuation of Thrips tabaci L. and Liriomyza Trifolii B. in commercial

spreads of onions using accompanying crops." Journal of Agriculture of the University of Puerto Rico 90(1-2): 129-131.

Inoue, T. and T. Sakurai (2006). "Infection of tomato spotted wilt virus (TSWV) shortens the life span of thelytokous Thrips tabaci

(Thysanoptera : Thripidae)." Applied Entomology and Zoology 41(2): 239-246.

The effect of tomato spotted wilt virus (TSWV) infection on the life span of thelytokous Thrips tabaci, which is known as

a TSWV vector with a low transmission rate, was studied in two populations, Shimane (SM) and lwate (IW). No effects of

virus infection were found in the developmental period and mortality of the thrips before adult emergence, but a

significant increase was observed in age-specific mortality during the adult lifespan of the TSWV-exposed thrips group

when compared with the non-exposed group (mean total longevity of thrips exposed and not exposed to virus was

18.1 and 20.1 d in the SM population and 19.9 and 21.5 d in the IW population). The latent period (LP) was 14.2 d in the

SM population and 17.2 d in the IW population, indicating a relatively longer LP than the LPs reported for Frankliniella

occidentalis and F. fusca. The potential transmission period (PTP) from the end of the LP to vector death was only 3.3 d

in both of the populations. The higher the level of virus infection, the greater the reduction in adult thrips survival.

These results suggest that a long LP and TSWV-induced reduction of thrips survival shorten the PTP. This may be

responsible for the low transmissibility of TSWV as well as the low transmission rate in thelytokous T tabaci populations.

Jasrotia, P. and D. Ben-Yakir (2006). "An immuno-marking technique for thrips." Entomologia Experimentalis Et Applicata 120(2):

155-160.

Rabbit immunoglobulin G (R-IgG) was used successfully as an external mark for thrips. Females of both Thrips tabaci

Lindeman and Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) were marked with 1 mg ml(-1) R-IgG

solution with 1% 'Tween 20' by the contact exposure method. Determining the retention of the mark was by running

the rinsing solution of individual thrips in an enzyme-linked immunosorbent assay ( ELISA). The sandwich ELISA method

was used with an additional biotin-avidin step. The threshold for a positive marking score was defined as three times

the mean optical density readings of the negative control thrips. Under laboratory conditions, on bean pods, all marked

thrips scored positive up to 6 days after marking ( DAM). When marked thrips were kept in the laboratory on marigold

flowers for 2 days, they all scored positive. When marked and unmarked thrips were placed together on these flowers,

the mark was transferred to 10-20% of the unmarked thrips and they became positive. Under field conditions, on sticky



74

traps covered with water-base glue, 100, 80, and 20% of the marked T. tabaci scored positive by the 3rd, 6th, and 9th

DAM, respectively. Under the same conditions 100, 90, and 10% of the marked F. occidentalis scored positive by the

3rd, 6th, and 9th DAM, respectively. The retention of the R-IgG decreased significantly under conditions of wetness and

high humidity. After 6 days on chive plants kept at 80-100% r. h., all marked thrips scored negative while on plants kept

at 40-60% r. h., 85% of the marked thrips scored positive. Rabbit IgG can be used as an external marker for thrips. The

suitability of this marking method for dispersal studies of these important pests needs to be evaluated.

Martin, N. A. and P. J. Workman (2006). "A new bioassay for determining the susceptibility of onion (Allium cepa) bulbs to onion

thrips, Thrips tabaci (Thysanoptera : Thripidae)." New Zealand Journal of Crop and Horticultural Science 34(1): 85-92.

A series of experiments was conducted to develop a bioassay for determining the susceptibility of Allium plants to

adult female onion thrips. Onion thrips (Thrips tabaci (Thysanoptera: Thripidae)) are the main insect pest on onions in

New Zealand. This research aimed to develop better methods for determining the susceptibility of Allium species leaves

and onion bulbs to onion thrips. Discs, 10 mm diam., cut from leek (Allium porrum) and onion (Allium cepa) leaves or

onion bulbs, were put singly into small plastic Petri dishes with 1-day-old adult female thrips, and kept at 25 degrees C

in 16h light: 8 h dark. After 3 days the discs were stained in acid fuchsin and the eggs counted using a stereo

microscope with transmitted light. Adult thrips survived equally well on leek leaves and onion bulb scale, but laid more

eggs per day on onion leaves than on leek leaves and least on onion bulbs. Thrips laid fewer eggs per day when there

was more than one thrips per dish. Changing discs daily or leaving them for 3 days had no effect on the numbers of

eggs laid by thrips each day. Four cultivars of onions were grown with 50, 100, 150, and 200 kg nitrogen (N) fertiliser

per ha. The susceptibility of bulbs to onion thrips feeding and damage from the highest and lowest N treatments was

compared. Analysis of the proportion of discs with more than one egg showed that cultivar 'Kiwigold' (early brown) was

more susceptible than 'Meteor' (early red), and 'M&R Regular' (main crop brown) was more susceptible than 'Red Star'

(main crop red) to onion thrips. The proportion of discs with more than three eggs was higher for brown onions in the

high N treatment than in the low N treatment, suggesting that brown onions from the high N treatment were more

susceptible. After 5 months in storage, red onions were softer and had more sprouts than brown onions, and their

innermost skins and the outermost scales had more thrips damage. This apparent increase in susceptibility of red

onions may be related to changes in the physiology of the outer scale as it shrinks to become a skin. The bioassays

confirmed that both genetic (cultivar) and agronomic (N fertiliser) factors affect the susceptibility of onion bulbs to

onion thrips.

Nault, B. A., A. M. Shelton, J. L. Gangloff-Kaufmann, M. E. Clark, J. L. Werren, J. C. Cabrera-La Rosa and G. G. Kennedy (2006).

"Reproductive modes in onion thrips (Thysanoptera : Thripidae) populations from New York onion fields." Environmental

Entomology 35(5): 1264-1271.

Thrips exhibit different reproductive modes including thelytoky (females produced from unfertilized eggs), arrhenotoky

(males produced from unfertilized eggs and females produced from fertilized eggs) and deuterotoky (females and

males produced from unfertilized eggs). We investigated patterns of reproductive modes in onion thrips, Thrips tabaci

Lindeman, populations and potential effects of the bacterium Wolbachia and temperature on these modes. We also

examined the possibility that male-producing T tabaci populations were resistant to the frequently used insecticides,

lambda-cyhalothrin and methomyl. In New York during 2002-2004, T tabaci populations were sampled from 20 onion

fields and reproductive mode was determined by identifying sex of progeny from virgins. Half of the populations were

thelytokous and half were a mix of thelytokous, arrhenotokous and deuterotokous individuals, which we refer to as a

male-producing population. In two of four cases, the reproductive mode of a population from the same onion field

changed across years, suggesting that populations either mix or an external factor caused the change. To address the

latter, we speculated that Wolbachia or high temperature mediated reproductive modes. Samples of T tabaci

representing each reproductive mode were examined for Wolbachia using diagnostic polymerase chain reaction (PCR),

but it was not detected. Cytological examination of ovaries from two additional thelytokous lines also showed no

evidence of Wolbachia. Similarly, high temperature did not affect sex allocation ratios in either thelytokous or male-

producing populations. Male-producing T tabaci populations were not positively correlated with resistance to lambda-

cyhalothrin, or tolerance to methomyl. The role of the different reproductive modes in T tabaci populations in onion

fields remains unclear.



75

Shelton, A. M., J. Z. Zhao, B. A. Nault, J. Plate, F. R. Musser and E. Larentzaki (2006). "Patterns of insecticide resistance in onion

thrips (Thysanoptera : Thripidae) in onion fields in New York." Journal of Economic Entomology 99(5): 1798-1804.

To develop an insecticide resistance management program for onion thrips, Thrips tabaci Lindeman

(Thysanoptera: Thripidae), on onions (Allium spp.), we surveyed populations in commercial onion fields in New

York and evaluated their susceptibility to the two most widely used classes of insecticides plus two new

insecticides during 2003-2005. All insecticide evaluations were conducted using the Thrips Insecticide Bioassay

System (TIBS). As in our surveys conducted during 2002-2003, there were large temporal and spatial variations

in susceptibility to the pyrethroid lambda-cyhalothrin (Warrior) across onion-growing regions in 2003. New

data indicate that the field rate of methomyl (Lannate LV) still provides control but that the genes for

resistance to methomyl are present in some populations. Tests with the two new insecticides, acetamiprid

(Assail 70 WP) and spinosad (SpinTor 2CS), indicated they provided > 85% mortality at the field rate. To

determine the spatial variation in insecticide susceptibility within a region, a series of systematic assays were

conducted with lambda-cyhalothrin and methomyl. In 2004 and 2005, our data indicated that the within-

region spatial variation in susceptibility to lambda-cyhalothrin was not large at the field rate or for the 100

ppm rate of methomyl. In 2005, a year in which T. tabaci densities in most fields were much higher than in

2004, growers were unable to control T. tabaci in particular fields and attributed this lack of control to

resistance. Yet, we found similar levels of high susceptibility in all fields when using TIBS. This finding suggests

that resistance had not developed and that variation in control may have been due to other factors, such as

localized higher populations, poor spray coverage, too much time between spray applications, or different

onion varieties.

Thungrabeab, M., P. Blaeser and C. Sengonca (2006). "Effect of temperature and host plant on the efficacy of different

entornopathogenic fungi from Thailand against Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman (Thysanoptera :

Thripidae) in the laboratory." Journal of Plant Diseases and Protection 113(4): 181-187.

The current study is focusing on the effect of temperature and host plant on the efficacy of different entomopathogenic

fungi from Thailand against western flower thrips, Frankliniella occidentalis (Pergande) and onion thrips, Thrips tabaci

Lindeman (Thysanoptera: Thripidae). The results showed that the efficacy of five entornopathogenic fungi, i.e. two

isolates of Beauveria bassiana (Balsarno) Vuillemin (Bb. 4591 and Bb. 5335), two isolates of Metarhizium anisopliae var.

anisopliae (Metsch) Sorokin (Ma. 6079 and Ma. 7965) as well as one isolate of Paecilomyces fumosoroseus (Wize)

Brown & Smith (Pfu. 5338) varied depending on the temperature and the fungal isolate in both thrips species. The

LC(50) values decreased with increasing temperature. All fungal isolates showed a significantly higher efficacy against

both thrips species at 25 and 30 degrees C than at 16 degrees C. Among five isolates, B. bassiana Bb. 5335 and M.

anisopliae Ma. 7965 were superior in terms of efficacy against both thrips species within a broader range of

temperature. The effect of host plants on the efficacy of B. bassiana (Bb. 5335) and M. anisopliae (Ma. 7965) was tested

against first instar larvae of R occidentalis and T tabaci. The results revealed that the efficacy of these two fungi against

E occidentalis and T tabaci varied with to the host plant, whether on crop or on ornamental plants. Both thrips species

reared on bean, cucumber, leek and swan river daisy were highly susceptible to fungal infection but significantly less

susceptible when reared on cotton and saintpaulia.

Trdan, S., D. Znidarcic, N. Valic, L. Rozman and M. Vidrih (2006). "Intercropping against onion thrips, Thrips tabaci Lindeman

(Thysanoptera : Thripidae) in onion production: on the suitability of orchard grass, lacy phacelia, and buckwheat as alternatives

for white clover." Journal of Plant Diseases and Protection 113(1): 24-30.

During 2004 and 2005, field experiments were done to compare the effectiveness of four different intercrops in

reducing onion thrips (Thrips tabaci Lindeman) damage on onion plants. The four intercrops were lacy phacelia

(Phacelia tanacetifolia Benth.), buckwheat (Fagopyrum esculentum Moench.), orchard grass (Dartylis glomerata L.) and

white clover (Trifolium repens L.). The experiment was done in a fertile soil in 2004 and a relatively infertile soil in 2005.

In both years, the thrips population was lower than expected due to two cold springs and wet summers. The amount of

damage on the two onion varieties tested, 'Rdeci baron' and 'Holandska rumena', exceeded the 20% leaf damage

threshold only on some onion plants. In both years, white clover was the least attractive intercrop for onion thrips, and

orchard grass was only slightly more attractive. Although the damage to the onion leaves was the highest in these two

intercrops, these plots still produced the highest yield of onions. In contrast, lacy phacelia and buckwheat were both



76

highly attractive to onion thrips, but were not suitable as intercrops, as they competed too strongly with the onion

crop. Hence, lacy phacelia, buckwheat and orchard grass should not be used in onion production to replace white

clover, the intercrop used currently. In the current experiments, intercropping with white clover resulted in the highest

yield of onions in both high and low fertility soils.

Allen, J. K. M., C. D. Scott-Dupree, J. H. Tolman and C. R. Harris (2005). "Resistance of Thrips tabaci to pyrethroid and

organophosphorus insecticides in Ontario, Canada." Pest Management Science 61(8): 809-815.

Onion thrips, Thrips tabaci Lindeman, were collected from commercial onion fields in 2001, 2002 and 2003 to assess

resistance to lambda-cyhalothrin, deltamethrin and diazinon. In 2001, six of eight adult populations were resistant to

lambda-cyhalothrin, with resistance ratios (RR) ranging from 2 to 13.1 and four of these were also resistant to

deltamethrin, with RR ranging from 19.3 to 120. Three of four adult populations were resistant to diazinon with RR

ranging from 2.5 to 165.8. In 2002, four of seven nymphal populations and three of six adult populations were resistant

to deltamethrin, with RR ranging from 4.3 to 72.5 and 9.4 to 839.2, respectively. Only one of six nymphal populations

and one of five adult populations were resistant to diazinon, with RR of 5.6 and 2.3, respectively. In 2003 diagnostic

dose bioassays, 15 of 16 onion thrips populations were resistant to lambda-cyhalothrin and all were resistant to

deltamethrin. Eight of the 16 were resistant to diazinon. These results indicate that insecticide resistance is widespread

in onion thrips in commercial onion fields in Ontario. (c) 2005 Society of Chemical Industry.

Atakan, E. and S. Uygur (2005). "Winter and spring abundance of Frankliniella spp. and Thrips tabaci Lindeman (Thysan.,

Thripidae) on weed host plants in Turkey." Journal of Applied Entomology 129(1): 17-26.

The species composition of thrips and abundance of three pestiferous thrips species, Frankliniella occidentalis

(Pergande), Thrips tabaci Lindeman and Frankliniella intonsa (Trybom) (Thysan., Thripidae) on weed species during

winter and spring time were studied in vegetable production and polycultured areas in the eastern Mediterranean

region of Turkey in years 2002 and 2003. Of a total of 61 543 thrips extracted from 8933 samples collected, 77% were

adults. F. occidentalis was collected from all of 49 weed species sampled and F. intonsa was detected on 18 plant

species between May and June. T. tabaci was collected from 42 of a total of 49 weed species. Immature thrips were

extracted from 42 of a total of 49 weed species. Four weed species of a total 35 weed species sampled between April

and May in the sampling areas hosted 63% of larvae and approximately 50% of F. occidentalis collected. A total of 23

thrips species was recorded from weeds sampled in this study. F. occidentalis accounted for 83% of a total 47 640 adult

thrips collected and followed by low rates of T. tabaci and F. intonsa (9 and 1%, respectively). Melanthrips spp.

accounted for 3.54% of total numbers of adult thrips. Flower-inhabiting thrips species and T. tabaci were most

abundant on weeds between April and May when the number of weed species in bloom was greatest, then decreased

to low levels after May. Most pestiferous thrips on weeds species were collected from vegetable production areas. F.

occidentalis was the predominant thrips comprising over 80% in most months in the vegetable grown area. In

polycultured area, the composition of adult thrips shifted monthly. While Melanthrips was the more prevailing thrips by

rates 53% in February and 81% in March, F. occidentalis was the predominant thrips with 60 to 62% in spring,

respectively.

Bergant, K., S. Trdan, D. Znidarcic, Z. Crepinsek and L. Kajfez-Bogataj (2005). "Impact of climate change on developmental

dynamics of Thrips tabaci (Thysanoptera : Thripidae): Can it be quantified?" Environmental Entomology 34(4): 755-766.

We attempt to quantify the impact of future climate change on the developmental dynamics of onion thrips in

Slovenia. Monthly averaged results of simulations of future climate from four different general circulation models

(GCMs) were projected to local scale by empirical down-scaling. The GCM simulations were based on two emission

scenarios (IPCC SRES A2 and B2). Local estimates of monthly averaged air temperatures for five locations in Slovenia

were adjusted for an additional four emission scenarios (SRES A1T, A1F1, A1B, and B1) using a pattern scaling

technique. They were further transferred to a daily scale using a first-order autoregressive model, A simple degree-day

model, based on data reported in the literature, was used to relate the development of onion thrips to temperature.

Potential changes in the period with favorable developmental conditions for onion thrips (i.e., temperatures above the

lower developmental threshold) and in the number of generations per season were estimated with regard to the

expected future climate change in Slovenia. The changes are influenced by the magnitude of temperature increase, its

asymmetry within the year, and present climate conditions. Using this approach, one can obtain quantitative estimates



77

of the impact of climate change on the developmental dynamics of an insect pest, but one must be fully cognizant of

all the assumptions made in the procedure, which introduce uncertainties in the final results. Further research is needed

to evaluate the plausibility of such simplified projections.

Deligeorgidis, P. N., C. G. Ipsilandis, M. Vaiopoulou, G. Kaltsoudas and G. Sidiropoulos (2005). "Predatory effect of Coccinella

septempunctata on Thrips tabaci and Trialeurodes vaporariorum." Journal of Applied Entomology 129(5): 246-249.

The predatory effect of adult ladybird Coccinella septempunctata L. on adults of thrips, Thrips tabaci Lindeman, and

whiteflies, Trialeurodes vaporariorum (Westwood), was examined in controlled environment chambers, on tomato

leaves, in transparent small plastic cages at proportions of 1/(10 + 10), 1/(20 + 20), 1/(30 + 30) and 1/(40 + 40)

predator/number of thrips and whiteflies. We conclude that C. septempunctata could be used with success for the

biological control of thrips and whiteflies in greenhouse crops, with almost the same effectiveness as for aphids, at

predator/prey proportions near 1 : 30. Additionally, it was found a prey preference for T. tabaci in comparison with T.

vaporariorum. According to the model used, effective predation is correlated with predator/prey ratio rather than to

prey preference.

Jean-Simon, L., J. R. Victor and Fshs (2005). Integrated management of onion thrips (Thrips tabaci) in onion (Allium cepa L.).

Proceedings of the 118th Annual Meeting of the Florida State Horticultural Society. 118: 125-126.

A field experiment was conducted at Mersan, South Haiti during the period of November 2003 to April 2004 to evaluate

the effect of wood shaving mulch and sequential applications of the insecticides azadirachtin, lambda-cyhalothrin and

profenfos on onion thrips (Thrips tabaci Lindeman) infestation and the yield of onion (Allium cepa L.). A randomized

complete block factorial design was utilized in four replications. The first factor consisted of unmulched and wood

shavings mulched onion; while the second factor consisted of control (without insecticide), azadirachtin, profenfos,

lambda-cyhalothrin, azadirachtin alternated with profenfos, azadirachtin alternated with lambda-cyhalothrin, profenfos

alternated with lambda-cyhalothrin, azadirachtin alternated with profenfos and lambdacyhalothrin. The cultivar Yellow

Granex was utilized. Thrips infestation was lowest when the onion crop received three consecutive applications of

Lambda-Cyhalothrin. Onion yield was not significantly influenced by pesticide application sequences, but mulching

increased both the total yield and the commercial yield of onion. The results of this experiment suggest that wood

shaving mulch can improve onion yield under the agroecological settings of the area of Mersan. They also lead to the

conclusion that Lambda-Cyhalothrin can be recommended for the control of onion thrips.

Kazlauskaite, S., A. Saluchaite, V. Tamutis, A. Amsiejus, A. Ziogas and Lua (2005). The Effectiveness of Insecticide Neemazal T/S

1%e.c. for protection of common China-aster (Callistephus chinensis (L.)) seedlings against onion thrips (Thrips tabaci (Lind.)).

Rural Development 2005, Vol 2, Book 2, Proceedings: Globalisation and Integration Challenges to Rural Development in Eastern

and Central Europe: 27-28.

Neemazal T/S 1%e.c. is quite new insectoacaricide appeared in Lithuanian market. The product is exclusive due to its

active ingredient azadirachtin A which is derived on botanical background, Also it is listed for use even in certified

organic production. The product registered mainly for protection of greenhouse crops against thrips, aphids, whitefly,

spider mites. Neemazal T/S 1%e.c. in the trial was applied for protection seedlings of widely grown ornamental plant

common China-aster (Callistephus chinensis (L.)) against onion thrips (Thrips tabaci (Lind.)). Three different

concentrations of the spraying solution were applied (0,5%, 0,3% and 1%). The calculation of the pests accomplished

before application and repeated 7 days after treatment. The efficiency of Neemazal T/S 1%e.c. for protection of

common China-aster seedlings against onion thrips was compared with efficiency of systemic insecticide Actara

25%w.g.. The effectiveness of Neemazal T/S 1%e.c. in the trial corresponded with efficiency of Actara 25%w.g..

Leite, G. L. D., M. Picanco, G. N. Jham and M. D. Moreira (2005). "Bemisia tabaci, Brevicoryne brassicae and Thrips tabaci

abundance on Brassica oleracea var. acephala." Pesquisa Agropecuaria Brasileira 40(3): 197-202.

Kale Brassica oleracea var. acephala is attacked by whitefly Bemisia tabaci, aphid Brevicoryne brassicae and Thrips

tabaci. One of the main reasons for extensive insecticide application is the lack of information about factors that control

insect population. The objectives of this study were to investigate the relationships between predators and parasitoids,

organic compound leaves, levels of leaf nitrogen and potassium, total rainfall, relative humidity, sunlight and median

temperature on the abundance of whitefly, aphid, and thrips in kale genotype "Talo Roxo". The beating tray method,



78

direct counting and magnifying lens were used to estimate the number of these pests, predators and parasitoids.

Median temperature, sunlight and relative humidity correlated to the amount of leaf nonacosane, which in turn was

associated with aphids population increase. A tendency in the reduction of aphids and thrips populations with increase

in total rainfall was observed. The whitefly can be a harmful pest in kale producing regions of higher temperature and

smaller rainfall. In regions which present moderate temperature, where there is a high incidence of aphids, genotype

with low leaf wax content should be chosen. Natural enemies, especially the parasitoid Adialytus spp., can control

agents of the aphids population in kale.

MacIntyre-Allen, J. K., C. D. Scott-Dupree, J. H. Tolman and C. R. Harris (2005). "Evaluation of sampling methodology for

determining the population dynamics of onion thrips (Thysanoptera : Thripidae) in Ontario onion fields." Journal of Economic

Entomology 98(6): 2272-2281.

Onion thrips, Thrips tabaci Lindeman, are an economic pest of alliums worldwide. In Ontario onion-growing regions,

seasonal abundance and population trends of onion thrips are not well known. The objectives of this research were to

investigate onion thrips population dynamics by using both white sticky traps and plant counts, to gain insight into

flight height, and to determine the genus and sex of thrips fauna present in monitored fields. Adult thrips were

captured on white sticky traps placed in two commercial onion fields in the Thedford-Grand Bend Marsh region as early

as mid-May in 2001, 2002, and 2003. Thrips were not recorded on onion plants in these fields until late June and early

July. A comparison of sticky trap captures to plant counts revealed a strong, positive correlation, indicating that sticky

traps, which consistently detected thrips earlier than plant counts, could be used instead of plant counts early in the

season to monitor onion thrips populations. Pole traps placed in onion and an adjacent soybean, Glycine max (L.) Merr.,

field revealed that regardless of crop type, most thrips were captured 0.7-0.95 In above the soil surface. During this

study, 70% of 137,000 thrips captured on sticky traps and 89% of 1,482 thrips captured in pan traps were female onion

thrips. No male onion thrips were identified in this study; most of the remaining thrips were Frankliniella spp.

Morishita, M. (2005). "Seasonal abundance of the western flower thrips, Flankliniella occidentalis (Pergande), and onion thrips,

Thrips tabaci (Lindeman) (Thysanoptera : Thripidae), on weeds in persimmon and mandarin orange orchards." Japanese Journal

of Applied Entomology and Zoology 49(4): 195-203.

The western flower thrips, Flankliniella occidentalis (Pergande), and onion thrips, Thrips tabaci (Lindeman), cause serious

damage to fruits of the 'Tonewase' persimmon when the fruit color turns yellow in early September. 1 investigated the

seasonal abundance of the two thrips species on the various weed hosts in persimmon and mandarin orange orchards.

Both F. occidentalis and T. tabaci overwintered on the biennial weeds such as chickweed, Lamium amplexicaule, and

henbit, Stellaria neglecta. F. occidentalis showed two peaks in population density on weeds of orchards: one in May-

June with the growth of biennial weeds and the other in July-August with the growth of annual weeds. Thus, the F.

occidentalis population was shown to increase in association with the growth of wild plants. T. tabaci, on the other

hand, had only one population peak in May, following the population continued to decrease toward the winter.

Trdan, S., L. Milevoj, I. ZeZlina, E. Raspudic, L. Andjus, M. Vidrih, K. Bergant, N. Valic and D. Znidarcic (2005). "Feeding damage by

onion thrips, Thrips tabaci Lindeman (Thysanoptera : Thripidae), on early white cabbage grown under insecticide-free

conditions." African Entomology 13(1): 85-95.

The effects of cultivar choice and plant density on onion thrips (Thrips tabaci) damage to early white cabbage was

studied on five varieties of early white cabbage grown at three different densities over two years. In the drier year the

cabbage yield was smaller and greater thrips damage was recorded. The cabbage variety 'Vestri, which had on average

the firmest head, showed itself to be the most resistant to Thrips tabaci attack and gave the highest yield. The 'Parel'

variety, with the shortest growing period, was the most damaged by the thrips. Most densely planted cabbage had the

lowest mean weight of heads and the lowest mean index of damage on the exterior leaves. Most of the economically

important damage occurred between the third and sixth exterior leaf, although the damage extended to the fifteenth

exterior leaf.

Trdan, S., N. Valic, I. Zezlina, K. Bergant and D. Znidarcic (2005). "Light blue sticky boards for mass trapping of onion thrips,

Thrips tabaci Lindeman (Thysanoptera : Thripidae), in onion crops: fact or fantasy?" Zeitschrift Fur Pflanzenkrankheiten Und

Pflanzenschutz-Journal of Plant Diseases and Protection 112(2): 173-180.

79

In 2001-2002, efficiency of light blue sticky boards for mass trapping of onion thrips (Thrips tabaci Lindeman) in onion

crops was investigated. The aim was to reduce the damage Caused by thrips on the onion leaves. The lowest

percentage of a damaged leaf Surface was determined on plants, which were treated twice with deltamethrin. The

sticky boards did not prove to be efficient for thrips control. In (he drier year 2001, the mean yield of onion was not

statistically significantly different between four treatments (insecticide, One Sticky board (11.0 x 14.0 cm) per plot (1.5

m(2)), two sticky boards per plot and control). 2002 was more convenient for onion growing and the highest mean yield

was in plants, treated with the insecticide. Though light blue sticky boards were not suitable for thrips control in Onion,

the), were useful for monitoring.

Brunner, P. C., E. K. Chatzivassiliou, N. I. Katis and J. E. Frey (2004). "Host-associated genetic differentiation in Thrips tabaci

(Insecta; Thysanoptera), as determined from mtDNA sequence data." Heredity 93(4): 364-370.

We tested for host-associated genetic differentiation in 22 populations of Thrips tabaci collected from tobacco and

leek, respectively. Clustering analyses and haplotype networks based on sequence variation at a fragment of the

mitochondrial cytochrome oxidase I gene yielded three major evolutionary lineages; two were clearly associated with

leek and the third with tobacco. These genetic findings corroborated recent experimental observations on the

heterogeneity of T. tabaci populations with regard to host-plant preference and their capacity to be vectors for tomato

spotted wilt virus. Estimated divergence times suggested an ancient divergence of these lineages dating back to the

Miocene 28 - 21 million years ago. F-ST values between these lineages ranged between 0.824 and 0.954 (P<0.001 for all

comparisons), and sequence divergences ranged between 4 and 11%. Given these findings and by the standards of

genetic and ecological differentiation in other published species groups, T. tabaci must be considered a complex of

cryptic ( sub) species.

Deligeorgidis, P. N. and C. G. Ipsilandis (2004). "Determination of soil depth inhabited by Frankliniella occidentalis (Pergande)

and Thrips tabaci Lindeman (Thysan., Thripidae) under greenhouse cultivation." Journal of Applied Entomology 128(2): 108-111.

The objectives of this study were to determine the depth of penetration into the soil by Frankliniella occidentalis

(Pergande) and Thrips tabaci Lindeman (Thysan., Thripidae) in cucumber and tomato crops in greenhouses. A metal

sampling apparatus sampled for the two species of thrips at five levels of soil depth (0-10 cm), over seven dates of

sampling, each in eight replications. In general, thrips were found to be in greater numbers in the first 2 cm of soil, with

the number of insects decreasing with depth increasing. In the depth of 8-10 cm, no insects were found. Number of

thrips found in the soil under cucumber plants was greater in comparison with the tomato samplings. Frankliniella

occidentalis was found in greater numbers in comparison with T. tabaci. The date of sampling showed a significant

interaction with soil depth, with the number of insects found increasing from the first to the last date of sampling.

Frey, J. E. and B. Frey (2004). "Origin of intra-individual variation in MR-amplified mitochondrial cytochrome oxidase I of Thrips

tabaci (Thysanoptera : Thripidae): mitochondrial heteroplasmy or nuclear integration?" Hereditas 140(2): 92-98.

The mitochondrial genome is increasingly being used as a species diagnostic marker in insects. Typically, genomic DNA

is PCR amplified and then analysed by restriction analyses or sequencing. This analysis system may cause some serious

problems for molecular diagnosis. Besides the errors introduced by the PCR process, mtDNA sequence variation of

amplified fragments may originate from mtDNA heteroplasmy or from nuclear integrations of mtDNA fragments, both

of which have been shown to occur in insects. Here we document abundant variation in PCR-amplified sequences of

the mitochondrial cytochrome oxidase I gene of Thrips tabaci. We confirm that the most common haplotype is of

mitochondrial origin. Some of the observed mutations were introduced by the amplification process. However, the

occurrence of some haplotypes at elevated frequencies indicates that within-individual variation of the respective

fragment exists at low levels in T. tabaci. The frequencies of these sequences are too low to negatively affect mtDNA-

based molecular diagnosis of T. tabaci. The possible origin of these variant haplotypes is discussed.

Gencsoylu, I. and I. Yalcin (2004). "Advantages of different tillage systems and their effects on the economically important pests,

Thrips tabaci Lind. and Aphis gossypii Glov. in cotton fields." Journal of Agronomy and Crop Science 190(6): 381-388.

An experiment to assess advantages of different tillage and their effects on Aphis gossypii Glov. and Thrips tabaci Lind

was conducted during the 2000 and 2001 cotton growing seasons in cotton fields at Adnan Menderes University,

Agricultural Faculty Research Center, located in Aydin Province, Turkey. The tillage systems examined were

80

conventional, strip, precision and ridge tillage. Two insect population densities were not affected by the type of tillage

systems during either year. However, significant differences in populations were observed in thrips populations on 31

May 2000 and 18 May 2001 and aphid populations on 24 May 2000 and 11 May 2001. The results show that the

highest yield was observed in all conservation tillage systems in 2000 and ridge tillage system in 2001. Early maturity

was higher in both precision and ridge tillage systems. In addition, tillage systems did not affect fibre properties. As a

result, the application of conservation tillage is more advantageous in cotton in respect of early maturity and total yield.

Liu, T. X. (2004). "Seasonal population dynamics, life stage composition of Thrips tabaci (Thysanoptera : Thripidae), and

predaceous natural enemies on onions in south Texas." Southwestern Entomologist 29(2): 127-135.

Onion thrips, Thrips tabaci Lindeman, is the most important insect pest of onions in the Lower Rio Grande Valley (LRGV)

of south Texas. The population dynamics and life stage composition of T tabaci populations and the predaceous natural

enemy populations on onions were determined in three consecutive seasons from 2000 to 2002. T tabad were first

present on onion plants in early February, increased in numbers gradually, and peaked in abundance in late March and

early April. Visual counts of field populations revealed approximate to75% of total thrips; and at least 77% of total

predators by absolute counts. Developmental stages of T tabaci on onion plants consisted of 76-85% larvae, <0.1%

pupae, and 10-28% adults. Although insecticide applications reduced thrips density, an average of 92 thrips was found

on each onion plant over the season, which far exceeded the economic threshold. Several species of predators were

found on onion plants. Orius insidiosus (Say) was the most abundant predator species, with 37.4-74.5% on onion plants,

depending on the season and insecticide application. There were significant correlations between predators and thrips

densities on untreated onion plants (r = 0.7327-0.8234), but there were no such correlations on insecticide-treated

onion plants (r = 0.0536-0.4537). It appears that predators were not a major factor regulating thrips; populations. Of the

weather conditions, temperature affected only the early infestation in January and February, and a daily rainfall of 1.8

cm or more caused temporary reduction of thrips densities on onion plants.

Liu, T. X. and C. C. Chu (2004). "Comparison of absolute estimates of Thrips tabaci (Thysanoptera : Thripidae) with field visual

counting and sticky traps in onion field in south Texas." Southwestern Entomologist 29(2): 83-89.

Absolute estimates of onion thrips, Thrips tabaci Lindeman, on onions were used to determine the reliability of field

visual counting, and blue and white plastic cup traps and CC traps for monitoring thrips in onion fields. It took >140

min to sample one plant for the absolute estimates of thrips, which was approximate to15-fold longer than needed to

sample one plant by field visual counting, and 3.8- and 4.3-fold longer than processing a sample using a plastic cup

trap or a CC trap sample, respectively. Results indicated that adult thrips comprised approximate to16.4 and 15.8% of

total thrips in the absolute estimates and field visual counting, respectively, and were well correlated with total thrips in

each sampling method (r = 0.81 and 0.73, respectively). Total thrips and adults by field visual counting estimated

approximate to75% of total thrips and approximate to78% of adults of the absolute estimates, and were highly

correlated with the absolute estimates (r = 0.98 and 0.95, respectively). Blue plastic cup traps caught the most thrips

(19-23 thrips/trap/day), followed by white plastic cup traps (10-12 thrips/trap/day), compared with <1 adult

thrips/trap/day on CC traps. Adults caught on the sticky traps were not well correlated with numbers of thrips on onion

plants in the field (r = 0.07-0.61). Field visual counting of either all thrips or only adults on onion plants was quick and

provided >95% precision.

Van Epenhuijsen, C. W. and J. P. Koolaard (2004). Effective aerosol treatment of mould mites and onion Thrips in tissue culture.

New Zealand Plant Protection, Vol 57. S. M. Zydenbos: 202-208.

Ethyl formate applied as an aerosol killed almost 100% of the mould mites (Tyrophagus putrescentiae) present in tissue

culture tubs. Mite mortality showed dose responses to the chemical and mortality increased with duration of exposure.

Other aerosol formulations, and vacuum and controlled atmosphere treatments were also tested but were not effective

in controlling mites. Onion thrips (Thrips tabaci) in open and closed tissue culture tubs were killed by ethyl formate,

65% and 85% CO2 atmospheres, or dichlorvos plus CO2 propellant. Further work is needed to define effective dose

rates and exposure times and to determine the possible phytotoxicity of the aerosols to various plant species.

Van Toor, R. F., C. M. Till, D. E. James and D. A. J. Teulon (2004). Evaluation of UV reflective mulches for protection against thrips

(Thrips tabaci) in onion (Allium cepa) crops. New Zealand Plant Protection, Vol 57. S. M. Zydenbos: 209-213.



81

The efficacy of the ultraviolet (UV) reflective plastic mulch Extenday (R) for preventing onion thrips (Thrips tabaci) from

colonising onions was evaluated. The mulch reflected 35% of incident UV at 250 run wavelength and 25% of incident

UV at 360 nm, while bare soil reflected 11% and 4% UV at these wavelengths, respectively. In a field trial, the total

number of thrips at 8 weeks after transplanting was lower with mulch (18.5 thrips/bulb) than in the control (28.0

thrips/bulb). However, thrips populations were similar for both treatments in subsequent assessments. When onions in

seedling trays were placed adjacent to an onion field for 8-18 days during early, mid and late summer, aluminium foil,

which reflected UV 250 nm by 43% and UV 360 nm by 35%, and Extenday (R) did not reduce numbers of T tabaci

compared to the control. The use of reflective mulches for repelling thrips in onions does not appear promising.

Jensen, L., B. Simko, C. Shock, L. Saunders and Bcpc (2003). Alternative methods for controlling onion thrips.

Onion thrips (Thrips tabaci) is the major insect pest for dry bulb onions grown in the and production regions of the

western United States. High thrips populations reduce yield and bulb size, decreasing the per cent of colossal sized

bulbs (> 9.53 cm). Pesticide resistance to commonly used insecticides has increased substantially over the past eight

years. The number of insecticide applications required to keep onion thrips controlled has also increased. The fairly

recent development of a mechanical straw mulching machine coupled with the development of "soft" insecticides has

led to new strategies to improve thrips control. Straw mulch applied at layby was coupled with applications of spinosad

and azadirachtin in an integrated pest management program designed to suppress onion thrips populations while

allowing predator populations to increase to the level where they can give economic thrips control. Onion thrips

populations and predator populations were monitored throughout the growing season. Yield and grade measurements

were made to determine the impact of control measures. The alternative program of straw mulch, spinosad and

azadirachtin gave significantly higher yields and gross return compared to standard grower practices.

Jenser, G., R. Gaborjanyi, A. Szenasi, A. Almasi and M. Grasselli (2003). "Significance of hibernated Thrips tabaci Lindeman

(Thysan., Thripidae) adults in the epidemic of tomato spotted wilt virus." Journal of Applied Entomology-Zeitschrift Fur

Angewandte Entomologie 127(1): 7-11.

Tomato spotted wilt tospovirus (TSWV) was transmitted to indicator plants by Thrips tabaci , and was detected even in

single specimens collected from different plants from September until May in Hungary. Consequently, the specimens of

the hibernating generation are able to harbour TSWV from autumn until spring, for 6 months. They could infect the

young seedling in the forced beds, or in the field in May, and thereby they have a significant role in the TSWV epidemic

in spring under Hungarian climatic conditions.

Koschier, E. H. and K. A. Sedy (2003). "Labiate essential oils affecting host selection and acceptance of Thrips tabaci lindeman."

Crop Protection 22(7): 929-934.

Essential oils from plants within the Lamiaceae family at several concentrations were evaluated for their repellent and

deterrent properties against Thrips tabaci Lindeman (Thysanoptera: Thripidae), the onion thrips. Rosemary (Rosmarinus

officinalis L.) essential oil repelled onion thrips females at 10% concentration in olfactometer bioassays. In leaf disc

bioassays on leek (Allium porrum L.), 1% concentration of rosemary oil inhibited settling within a 4-h period. In dual-

choice experiments marjoram (Origanum majorana L.) and mint (Mentha arvensis L.) oil both at 0.1% and 1%

concentrations significantly deterred the egg-laying activity of thrips females on treated leaf discs. Lavender (Lavandifla

angustifolia L.) oil at 1% and sage (Salvia officinalis L.) oil at 0.1% concentration affected oviposition. In no-choice

assays, thrips oviposition rate was significantly reduced by about 45-60% compared to the untreated control after

application of marjoram and lavender oil at 1% or 0.1% concentration. With mint oil, oviposition deterrence was found

only at 1% concentration. Repellent and/or deterrent essential oils combined with other control measures against T

tabaci may contribute to the enhancement of biological or integrated pest management strategies. (C) 2003 Elsevier

Science Ltd. All rights reserved.

Liu, T. X. (2003). "Effects of a juvenile hormone analog, pyriproxyfen, on Thrips tabaci (Thysanoptera : Thripidae)." Pest


Effects of a juvenile hormone analog, pyriproxyfen, on various developmental stadia of the onion thrips, Thrips tabaci

Lindeman, were determined on cabbage leaves in the laboratory. Pyriproxyfen was applied at 0.064 or 0.128 g AI liter(-

1) on leaves (residual contact-ingestion), thrips (direct contact) and leaf-thrips (residue contact-ingestion-direct



82

contact). Pyriproxyfen did not have any significant lethal effects on thrips pupae in any treatment. Lethal effects on

thrips larvae varied depending on application method and dosage. In the leaf and the leaf-thrips treatments, few larvae

and pre-pupae molted to the next stage, and none developed to adults. In contrast, in the thrips-only treatment,

pyriproxyfen did not show any significant lethal effects. The developmental times of larvae and pre-pupae were

prolonged when larvae were treated with pyriproxyfen, and those of pre-pupae and pupae were shortened when pre-

pupae and pupae were treated. The longevity and survival rates of thrips adults were generally shorter when they

contacted and ingested pyriproxyfen-treated leaves than those in water control. Significantly fewer progeny (0.22-1.15

larvae per female) were produced by females that had fed on and been in contact with the pyriproxyfen-treated leaves

than by those in the water control (11.94 larvae per female). However, the number of progeny produced by the thrips

females increased significantly (3.32-7.28 larvae per female) when the females were transferred to untreated leaves

after feeding on treated leaves for 5 days; the daily larval hatching pattern was similar to those in water control,

indicating that female adults were able to produce viable eggs when untreated food was offered. (C) 2003 Society of

Chemical Industry.

Maniania, N. K., S. Sithanantham, S. Ekesi, K. Ampong-Nyarko, J. Baumgartner, B. Lohr and C. M. Matoka (2003). "A field trial of

the entomogenous fungus Metarhizium anisopliae for control of onion thrips, Thrips tabaci." Crop Protection 22(3): 553-559.

In Kenya, Thrips tabaci Lind., is an important constraint to onion production. The current strategy to use synthetic

pesticides is inadequate and unsustainable. An isolate of Metarhizium anisopliae (Metsch.) Sorok. with high

pathogenicity to legume thrips, Megalurothrips sjostedti, and western flower thrips, Frankliniella occidentalis, was

tested in field trials as a potential alternative for control of onion thrips. Weekly and bi-weekly applications of the

fungus M. anisopliae and bi-weekly spray of the chemical insecticide dimethoate (Rogor((R)) 50) were compared for 3

seasons. M. anisopliae was applied at the rate of 1 x 10(11) conidia ha(-1) and dimethoate was applied at the

recommended rate of 17.5 g a.i. ha(-1). In all the trials, thrips density and damage were significantly lower in the fungal

and chemical insecticide treatments compared with the untreated control. Onion bulb yield did not differ significantly

among the treatments during the first season trial. However, in the second season trial, dimethoate-treated plots

provided the greatest bulb yield (17 metric tons ha(-1)) and in the third season trial, M. anisopliae applied weekly

recorded the highest yield (24 metric tons ha(-1)). With the exception of spiders, densities of nontarget organisms were

higher in plots treated with M. anisopliae than in dimethoate-treated plots. The results indicate the potential of using

M. anisopliae for the control of T. tabaci while protecting biodiversity in the onion agroecosystem. (C) 2003 Elsevier


Martin, N. A., P. J. Workman and R. C. Butler (2003). "Insecticide resistance in onion thrips (Thrips tabaci) (Thysanoptera :

Thripidae)." New Zealand Journal of Crop and Horticultural Science 31(2): 99-106.

Onion thrips from onion (Allium cepa) crops were tested for resistance to four insecticides (deltamethrin, diazinon,

dichlorvos, and endosulfan) following reports of failure of insecticides to control onion thrips in the field. Bioassays to

determine baseline concentration-mortality responses used thrips from two insecticide susceptible populations. Leaf

discs (24 min diam.) cut from leek (Allium porrum) were dipped in insecticide solutions and placed, when dry, in Petri

dishes (50 min diam.) with ventilated lids. Ten adult female thrips were added, and mortality was recorded after 24 h at

25degreesC. Five or six concentrations of each insecticide were tested and bioassays were usually repeated 3 times'.

The lowest concentration, which consistently killed over 90% thrips, was used as a diagnostic concentration to screen

thrips populations collected from four onion crops and compared with both susceptible populations using the same

bioassay. Each test population was also exposed to leaves dipped in water. One Canterbury and three Auckland

populations were resistant to deltamethrin, whereas only the three Auckland populations were resistant to diazinon and

dichlorvos. No population was resistant to endosulfan. Concentration-mortality responses were determined for

deltamethrin and diazinon. Based on the LC(50)s, one Auckland population was 40 times more resistant to diazinon and

the Canterbury population was 550 times more resistant to deltamethrin than susceptible populations. The New

Zealand onion industry responded to the initial failure of insecticides by developing and implementing an insecticide

resistance management strategy and research to improve onion thrips control.

Rueda, A. and A. M. Shelton (2003). "Development of a bioassay system for monitoring susceptibility in Thrips tabaci." Pest




83

A system is described for collecting adult and larva of Thrips tabaci from onion foliage into insecticide-treated vials to

evaluate susceptibility to insecticides. The thrips insecticide bioassay system (TIBS) allows one to treat vials and store

them for 3 weeks before thrips are collected. Depending on the population density in the field, collection of the insects

for the test required from 3-6h for one person. Assays are read after 24 h. This system was used in 1997 and 1998 in

commercial onion fields in Honduras and Nicaragua, and TIBS was sensitive enough to detect differences to the

insecticides tested, to thrips life stages and to different generations within an onion-growing season. Data collected

suggest that there were not serious problems with thrips insecticide resistance, with the possible exception of

cypermethrin in Nicaragua which had a resistance ratio (RR) value of 26.9 for adult thrips. The largest RR values were

observed at the end of the growing season, and this may be caused by the season-long selection by insecticide sprays.

The mortality of adults and larvae followed the same general pattern, but the ratio between larvae and adults differed

for each chemical group. (C) 2003 Society of Chemical Industry.

Sedy, K. A. and E. H. Koschier (2003). "Bioactivity of carvacrol and thymol against Frankliniella occidentalis and Thrips tabaci."

Journal of Applied Entomology 127(6): 313-316.

Two constituents of essential oils, carvacrol and thymol, were tested for their effects on the feeding activity, oviposition

preference and oviposition rate of Frankliniella occidentalis and Thrips tabaci. Given a choice between treated and

untreated leaf discs, F. occidentalis avoided ovipositing on leaf discs treated with 1 or 0.1% thymol. In no-choice

experiments, 1 and 0.1% thymol and 1% carvacrol resulted in a reduced oviposition rate of F. occidentalis compared

with the control. Both constituents caused a slight reduction of the feeding damage of F. occidentalis. 1 and 0.1%

carvacrol had a pronounced deterrent effect on the oviposition site selection of T. tabaci . Both constituents served as

anti-ovipositants for both thrips species, albeit F. occidentalis was more affected than T. tabaci.

Shelton, A. M., B. A. Nault, J. Plate and J. Z. Zhao (2003). "Regional and temporal variation in susceptibility to lambda-cyhalothrin

in onion thrips, Thrips tabaci (Thysanoptera : Thripidae), in onion fields in New York." Journal of Economic Entomology 96(6):

1843-1848.

Populations of onion thrips, Thrips tabaci Lindeman, from commercial onion fields in New York were evaluated for their

susceptibility to the commonly used pyrethroid, lambda-cyhalothrin (Warrior T), using a novel system called the Thrips

Insecticide Bioassay System (TIBS). To use TIBS, thrips are collected directly from the plant into an insecticide-treated

0.5-ml microcentrifuge tube that has a flexible plastic cap with a small well into which 0.08 ml of a 10% sugar-water

solution with food colorant is deposited. The solution is sealed into the well with a small piece of stretched parafilm

through which the thrips can feed on the solution. Thrips mortality is assessed after 24 h with the help of a dissecting

stereoscope. In 2001, onion thrips populations were collected from 16 different sites and resistance ratios were >1,000

in five populations. Percent mortality at 100 ppm, a recommended field rate, varied from 9 to 100%, indicating high

levels of variation in susceptibility. Particular instances of resistance appeared to be the result of practices within an

individual field rather than a regional phenomenon. In 2002, we also observed large differences in onion thrips

susceptibility, not only between individual fields but also between thrips collected in a single field at mid season and

late season, again suggesting that insecticide-use practices within an individual field caused differences in susceptibility.

Additional tests indicated no differences in susceptibility between adult and larval onion thrips populations and only

relatively minor differences between populations collected from different parts of the same field. Using TIBS, several

populations of onion thrips with different susceptibilities to lambda-cyhalothrin were identified and then subjected to

lambda-cyhalothrin-treated onion plants. There was a highly significant positive relationship between percent mortality

of thrips from TIBS and percent mortality from the treated onion plants, indicating that results from TIBS could be used

to predict spray performance. These data suggest that use of TIBS for evaluating susceptibility to particular insecticides

could be instrumental for developing a resistance management strategy for onion thrips.

Chatzivassiliou, E. K., D. Peters and N. I. Katis (2002). "The efficiency by which Thrips tabaci populations transmit Tomato spotted

wilt virus depends on their host preference and reproductive strategy." Phytopathology 92(6): 603-609.

Arrhenotokous and thelytokous populations of Thrips tabaci from tobacco or leek plants were evaluated for their ability

to transmit Tomato spotted wilt virus (TSWV) and for their host preference. Transmission efficiencies were

comparatively studied using leaf disks of Petunia hybrida, Datura stramonium, and Nicotiana tabacum cv. Basmas.

Adults of arrhenotokous populations collected on infected tobacco plants in the field were efficient transmitters (up to



84

48.5% transmission) and remained so when maintained on tobacco for several generations. Arrhenotokous T tabaci

populations from leek plants were poor transmitters (up to 3.1% transmission), whereas no transmission was obtained

with thelytokous populations from leek. All populations could infest leek, however none of the arrhenotokous and

thelytokous populations from leek plants was able to infest tobacco. TSWV could be acquired by both first and second

larval instars of a T tabaci population from tobacco. However, the transmission by adults decreased with the age at

which the virus was acquired by larvae. The highest efficiencies (61% of males and 51% of females transmitted) were

obtained when newborn (0- to 24-h old) larvae acquired the virus. The majority of thrips started to transmit after

becoming adult and rates were positively correlated with the temperature at which the thrips were kept, The median

latent period values found for adults decreased with increasing temperature. The median acquisition access period

(AAP(50)) of the population was 41 min, whereas the AAP(50) was 65 min for males and 35 min for females. The median

inoculation access period of males was 246 and 365 min on tobacco and petunia, respectively, and 96 and 345 min for

females. The results show that T tabaci forms a complex in terms of host preference, reproductive strategy, and ability

to transmit TSWV. The transmission parameters show that the thrips of arrhenotokous populations infesting tobacco

are highly efficient vectors.

Deligeorgidis, P. N. (2002). "Predatory effect of Orius niger (Wolff) (Hem., Anthocoridae) an Frankliniella occidentalis (Pergande)

and Thrips tabaci Lindeman (Thysan., Thripidae)." Journal of Applied Entomology-Zeitschrift Fur Angewandte Entomologie

126(2-3): 82-85.

The predatory effect of adult female Orius niger (Wolff) (Hem., Anthocoridae) on the larvae I-II and adults of two

injurious thrips, Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman (Thysan., Thripidae), was examined in

June 1997, in controlled environment chambers (temperature 22 +/- 0.2degreesC, 65 +/- 3% RH, a 16 h light : 8 h dark

photoperiod and light intensity 9000 Lux). This study took place on sweet popper leaves (Capsician annuum L.) in

transparent small plastic cages at proportions of 115, 1/10, 1/20 and 1/30 predatory umber of thrips for larvae I-I I and

adults separately for each thrips species. O. niger was proved an effective predator for the immature stages (larvae I-II)

and for the adults of the two thrips species, We concluded that O. niger could be used with success for the biological

control of thrips in greenhouses crops.

Koschier, E. H., K. A. Sedy and J. Novak (2002). "Influence of plant volatiles on feeding damage caused by the onion thrips Thrips

tabaci." Crop Protection 21(5): 419-425.

Leaf disc bioassays were conducted to determine the effects of essential oils and their volatile constituents from plant

species (Lamiaceae family) at three concentrations ranging from 0.01% to 1% on the feeding activity of adult female

onion thrips (Thrips tabaci Lindeman; Thysanoptera: Thripidae). The percentage of feeding damage area on leek (Allium

porrum L.) leaf discs and the adult survival was assessed after 24 h. Onion thrips were significantly deterred by the

essential oils of marjoram (Origanum majorana L.), lavender (Lavandula angustifolia L.) and mint (Mentha arvensis L.) at

several concentrations, and by the oil of rosemary (Rosmarinus officinalis L.) at 1% concentration. Furthermore, thrips

feeding damage was reduced as a result of linalool and eugenol application at three concentrations. Adult survival on

the leaf disc surface was significantly decreased by application of terpinen-4-ol at 1% concentration. Evaluation of the

potential of biologically active plant volatiles against T. tabaci may provide a new approach to the development of

antifeedants and/or natural insecticides for use in both biological and integrated pest management strategies. (C) 2002

Elsevier Science Ltd. All rights reserved.

Page, B. B. C., M. J. Bendall, A. Carpenter, C. W. Van Epenhuijsen, I. N. C. New Zealand Plant Protection Society, I. N. C. New

Zealand Plant Protection Society and I. N. C. New Zealand Plant Protection Society (2002). Carbon dioxide fumigation of Thrips

tabaci in export onions. New Zealand Plant Protection, Vol 55. 55: 303-307.

As an alternative to chemical pesticides, elevated carbon dioxide atmospheres were examined as a method for

controlling thrips on export onions. A replicated gas delivery system was used to deliver a constant supply of various

concentrations of carbon dioxide (CO(2)) to thrips-infested onions within sealable bags. Six CO(2) treatments - an air

control and 15, 30, 45, 60 and 100% CO(2), (all in balance air) - were applied for 6, 12, 24, 48 and 72 h. Mortality was

100% at CO(2) concentrations of 30% or more after at least 24 h. However, the control treatments also had a high level

of mortality and although there were significant differences between the control treatment and the CO(2) treatments,

these differences were not large.



85

Tsuchiya, M. (2002). "Infestation and oviposition of Thrips tabaci (Lindeman) on Satsuma mandarin (Citrus unshiu Marc.)."

Japanese Journal of Applied Entomology and Zoology 46(4): 217-224.

Infestation and oviposition of Thrips tabaci (Lindeman) on Satsuma mandarin (Citrus unshiu Marc.) were examined in an

orchard and a greenhouse in Shizuoka Prefecture in 2000 and 2001. T tabaci infested the flowers and fruit, but they did

not infest the flower buds, young fruits, or leaves. In the orchard, the number of adults and larvae was greatest at the

end of the blossoming season. Since no damage was observed on fruits at harvest time, control for the thrips was not

considered necessary. In the greenhouse, infestation by adults and larvae was observed on fruits after opening the side

window of the greenhouse. The number of thrips on fruits left on the trees increased through the harvest. A low

survival rate of 15.7% was observed five days after artificial infestation of adult thrips to the young fruits (27-41 mm in

diameter) in July. The thrips preferred orange colored rind for infestation and oviposition. Consequently, controlling the

thrips in the greenhouse was considered necessary from the time the side window was opened to the end of the

harvest.

Workman, P. J., N. A. Martin, I. N. C. New Zealand Plant Protection Society, I. N. C. New Zealand Plant Protection Society and I. N.

C. New Zealand Plant Protection Society (2002). Towards integrated pest management of Thrips tabaci in onions. New Zealand

Plant Protection, Vol 55. 55: 188-192.

Populations of onion thrips, Thrips tabaci, and their natural enemies were monitored in small field plots of onions to

which standard insecticide (methamidophos, endosulfan and chlorpyrophos), selective insecticide (imidacloprid and

spinosad), organic (YR015) insecticide or no insecticide treatments were applied. The mean number of thrips per plant

was kept below 12 in the standard and selective treatments. The numbers of thrips in the organic and no insecticide

treatments were comparable, reaching over 60 thrips per plant. This resulted in increased plant damage and shorter

leaves. High rainfall in 2001-02 coincided with a reduction in thrips numbers in untreated plots, which peaked at 70

thrips per plant, compared with nearly 500 thrips per plant in the drier 2000-01 season. Natural enemies observed in

the unsprayed and organic treatments included Ceranisius menes, Aeolothrips fosciatum. Buchananiella whitei, syphids

and entomogenous fungi. None of these natural enemies increased sufficiently to provide effective thrips control. No

natural enemies were found in the standard or selective insecticide treated plots.

Kannan, H. O. and M. B. Mohamed (2001). "The impact of irrigation frequency on population density of thrips, Thrips tabaci Rom

(Thripidae, Thysanoptera) and yield of onion in El Rahad, Sudan." Annals of Applied Biology 138(2): 129-132.

Vegetable farmers of the El Rahad Scheme (a newly developed scheme situated between latitude 13 degrees 31'-14

degrees 25' north and longitude 33 degrees 31-34 degrees 32' east) used to extend irrigation frequency for onion

production as they believed it would hamper and suppress thrips incidence. Thrips, T. tabaci, is the only major insect

pest of onion in the El Rahad Scheme and the influence of irrigation intervals on the population density of the pest and

on onion yield was not quantified. Irrigation is a factor in the development of crop pests and the levels of the pest

population are related to the commencement of irrigation. The effect of irrigation frequency on the development of

onion thrips and yield was investigated and the response was found to be a significant increase in the population

density of the pests from February to March with shorter irrigation frequency. A steady increase of thrips population

was noted from February and March and a sharp decline was recorded in April during both the 1992/93 and 1993/94

seasons. At wider irrigation intervals, levels of the pest population were significantly less from February to March during

both seasons. Total bulb yield and average bulb weight were significantly higher at shorter irrigation frequencies when

compared with extended frequencies. The same pattern of results existed throughout the course of the experiment.

Krauthausen, H. J., E. Richter, S. Hagner and M. Hommes (2001). Epidemiology and control (based on thresholds) of leaf diseases

(Peronospora destructor, Botrytis spp.) and thrips (Thrips tabaci) in onion. Proceedings of the Second International Symposium

on Edible Alliaceae. J. Armstrong: 137-140.

During a 3 year testing program a threshold strategy for the control of onion (Allium cepa L.) leaf diseases and pests

was compared with growers' spraying schemes. By employing the threshold strategy more than 50% of the pesticides

could be saved without any concession to yield or quality.



86

Sengonca, C. and K. Drescher (2001). "Laboratory studies on the suitability of Thrips tabaci Lindeman (Thysanoptera, Thripidae)

as prey for the development, longevity, reproduction and predation of four predatory mite species of the genus Amblyseius

(Acari, Phytoseiidae)." Zeitschrift Fur Pflanzenkrankheiten Und Pflanzenschutz-Journal of Plant Diseases and Protection 108(1):

66-76.

In the present study, the suitability of Thrips tabaci Lindeman (Thysanoptera, Thripidae) larvae as prey of the predatory

mites Amblyseius (Iphiseius) degenerans Berlese, Amblyseius umbraticus Chant, Amblyseius andersoni Chant and

Amblyseius limonicus Carman and McGregor was examined under laboratory conditions. The spider mire Tetranychus

urticae Koch (Acari, Tetranychidae), standard prey in rearing predatory mites, was used as comparative prey. The

suitability of T. tabaci as prey for the development, longevity, reproduction, and predation of the predatory mites was

determined. Since the onion thrips is the most important economic pest in the field production of leek (Allium porrum

L.) in Germany, the results of this study should provide information on the potential of these predatory mites as

biological control agents. Results showed that I: tabaci larvae as prey had a negative influence on the examined

parameters of most: predatory mite species when compared with T. urticae as control prey. A. degenerans was not able

to develop beyond the protonymph stage with thrips lan ae being the only prey available. Longevity of A. umbraticus

and A. limonicus was reduced to half and one third, respectively. Daily and total reproductive rates were reduced for all

four predatory mite species examined. A. andersoni tvas the only predatory mite that showed comparable results when

fed with T. tabaci. Its total developmental time was not prolonged significantly and longevity was only reduced by a few

clays. Furthermore, A. andersoni showed the highest mean lifetime predation rare of all examined species amounting to

35 T. tabaci-larvae. How well these predatory mites will actually perform in biological control of T. tabaci in the field

cannot yet: be concluded from the assessed laboratory potential and has to be evaluated in the field.

Tedeschi, R., M. Ciuffo, G. Mason, P. Roggero and L. Tavella (2001). "Transmissibility of four tospoviruses by a thelytokous

population of Thrips tabaci from Liguria, northwestern Italy." Phytoparasitica 29(1): 37-45.

Studies were carried out on a population of Thrips tabaci Lindeman (Thysanoptera: Thripidae) from Liguria to assess its

sex-ratio and its ability to transmit four tospoviruses: tomato spotted wilt (TSWV), impatiens necrotic spot, tomato

chlorotic spot and groundnut ringspot. The population was composed of females only (therefore thelytokous). The first

instar larvae were allowed to acquire the virus for 48 h on infected leaves of datura, basil or pepper, and then reared on

cucumber until emergence, which medially occurred 9.5 days after latching. Transmission capacity was checked using

two inoculation access periods (IAPs) of 48 h each on pepper leaf disks. T. tabaci was able to transmit TSWV isolate

P105 with an efficiency of 16.7% and 4.4% in the first and second IAP, respectively, and TSWV isolate BR-01 with an

efficiency of 2.0%. The onion thrips did not transmit the three other tospoviruses. During the IAPs, almost all adults fed

on the leaf disks, producing evident silvery scars. The presence of tospovirus nucleocapsids in thrips was assayed by

Triple Antibody Sandwich (TAS) and cocktail ELISA. Not all adults that had transmitted TSWV were positive in the tests,

whereas some non-transmitter individuals proved positive. For each of the other tospoviruses, some thrips were

positive in at least one test, although none was able to transmit the virus.

den Belder, E., J. Elderson and P. F. G. Vereijken (2000). "Effects of undersown clover on host-plant selection by Thrips tabaci

adults in leek." Entomologia Experimentalis Et Applicata 94(2): 173-182.

The suppressive effects of undersown clover on Thrips tabaci Lindeman infestation in leek is known but not the stages

in thrips population dynamics that are affected by intercropping and the mechanisms involved. Colonization or settling

of adult onion thrips (T. tabaci) in monocropped leek (Allium porrum L.) and in leek intercropped with strawberry clover

(Trifolium fragiferum L.) was studied in two potted plant experiments. Potted leek plants with and without undersown

clover were placed for a short period (2 and 5 days) in monocropped or intercropped field plots when high thrips

infestation was expected. Thrips adults were counted on all leaves and in the shaft during this observation period.

Thrips populations were monitored weekly in the field plots throughout the entire growing season. In both potted plant

experiments, there were consistently fewer thrips adults on intercropped leek plants than on monocropped plants. The

plant growth parameters - number of leaves and stem diameter - were similar in all treatments and thus did not explain

differences in thrips adults. Natural enemies were absent on both leek and clover, and thus cannot explain the

differences in adult thrips numbers. Furthermore, no adults of T. tabaci were found on the clover in the potted plant

experiment and only very few in the field experiment. Thus it was concluded that strawberry clover was not an effective

trap crop for thrips. In the second potted plant experiment, clover was removed just before the leek plants were



87

introduced to the field, thus eliminating direct physical, visual and olfactory interference by clover. After the undersown

clover was removed, the leek plants harboured only one-third of the number of thrips adults, as compared to the

monocropped plants. This study supports the notion that there are subtle links between intercropping and plant

quality, and indicates that host-plant quality is an underlying cause of the reduction in adult thrips numbers in

leek/clover intercropping.

Ester, A., B. Nawrocka, I. Commandeur, G. Universiteit and G. Universiteit (2000). Evaluation of the Thrips tabaci (Lind.) resistance

of white cabbage varieties stored at different temperatures. 52nd International Symposium on Crop Protection, Pts I and Ii,

Proceedings. 65: 325-334.

A range of commercially important white cabbage (Brassica oleracea L. convar. capitata (L.) Alef. var, alba DC) Varieties

has been evaluated in The Netherlands and Poland for resistance to the onion thrips, Thrips tabaci (Lind.). These

varieties were stored for a short or a long period, to investigate their susceptibility to onion thrips and their yield. Five

storage experiments were carried out between 1995 and 1998. For the short storage, thirteen varieties were

investigated in a 18-week trial in The Netherlands and eight varieties in a 2-week trial in Poland. For the long storage,

ten varieties were investigated in 25-week trials in The Netherlands. The short storage experiments were performed at 0

degreesC in The Netherlands and 10 degreesC in Poland. In the long storage experiments in The Netherlands, storage

at 0 degreesC and 8 degreesC were compared to investigate the development of the thrips damage. In short storage,

varieties Binge, Bison, Caid, Delus, Eton, Jaguar, Goldie, Kalorama, Sphinx, Krypton, Rivera, Galaxy, Oskar, Almanac and

Kamienna Glowa had a high level of resistance to onion thrips and the varieties Caid, Galaxy and Sphinx had the highest

yield, with all cabbage heads in quality class I. In long storage, varieties Galaxy and Robustor showed high resistance to

onion thrips and Galaxy had the highest yield. Storing white cabbage at 0 degreesC resulted in a lower percentage of

attacked cabbage heads, with a higher score of thrips in comparison with cabbage heads stored at 8 degreesC.

Ghosheh, H. Z. and H. K. Al-Shannag (2000). "Influence of weeds and onion thrips, Thrips tabaci (Thysanoptera : Thripidae), on

onion bulb yield in Jordan." Crop Protection 19(3): 175-179.

Field experiments were conducted in two seasons to investigate the effects of weeds and onion thrips on onion bulb

yield grown under irrigation. Treatments were combinations of three levels of weed infestation and two onion thrips

infestation levels. Weed interference was found to severely reduce bulb yield, whereas reductions from onion thrips

infestations were of lower magnitude. Hand weeding was more effective in weed control than a single oxyfluorfen

application. No significant interactions were detected in this investigation between weeds and onion thrips infestations,

which could be attributed to the strong preference of onion thrips towards the crop over the weeds. (C) 2000 Elsevier


Murai, T. (2000). "Effect of temperature on development and reproduction of the onion thrips, Thrips tabaci Lindeman

(Thysanoptera : Thripidae), on pollen and honey solution." Applied Entomology and Zoology 35(4): 499-504.

The effects of five constant temperatures (15 degreesC, 20 degreesC, 23 degreesC, 25 degreesC and 30 degreesC)

under 16L8D photoperiod on development, reproduction and population growth of Thrips tabaci reared on a diet of

pollen and honey solution were studied. Although hatchability was more than 80% at temperatures between 15 and 25

degreesC, it was low at 30 degreesC. Survival rates from hatch to adult were higher than 65% at all temperatures.

Developmental rates increased linearly as rearing temperature increased. It was estimated that 232.6 degree-days,

above a developmental zero of 10.8 degreesC, were required to complete development from egg to adult oviposition.

These data were related to records of held temperatures in Kurashiki, western Japan, to estimate the potential number

of generations per year that could complete development under outdoor conditions. Using this data, a maximum of

between seven and 11 generations could have developed annually between 1990 and 1998. Mean adult longevity

decreased with increasing temperature, from a maximum of 86.6 days at 15 degreesC to a minimum of 12.8 days at 30

degreesC. The mean fecundity on pollen and honey solution was the highest at 23 degreesC and 270 eggs per female.

The intrinsic rate of natural increase (r(m)) was highest at 25 degreesC and 0.1709.

Vierbergen, G., A. Ester, G. Universiteit and G. Universiteit (2000). Natural enemies and sex ratio of Thrips tabaci (Thysanoptera :

Thripidae), a major pest of Allium porrum in The Netherlands. 52nd International Symposium on Crop Protection, Pts I and Ii,

Proceedings. 65: 335-342.

88

The mild, but wet Atlantic climate of the Netherlands is unsuitable for many leaf feeding Thysanoptera to attack crops

in high numbers. Nevertheless, the building up of large populations and the successful overwintering capabilities of

Thrips tabaci on leek (Allium porrum) results commonly in economical damage to the crop and the use of insecticides

for control. In three successive years the predator and the parasitoid fauna is investigated in order to partly unravel the

suitability of leek for T. tabaci. In The Netherlands the fauna of leek revealed the occurrence of six species of

Thysanoptera, of which the predator Aeolothrips intermedius and the major pest T. tabaci were the only Thysanoptera

reproducing on the crop. The most common predators of T. tabaci observed were Heteroptera (Orius), but Phytoseiidae

and hymenopterous parasitoids were absent. In the Netherlands the polyphagous and very commonly occurring T.

tabaci is normally thelytokous; males are known only from propagation rooms and in the open from leek, garlic (A.

sativum), onion (A. cepa) and shallot (A. cepa), Possibly only inside Allium plants the physical factors are present to

explain the occurrence of arrhenotokous populations in temperate areas. The male/female ratio observed on leek (1/26)

differs from the reported ratios. It is concluded the suitability of leek for arrhenotokous populations of T. tabaci is

caused by the absence of effective predators and parasitoids. Additionally this suitability may be induced by the

building-up of insecticide resistance as a result of sexual reproduction and the overwintering in the crop. Introduction

in the Dutch leek culture of a diapause strain of the phytoseiid Amblyseius cucumeris may give satisfactory control of

thrips populations.

Yokoyama, V. Y. and G. T. Miller (2000). "Response of omnivorous leafroller (Lepidoptera : Tortricidae) and onion thrips

(Thysanoptera : Thripidae) to low-temperature storage." Journal of Economic Entomology 93(3): 1031-1034.

Eggs and first-fifth instars of omnivorous leafroller, Platynota stultana Walshingham, had a mean percentage survival to

the adult stage of 60.7-95.2% for nonexposed immatures and 145-54.3% for immatures exposed to 1 wk at 0-1 degrees

C. Exposures of 2-5 wk resulted in 0-6.7% survival, and a 6-wk exposure resulted in <1% survival of all stages tested. A

significant reduction in survival of all larval stages occurred between exposures of 0 and 1 wk and between 1 wk and 2-

6 wk. Survival of eggs after exposures of 0 and 1 wk was significantly different than survival after exposures of 2-6 wk.

The second instar was the stage least susceptible to low-temperature storage. Adults that were exposed to low

temperature for 1 wk in the third through fifth instars laid a mean of 120-289 eggs per female, and the mean

percentage viability of the eggs ranged from 56.2 to 71.4%. Mean percentage survival of adults and nymphs of onion

thrips, Thrips tabaci Lindeman, was inversely related to the duration of exposure from 1 through 3-6 wk at 0-1 and 5

degrees C and was lower at 0-1 (0.2-52.5%) than at 5 degrees C (17.6-66.6%). Exposure to 0-1 degrees C for 4 wk

attained 91.2% control, which increased to 99.8% after 6 wk. Low-temperature storage has potential to control

omnivorous leafroller in table grapes, Vitis vinifera L., and onion thrips in onions, Allium cepa L.

Chatzivassiliou, E. K., T. Nagata, N. I. Katis and D. Peters (1999). "Transmission of tomato spotted wilt tospovirus by Thrips tabaci

populations originating from leek." Plant Pathology 48(6): 700-706.

The transmission of tomato spotted wilt tospovirus (TSWV) by Thrips tabaci collected from leek was studied using the

petunia local-lesion leaf-disc assay. After an acquisition-access period of 72 h given to newborn larvae up to 8 h old,

the efficiency of transmission by adults was determined in three inoculation-access periods of 48 h. This efficiency

varied for six T. tabaci populations from 0.7 to 11.6% in experiments using the Greek TSWV isolate GR-04. Males were

more efficient transmitters than females (19 out of 176 versus five out of 494). Frankliniella occidentalis transmitted the

same virus with a higher efficiency (34.8%). The transmission rate differed also among TSWV isolates, as shown in tests

with four T. tabaci using two isolates. The virus was more efficiently acquired from infected leaf material of Datura

stramonium than from that of Emilia sonchifolia. Plants of the latter species were more susceptible than Nicotiana

tabacum in thrips transmission tests.

Drescher, K., M. Schade and C. Sengonca (1999). Is a biological control of Thrips tabaci LINDEMAN in the field achievable?

Communications of the German Society for General and Applied Entomology, Vol 12, Nos 1-6, Feb 2000. D. Mossakowski. 12:

97-100.

In this field study, the possibility of a biological control of the major pest in the production of leek, Thrips tabaci

(Thysanoptera, Thripidae), was examined by mass release of the two predatory mite species Amblyseius andersoni

CHANT and Amblyseius limonicus CARMAN and MCGRECOR (Acari, Phytoseiidae). Furthermore, the influence of

different predator/prey densities and number of release dates on the efficacy of the predatory mites towards T. tabaci

89

was determined. This was accomplished by introducing the beneficial arthropods either at two dates at a density of 20

individuals per plant, or at four dates in a density of 10 individuals per plant. Prior to their release the mites were

transferred from their rearing cages to pieces of French bean leaves infested with Tetranychus urticae KOCH (Acari,

Tetranychidae) and then contained in a parafilm-sealed small petri-dish. These leaves were then placed within the plant

on the treated plots. The population dynamics of the pest as well as the beneficials were monitored on a weekly basis

by extraction of whole plants from the field and examination of their leaves in the laboratory. At this point the number

of thrips and beneficials found per plant was determined. Even though differences in efficacy of the different predatory

mite species could be observed, the number of release dates and consequently the different predator/prey densities

did not influence the efficacy of each species. Both species were able to reduce the number of thrips per plant

throughout the duration of the experiment and to keep their numbers below the level of the pesticide-treated area

used as control. The even distribution of the release of the mites did not increase the efficacy in comparison to

pinpointing the mass release on two dates.

Hamilton, B. K., L. M. Pike, A. N. Sparks, D. A. Bender, R. W. Jones, J. Candeia and G. de Franca (1999). "Heritability of thrips

resistance in the 'IPA-3' onion cultivar in South Texas." Euphytica 109(2): 117-122.

A two season study was conducted to compare the onion cultivars TG1015Y and IPA-3 for resistance to thrips in South

Texas. Narrow and broad sense heritabilities were estimated from populations developed from the cross, 'IPA-3' x

'TG1015Y'. Parents, F1, F2, and the respective backcross populations were evaluated for thrips numbers at the Texas

Agricultural Experiment Station, Weslaco, TX. 'IPA-3' had significantly fewer thrips than 'TG1015Y' in both seasons. Yield

was significantly different only in the 1996-97 season. The heritability of thrips resistance in this study was very low.

Depending on the methods of estimation h(2) was 5.3% and 4.0%, and H-2 was 4.1% and 8.0%. These results suggest

that greater genetic gains for thrips resistance in onion can be achieved by selection on a family basis rather than using

single plant selection.

den Belder, E. and J. Elderson (1998). Suitability of leek for Thrips tabaci is reduced by intercropping with clover.

The focus of this report is on the reduction of onion thrips, Thrips tabaci Lindeman in leek/clover intercropping and the

mast likely mechanisms underlying this reduction. Our results showed that in the range of fertiliser dosages tested (0,

50 and 150 kg/ha), thrips suppression in the leek-clover intercropping was not affected by nitrogen concentration in

the plant or size of the plant (expressed as leaf area index). In contrast to the response-of other pest species to plant

quality as mediated by nitrogen application, T. tabaci population dynamics appeared not to be influenced by this factor.

Analysis of initial colonisation by Thrips tabaci adults in leek interplanted with clover indicated that colonisation rates in

the intercropped leek plants were lower in comparison with the leek monocrop. Seventy percent of the newly

established thrips adults were found on the monocrop leek plants. After cutting the clover around leek plants the thrips

suppression persisted. This supports the conclusion that attractiveness or nutritional quality of the leek plant for onion

thrips is reduced as a direct result of the interaction of leek with clover.

Ester, A. and A. Evenhuis (1998). Effect of plant density and seed treatment on the population of Thrips tabaci (Lind) in leek.

Field trials were carried out in 1996 and 1997. Leek seeds were sown at 1 cm (seed bed) and at 4 cm (direct drilling)

seed distance. On plants sown at 4 cm seed distance significant (p<.001) more thrips (immature and adult) were

present in comparison to the plants at 1 cm. Also, the damage caused by thrips at the 4 cm was more severe than at 1

cm, in both treated and untreated seeds.

Kazak, C., K. Karut, S. Yildiz and E. Sekeroglu (1998). Biological, control of Thrips tabaci Lindeman (Thysanoptera : Thripidae) by

Amblyseius cucumeris (Oudemans) (Acarina : Phytoseiidae) on greenhouse cucumber in Adana, Turkey. First International

Symposium on Cucurbits. K. Abak and S. Buyukalaca: 169-174.

Biological control of Thrips tabaci was studied on greenhouse grown cucumbers by using predatory mite, Amblyseius

cucumeris. Trials were conducted on cv. Kahya of cucumber in 1995, and on cv. Kahya and cv. Ozde in 1996. In both

years plot size consisted of 3 rows of 40 plants for each predator release and non-release control plots. Predators were

released at a rate of 4-5 individuals per plant as soon as thrips were detected on host plants. In both years predator

was able to bring thrips populations down to low levels. Immature populations of thrips reached to a peak of about

260/leaf in non-release control plots but never exceeded 160/leaf on cv. Ozde and 80/leaf on cv. Kahya. Adult



90

populations of thrips were also higher in control plots compared to predator released plots. In all plots age distribution

of thrips populations were similar (85-90 % immatures, 10-15 adults), however the low numbers of immatures in

predator release plots indicated that predation was heavier on immatures. A. cucumeris was more effective on cv. Kahya

compared to cv. Ozde. This might be due to an allowance of plant characteristics to the predator to prey more

efficiently.

Milne, M. and G. H. Walter (1998). "Host species and plant part specificity of the polyphagous onion thrips, Thrips tabaci

Lindeman (Thysanoptera : Thripidae), in an Australian cotton-growing area." Australian Journal of Entomology 37: 115-119.

We determined the pattern of host plant use of Thrips tabaci by surveying wheat and five weed species growing near

cotton crops in the area centred on the Namoi Valley, northern New South Wales. Highest densities of T. tabaci females

and larvae were found on inflorescences and vegetative parts of turnip weed, Rapistrum rugosum, and lowest on wheat,

Triticum aestivum. The other plant species (Paterson's curse, Echium plantagineum, curled dock, Rumex crispus,

Mayne's pest, Verbena tenuisecta and sowthistle, Sonchus oleraceus) hosted intermediate densities of T. tabaci. The

presence of high densities of reproductive T. tabaci on flowering and vegetative parts of turnip weed suggests that this

species is a primary host of T. tabaci in the study area.

Milne, M. and G. H. Walter (1998). "Significance of mite prey in the diet of the onion thrips Thrips tabaci Lindeman (Thysanoptera

: Thripidae)." Australian Journal of Entomology 37: 120-124.

Second-instar larvae of the phytophagous thrips, Thrips tabaci, consumed significantly more spider mite (Tetranychus

urticae Koch) eggs than did any other T. tabaci life stage. We supplemented two plant diets with mite eggs to assess

whether the inclusion of prey could make up completely for dietary deficiencies in the host plant. Therefore, turnip

weed (Rapistrum rugosum L.) floral tissue (a major breeding host of T. tabaci) and cotton vegetative tissue (a host on

which T. tabaci populations dwindle) were compared. In both cases, prey in the diet reduced the developmental time

from egg to adult and increased fecundity over that achieved on a host-plant diet alone, but had no effect on immature

mortality or adult life span. Females on turnip weed plus mite eggs produced more eggs than those on cotton

cotyledons plus mite eggs. We discuss the role of facultative predation (or opportunism) in the ecology of T. tabaci.

Schade, M. and C. Sengonca (1998). "On the development, feeding activity and prey preference of Hippodamia convergens

Guer.-Men. (Col., Coccinellidae) preying on Thrips tabaci Lind. (Thys., Thripidae) and two species of Aphidae." Anzeiger Fur

Schadlingskunde Pflanzenschutz Umweltschutz 71(4): 77-80.

Thrips tabaci Lind. is very difficult to control and thus one of the most important pests of leek in Europe. As an

alternative to insecticides biological control may be carried out by making use of beneficial insects, the Coccinellidae

being one of the most important predatory families. In the present study laboratory trials were carried out with

Hippodamia convergens Guer.-Men, one of the polyphagous representatives of the lady birds, to figure out the feeding

activity, development and prey preference of H. convergens against the onion thrips in comparison with two aphid

species. H. convergens developed fully when fed exclusively T. tabaci larvae, although mortality was considerably higher

and development took much longer. When fed thrips the complete development lasted 29,8 days on an average, the

mortality reaching 88%. When offered Acyrthosiphon pisum (Harris) H. convergens took only 24 days for development

with a mortality of only 16%. Above all, the fourth larval instar and the pupa suffered from a very high mortality,

reaching 45 and 50% respectively. With A. pisum as a prey mortality decreased to only 6%. The duration of the pupal

development was not affected by the prey species. The feeding activity of H. convergens increased significantly during

the development. The larvae of the second and fourth instar predated 28 and 170 thrips larvae respectively per day as a

maximum. The adults achieved the highest feeding activity, predating more than 300 thrips larvae in 24 hours. When

adding up the number of prey individuals per day for each developmental instar, the L-2 larvae predated more than 90

and the L-4 larvae more than 1000 thrips larvae. When offered thrips larvae and Myzus persicae (Sulz.) simultaneously,

there was an increasing prey preference during the development of H, convergens from first larval instar to adult. As to

the last instars there was 20-25% less predation of thrips larvae compared to the aphids during 24 hours.

Shelton, A. M., W. T. Wilsey and M. A. Schmaedick (1998). "Management of onion thrips (Thysanoptera : Thripidae) on cabbage

by using plant resistance and insecticides." Journal of Economic Entomology 91(1): 329-333.



91

Control of Thrips tabaci Lindeman was evaluated using insecticides and host plant resistance. In 7 insecticide trials

conducted from 1987 to 1996, using a total of 17 different insecticides, insecticide applications reduced thrips damage

in only 2 of the trials. In 8 plant resistance trials conducted from 1985 to 1993 using >300 varieties or inbreds, some

plant lines significantly reduced thrips injury in each trial. A 1996 trial testing variety and insecticide together found that

both factors significantly affected thrips damage, although their inter-action was not significant. Insecticide treatments

in the 1996 experiment were unnecessary for the more tolerant varieties but helped reduce damage to acceptable

levels in many of the moderately susceptible cultivars. In the highly susceptible varieties, we concluded that even the

frequent application of insecticides was not sufficient to keep thrips damage at acceptable levels. Planting tolerant

varieties, however, is a reliable way to keep thrips damage at low levels, even without insecticides.

Theunissen, J. and G. Schelling (1998). "Infestation of leek by Thrips tabaci as related to spatial and temporal patterns of

undersowing." Biocontrol 43(1): 107-119.

Full field undersowing of leeks with clovers suppresses populations of adult and larval Thrips tabaci. To explore the

conditions for application of this approach of IPM in commercial practice, variations in the spatial and temporal pattern

of clover undersowing were studied. Effects on thrips populations, crop growth and the development of thrips feeding

symptoms were recorded. Assessment of the yield in quantity and quality was made. Sowing clover (Trifolium

fragiferum) between rows resulted in significant and sufficient thrips population suppression and good yields. Similar

results were achieved by full field sowing of clover simultaneous with leek crop planting. Reduced thrips feeding

symptoms were found in intercropped leeks.

Drescher, K., M. Schade and C. Sengonca (1997). Field study examining the efficacy of two beneficials to control Thrips tabaci

Lindeman (Thys, Thripidae) in the production of leek. Mitteilungen Der Deutschen Gesellschaft Fur Allgemeine Und Agewandte

Entomologie, Band 11, Heft 1-6, Dezember 1997: Entomologists Conference. K. H. Hoffmann and W. Volkl. 11: 381-384.

In this field study the efficacy of two beneficial organisms, a predatory mite and a lacewing, against the vegetable pest

Thrips tabaci LINDEMAN (Thys., Thripidae) in the production of leek was examined. As a supportive measurement

preventive insect netting was used for covering the plants. The predatory mite Amblyseius cucumeris OUDEMANS

(Acari, Phytoseiidae) and the lacewing Chrysoperla carnea STEPHENS (Neur., Chrysopidae) were released at two dates at

a density of 30 individuals in a wheat bran mixture and 6 eggs manually applied per plant respectively. The population

dynamics of the pest as well. as the beneficials were monitored by extraction of whole plants from the field and the

examination of their leaves in the laboratory determining the number of thrips and beneficials found per plant on a

weekly basis. The combination of the: release of the beneficials and the supportive measurement of the plant covered

by insect netting showed that there is a difference in the efficacy between the predatory mite and the lacewing. While

during the whole experiment A. cucumeris was able to keep the thrips population below the level of the pesticide-

treated area and the area solely covered with the netting both of which being used as control areas, the treatment with

C. carnea was only able to decrease the number of thrips until the end of July.

Ester, A., R. deVogel and E. Bouma (1997). "Controlling Thrips tabaci (Lind.) in leek by film-coating seeds with insecticides." Crop

Protection 16(7): 673-677.

From 1993 to 1995 the effectiveness of various insecticides applied as a seed-coating to control Thrips tabaci in winter

leeks (Allium porrum L.) was investigated in the field. Seed-coatings with fipronil and imidacloprid gave a good control,

but carbofuran, diflubenzuron, methiocarb, teflubenzuron and vamidothion were not effective. The most effective

insecticide, fipronil, did not cause phytotoxicity, whereas imidacloprid reduced and slowed germination. (C) 1997

Elsevier Science Ltd.

Theunissen, J. and G. Schelling (1997). "Damage threshold for Thrips tabaci (Thysanoptera: Thripidae) in monocropped and

intercropped leek." European Journal of Entomology 94(2): 253-261.

Based on field data collected during three consecutive years, in experiments with leek and leek intercropped with

subterranean clover (Trifolium subterraneum), the relationship between larval populations of Thrips tabaci on leeks, the

level of injury and the market quality of the product were described. This resulted in a way to monitor both thrips

populations and market quality during the growing season by the feeding symptoms and in damage thresholds in

monocropped and intercropped leeks. It was found that a given number of thrips larvae per plant caused less injury on



92

intercropped leek plants than on monocropped leeks. This proved to have consequences for the damage thresholds in

both growing systems. The total effect of intercropping in leeks is based on thrips population suppression and a

reduced development of feeding symptoms.

Weber, A., M. Hommes and S. Vidal (1997). Influence of different mulches in leek (Allium porrum L) on the population densities

of the onion thrips (Thrips tabaci Lind). Mitteilungen Der Deutschen Gesellschaft Fur Allgemeine Und Agewandte Entomologie,

Band 11, Heft 1-6, Dezember 1997: Entomologists Conference. K. H. Hoffmann and W. Volkl. 11: 271-275.

Thrips tabaci LINDEMAN (Thysanoptera: Thripidae) is the most important pest in leek (Allium porrum) in Germany.

Undersowings of Trifolium subterraneum, Trifolium fragiferum and straw mulches were used to test the effects of these

living and dead mulches on the population dynamics of T. tabaci. Both clover undersowings significantly reduced the

mean number of onion thrips on leek whereas straw mulch was not suitable to decrease the population densities of this

pest species. We found no evidence for the enemies hypothesis because predators were nearly almost absent on leek.

Basal diameter of the leek plants was regressed against mean numbers of thrips to check if plant heights correlated

with thrips infestations. Although these correlations fitted to the data in most cases, the different slopes of the

regressions in controls and living mulches suggest that plant growth parameters are not the only important predictors

for thrips numbers in undersown leek. We suggest that host plant quality and host plant finding might be the crucial

factors for the thrips populations dynamics in intercropped leek as well. Further experiments will evaluate if the

interference between leek plants and the undersowings alters the plant quality and subsequent the host choice of the

onion thrips.

Goncalves, P. A. D. (1996). "Evaluation of insecticides doses against onion thrips, Thrips tabaci Lind." Pesquisa Agropecuaria

Brasileira 31(4): 233-236.

The objective of this work was to evaluate insecticides against onion thrips, Thrips tabaci. The treatments used were:

deltamethrin + triazophos (CE) 3.0 + 105.0 g a.i./ha, 4.5 + 157.5 g a.i./ha, and 6.0 + 210.0 g a.i./ha; cypermethrin (CE)

120.0 g a.i./ha, 150.0 g a.i./ha and 50.0 g a.i./ha; lambdacyhalothrin (WP) 15.0 g a.i./ha; alternated spraying of

lambdacyhalothrin (CE) 15.0 g a.i./ha and pirimiphos-methyl (CE) 120.0 g a.i./ha; lambdacyhalothrin (CE) 15.0 g a.i./ha;

pirimiphos-methyl (CE) 120.0 g a.i./ha; deltamethrin (CE) 7.5 g a.i./ha; check. The treatments lambdacyhalothrin (all

doses) and cypermethrin were effective against onion thrips, but only cypermethrin 150.0 g a.i./ha were superior in

yield. The yield didn't differ among the majority of the treatments with insecticide and the untreated check, probably

due to the late beginning and the relatively reduced number of sprayings.

Goncalves, P. A. D. (1996). "Determination of damage of Thrips tabaci Lind. In onion cultivars." Pesquisa Agropecuaria Brasileira

31(3): 173-179.

This work determines the damage of Thrips tabaci Lind. in onion cultivars at differents dates of transplanting. The work

was carried out in the Estacao Experimental de Ituporanga, Santa Catarina State, during 1986, 1987 and 1988. Three

experiments were conducted with cultivars and respectives times transplanting, as follow: 1) ''Baia Periforme'' (1986,

1987), ''EMPASC 352 Bola Precoce'' (1988) - transplanting in July; 2) ''EMPASC 351 Selecao crioula'' - transplanting in

August; and 3) ''Norte 14'' transplanting in September. The treatments were: application intervals each 7, 14 and 21

days; check free of onion thrips; and check untreated. The spray of insecticides decreased thrips populations, but it did

not increase yield. The reductions in yield due to thrips infestation were higher in plants transplanted late in the season

(September). Early planted cultivars ''escaped'' from high thrips populations, and consequently the yield losses were

lower. The chemical control of T. tabaci is one more practice to be considered in crop management.

Dejager, K. M., R. P. T. Butot and A. Guldemond (1995). Genetic variation in chrysanthemum for resistance to western flower

thrips and Thrips tabaci. Thrips Biology and Management. B. L. Parker, M. Skinner and T. Lewis. 276: 403-406.

Fournier, F., G. Boivin and R. K. Stewart (1995). "EFFECT OF THRIPS-TABACI (THYSANOPTERA, THRIPIDAE) OIL YELLOW ONION

YIELDS AND ECONOMIC THRESHOLDS FOR ITS MANAGEMENT." Journal of Economic Entomology 88(5): 1401-1407.

The proper management of onion thrips, Thrips tabaci Lindeman, on yellow onions requires the determination of their

effect on yields and the establishment of an economic threshold. In field plot experiments, we observed no difference

in onion thrips population densities among 6 yellow onion cultivars during 1988 and 1989. Onion thrips infestations



93

resulted in onion yield losses of 43 and 34.5% with maximum seasonal averages of 149.2 and 172.0 thrips per plant in

untreated plots in 1988 and 1989, respectively. No effect on onion yields was observed in 1990 when seasonal thrips

densities did not exceed 35.2 thrips per plant. The effect of thrips on onion yields was best described by nonlinear

models and by the use of the cumulative number of thrips-days per plant as a measure of thrips pressure. Plants were

relatively insensitive to thrips feeding early and late in phenological development. Important differences in the onion

plant response to thrips damage were observed between 1988 and 1989. These differences were likely linked with the

duration and intensity of the water deficit recorded during both seasons. Economic thresholds of 2.2 and 0.9 thrips per

leaf were estimated during the summers of 1988 and 1989, respectively. These thresholds can be used for onions sold

at harvest or stored because costs associated with storage are compensated for by a higher return price. The use of the

0.9 thrips per leaf economic threshold in 1990 would have resulted in unnecessary treatments, making this threshold

suitable for severe drought situations only.

Fournier, F., G. Boivin and R. K. Stewart (1995). Impact and economic threshold of Thrips tabaci on onions. Thrips Biology and

Management. B. L. Parker, M. Skinner and T. Lewis. 276: 71-76.

Fournier, F., G. Boivin and R. K. Stewart (1995). Sequential sampling for Thrips tabaci on onions. Thrips Biology and Management.

B. L. Parker, M. Skinner and T. Lewis. 276: 557-562.

Hildenhagen, R., E. Richter, M. Hommes, A. Deut Gesell and E. Angewandte (1995). "Occurrence and integrated control of Thrips

tabaci in leek and onion." Mitteilungen Der Deutschen Gesellschaft Fur Allgemeine Und Angewandte Entomologie, Band 10, Heft

1-6, Dezember 1995: Vortrage Der Entomologentagun in Gottingen, Vom 27. Marz - 1. April 1995 10(1-6): 183-187.

Hoffmann, M. P., C. H. Petzoldt, C. R. Macneil, J. J. Mishanec, M. S. Orfanedes and D. H. Young (1995). "EVALUATION OF AN

ONION THRIPS PEST-MANAGEMENT PROGRAM FOR ONIONS IN NEW-YORK." Agriculture Ecosystems & Environment 55(1): 51-

60.

An integrated pest management (IPM) program which includes sampling plans and treatment thresholds for onion

thrips has been developed for use in New York State. In 1986, a service-oriented IPM scouting program was conducted

for onion growers in several areas of New York. Growers were informed of pest infestation levels, but used their own

judgment as to whether or not to apply an insecticide. In 1993, on-farm demonstrations of the IPM program consisted

of pairs of onion fields, one managed using the IPM program and the other using grower practices, Pest densities and

pesticide inputs were obtained for all fields. In 1993, yield and quality at harvest were also quantified. Results from both

years were evaluated to determine compliance by onion growers to the recommended IPM protocols and their impact

on pest control practices. Results confirmed that the use of the IPM program significantly reduced insecticide inputs

without adversely affecting onion yield or quality. The number of insecticide applications and amount of formulated

insecticide per hectare were significantly less in IPM than in conventional fields. In addition, insecticide costs and

environmental impact were reduced significantly in the IPM fields. An economic comparison of IPM vs. conventional

fields showed that IPM resulted in a small savings after subtracting the cost of scouting, These demonstrations have

shown that there are ecological and economic savings when using IPM. Grower interest in adopting onion IPM

strategies should increase as a result of these demonstrations.

Kumar, N. K. K., D. E. Ullman and J. J. Cho (1995). "FRANKLINIELLA-OCCIDENTALIS (THYSANOPTERA, THRIPIDAE) LANDING AND

RESISTANCE TO TOMATO SPOTTED WILT TOSPOVIRUS AMONG LYCOPERSICON ACCESSIONS WITH ADDITIONAL COMMENTS

ON THRIPS TABACI (THYSANOPTERA, THRIPIDAE) AND TRIALEURODES-VAPORARIORUM (HOMOPTERA, ALEYRODIDAE)."

Environmental Entomology 24(3): 513-520.

Thirteen Lycopersicon accessions were compared for landing of the western flower thrips, Frankliniella occidentalis

(Pergande), on leaves and flowers and resistance to tomato spotted wilt tospovirus (TSWV) in field experiments on the

Hawaiian island of Maul. Occurrence of the onion thrips, Thrips tabaci Lindeman, and the greenhouse whitefly

Trialeurodes vaporariorum (Westwood), on leaves was also recorded. Adult western flower thrips occurred on all

Lycopersicon accessions, and no significant difference was found among accessions in western flower thrips landing per

leaf. Significant differences were found among accessions with regard to number of western flower thrips occurring per

flower and incidence of TSWV. Landing of onion thrips and greenhouse whitefly on leaves varied significantly among



94

accessions. Lycopersicon esculentum Mill.'Anahu' was the only accession infected with TSWV at the foliar stage. L.

esculentum 'Pearl Harbor', L. parviflorum (Jusl.) Mill., and L. hirsutum Humb. and Bonpl. were infected after flowering,

and TSWV infection was not observed in L. peruvianum (L.) Mill., L. hirsutum f. glabratum C. H. Mull., L. chmielewskii

Rick et al., L. pennellii, L. pimpinellifolium (Jusl.), and L. chilense Dun. even after 7 mo in the field, suggesting field

resistance in these accessions. Among L. esculentum cultivars,'Rey de los Tempranos' was the only accession that did

not become infected with TSWV. Because thrips landing did not correlate with TSWV infection in our experiment, we

suggest that TSWV susceptibility and thrips feeding after landing are likely more important in influencing virus

incidence under field conditions than landing behavior or direct resistance to insect colonization.

Schade, M., C. Sengonca, A. Deut Gesell and E. Angewandte (1995). Field study on the influence of the release of two predators

on the abundance of Thrips tabaci Lindner (Thysanoptera, Thripidae) on single leek plant-cages. Mitteilungen Der Deutschen

Gesellschaft Fur Allgemeine Und Angewandte Entomologie, Band 10, Heft 1-6, Dezember 1995: Vortrage Der

Entomologentagun in Gottingen, Vom 27. Marz - 1. April 1995. 10: 199-202.

Trjapitzin, S. V. (1995). Biological control of Thrips tabaci on tobacco seedlings in Ukraine. Thrips Biology and Management. B. L.

Parker, M. Skinner and T. Lewis. 276: 237-237.

Vanrijn, P. C. J., C. Mollema and G. M. Steenhuisbroers (1995). "COMPARATIVE LIFE-HISTORY STUDIES OF FRANKLINIELLA-

OCCIDENTALIS AND THRIPS TABACI (THYSANOPTERA, THRIPIDAE) ON CUCUMBER." Bulletin of Entomological Research 85(2):

285-297.

Shortly after its invasion into Europe, the western flower thrips, Frankliniella occidentalis (Pergande), became a more

severe pest of greenhouse crops than the onion thrips, Thrips tabaci Lindeman. To test whether this differential pest

status was due to a larger capacity of population increase, a comparative life history study was carried out on cucumber

(Cucumis sativus cv. Corona). Experiments at 25 degrees C showed that the egg-to-egg period of F. occidentalis was

shorter, but its peak ovipositional rate was lower and its offspring sex ratio more male biased. These differences

resulted in a slightly lower intrinsic rate of population increase (r(m)) for F. occidentalis than for T. tabaci (0.166 vs.

0.176/day). It was shown experimentally that between 15 and 28 degrees C, developmental rate of F. occidentalis is

linearly related to temperature, with a theoretical threshold temperature similar to the value reported for T. tabaci (10.9

vs. 11.5 degrees C). It is argued that the r(m)-value of F. occidentalis will not be higher than that of T. tabaci for any

temperature within this range. Alternative explanations for the difference in pest status between the two thrips species

are discussed.

Fournier, F., G. Bolvin and R. K. Stewart (1994). "COMPARISON OF BINOMIAL AND IWAO TYPE SEQUENTIAL SAMPLING PLANS

FOR MONITORING ONION THRIPS (THRIPS TABACI) THYSANOPTERA, THRIPIDAE IN ONIONS." Phytoprotection 75(2): 69-78.

Transient differences in onion thrips (Thrips tabaci) densities were observed between the margins and the centre of

some onion (Allium cepa) fields. Onion thrips populations consist in aggregates contagiously dispersed within onion

fields. Two types of sequential sampling plans were established for T. tabaci in onions: a binomial plan based on the

presence of 5 thrips plant(-1), and one of the Iwao type, requiring counts of all thrips present. Acceptation boundaries

for these plans were calculated for economic thresholds of 0.9 and 2.2 thrips leaf(-1). Plans were validated in fields with

thrips populations varying between 0.01 and 32.33 thrips leaf(-1). Binomial sequential sampling plans were found to be

as reliable as plans requiring counts of all thrips, with an error rate not exceeding 4%, a level below the theoretical error

rates of 5 and 10% used in the calculations. Correct decisions were reached in 90.4 and 83.6% of the situations with

plans requiring counts of all thrips, and in 84.8 and 82.4% of the situations with binomial plans for economic thresholds

of 0.9 and 2.2 thrips leaf(-1), respectively. The average number of samples needed to reach a decision varied between

10 and 14 plants according to the plan used. Use of binomial plans can save up to 62 and 88% of the counting effort

for thresholds of 0.9 and 2.2 thrips leaf(-1), respectively.

Grahn, B. and H. Schmutterer (1994). THE INFLUENCE OF AN AQUEOUS NEEM SEED KERNEL EXTRACT (NSKE) ON THE

POPULATION DENSITY OF THRIPS-TABACI IN EGYPT.



95

Talpur, M. A., T. Hussain, M. A. Rustamani, H. B. Baloch and M. M. Lakho (1994). "Relative toxicity of different insecticides to

yellow thrips, Thrips tabaci Lind and jassid, Amrasca devastans Dist." Proceedings of Pakistan Congress of Zoology, Vol 14, 1994

14: 83-87.

Ali, A., M. A. Bahtti and K. J. Ahmad (1993). "ROLE OF WEATHER IN FLUCTUATING THE POPULATION OF AMRASCA-DEVASTANS

(DIST) AND THRIPS-TABACI (LIND)." Proceedings of Pakistan Congress of Zoology, Vol 13, 1993 13: 133-139.

Baloch, H. B., M. A. Rustamani, T. Hussain, M. M. Khan, M. A. Talpur and N. A. Alizai (1993). "EFFICACY OF DIFFERENT

INSECTICIDES IN CONTROLLING THRIPS-TABACI LIND ON GARLIC." Proceedings of Pakistan Congress of Zoology, Vol 13, 1993

13: 529-533.

Bocak, L. (1993). "EVALUATION OF INSECTICIDES AGAINST THRIPS TABACI ON ONION." Annals of Applied Biology 122: 22-23.

Doederlein, T. A. and R. W. Sites (1993). "HOST-PLANT PREFERENCES OF FRANKLINIELLA-OCCIDENTALIS AND THRIPS-TABACI

(THYSANOPTERA, THRIPIDAE) FOR ONIONS AND ASSOCIATED WEEDS ON THE SOUTHERN HIGH-PLAINS." Journal of Economic

Entomology 86(6): 1706-1713.

Thrips species composition and host preference for onions and eight common weed species were determined in onion

fields on the Southern High Plains in Texas. Eleven thrips species were collected, and Frankliniella occidentalis

(Pergande) was the most abundant in both 1989 (57.1%) and 1990 (99.5%). Thrips tabaci Lindeman was abundant

(40.4%) in 1989; however, only two specimens were collected in 1990. T. tabaci exhibited a strong preference for Allium

cepa L. F. occidentalis did not exhibit a preference for A. cepa but rather, in 1989, exhibited preference for Salvia sp.,

Amaranthus palmeri Wats, and Kochia scoparia (L.) Schard., in descending order of preference, and in 1990 exhibited a

preference for K. scoparia in only one field. Immature thrips occurred predominantly on A. cepa in 1989 and on the

weed species in 1990. These associations indicate that the immatures collected in 1989 were probably T. tabaci,

whereas those collected in 1990 were probably F. occidentalis because they followed similar patterns of association as

the respective adults. In addition, a modified aromatic Berlese funnel for rapid plant sampling and thrips extraction in

the field is described. Percentage extraction efficiency was dependent on plant species and ranged from 81 to 98.3 for

adult thrips and 72.2 to 100 for immatures.

Lemmetty, A. and I. Lindqvist (1993). "THRIPS-TABACI (LIND) (THYSANOPTERA, THRIPIDAE), ANOTHER VECTOR FOR TOMATO

SPOTTED WILT VIRUS IN FINLAND." Agricultural Science in Finland 2(2): 189-194.

Populations of Thrips tabaci transmitted the isolate of tomato spotted wilt virus (TSWV) from infected china asters to

healthy china asters in laboratory experiments. Great variation was observed among absorbance values between thrips

infested china asters. The highest absorbance values were obtained from stems of thrips inoculated plants. According

to our results, T. tabaci seems to be a noteworthy TSWV vector in Finland, where it is the only naturally occurring TSWV

vector species. It is also one of the main pests on greenhouse crops in addition to Frankliniella occidentalis, the primary

vector of TSWV.

McKenzie, C. L., B. Cartwright, M. E. Miller and J. V. Edelson (1993). "INJURY TO ONIONS BY THRIPS-TABACI (THYSANOPTERA,

THRIPIDAE) AND ITS ROLE IN THE DEVELOPMENT OF PURPLE BLOTCH." Environmental Entomology 22(6): 1266-1277.

Greenhouse studies were conducted to determine the role of Thrips tabaci Lindeman injury to onion, Allium cepa L., in

the invasion of the fungal pathogen Alternaria porri (Ellis) and the subsequent development of the disease purple

blotch. Individually caged onions were infested with 25 thrips per plant and inoculated 20 d later with A. porri (1,000

spores per ml of H2O). Onions were rated 6 and 7 d after inoculation. Plants infested with thrips and inoculated with A.

porri developed more and larger lesions that coalesced as the plant matured. Older leaves were more susceptible to A.

porri infection in the absence of thrips injury. Purple blotch infection shifted to younger leaves as a result of thrips

injury to onion, and more tissue was killed by thrips in the presence of purple blotch. Plant growth was negatively

correlated with thrips feeding injury. Scanning electron microscopy was used to determine morphological changes in

leaf tissue resulting from thrips feeding injury and the development of purple blotch. In the absence of thrips injury, A.

porri enters onion leaf tissue through stomates and directly through the epidermal cell layer. When both thrips injury

and purple blotch are present, leaf tissue is extremely necrotic and A. porri appears to use areas of insect damage as



96

alternative penetration sites. Thus, the feeding wounds caused by thrips enhance entry and development of the disease

by providing alternative penetration sites for A. porri.

Sdoodee, R. and D. S. Teakle (1993). "STUDIES ON THE MECHANISM OF TRANSMISSION OF POLLEN-ASSOCIATED TOBACCO

STREAK ILARVIRUS VIRUS BY THRIPS-TABACI." Plant Pathology 42(1): 88-92.

Mixed instars of Thrips tabaci were allowed to feed on test seedlings of cucumber, the thrips were removed and

wounds caused by thrips feeding dusted with tobacco streak virus (TSV) carried in tomato pollen. Transmission of TSV

occurred in three out of the four experiments conducted. When Chenopodium amaranticolor test seedlings were

dusted with infective tomato pollen, and thrips introduced for varying periods before being killed with insecticide, TSV

transmission occurred after exposure to thrips for 1 h, 5 h, 1 day or 2 days, but not 5 min. Pollen-washing experiments

indicated that TSV was carried both internally and externally in pollen of tomato and several weed hosts. T. tabaci was

able to transmit TSV from pollen of Nicotiana clevelandii and Nicandra physalodes, and TSV from tomato pollen was

transmitted to several weed species. It is concluded that T. tabaci transmits TSV associated with tomato pollen by a

mechanical mechanism whereby virus carried externally, or released from inside the pollen, infects feeding wounds.

Theunissen, J., G. Schelling and G. Universiteit (1993). SUPPRESSION OF THRIPS-TABACI POPULATIONS IN INTERCROPPED LEEK.

Mededelingen Van De Faculteit Van De Landbouwwetenschappen, Vol 58, Pts 2a, 2b, 3a, 3b, 1993. 45: 383-390.

Brodsgaard, H. F. and L. S. Hansen (1992). "EFFECT OF AMBLYSEIUS-CUCUMERIS AND AMBLYSEIUS-BARKERI AS BIOLOGICAL-

CONTROL AGENTS OF THRIPS-TABACI ON GLASSHOUSE CUCUMBERS." Biocontrol Science and Technology 2(3): 215-223.

Biological control of Thrips tabaci by the phytoseiid mites Amblyseius cucumeris and Amblyseius barkeri was

investigated on glasshouse parthenocarpic cucumbers. The mite species were used in combination and singly.

Successful thrips control was obtained with A. cucumeris alone, whereas control was not reliable with A. barkeri alone

nor with the combination of A. cucumeris and A. barkeri. The establishment period was long for both phytoseiid

species. At the beginning of the trial, when thrips were absent or very low in numbers, only A. cucumeris was found on

the leaves. Mite populations did not increase until the number of thrips were ca. two and five per leaf for A. cucumeris

and A. barkeri, respectively. A. cucumeris seemed to show a better numerical response to T. tabaci than A. barkeri. At

the end of the trial (three months after the last introduction of mites) only A. barkeri was found in the combination plot,

indicating that A. cucumeris is displaced by A. barkeri in situations of interspecific competition between the two species

on glasshouse parthenocarpic cucumbers.

Hardy, V. G. and D. S. Teakle (1992). "TRANSMISSION OF SOWBANE MOSAIC-VIRUS BY THRIPS-TABACI IN THE PRESENCE AND

ABSENCE OF VIRUS-CARRYING POLLEN." Annals of Applied Biology 121(2): 315-320.

When pollen of sowbane mosaic sobemovirus (SoMV)-infected Chenopodium amaranticolor was dusted onto C.

amaranticolor and C. quinoa test seedlings which were then infested with 5-10 adult Thrips tabaci, SoMV was

transmitted to 25% C. amaranticolor and 88% of C. quinoa plants. Five hours access of T. tabaci to pollen-contaminated

C. quinoa seedlings was sufficient for SoMV transmission, but 1 h was not. SoMV was also transmitted when T. tabaci

was mixed with pollen of C. amaranticolor and then placed on C. quinoa test seedlings. Further, plant-to-plant

transmission of SoMV occurred in the absence of virus-carrying pollen when T. tabaci was caged on infected non-

flowering C. amaranticolor or C. quinoa for 1-8 days and then adults transferred to C. quinoa test seedlings. This is the

first time that thrips have been shown to be a vector of SoMV, and that a virus outside the ilarvirus group is reported to

be transmitted using pollen and thrips.

Sites, R. W., W. S. Chambers and B. J. Nichols (1992). "DIEL PERIODICITY OF THRIPS (THYSANOPTERA, THRIPIDAE) DISPERSION

AND THE OCCURRENCE OF FRANKLINIELLA-WILLIAMSI ON ONIONS." Journal of Economic Entomology 85(1): 100-105.

Diel periodicity of the intraplant dispersion of thrips on onions, Allium cepa L., was determined by taking 10-plant

samples at hourly intervals on each of four dates from late May to late June 1988, and recording the kinds and numbers

of thrips in four onion growth zones (bulb, or portion below ground; neck from soil surface to the point of leaf

divergence [i.e., distal end of sheath]; basal half of leaves above the neck; and the remaining apical half of leaves).

Thrips tabaci Lindeman was significantly most abundant on the basal half of leaves from late May to mid-June. In late

June, T. tabaci was significantly most abundant on both apical and basal halves of leaves, and density declined almost



97

5-fold during early afternoon hours, indicating flight activity was taking place. Frankliniella occidentalis (Pergande) was

associated mostly with basal half of leaves in late May. In early June, it exhibited a nocturnal pattern of random

dispersion, followed by an afternoon aggregation on the apical half of leaves, and subsequent evening return to

random dispersion. Although it is not known as an onion pest, Frankliniella williamsi Hood was found consistently

throughout the study at a density of almost-equal-to 1.2 thrips per plant. Numbers of immature thrips of each species

were pooled because of difficulty with identifications. In late May and early June, immatures were most abundant in the

neck; whereas, in mid- and late June, significance was exhibited for the basal half of leaves.

Srivastava, P. K., B. S. Bhardwaj and R. P. Gupta (1992). "CHEMICAL CONTROL OF ONION THRIP (THRIPS-TABACI)." Indian Journal

of Agricultural Sciences 62(5): 358-359.

Gupta, R. P., B. S. Bhardwaj and U. B. Pandey (1991). "EFFICACY OF SOME INSECTICIDES AGAINST ONION THRIPS (THRIPS-

TABACI)." Indian Journal of Agricultural Sciences 61(5): 353-355.

Hoy, C. W. and C. S. Glenister (1991). "RELEASING AMBLYSEIUS-SPP ACARINA, PHYTOSEIIDAE TO CONTROL THRIPS-TABACI

THYSANOPTERA, THRIPIDAE ON CABBAGE." Entomophaga 36(4): 561-573.

Two species of predaceous mites, Amblyseius barkeri (Hughes) [= A. mckenziei Schuster & Pritchard] and A. cucumeris

(Oudemans) [Acarina: Phytoseiidae] were evaluated as potential biological control agents for Thrips tabaci Lindeman

[Thysanoptera: Thripidae] on cabbage. A. barkeri colonized cabbage heads in preliminary trials. Field releases of

different numbers of mites per plant during 1987 showed that A. barkeri reduced the number of thrips in cabbage

heads at harvest, and the reduction was proportional to the number of mites released, but thrips damage was

unaffected. Releasing A. cucumeris at different times during 1988, but releasing the same number of mites each time,

we found that earlier releases resulted in fewer thrips and less damage at harvest; these relationships were not present,

however, in plots treated with pyrethroid insecticides. We conclude that inoculative release of Amblyseius spp. is a

potentially useful thrips management strategy, but improvements in release timing and strategy will be required to

provide commercially acceptable control.

Theunissen, J. and H. Legutowska (1991). "THRIPS-TABACI LINDEMAN (THYSANOPTERA, THRIPIDAE) IN LEEK - WITHIN-PLANT

DISTRIBUTION." Journal of Applied Entomology-Zeitschrift Fur Angewandte Entomologie 112(3): 309-316.

Both larvae and adults of the onion thrips (Thrips tabaci Lindeman) showed a preference for particular parts of leek

(Allium porrum L.) plants. In the vertical plane most thrips were located in the transition zone where the leaves in the

shaft were still white but gradually changed through yellow to pale green. At high population densities mixed groups of

adults and larvae could be found along the entire leaf. In the horizontal plane larvae and adults showed a normal

distribution pattern preferring certain leaves. Chemical treatments did not influence the within-plant distribution

pattern of larvae and adult thrips in the horizontal plane when compared to distribution patterns in untreated plants.

Reinfestation of treated plants by immigrating adults took place swiftly and developed into the characteristic pattern

within a few days.

Theunissen, J. and H. Legutowska (1991). "THRIPS-TABACI LINDEMAN (THYSANOPTERA, THRIPIDAE) IN LEEK - SYMPTOMS,

DISTRIBUTION AND POPULATION ESTIMATES." Journal of Applied Entomology-Zeitschrift Fur Angewandte Entomologie 112(2):

163-170.

The onion thrips, Thrips tabaci Lindeman is a major pest of leek (Allium porrum L.) in Europe. To develop supervised

control methods for pests and diseases in vegetable crops such as leek more information is needed on the within-field

distribution and population levels of pests. For the onion thrips various methods of assessing population levels in leek

have been tested and compared during one cropping season. The distribution of larvae in the field is more clustered

than that of the adults. The effects of control treatments using parathion and cypermethrin are reflected in the

population levels as estimated by dissection of individual plants. The variability of thrips populations per plant causes

problems with regard to the attainable accuracy of the population estimates.

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