Abstracts of papers presented at the 14th conference of the Weed Science Society of Israel Abstracts...

MEETINGS

ABSTRACTS OF PAPERS PRESENTED AT

THE 14TH CONFERENCE OF THE WEED SCIENCE SOCIETY OF I S R A E L

March 13, 1996 ARO, The Volcani Center, Bet Dagan, Israel

A: HERBICIDES: NOVEL PRODUCTS, FORMULATIONS OR COMBINATIONS AND THEIR USE FOR WEED CONTROL IN VEGETABLES, FIELD CROPS AND ORNAMENTALS

Sulfentrazone - A New Herbicide

E. Yogev, M. Berson and Y. Benyamini Luxembourg Chemicals and Agriculture Ltd., Tel Aviv 61000, Israel [Fax: +972-3-5100474]

Sulfentrazone (F-6285) is a new herbicide, manufactured by FMC, U.S.A. The product is an aryl triazolinone, applied to existing weeds as well as pre-emergence. Sulfentrazone is formulated as 75% w/w water-dispersible granules. It is not volatile, is moderately mobile in the soil, and not sensitive to UV light. It appears to be relatively persistent in the soil; it is decomposed mainly by microbial degradation. Sulfentrazone controls weeds by the same mechanism as the diphenyl ethers, in which membrane disruption is initiated by the inhibition of protoporphyrinogen oxidase in the chlorophyll biosynthetic pathway, which leads to the subsequent buildup of toxic intermediates. Plants emerging from soils treated with sulfentrazone absorb the product through the root system, the weeds turn necrotic and die shortly after exposure to light. When the product is sprayed on existing weeds (foliar application), it is absorbed by the leaves but the movement in the phloem is limited because of rapid foliar desiccation.

Sulfentrazone is designed by the manufacturer for the control of weeds in soybeans. In Israel, the product is being tested in various field crops, in orchards and in turf. In field trials it was found to be safe to chickpeas, in pre-emergent application at the rate of 430 g a.i./ha. At this rate, the product prevented emergence of Solanum nigrum, Amaranthus retroflexus, A. blitoides, Polygonum equisetiforme and Cyperus rotundus for the entire chickpea season, without the necessity of manual weeding. At 960 g a.i./ha in preplant application, sulfentrazone was safe to cauliflower and cabbage, and at 1920 g a.i./ha it was safe to citrus seedlings. The product was effective in controlling and preventing emergence of Malva nicaeensis, Senecio vernalis, Urtica urens, Conyza spp. and other winter broadleaved weeds. Winter cereals, including Lolium rigidum, Avena sterihs and wheat, were also controlled by it.

Sulfentrazone was sprayed on commercial turf areas after cuttings of the turf carpets. At the rate of 960 g a.i./ha it prevented emergence of Portulaca oleracea, Amaranthus viridis and C. rotundus for a period of more than 90 days after spraying. Sulfentrazone is also being tested in foliar applications on existing turf, for the control of C. rotundus.

The characteristics of sulfentrazone, including control of existing weeds, preventing emergence of many widespread winter and summer weeds, long-lasting effect, and its safety to various crops, reveal a good potential for its use in the future.

Phytoparasitica 24:3, 1996 199

Oxadiargyl (R.E-0206630) - A Selective Pre- and Early Postemergence Herbicide for Vegetables before Transplantation

Y. Sheinboim, T. Lev-Ran, A. Bahat, Y. Barkai, Y. Gatti, M. Zaidan, O. Barazani and

Y. Boshvize Agrochemicals Dept., Milchan Bros. Ltd., Ramat Can 52117, Israel [Fax: +972-3-7518103]

Raft (400 g/l S.C.) is the trade name of oxadiargyl, a new Rhfne-Poulenc oxadiazol herbicide. Its mode of action and range of activity are quite similar to those of oxadiazon (Ronstar) and oxifluorfen (Goal), which are well known and recommended as standards in Israel. Oxadiargyl is primarily a pre- but also a postemergence weed killer. Its herbicidal action is much more effective and vigorous when applied pre-emergence or at early postemergence, on young and actively growing weeds.

Oxadiargyl, applied at a rate of 0.5-0.8 kg/ha, prevented the emergence of susceptible weeds such as: Malva nicaeensis, Lavatera spp., Urtica urens, Lamium amplexicaule, Amaranthus spp., Portulaca oleracea, Sinapis spp., Solanum nigrum, S. villosum, Phalaris spp., Avena sterilis, Echinochloa spp. and Digitaria sanguinalis for 2-3 months.

Transplanted cabbage, cauliflower, broccoli and tomato in the open field demonstrated very good tolerance to oxadiargyl at a rate of 0.6 kg/ha, when applied prior to transplantation. Watermelon, transplanted into the treated mulched beds, tolerated oxadiargyl at rates up to 1.0 kg/ha. The tested herbicide was applied and activated by rainfall approximately 2 months before transplanting. The treated area was mulched with polyethylene film one month after the herbicide application. A drip irrigation system was placed on the beds, just before mulching.

Oxadiargyl, at rates up to 0.8 kg/ha, was found very selective to garlic, when applied pre- or early postemergence. Sown onion, when treated at the phenological stage of 1�89 leaves, tolerated oxadiargyl at rates up to 0.5 kg/ha without any yield decrease.

The broad spectrum of activity and the good safety margin make Raft a valuable tool to use with the standard practices when applied as a pre- or early postemergence treatment before transplanting vegetables.

Control of Weeds in Tomatoes Grown for Processing in the Golan Heights Region

S. Graph I and U. Luchinsky 2 aExtension Service, Ministry of Agriculture, Zefat 13111 [Fax:+972-6-921021]; and 2Mevo

Hamma, Ramat HaGolan 12480, Israel

The incorporation of pendimethalin at 1750 g/ha, 3 months and 2 weeks, respectively, before transplanting gave good control ofSolanum sp. andAmaranthus sp. However, without incorporation, this treatment was less effective in Solanum sp. control. The tomato plants were not affected by the earlier treatment; the 2-week pre-transplanting treatment caused, however, some growth retardation.

In another trial it was found that oxadiazon at 500 g/ha; oxadiargyl at 500 and 1000 g/ha; oxyfluorfen at 357 g/ha; and pendimethalin at 1750 g/ha were all effective in the control of Solanum sp., whereas dilufenican was not sufficiently effective at 125 g/ha or even 250 g/ha.

None of the herbicides used in this trial caused any symptoms of injury to the tomato plants.

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Control of Annual Weeds in Transplanted Tomatoes

T. Blumenfeld, Y. Kleifeld, G. Herzlinger, H. Bucsbaum, S. Golan, T. Chilf and R. Aly Dept. of Weed Science, ARO, Newe Ya'ar Research Center, Haifa 31900, Israel

[Fax: +972-4-9836936]

During 1994 and 1995 we conducted field experiments testing herbicides for control of annual weeds such as Amaranthus spp., Solarium spp. and Polygonum spp. in transplanted tomatoes.

Preplanting treatments with oxyfluorfen (Goal, 240 g/l, EC) or pendimethalin (Stomp, 500 g/l, EC) on tomato beds, followed by sprinkler irrigation or rain, usually prevented the emergence of annual weeds up to the beginning of the drip irrigation. In early transplanting the lower leaves were damaged by oxyfluorfen, and light to medium damage was observed following pendimethalin treatments, in loess soils, following hand-planting in cold soil. In a similar application method the new herbicides flazasulfuron (Lux-40, 250 g/l, WG) and sulfentrazone (F-6285, 480 g/l, SC) were selective to tomatoes transplanted in loess soil and prevented annual weed infestation at least up to the application of metribuzin (Lexone, 75%, WG).

In a field experiment in the Golan Heights, fomesafen (Flex, 250 g/l, SL) and diflufenican (Quartz, 500 g/l, SC) did not damage tomatoes in preplanting treatments. In organic soil in the Hula Valley, experiments showed that preplanting application of oxadiargyl (Raft, 400 g/l, SC) and oxyfluorfen controlled Polygonum spp., Chenopodium spp. and weeds belonging to the Cruciferae.

Weed Control in Wheat in Northern Kazakhstan

Y. Ohali Agrochemicals Department, Milchan Bros. Ltd., Ramat Gan 52117, Israel [Fax: +972-3-7518103]

The northern regions of Kazakhstan, in terms of geomorphology and climate, are an inherent part of southern Siberia. Temperatures fall to -45~ in winter, and can reach up to +40~ in summer. Freezing conditions exist generally from October until mid-April. In summer, weather conditions are unstable and vary greatly from day to day. For example, summer temperatures may range from 30~176 but may drop, from time to time, to below 10~ Precipitation varies between 200 and 400 mm annually, depending on the region and year, mostly as rainfall in summer, and in small part as snow in winter. Very strong winds prevail in both winter and summer, causing snowdrift from the fields in winter and desiccating the crops in summer. Over 95% of the wheat fields in Kazakhstan are grown during the summer; winter wheat has greater yield potential, but involves a higher risk factor due to freezing of seeds and young seedlings. 'Minimal cultivation' is quite common in northern Kazakhstan and southern Siberia, mostly for soil preservation reasons. This aggravates weed infestation, mainly perennial weeds.

The most common perennial weeds are: Compositae: Sonchus arvensis, Cirsium arvensis, Lactuca tatarica; Convolvulaceae: Convolvulus arvensis; and Euphorbiaceae: Euphorbia sp. The most common annual weeds are: Amaranthus sp., Chenopodium sp., Polygonum tatarica, Cruciferae species. The major herbicides in use are the phenoxy compounds, especially of Russian production. Due to weed resistance to those herbicides which has developed during recent years, Kazakhstani farmers are searching for additional solutions for weed control. Sulfonylurea products are not widely used. Applications of a formulation containing chlorsulfuron (Glean) and dicamba (Banvel, Mediben) are quite limited due to soil residues problems. Triasulfuron (Amber) does not show good efficacy in controlling Chenopodium sp. Tribenuron-methyl (Express, Granstar) is effective on most


varieties, but when Convolvulus sp. is the dominant weed, the combination of tribenuron-methyl and phenoxy compounds (each component at half rate) is the optimal solution.

The main grass weeds in north Kazakhstan are Panicum sp., Setaria sp. and Avena fatua. Triallate (Avadex BW, Far-go) is the main grass killer due to its relatively low price. Additional products in but little use are: diclofop-methyl (llloxan), fenoxaprop-ethyl (Puma) and clodinafop- propargyl (Topik).

Snapshot T M 2.5G, a Granular Herbicide for Pre-Emergence Weed Control in Nursery and Ornamental Flowers and Trees

A. Ovadia, Y. Chachlon, H. Yovel, Y. Tesler and G. Colodney Tarsis-Agrichem, Tel Aviv 61001, Israel [Fax: +972-3-9243618]

Snapshot TM 2.5G is a granular herbicide containing 2.0% trifluralin, a dinitroaniline, and 0.5% isoxaben, a benzamide. Snapshot should be dispersed at rates of 100-200 kg/ha in nurseries, greenhouses and in open fields on pots or on soil surface to prevent annual weeds' emergence. Trifluralin complements isoxaben's herbicidal activity. Whereas isoxaben is effective in prevention of broadleaved emergence, trifluralin is effective in preventing emergence of grass weeds and a variety of broadleaved weeds. Both trifluralin and isoxaben inhibit cell division, and have very low water solubility (less than 1 ppm) and long residual activity.

Snapshot can be safely applied when the crop is well established or after full blooming. Dispersing the product right after cutting or before blooming may inhibit or damage the blooming buds, if some granules are left on the nodes. No phytotoxic damage was observed on existing leaves in crops. Numerous trials were conducted in crops such as Aspidistra, Hypericum, asparagus and roses, and in citrus, apple and myrtle nurseries, and others.

The following weeds are susceptible to Snapshot: Cardamine hirsuta, Stellaria media, Conyza canadensis, Senecio vulgaris, Beta vulgaris, Lactuca serriola, Oxalis corniculata, Euphorbia prostrata, Urtica urens, Galinsoga parviflora, Fumaria sp., Galium sp., Digitaria sanguinalis, Setaria verticillata, Oryzopsis miliacea (Piptatherum holciforme) and others.

B: RESISTANCE OF WEEDS TO HERBICIDES AND USE OF SYNERGISM TO CONTROL RESISTANT AND HARD-TO-KILL WEEDS; BIOASSAY OF HERBICIDES IN SOIL AND WATER

Vegetation Management on Roadsides and at Industrial Sites in Israel

A. Nir Weed Control Co. Ltd., Bet Dagan 50250, Israel [Fax: +972-3-9663020]

Israel, an east Mediterranean country, has a short and rainy winter season, a mild spring and a long and arid summer and autumn, Under these conditions most of the winter annual weeds dry up by mid summer and constitute a serious fire hazard. The main goals achieved by proper vegetation management along roads and highways are: (i) effective prevention of weed fires; (ii) enhancement of road traffic safety; (iii) improvement of roadside shoulders safety; and (iv) enhancement of ditchbanks' soil erosion protection.

The triazine group of herbicides was introduced in the early 1960s. With time and their constant use, triazine-resistant annual grasses such as Phalaris paradoxa, Lolium rigidum, Alopecurus myosuroides, Polypogon monspeliensis, Brachypodium distachyon and others, started to prevail.

Trials conducted to find replacement or complementary herbicides yielded good results with the combinations simazine + metolachlor at 2.5 kg/ha each; simazine + diuron at 2.0 kg/ha each;

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sulfometuron-methyl (alone) at 0.075 kg/ha; and imazapyr (alone) at 0.5 kg/ha. Sulfometuron- methyl gave good control of Sorghum halepense at 0.075 and 0.188 kg/ha but did not affect Hyparrhenia hirta or Cynodon dactylon, whereas imazapyr at 1.25 kg/ha gave almost 100% control of these three perennials; imazapyr at 0.625 kg/ha performed only very slightly inferior to the higher rate.

Former vegetation management programs were described and evaluated in comparison with recent findings from extensive field trials. An updated review of the latest roadside weed control recommendations and some thoughts about the future were included.

Characterization of Littleseed Canarygrass (Phalaris minor) Resistance to Fenoxaprop-ethyl

S. Zarka, A. Tal and B. Rubin Dept. of Field Crops, Vegetables and Genetics, The Hebrew University of Jerusalem, Faculty of

Agriculture, Rehovot 76100, Israel [Fax: +972-8-9362083]

In recent years, evolution of resistant graminaceous weeds to aryloxyphenoxypropionate (AOPP) and cyclohexanedione (CHD) herbicides has been reported frequently from many countries worldwide. In most cases, resistance is due to the widespread and intensive use of selective graminicides in cereal crops.

Recently, we discovered in a wheat field in southern Israel a population of littleseed canarygrass (Phalaris minor) which was poorly controlled by fenoxaprop-P-ethyl (Puma super, 75 g/l EC). Seeds of the resistant population (R) were collected, tested under controlled conditions, and compared with a susceptible population (S) collected from nearby untreated fields. The R biotype was found to be highly resistant to fenoxaprop-P-ethyl and other AOPP and CHD herbicides. The ratios R/S of the calculated EDso for fenoxaprop-P-ethyl, fenoxaprop-ethyl (Forure, 90 gll EC), diclofop-methyl (Illoxan, 360 g/l EC) and tralkoxydim (Grasp, 100 g/l EC) were 24, 9, 1.6 and 1.5, respectively. No differences between the R and S biotypes were found for EDso in the case of haloxyfop-methyl (Gallant, 125 g/l EC) and clodinafop (Topik, 100 g/l EC). Similarly, no differences between the biotypes were observed in response to propanil (Stam, 480 g/l EC), methabenzthiazuron (Tribunil, 70% WP) and isoproturone (Tolkan, 50% SC).

To elucidate the mechanism of the resistance, comparative tests of 14C-fenoxaprop-P-ethyl uptake, translocation and metabolism were carried out. The results indicated that R and S biotypes did not differ in these parameters. However, the enzyme ACCase (acetyl coenzyme A carboxylase, the target site of AOPP and CHD) extracted from R plants was less sensitive than the enzyme from S plants. For example, the 15o (50% enzyme inhibition) in response to fenoxaprop was 20-fold higher for the R biotype than for the S biotype. This trend of less sensitivity of ACCase from the R biotype was also detected for other AOPP and CHD herbicides. The close correlation between the whole- plant level (EDso) and the enzyme level (I5o) results, suggests that resistance of littleseed canarygrass to fenoxaprop-ethyl is conferred by a modification at the target site, i.e., ACCase gene.

Synergy between Flumioxazin and Other Herbicides for Improved Weed Control

T. Yaacoby, 1 A. Tal, 2 Y. Alon, 3 Y. Kedar 3 and B. Rubin 2 1 Plant Protection and Inspection Services, Ministry of Agriculture, Bet Dagan 50250

[Fax: +972-3-9681507q; 2Dept. of Field Crops, Vegetables and Genetics, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot 76100; and 3Agan Chemical Manufacturers Ltd.,

Ashdod 77102, Israel

Flumioxazin (S-53482) is a new phenyl-phthalimide herbicide which acts like a diphenylether by inhibiting protoporphyrin IX synthesis. It was introduced recently by Sumitomo Chemicals for


pre- and postemergence control of annual broadleaved weeds in soybeans and other crops. Pot and field experiments were conducted in order to examine the synergy between flumioxazin and other postemergence herbicides. Weeds which require special measures or high rates for their control were treated at the 3- to 4-leaf stage with a low rate of flumioxazin with and without glyphosate, triazines, diclofop or fenoxaprop, using a chain-driven sprayer. The combination of very low rates (1 to 10 g/ha) of flumioxazin with reduced rates of glyphosate (0.5 kg/ha) synergistically controlled hard-to-kill annual weeds such as Malva spp., Medicago spp. and Urtica urens, which tolerate the recommended rate of glyphosate applied alone. Similarly, pot and field experiments demonstrated that combinations of flumioxazin with triazines result in efficient control of triazine- resistant biotypes ofAmaranthus hybridus and A. blitoides. In addition, mixtures of flumioxazin and fenoxaprop effectively overcame fenoxaprop resistance in Phalaris minor. Volunteer wheat was not injured by the field rates of flumioxazin or diclofop applied alone. However, significant synergistic effects were observed when the plants were treated with low rates of flumioxazin combined with dictofop. Furthermore, the combined treatments of flumioxazin with slow-acting herbicides such as glyphosate, triazines and aryloxyphenoxy propanoates resulted in a unique and rapid necrosis of the foliage, indicating the major contribution of flumioxazin to the observed synergism.

A Sensitive Bioassay Suitable for Quantitative Estimation of Sulfonylurea Herbicides in Soil and Water

Orit Ben-Zvi Assaraf and B. Rubin Dept. of Field Crops, Vegetables and Genetics, The Hebrew University of Jerusalem, Faculty of


Sulfonylurea herbicides exhibit soil activity at extraordinarily low rates of application (g/ha). However, even at this low rate, some of these herbicides persist in the soil for more than one season, and may cause injury to the following crop. Analytical methods, such as GC (gas chromatography) and HPLC (high performance liquid chromatography), are not sensitive enough for determination of biologically active residues of sulfonylureas. The aims of this study were to (i) develop a sensitive bioassay suitable for quantitative estimation of sulfonylurea herbicides in soil and water, and (ii) evaluate their persistence as affected by soil characteristics. Red beet was the most sensitive species to triasulfuron and tribenuron-methyl, and sweet corn was the most sensitive to chlorsulfuron and sulfometuron-methyl. ECs0 (the herbicide concentration that causes 50% inhibition in root length) for these herbicides was in the range of 0.1 to 0.5 ppb in soil and water.

The sulfonylurea sulfometuron-methyl and imazapyr (an imidazolinone), are widely used in Israel. The root length bioassay showed that bean, lentil, pea, sunflower and sorghum seedlings are sensitive to sulfometuron-methyl (1 ppb) and relatively tolerant to imazapyr (10 ppb). Therefore, they can be used as bioassay plants to identify the applied herbicide.

The study of the sulfonylureas' persistence as affected by soil characteristics showed that tribenuron-methyl dissipation was the fastest, whereas the dissipation rates of sulfometuron-methyl, chlorsulfuron and triasulfuron were similar. The rate of chemical hydrolysis of all herbicides was lower than that of microbial degradation.

A bioassay was conducted to estimate the movement of sulfonylureas in soil. Sulfometuron- methyl movement was greater in loamy sand than in clay loam. Herbicide movement was influenced, to a large extent, by the irrigation regime. Concentrations higher than 10 ppb in the leachate water of 20-cm soil columns, indicated the potential of sulfonylureas to leach below the plowing layer. The developed bioassay is simple, rapid and suitable for detection and quantification of sulfonylurea residues in soil and water, and can be applied as a tool to study the behavior and fate of sulfonylureas in different soils.

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C: TOLERANCE TO HERBICIDES AND RESISTANCE TO BROOMRAPE OF CROP PLANTS

Oxidative Stress Response in Beans (Phaseolus vulgaris)

O. Shainberg, 1 B. Rubin, 1 H.D. Rabinowitch 1 and E. Tel-Or z 1Dept. of Field Crops, Vegetables and Genetics [Fax: +972-8-9468265] and 2Dept. of Agricultural

Botany, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot 76100, Israel

The effect on the antioxidative enzymes in the cell of exposing bean (Phaseolus vulgaris L.) plants to two different light intensities for a short period of time was examined. The plants were grown under a 16-h photoperiod in a phytotron. Twelve days after sowing, the plants were separated into two different light regimes: some of the plants continued growing under a light intensity of 1300 # E.m-2.sec-1; other plants were shaded to 20% of the light intensity for 48 h. Light intensities affected the activity of some protective enzymes involved in the antioxidative system. The main influence was found with cytosolic superoxide dismutase (SODcyt) and glutathione reductase (GR) activities, which were significantly increased by the high light intensity. Other enzymes, chloroplastic superoxide dismutase (SODchl) and catalase, were less affected. Protein and chlorophyll contents were unaffected. Plants with the higher activity of GR and SODcyt showed increased tolerance to additional oxidative stresses imposed by paraquat and SO2 treatments. We suggest that those enzymes are responsible for the cross-protection observed in bean leaf from additional oxidative stresses.

Response of Vetch (V/c/a spp.) Genotypes to Orobanche aegyptiaca

Y. Goldwasser, 1 Y. Kleifeld, 1 D.M. Joel, 1 D. Plakhine 1 and B. Rubin 2 1Dept. of Weed Science, ARO, Newe Ya'ar Research Center, Haifa 31900 [Fax: +972-4-9836936];

and 2Dept. of Field Crops, Vegetables and Genetics, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot 76100, Israel

Most vetch genotypes, which are important forage crops in the Mediterranean region, are susceptible to the holoparasites Orobanche aegyptiaca and O. crenata. Greenhouse experiments conducted in pots containing loamy clay soil inoculated with O. aegyptiaca seed, demonstrated that purple vetch (Vicia atropurpurea) genotypes 'Popany' and 'Sadot' are resistant (R) to the parasite, whereas common vetch (V. sativa) genotypes 'Yovel' and '473-A' are susceptible (S). When R genotypes were grown on glass fiber paper in plastic bags, a significantly higher rate of parasite seed germination and attachments was observed as compared with that on S genotypes. On the S host roots, O. aegyptiaca attachments developed into tubercles and flowering stems, whereas on the R host roots no further development of the parasite was observed. The resistance of purple vetch genotypes to O. aegyptiaca was sustained at different temperature regimes (day/night 17/12, 22/17 and 27/22~ Microscope studies revealed that on the R vetch genotypes' roots, necrotic lesions were developed, surrounding the contact points of the parasites, radicle. Further development of the parasite ceased either in the root cortex or when reaching the vascular cylinder. A reddish- brown secretion was detected at the host-parasite interface, filling the apoplastic spaces including the cavities of R host vessel elements. These findings suggest involvement of defense mechanism(s) induced by parasite attachment.


D: PARASITIC WEEDS

Orobanche Species Identification Using Molecular Markers

D.M. Joel, V. Portnoy, G. Tzuri and N. Katzir Dept. of Weed Science, ARO, Newe Ya 'ar Research Center, Haifa 31900, Israel

[Fax: +972-4-9836936]

Five Orobanche (broomrape) species are known as serious weeds in Israel. The distinction between the species is highly relevant, because they attack different crops.

DNA markers were raised for the identification of each of the important Orobanche species, using a random amplified polymorphic DNA (RAPD) technique that is based on the use of short primers of arbitrary nucleotide sequence in the polymerase chain reaction (PCR). This method has been shown to be useful for a wide range of applications including DNA fingerprinting, and for the estimation of genetic relationships within and between species. In contrast to the isozyme markers, DNA-based markers are not dependent on environmental and developmental factors and have been applied successfully to discriminate between individual genotypes.

In order to confirm the interpretation of RAPD bands, Southern hybridization patterns of RAPD products of the various species were used. Hybridization is very important especially in species diagnostics, because parallel RAPD bands of a specific primer are similar only in molecular size, whereas parallel hybridization bands are similar also in molecular sequence. The diagnostic information obtained from RAPD products is valuable for the study of Orobanche in agricultural areas. Probes are now available for most relevant species.

Using RAPD primers we were able to confirm the separation of species belonging to section Trionychon from species belonging to section Osproleon and to distinguish clearly O. cernua Loefl. from O. cumana Wallr., and O. aegyptiaca Pets. from O. ramosa L. The validity of the molecular markers found for O. cumana and O. crenata was confirmed on plants of the same species that were collected in Spain and Bulgaria.

Developmental Mechanisms in the Parasitic Plant Orobanche and Its Relations with the Host

Dalia Losner-Goshen, 1 D.M. Joel 1 and A.M. Mayer 2 1Dept. of Weed Science, ARO, Newe Ya'ar Research Center, Haifa 31900 [Fax: +972-4-9836936];

and 2Dept. of Botany, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

Orobanche has two life phases. The first is a short independent phase, the elongation phase, which begins with germination of the seed. When the radicle reaches a host root, the elongation phase stops and the second life phase of the parasite, the parasitic phase, starts. The conical root apex becomes roundish at this stage as a result of cell divisions in the external cell layer. The cells around the apex become papillate as a result of cell extension at the outer surface. The extended root apex with its papillae form the attachment organ of Orobanche. At this stage starch, instead of lipids, accumulates in the apical cells. The papillae have a dense cytoplasm with many mitochondria and a well developed Golgi apparatus. The outer cell walls of the papillae have a pecto-cellulotic wall layer covered by an outer cuticular wall. These walls carry small (up to 2 #m) and large (4--6 #m) external protuberances. A secretory substance that stains for carbohydrates accumulates between the cell walls and the cuticle that covers them, forming a bubble-like structure. Seedlings and calli of Orobanche are able to produce and secrete pectinmethylesterase (PME) and polygalactur6nase (PG). Immunogold staining using antibodies to PME showed that most of the labeling is in cell wails.

Based on the studies of the enzyme involved, on light microscope work and on the ultrastructural studies using conventional and immunogold staining, we were able to clarify some points regarding

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the penetration mechanisms. The first stage of penetration is facilitated by enzymatic separation between the epidermal cells. A decrease in immunogold labeling of pectins was found in host cell walls attached to parasite cells; this seems to be evidence of PME and PG activity. Crushed epidermal cells and folding of epidermal cell walls near the penetration site provide evidence for mechanical penetration. The penetration process through the epidermis is probably a combination of enzymatic and mechanical activities.

In the root cortex and the vascular cylinder, degraded host cell walls were seen beside crushed host cells, foldings of host cells and changes in wall pectin composition. This is evidence that additional enzymes are involved in the penetration processes.

Selective Control of Broomrape in Carrots and Vetch with Foliar-Applied Imidazolinone Herbicides

R. Jacobsohn, Z. Tanaami and H. Eisenberg Dept. of Vegetable Crops, ARO, The Volcani Center, Bet Dagan 50250, Israel

[Fax: +972-3-9669642]

Various herbicides of the imidazolinone group, foliar-applied, have demonstrated activity against broomrape (Orobanche spp.) in experiments in carrots (Daucus carota L.) and in vetch (Vicia sativa L. var. 'Yovel'). The purpose of the experiments in carrots was to replace glyphosate, which is widely used as a foliar treatment for broomrape control in Umbelliferae crops and has a narrow margin of safety. Glyphosate can be hazardous to carrots if under stress; the problem is even more severe in vetch.

The effect of imazethapyr, imazameth and imazamox (AC-299263) (American Cyanamid Co.) as well as flumetsulam (DE 498) (DowElanco) on selective broomrape control was tested in two commercial fields of carrots, planted on Oct. 3, 1994 and Nov. 13, 1994, in Kibbutz Sheluhot in the Bet She'an Valley. The three imidazolinone herbicides as well as two sulfonyl urea herbicides and flumetsulam were tested for selective broomrape control in vetch, in an experimental field at Bet Dagan.

Carrots The herbicides belonging to the imidazolinone group controlled almost all the broomrape plants in carrots of both planting dates, with somewhat greater activity in the first planting. Three applications of imazameth at a rate of 1.25 g a.i./ha did not provide complete broomrape control. However, three applications of all other treatments at rates ranging from 1.25 to 5.0 g a.i./ha resulted in excellent broomrape control. Three applications of various combinations of 20 and 40 g a.i./ha of imazethapyr and imazamox also resulted in nearly complete broomrape control. Imazamox was slightly less successful in the control of broomrape in the second planting; metosulam (DE 511) and glyphosate suppressed broomrape emergence but damaged the crop.

Vetch Foliar applications of the imidazolinone herbicides provided good control of both Egyptian and crenate broomrape in vetch, at rates generally twice as high as in carrots. Three applications of 1 g a.i. of imazameth and three applications of 20, 40 and 40 g a.i./ha imazethapyr resulted in complete selective control of the two broomrape species. Glyphosate and flumetsulam gave complete broomrape control but resulted in crop damage. Metosulam caused heavy damage to the crop. Cyclosulfamuron damaged the crop and not the broomrape.

Isolation of Mycoherbicidal Pathogens from Juvenile Broomrape Plants

Ziva Amsellem, 1 Y. Kleifeld, 2 Z. Kernyi, s L. Hornok, 3 Y. Goldwasser 2 and J. Gressel 1 1Dept. of Plant Genetics, Weizmann Institute of Science, Rehovot 76100, Israel

[Fax: +972-8-9344181]; Z Dept. of Weed Science, ARO, Newe Ya'ar Research Center, Haifa 31900, Israel; and 3 Inst. for Plant Science, Agricultural Biotechnology Center, GOd6110, Hungary


The parasitic broomrapes (Orobanche spp.) are widely spread weeds, halving yields of ca 4% of the world's crops. As these plants attach to crop roots, they cannot be controlled mechanically except by removing their flower stalks after much of the damage to the crop yield has already been done. They are not usually amenable to selective herbicides (except those applied postemergence), as most herbicides cannot differentiate between crop and parasite. Biological control could be an effective answer. The isolation of two highly parasitic fungi, Fusarium arthrosporioides strain E4a and E oxysporum strain Eld, is reported from diseased, juvenile, emerging Orobanche flower stalks. Both organisms meet Koch's criteria for being primary pathogens. DNA RAPD fingerprinting showed that they indeed differ from each other and from many other Fusarium spp. as well as other formae speciales of E oxysporum. Tomato plant roots dipped into a fungal suspension and planted in broomrape-infested soil were protected for long periods, There are still many experiments to be performed before agricultural use can be envisaged. These include studying the host range of the pathogens on different Orobanche strains and species, soil residue analyses, pathogenicity on crops cultivated in the same geographical region to determine incompatibilities, as well as the development of cost-effective application technologies. It is possible that basic studies of the defenses of broomrape can lead to synergies using chemical synergists to suppress defenses and/or facilitate the action of microorganisms.

Ethylene and Temperature Affect Induction of Resistance to Orobanche aegyptiaca Penetration in Helianthus annuus Inbred Line SW 501, in an In Vitro Bioassay

System

Adiva Shomer-Ilan Dept. of Botany, Tel-Aviv University, Tel Aviv 69978, Israel [Fax: +972-3-6409380]

The angiosperm weed Orobanche (broomrape) is a known root holoparasite causing severe economic damage in the Mediterranean area. Analyzing natural host resistance mechanisms might provide a lead to solving the problem. We used sunflower high-temperature-resistant inbred line SW 501, the resistance of which was evaluated by Noemi Ish-Shalom-Gordon et al. (1993). Seedlings were grown and assayed for resistance to broomrape penetration and inducers of such resistance, in an in vitro bioassay system of aluminum-foiled-polyethylene bags with 40% Hoagland solution. The seedlings were exposed to constant conditions (15+0.5 or 24+1~ 12-h photoperiod, 150 #M photon m -2 s-l) . When 2 weeks old, the seedlings were inoculated with germinated O. aegyptiaca seeds. The percentage of infested plants was recorded for another month.

Sunflower seedlings grown at 15+0.5~ were found to be susceptible to the parasite, 87% of 66 tested seedlings being infested. On the other hand, seedlings grown at 24-1-1~ were found to be resistant to broomrape; 18% of 46 tested plants were infested (in agreement with Ish-Shalom- Gordon's findings). To identify inducers of systemic resistance at 15.5+0.5~ 2-week-old seedlings were exposed for 24 h to salicylic acid or ethylene before inoculation. Only ethylene induced resistance, with 14% of 44 tested plants being infested. Thus, ethylene and temperatures above 20~ induce resistance. This phenomenon is currently being subjected to molecular analysis.

On the Biology and Selective Control of Field Dodder (Cuscuta campestris)

Ela Nir and B. Rubin Dept. of Field Crops, Vegetables and Genetics, The Hebrew University of Jerusalem, Faculty of


Field dodder (Cuscuta campestris), a non-specific parasitic weed, causes damage and yield loss in a wide range of host species worldwide. The parasite seedling coils around the host and penetrates its tissue and vascular system via haustoria. The dodder exploits the host by withdrawing assimilates,

208 Meetings

nutrients and water, thereby reducing crop quality and yield. Laboratory and field experiments were conducted to elucidate the effect of edaphic and environmental conditions on dodder germination and development, as well as its response to herbicides.

Maximum germination occurred at 15 ~ to 35~ no seed germination was observed below 10 ~ or above 40~ In a sandy soil (at Rehovot), maximum emergence occurred from the soil surface, where most of the seeds emerged within 3 days. Sowing in heavier soil and a deeper layer resulted in reduced and delayed emergence, with no emergence from a depth below 10 cm. The viability of seeds buried at various soil depths in the field, declined with time.

Soil-incorporated herbicides, known as cell division and development inhibitors (dinitroanilines, pronamide, thiazopyr and isoxaben), inhibited dodder germination and arrested its vegetative growth before or soon after attachment to the carrot plant. The hypothesis that dodder employs a strong sink ('super sink'), and hence that phloem-mobile, non-selective herbicides applied on the host will be withdrawn rapidly by, and accumulate in, the parasite, was examined. Preliminary results indicate that yields of carrots infested with dodder were higher than those of uninfested plants treated with certain rates of thiazopyr or imazethapyr. The potential of using low rates of non-selective herbicides for selective control of field dodder is currently being examined.

E: DIFFERENT APPROACHES TO WEED CONTROL

Inhibiting a Plant Defense Mechanism to Enhance the Biological Control of the Weed Abutilon theophrasti by the Fungus CoUetotrichum coccodes

Daphna Michaeli , 1 V. Kampel, 2 A. Warshawsky 2 and J. Gressel 1 1Dept. of Plant Genetics [Fax: +972-8-9344181] and 2Dept. of Organic Chemistry, The Weizmann

Institute of Science, Rehovot 76100, Israel

A specific fungus, Colletotrichum coccodes, can serve as a biological agent for control of the widespread pernicious weed Abutilon theophrasti. The lowest effective inoculum dose is more than 107 spores/ml, which is not economical. We are attempting to overcome this problem with compounds that specifically inhibit the weed's defense mechanism. The synthesis of callose is an important defense mechanism in various plants infected by Colletotrichum spp. Synergists specially synthesized for the Abutilon-C. coccodes pathosystem are aimed at preventing callose formation by inhibiting the enzyme callose synthase, an enzyme requiring calcium as a cofactor. The fungus has a minuscule calcium requirement, and when inoculum was pregrown in a calcium-containing medium, it did not lack calcium for growth, despite the inhibitor. Fiftyfold higher concentrations of inhibitor than the calcium content of the medium had no significant effect on fungus growth. Initial evidence for a possible synergism between C. coccodes spores in combination with the callose synthesis inhibitors was found in preliminary greenhouse and laboratory experiments with inoculated Abutilon plants. The most susceptible organs were cotyledons and young buds. An experimental system was calibrated using cotyledons from young Abutilon plants floating on water in plates that were point-inoculated for various incubation periods. Fungal growth on leaves was measured by ELISA (enzyme-linked immunosorbent assay), applying a specific anti-C, coccodes antibody. In parallel, Abutilon cotyledons were stained for callose. Small fluorescent spots resulting from callose synthesis appeared adjacent to inoculation drops 36 and 54 h after inoculation. This system is now used for quantification of fungal infection and callose formation with and without the inhibitors.

This research was kindly supported by a student scholarship in memory of Lynn Bilik and an award from the Weed Science Society of Israel.


Improved Control of Purple Nutsedge (Cyperus rotundus) Using Plant Growth Regulators

M. Yogev, 1 M. Negbi 2 and B. Rubin 1 1Dept. of Field Crops, Vegetables and Genetics [Fax: +972-8-9468265] and 2Dept. of Agricultural

Botany, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot 76100, Israel

Purple nutsedge (Cyperus rotundus) is a troublesome weed in many crops, and considered to be the world's most noxious weed. It propagates by forming tubers dispersed in different soil depths and shallow basal bulbs which develop into shoots. Traditional weed control methods hardly achieve any appreciable control of this weed or reduction in the number of tubers in soil. To reduce herbicide use and yet achieve acceptable control, a series of experiments was carried out in which purple nutsedge seedlings were treated with mixtures of plant growth regulators (PGR), in order to modify the seedlings' growth pattern. Spraying gibberellic acid at 10-3M and CPPU (Agan Chemical Manufacturers, Israel), a cytokinin, 10-4M over sprouting shoots, did not adversely affect their aboveground development but prevented that of tubers. In field experiments in which the PGR mixture was applied postemergence twice, the underground shoots (rhizomes) modified their potentially dia-plagio- and ortho-gravitropic growth response into a negative one, to become aboveground shoots. Under such conditions, virtually no tubers were formed. When PGR treatments were followed by application of reduced rates of herbicides, the weed control efficacy was increased synergistically. These promising results open up new possibilities to facilitate the control of this noxious weed.

New Approaches in the Control of Purple Nutsedge (Cyperus rotundus)

J. Hershenhorn, R. Aly, Y. Lavan, S. Golan, G. Herzlinger and T. Hilf Dept. of Weed Science, ARO, Newe Ya'ar Research Center, Haifa 31900, Israel

[Fax: +972-4-9836936]

Purple nutsedge (Cyperus rotundus L.) is considered to be one of the world's worst weeds, especially in the tropical and subtropical regions; it is exceedingly noxious also in Israel. Its rapid growth, prolific propagation through a complex underground system of rhizomes and tubers, and its narrow leaves with a thick cuticle, make it extremely refractory to control by mechanical or chemical means.

The following alternative approaches to control this noxious weed are being investigated: (i) B. Rubin et al. (Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel) reported that purple nutsedge plants sprayed with a combination of plant hormones did not produce tubers. We are investigating the possibility that transformation of the biological control agent Cercospora caricis pt. rotundus, a pathogen of purple nutsedge, with the genes for IAA and cytokinin production, will achieve the same results. A transformation system was already established.

(ii) We have recently demonstrated that exposure of C. rotundus tubers to minute quantities (5-15 #1) of essential oil from lemongrass (Cymbopogon flexuosus), Syrian oregano (Origanum syriacum) and Micromeria fruticosa completely inhibited germination. Purification of the active fractions and possible application in the field are under study.

(iii) Under greenhouse conditions, more than 85% of C. rotundus tubers did not germinate in the presence of Cicer arietinum plants. Root exudates of the 'Hadas' variety showed the greatest inhibitory effect. Similar results were obtained with concentrated root exudates from the same variety applied on tubers in petri dishes. Purification of the active compound(s) and tests of possible application in the field are being conducted.

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How was Bermudagrass Controlled before the Era of Herbicides?

M. Horowitz Dept. of Ornamental Horticulture, ARO, The Volcani Center, Bet Dagan 50250, Israel

[Fax: +972-3-9660589]

The perennial bermudagrass, Cynodon dactylon, is characterized by subterranean rhizomes capable of rapid growth and regeneration under favorable moisture and temperature conditions. Due to its large biomass and allelopathic effects, bermudagrass is strongly competitive to cultivated plants,

Bermudagrass was identified in the 19th Century as a common weed by botanists touring the region. The intensification of local agriculture and the introduction of modem techniques of irrigation and tillage, from 1900 onwards, strongly increased the infestation by bermudagrass, which eventually became the most noxious weed in irrigated land.

Since there was no other effective control method at the time, 'bahar' - manual removal of weeds from the soil - was the technique recommended in preparation of new plantations. A ditch was dug as deep as rhizomes penetrated - down to 50 cm and more in sandy soil - and all pieces of rootstock were individually pulled out. The labor was hard and slow; under optimal conditions, a worker would clean 40 m 2 per day. The method remained in use until the 1930s, mainly for export crops such as citrus, and was gradually replaced by mechanical cultivation.

Trials with deep soil tillage showed that cutting the subterranean system often increased infestation, since dormant sections sliced off the rhizome sprouted and generated new plants. However, repeated cultivation which suppressed the foliage, led to depleted plant reserves and gradually killed the weed. This method was introduced in the late 1920s for field crops and citrus plantations. Successful control of established bermudagrass was reported after 10--12 cultivations at 1-2 week intervals; however, irregular timing of the cultivation resulted in renewed infestation.

In the 1940s, herbicidal oils were tested for control of bermudagrass. Dalapon and mixtures of amitrole and simazine were introduced in the late 1950s, and bromacil, selective to citrus, was registered in 1966.

Effect of Drift-Retarding Chemicals

M. Cohen, 1 I. Hirsch 2 and A. Veneziani 3 1Weed Control Co. Ltd., Bet Dagan 50250 [Fax: +972-3-9663020]; 2 Chem-Nir Ltd., Kefar

Shemaryahu 46910; and 3Tiveon-Chem Co., Haifa 31333, Israel

Spray drift is an unavoidable accompaniment to all spraying activities, but can be reduced and regulated by appropriate, drift-retarding materials. During 1995 several trials were carried out to determine the degree of efficacy of such materials. Drop Zone DC* (Helena Chemical Co., Memphis, TN, USA) at 50 ml/100 l; Nalcotrol* (Nalco Chemical Co., Naperville, IL, USA) at 40 ml/100 l; and A-41* (San Ag, Los Angeles, CA, USA) at 30 ml/100 1 of total volume were sprayed by helicopter at 50 l/ha. The number of droplets per square inch on marked targets was counted. Drop Zone DC* was also applied from the ground, by a motorized backpack sprayer, at 50 and 75 g/l of spray solution, to 30x40-cm white paper target sheets; and at 0, 0.025%, 0.05% and 0.075% of a spray solution, containing 1675 g a.i./ha of 2,4-D, to young cotton seedlings. Under the test conditions, all trials throughout indicated a good drift-retarding effect by the three products tested.

*Proprietary name; common names or chemical formulae not applicable.


By title only

Germination of Orobanche seeds: Scome aspects of metabolism during preconditioning - A.M. Mayer and Nurit Bar Nun

Witchweed (Striga spp.), a root parasite of cereals and legumes - D.M. Joel

212

MEETINGS


THE INTERNATIONAL CONFERENCE ON CONTROLLED ATMOSPHERE AND FUMIGATION (CAF)

IN STORED PRODUCTS

April 21-26, 1996

Cyprus International Conference Centre, Nicosia, Cyprus

Institutions assisting in organizing the Conference: Cyprus Grain Commission, Nicosia, Cyprus

Agricultural Research Organization, Bet Dagan, Israel

A: BIOLOGICAL RESPONSES OF ARTHROPODS TO CA AND~OR FUMIGATION, AND FOOD OFFERED

Effect of Modified Atmospheres on the Juvenile Stages of Six Grain Beetles

S.T. Conyers and C.H. Bell Central Science Laboratory, Ministry of Agriculture, Fisheries and Food, Slough,

Berks. SL3 7HJ, UK [Fax: +44-1753-824058]

Adult emergence after exposure of the juvenile stages of six species of grain beetle, Cryptolestes ferrugineus (Stephens), Oryzaephilus surinamensis (L.), Rhyzopertha dominica (E), Sitophilus granarius (L.), S. oryzae (L.) and Tribolium castaneum (Herbst), to three modified atmosphere (MA) mixtures, was assessed at 15~ and 70% r.h. The use of this low temperature was important as it is representative of the conditions prevailing in grain stores at the start of the U.K. storage season.

The juvenile stages were exposed to three separate MAs, based on nitrogen, simulated burner gas and carbon dioxide, with 0.5% or 2% oxygen. The internal grain feeders, R. dominica, S. granarius and S. oryzae, were able to emerge even after lengthy exposures to the MAs and of these three species, S. granarius was the most tolerant. Of the other species, T. castaneum was the most tolerant, its pupae requiring 10 days of exposure to prevent emergence. Carbon dioxide was the most effective of the MAs, followed by simulated burner gas and then nitrogen. (L)*

Control of the Dermestid Beetle Dermestes maculatus with Controlled Atmospheres

Ana C. S~i-Fischer, C.S. Adler and Ch. Reichmuth Federal Biological Research Centre for Agriculture and Forestry, Inst. for Stored Product

Protection, D-14195 Berlin, Germany [Fax: +49-30-8304284]

The leather or hide beetle, Dermestes maculatus De Beer, is one of the most important pests on dried products of animal origin as well as on leather, furs and other materials. Museums fear the

*L = lecture sessions; P = poster (market place) sessions.


potential of this pest to destroy insect collections, mummies and other valuable goods. Also the long larval hairs break off easily and can have severe allergic effects.

Various hypoxic controlled atmospheres were tested under laboratory conditions against all stages of D. maculatus at 25 ~ and 30~ r.h. Using an atmosphere of pure nitrogen or pure carbon dioxide, respectively, complete control of all stages could be achieved within 48 h. The same effect was achieved with an atmosphere consisting of 98% N2 and 2% O2. With 40% CO2, 44% N2 and 16% 02 or 60% CO~ in air, an exposure time of 96 h controlled all stages except the pupae at 30~ (L)

Simulation Model of Low Oxygen Atmospheres on Insect Population Dynamics in Stored Grain

EW. Flinn and D.W. Hagstrum USDA-ARS Grain Marketing and Production Research Center, Manhattan, KS 66502, USA

[Fax: +I-913-5375584]

A simulation model was developed for predicting the efficacy of low oxygen atmospheres to suppress insect pests in bins of stored grain. A 2-D spatial model was used to predict population growth of Tribolium castaneum and Sitophilus oryzae as a function of grain temperature and moisture. In the model, the bin is divided into 16 compartments, which allows the model to simulate different growth rates based on a compartment's temperature and moisture level. Equations were incorporated into the model that predict the effects of low oxygen atmospheres, grain temperature, and insect stage on insect mortality. Based on grain temperature, the model can predict the length of time required to produce a given mortality. It can also be used to predict insect density in grain 1-2 months post-fumigation. Simulations showed that fumigating cool grain required much longer intervals to kill all insect stages than fumigating warm grain. (L)

Effect of Low Amounts of Oxygen in the Control of Some Stored-Product Insects by Carbon Dioxide and Nitrogen t

G.N. Mbata 1 and Ch. Reichmuth 2 1School of Biological Sciences, Abia State University, Uturu, Abia State, Nigeria

[Fax: +234-601-3258837]; and 2Federal Biological Research Centre for Agriculture and Forestry, Inst. for Stored Product Research, D-14195 Berlin, Germany

Atmospheres containing carbon dioxide and nitrogen were investigated to elucidate the effect various concentrations of oxygen would have on such atmospheres' toxicity to some stored-product insect species. Different developmental stages of these insects were studied and the percentage mortality, as well as duration of exposure required to produce 100% mortality, were determined and compared. For some insects the addition of 2% oxygen enhanced their mortality, although this prolonged the exposure period required to achieve 100% mortality in other species. There was also differential tolerance among the various developmental stages of the insects. (L)

Rapid Disinfestation through the Combination of Controlled Atmospheres and Heat

C.S. Adler Federal Biological Research Centre for Agriculture and Forestry, Inst. for Stored Product


Paper not presented at the Conference.

214 Meetings

The suggested phaseout of methyl bromide production and use by the year 2000 increases the need for alternative rapid disinfestation methods, High temperatures increase metabolic rates of insect pests and thus enhance the lethal action of both fumigants and controlled atmospheres. Experiments with the granary weevil Sitophilus granarius revealed that treatments with 60% or 90% COs (the rest air) or 98% N2 (the rest O2), which took 46 or 77 days, respectively, for complete control at 10~ could be reduced to 8 days for both atmospheres at 35~ and less than 2 days at 40~ Therefore, valuable products such as spices, nuts or herbs that can be heated to such temperatures without loss of quality could be rapidly disinfested by either of these two CAs. Moreover, the data show that CAs hold special promise for warm climates where the stored-product temperatures are naturally high. Under such conditions, increased respiration rates of all living organisms present, and low stored-product moisture contents that minimize the risk of condensation, may even allow for continuous hermetic storage under hypoxic conditions. (L)

The Use of Mixed-Age Cultures in the Measurement of Response to Phosphine

R.G. Winks 1 and Elisabeth A. Hyne 2 CSIRO, Division of Entomology, 1SCMC Nambour, QId 4560 [Fax: +61-74-789489] and

Canberra, ACT 2601, Australia

The conventional approach to the measurement of response to pesticides has been to use stable- age distributions of selected stages of insects so that the data can be subjected to rigorous statistical analysis using such methods as probit analysis. This approach may have merit when comparing the efficacy of different poisons and when determining changes in tolerance associated with the quantal response. However, it is usually not suitable for determining dosages likely to be effective in practice. A more effective approach is to use mixed-age cultures and to determine times to population extinction. An advantage of this method is that it is not necessary to know which stage is the most tolerant. In addition, this approach allows for changes in tolerance during the exposure periods. However, it is essential that material used for testing contains all developmental stages and that adequate numbers of each stage are present to ensure a satisfactory degree of repeatability. We described a method that is suitable for determining dosages that can be expected to be effective in practice. Data are presented to show the relative abundance of the different stages with a number of insect species and strains, together with data to demonstrate the repeatability of the method. (L)

Effect of Temperature on the Response of Susceptible and Resistant Strains of Stored-Product Beetles to Phosphine

Elisabeth A. Hyne 1 and R.G. Winks 2 CSIRO, Division of Entomology, 1Canberra, ACT2601 [Fax: +61-6-2464202] and 2 SCMC

Nambour, Qld 4560, Australia

Around the world phosphine fumigations are performed over a wide range of stored commodity temperatures. Generally it is held that insects are tolerant of phosphine at lower temperatures and this tolerance decreases with increasing temperature. This is usually explained by an increase in the insect's metabolic rate. However, when resistant insects are examined, the model does not always hold. We examined the effect of temperature on the toxicology of phosphine.

Mixed-age cultures of susceptible strains of Sitophilus oryzae, S. granarius, S. zeamais and Rhyzopertha dominica as well as resistant strains of S. oryzae and R. dominica were exposed to constant phosphine concentrations of 0.03, 0.05 and 0.1 mg 1-1 at temperatures ranging from 15 ~ to 35~ All beetles were more tolerant of phosphine at 15~ Higher temperatures reduced the required exposure time for complete mortality at all concentrations for susceptible strains of Sitophilus spp. and R. dominica and resistant strains of S. oryzae. In contrast, the exposure time


to achieve complete mortality of resistant R. dominica was longer at 35 ~ than at 25~ for all concentrations except 0.1 mg 1-1. At this concentration complete mortality at 35 ~ was achieved in the same or slightly less time than at 25~ (L)

Toxicity o f Methylphosphine to Susceptible and Phosphine-Resistant Strains of Four Species of Stored-Product Insects

M.Q. Chaudhry, A.D. MacNicoll and N.R. Price Central Science Laboratory, Ministry of Agriculture, Fisheries and Food, Slough, Berks. SL3 7H J,

UK [Fax: +44-1753-517378]

The future use of phosphine as an ideal fumigant of stored commodities is threatened by the emergence of widespread resistance in stored-product insects in many countries. The mechanism of phosphine resistance apparently involves respiratory exclusion of the gas as well as detoxification by resistant insects. Our search for a suitable gaseous chemical to control phosphine-resistant insects led us to study the fumigant properties of methylphosphine (CH3PH2), a close analog of phosphine (PH3). Exposure to CH3PH2 produced much greater mortality in PHa-resistant strains of four species of stored-product insects than in their corresponding susceptible strains. It is likely that the presence of the methyl group in CH3PH2 prevents exclusion by the main resistance mechanism. Furthermore, greater toxicity of CH3PH2 to resistant, compared with susceptible, strains indicates that the PHa-resistance mechanism may be metabolizing CHaPH2 to toxic products. The possibilities of using CH3PH2 to control PH3-resistant insects, and potential strategies for resistance management, were discussed. (L)

On the Eff icacy o f Sul fury l Fluoride against Stored-Product Pest Moths and Beetles

Ch. Reichmuth, 1 M. Sch611er I and J.-E Dugast 2 1 Federal Biological Research Centre for Agriculture and Forestry, Inst. for Stored Product

Protection, D-14195 Berlin, Germany [Fax: +49-30-8304284]; and ~DowElanco Europe, Letcombe Laboratory, Letcornbe Regis, Wantage, Oxon 0X12 9JT, UK

Sulfuryl fluoride (SO2F2) is a pesticidal fumigant, applied mainly in the control of termites. In this work, the efficacy against eggs, larvae, pupae, and adults of eight species of stored-product pest insects was studied. Each insect sample was exposed for 24, 48 or 72 h to concentrations ranging from 11.7 to 35 g/m 3. Concentrations of SO2F2 were measured using an infrared absorption spectrometer.

Complete control of adults of all tested species, and of all larval stages and of pupa of the granary weevil Sitophilus granarius, the confused flour beetle Tribolium confusum, and the yellow mealworm beetle Tenebrio molitor, was achieved at 13 g/m 3 within a 24-h exposure period. Some individuals of the drugstore beetle Stegobium paniceum and of Trogoderma inclusum continued to develop to the adult stage, but did not reproduce. The sawtoothed grain beetle Oryzaephilus surinamensis survived and reproduced at 18.6 g/m 3 at all tested fumigation times. The Indianmeal moth Plodia interpunctella survived and reproduced at 18.2 g/m 3 within 24- and 48-h exposure times. S. granarius and the Mediterranean flour moth Ephestia kuehniella produced progeny within 6 weeks after fumigation for 24 h with 26.5 and 23.5 g/m 3, respectively. Complete control of eggs of S. granarius was achieved at 35 g/m 3 within a 24-h exposure time. This suggests that the eggs are the most tolerant stage of these species towards SO,F2, as known from treatment of wood-destroying insects.

The possible practical rate to control all stages of stored-product insect pests should be either a rather high dose of ca 80 g/m 3 (e.g. for S. granarius, considering a practical leak rate of 2.4% per day) or more than one treatment with ca 30 g/m a (e.g.E. kuehniella, second treatment 6 weeks after the first one). (L)

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Effects of Carbonyl Sulfide on Sitophilus granarius, Fusarium avenaceum and Fusarium culmorum, with Remarks Regarding Its Possible Corrosion on Copper

R. Plarre 1 and Ch. Reichmuth 2 1USDA-ARS, Stored Product Insects Research Unit, Dept. of Entomology, University of Wisconsin, Madison, W153706, USA [Fax: +1-608-2648822]; and 2Federal Biological Research Centre for

Agriculture and Forestry, Inst. for Stored Product Protection, D-14195 Berlin, Germany

All life stages of Sitophilus granarius, as well as the fungi Fusarium avenaceum and Fusarium culmorum, were tested for their susceptibility to different exposure times and concentrations of carbonyl sulfide (COS) at 20~ and 70% r.h. Complete kill of S. granarius occurred at concentrations of 18 g m -3 COS for 120 h or 32 g m -3 COS for 72 h. The eggs were most tolerant to the toxic gas, followed by pupae and adults, whereas larval stages were most susceptible to the fumigant. Sublethal dosages prolonged the developmental periods of the immature life stages. Dosages lethal to S. granarius caused growth inhibition in E avenaceum and E culmorum, although the fungi recovered fully after treatment. In the presence of high relative humidity, COS was presumably degraded partly to H2S, which caused corrosion on copper. The possibility was discussed of COS being an alternative to methyl bromide. (L)

Sensitivity of Narcissus Flies to Methyl Bromide

S. Navarro, E.J. Donahaye, R. Diaz, Mir iam Rindner and A. Azrieli Dept. of Stored Products, ARO, The Volcani Center, Bet Dagan 50250, Israel

[Fax: +972-3-9604428]

Two species of narcissus fly attack the bulbs of narcissus and amaryllis and pose a serious quarantine threat upon export of these crops from Israel. The only available fumigant for rapid treatment is methyl bromide (MB). However, recent indications of its phytotoxic effects on these bulbs required a re-evaluation of the fumigation schedule. The response of the large narcissus fly (Merodon eques) and the small narcissus fly (Eumerus spp.) to MB were examined in the laboratory. Maggots of both species and pupae of Eumerus were obtained from infested narcissus bulbs and exposed in glass chambers at 28~ to different dosages of MB for 4-h periods. Because M. eques develops inside the bulb, maggots of this species were transferred to chambers gouged inside sound bulbs and the bulbs were placed inside the fumigation chambers. For Eumerus, in which infestation is superficial, maggots and pupae were suspended in cages inside the fumigation chambers. Probit analyses of mortalities revealed that the LD99 was 20.4 g m -3 for Merodon, and 8.6 and 6.5 g m -a , respectively, for Eumerus larvae and pupae. The high dosage required to kill Merodon may be attributed to the requirement that the gas penetrate to the target site. (L)

Analysis of Development Rates of Sitophilus oryzae in Five Different Triticum spp.

E Trematerra, E Fontana and M. Mancini Department S.A. V.A., University of Molise, 1-86100 Campobasso, Italy [Fax: +39-874-98743]

A 'route' to the analysis and comparison of experimental data of Sitophilus oryzae (L.) at a fixed temperature and relative humidity, for five different kinds of cereal grains (Triticum aestivum, T. dicoccum, T. durum, T. monococcum, T. spelta) is proposed.

As far as the cumulative curves of the development rate are concerned, we suggest the use of a simple exponential model which is well known in chemical, physical and biological sciences. The


model takes into account the evolution of a given system from a stable state (e.g. in our case: no insects at all) to another- stable state (e.g. all the insects have reached the adult stage). The main point of our approach lies in the fact that no fitting parameters are required; the only ones required can be measured in a straightforward way from the experimental data.

Even if the model used is the same for all experimental sets, different behaviors appear which correspond to different survival strategies, depending on the food available. In all the examined cases a statistical reliability of over 95% of simulated data was reached.

The correlation between development rate and food choices has been examined, and preliminary results indicate that the relationship between genetic structure of the cereal grains and development rate curves of the insects is significant. (P)

B: BIOLOGICAL RESPONSES OF MICROFLORA TO CA AND~OR FUMIGATION

Growth of Fungi in Atmospheres High in Carbon Dioxide and Low in Oxygen

Ailsa D. Hocking 1 and Marta H. Taniwaki 2 a CSIRO, Division of Food Science and Technology, North Ryde, NSW 2113, Australia [Fax:

+61-2-8873107]; and 21nstituto de Technologia de Alimentos, Campinas SP 13073-001, Brazil

Food- and grain-spoilage fungi are traditionally regarded as aerobic organisms, but some species are efficient scavengers and are capable of near normal growth in very low concentrations of 02. The extent to which fungi are able to develop in low 02 atmospheres often depends on the concentration of CO2 that is present, as atmospheres high in CO2 are often more effective in controlling fungal growth. Although atmospheres of 20% CO2 inhibit the growth of many fungi, >80% CO2 may be required to prevent fungal deterioration in high moisture commodities. The growth of seven species of spoilage fungi was studied in atmospheres where residual 02 was controlled at less than 0.5%, and the COz concentrations were 20%, 40% or 60%, with the balance being the inert filler gas, nitrogen. The potential for mycotoxin production was also assessed. Residual 02 was a much more critical factor than CO2 concentration in reducing growth of Penicillium and Aspergillus species. Mucor plumbeus, Fusarium oxysporum and two Byssochlamys species were able to grow in all atmospheres tested, although growth was reduced as CO2 concentration increased. All species tested were able to grow in an atmosphere of 80% CO2 with 20% 02, but growth was slower than in air, particularly for the Penicillium spp. and A. flavus. Gas composition had a greater effect on mycotoxin production than on growth. (L)

Respiration of Wheat Grain Stored in Different Environments

J. Lacey, 1 A. Hamer 1'3 and N. Magan 2 l lACR-Rothamsted, Harpenden, Herts AL5 2JQ [Fax: +44-1582-760981]; ZBiotechnology Centre,

Cranfield University, Cranfield, Bedford MK45 GAL; and 3Present address: Pesticides Safety Directorate, York Y01 2PX, UK

During aerobic respiration, carbohydrates are oxidized to CO2 and water with the release of energy. Respiratory activity in grain may be measured by the uptake of 02 or the release of CO~ in a closed system or by temperature changes in a well insulated container. We have used an automatic electrolytic respirometer, which constantly monitored 02 uptake and allowed overall measurement of CO2 production, to obtain replicate determinations of respiration rates in 25-g samples of grain at different constant temperatures (15-35~ and water activities (0.65-0.95 a~). Oxygen uptake increased linearly with temperature up to 35~ and with time at water activities above (but not below) 0.90 aw. At low water activities with high germinability, most of the total respiration could be attributed to respiration by the grains themselves. However, at high water activities, germinability

218 Meetings

decreased and microbial respiration came to predominate. Autoclaved grain inoculated with either Eurotium amstelodami or Penicillium aurantiogriseum respired at similar rates at 0.85 a~ and 20~ but 02 uptake by P aurantiogriseum-inoculated grain was much greater than that of E. amstelodami- inoculated grain at 0.90 a,o. Grain inoculated with a mixture of the two species respired similarly to P aurantiogriseum at 0.90 a~, but at a faster rate than either species at 0.85 a~,. Comparisons of 02 consumption and CO2 production generally gave respiratory quotients less than 1.0 except at 15~ Molding was not visible after 7 days at 15~ but increased in intensity from 20 to 35~ Up to 0.13% dry matter was lost before grain was visibly moldy, whereas 0.13-1.24%, depending on temperature and water content, was lost from visibly moldy grain. (L)

Current Strategies for Non-Chemical Control of Molds and Mycotoxins in Stored Grain

N. Paster Dept. of Stored Products, ARO, The Volcani Center, Bet Dagan 50250, Israel

[Fax: +972-3-9604428]

Fungi growing on stored grain can cause heavy damage, which results in losses in quality and quantity. In addition, many species are capable of producing mycotoxins highly toxic to animals and humans. The principal means for controlling storage fungi is the application of mold-inhibiting chemicals. However, such treatments do not conform with the worldwide trend to restrict or even ban the use of chemicals in agriculture. As a consequence, there is an urgent need to find alternative means. The current strategies include: application of physical means, e.g. modified atmospheres and gamma irradiation; the use of natural products; biological control of grain pathogens; binding or inactivation of mycotoxins already present; and an integrated approach using different means, each at low levels, which have shown synergistic interactions. (L)

Effect of Gastight Storage on Growth of Fungi in Paddy Stored Outdoors

EM. Caliboso, 1 S. Navarro, 2 D.G. Alvindia, 1 E.J. Donahaye, 2 G.C. Sabio 1

and M.T. dela Cruz 1 1 National Post Harvest Institute for Research and Extension, Muaoz, Nueva Ecija, Philippines

[Fax: +63-2-9268159]; and 2Dept. of Stored Products, ARO, The Volcani Center, Bet Dagan 50250, Israel

Due to the high temperatures and relative humidity in the Philippines, significant grain losses occur as a result of mold deterioration. The problem is exacerbated when grains are not properly or uniformly dried before storage. This led to an investigation of the effect of hermetic storage using gastight flexible liners, on population changes of fungi in dry conditions (< 14% moisture content) and growth of fungi on intermediate moisture content (16%) paddy stored outdoors.

The concept of gastight storage was tested using specially designed enclosures and employing heavy duty flexible liners developed in Israel. Field evaluations showed that insect infestation was controlled in bagged paddy, with the added benefit of controlling mold growth. Following storage for 1�89 to 6 months no fungal activity was observed. This may be attributed to the effect of the modified atmosphere generated inside the gastight liners. Higher fungal counts were noted at the periphery, bottom and top of the gastight cube. Further observations revealed that the proliferation and prevalence of fungal species were affected by length of storage and by the modified atmosphere inside the gastight liners. (L)


Effects of Controlled Atmospheres and Fumigants on Storage Fungi: A Review of Research Activities at SEAMEO BIOTROP

Okky Setyawati Dharmaputra SEAMEO BIOTROP, Bogor, and Faculty of Mathematics and Natural Sciences, Bogor Agricultural

University, Bogor, Indonesia [Fax: +62-251-32685]

Research activities at SEAMEO BIOTROP on the effects of CO2 and fumigants on the development of fungi in stored products were reviewed in this paper. The effects on fungi of CO2 treatment of maize; phosphine in milled rice, maize and soybean meal; and methyl bromide in milled rice and soybean, were discussed as were studies of the combined effects of CO2 and phosphine on growth and sporulation of Aspergillusflavus.

In maize, CO2 had no significant effect on total fungal populations, but Eurotium chevalieri decreased during storage. Phosphine fumigation reduced Aspergillus wentii and increased E. chevalieri populations in maize, but in soybean meal it caused only a temporary reduction in fungal populations, which rose again during storage. In milled rice stored in jute and polypropylene bags, phosphine retarded growth of the predominant storage species, Aspergillus penicillioides. Methyl bromide reduced total fungal populations, and populations ofEurotium spp. and A. sydowii, in milled rice and soybean 2 days after fumigation, but populations increased again after 45 days of storage.

Mycelial growth and sporulation of A. flavus cultures were partially inhibited by 20% CO2 with 0.5 mg/l phosphine. At 80% CO2 and 3.5 mg/l phosphine, mycelial growth ofA. flavus was almost totally inhibited and there was no sporulation. (L)

Effects of Phosphine and Bag Type on Storage Fungi of Milled Rice

Okky Setyawati Dharmaputra, 1 A.S.R. Putri 1 and M. Sidik 2 1SEAMEO BIOTROP, Bogor, and Faculty of Mathematics and Natural Sciences, Bogor Agricultural

University, Bogor [Fax: +62-251-32685]; and 2Ministry of Food Affairs, The National Logistics Agency (BULOG), Jakarta, Indonesia

The effects of phosphine and bag type on storage fungi of milled rice were investigated together with changes in moisture content. Milled rice was stored in either jute or polypropylene bags under warehouse conditions for 49 weeks. Five stacks of each bag type were constructed, and their positions were selected at random. Each stack consisted of 50 jute bags of 100 kg or 100 polypropylene bags of 50 kg milled rice. The rice was fumigated with phosphine at a rate of 10 tablets/stack or 2 tablets/tonne and an exposure period of 5 days. Fumigation was repeated throughout the experiment, at intervals of 3 months. The fungal population on rice was determined using the dilution method on dicloran 18% glycerol agar (DG 18) before fumigation (at the beginning of storage, and subsequently after 11, 23, 35 and 47 weeks of storage), and immediately after fumigation (at l, 13, 25, 37 and 49 weeks of storage).

During 49 weeks of storage, 21 and 22 species of fungi were isolated from milled rice packed in jute and polypropylene bags, respectively. In both bag types the predominant fungus was Aspergillus penicillioides, which increased sharply from the first week, after which the population remained almost constant, either before or after fumigation. The total count of fungal and A. penicillioides populations on milled rice packed in jute bags was lower than that in polypropylene bags. The population increased until the 1 lth week of storage, thereafter declining slowly in line with the length of the storage period. The moisture content of milled rice packed in jute bags was lower than that of polypropylene bags, but varied with an increase in storage duration in both types of bags. (L)

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C: INFLUENCE OF HERMETIC STORAGE, TEMPERATURE, CA AND~OR FUMIGATION ON QUALITY PRESERVATION OF STORED PRODUCTS

Traditional Hermetic Methods of Grain Storage Used in Cyprus

Eleni Papademetriou I and A. Varnava 2 1Ministry of Education and Culture [Fax: +357-2-445021]; and 2 Cyprus Grain Commission,

Nicosia, Cyprus

Three structures, traditionally used since medieval times for storing grains, are described. Storage in these structures was based mainly on the concept of hermetic storage. The first structure, pilini (in Greek pilos - mud, clay), is a clay pot of 50-500 1 capacity. After the pot was filled with grain, its opening was hermetically sealed with mud. In some cases larger pots were built inside the houses, with an opening at the top for pouring in grain and another one at the bottom for emptying. The second structure,fournos (oven, kiln), was built with stones and mud, had a hemispherical shape, and was located outdoors in the farmyard. Its capacity was about 500-1000 l. Before storing grain in it, a fire was lit inside. Grains were placed inside the fournos after it had cooled off. The third structure, gouffer or gouppa or vouffer (cavity, hollow), was an underground pit built in the open. The walls were plastered with mud and before storing grain, a fire was lit inside it. After the temperature had dropped and the floor was cleaned, grain was poured in; then the opening was sealed with mud.

A pilini of 35-I capacity was tested experimentally for hermetic storage of local wheat for 2.5 months. Oxygen and carbon dioxide concentrations were measured. In the described structures, fire disinfested the space and reduced air humidity. The thick walls of the structures and the mud seal provided a semi-hermetic environment, in which 02 concentration was reduced and COz increased gradually due to respiration of the grain and insects. (L)

7-Year Results of Hermetic Storage of Barley under PVC Liner: Losses and Justification for Further Implementation of this Method for Grain Storage

A. Varnava and C. Mouskos Cyprus Grain Commission, Nicosia, Cyprus [Fax: +357-2-452141]

From 1988 until 1995, barley was stored for 1-3 years at 8-11% moisture content and 32- 38~ on two concrete platforms of 2500 and 4000 tons each, under a 0.8-mm-thick UV-protected PVC liner. In some cases platform floors were covered with a 0.2-mm-thick polyethylene (PE) liner. During storage, grain moisture, temperature, insect infestation, germination and some other parameters were recorded, as were oxygen and carbon dioxide concentrations. At the end of each storage period, mold and total losses were determined.

Covering the floor with a PE liner had a significant effect on intergranular 02 and CO2 concentrations, but not on grain losses. With the PE underliner, 02 and CO2 were 2-6% and 8-12%, respectively; without it, concentrations were 6-10% and 2-4%, respectively.

In samples of mold-damaged grain, zearalenone (760 ppb) and ochratoxin A (1990 ppb) were detected, with a total fungal count of 5.7• 109/g. In sound grain, concentrations of the mycotoxins were zero and total fungal count was 1.6• 106/g. The longer the storage, the higher the mold and total losses: after 1 year of storage they were 0.164-0.1% and 0.324-0.06%; after 2 years, 0.22% and 0.52%; and after 3 years, 0.66% and 0.96%, respectively. After 1 year of storage germination remained >95%, and after 3 years it was >88%. Hermetic storage under PVC protected the grain against insects, birds, rats and rain.

The costs of building and storing hermetically 4000 tons of barley on a concrete platform (25 m wide, 75 m long) under the PVC liner were US $4/ton/year, or US $7.5/ton/3 years. (L)

Phytoparasitica 24: 3, 1996 221

Effects of Variations in Temperatures on the Reproduction of the Rice Weevil, Sitophilus oryzae, and Losses of Wheat in Storage in Bangladesh t

M.A. Malek and B. Parveen BCSIR Laboratories, Rajshahi 6206, Bangladesh [Fax: +88-7214839]

Abundance of the rice weevil, Sitophilus oryzae (L.), in stored grain is directly related to temperature. All stages of S. oryzae died in 1-16 days at temperatures ranging from -9.4 ~ to -1.7~ respectively. Reproduction of S. oryzae was affected by temperature, as indicated by the reduction in number of progeny after 5 months. The rice weevil was dormant at 7.2~ and even failed to mate when the temperature fell below 13~ At 9.5~ the rate of oviposition was low. Hatching and development of the larvae at temperatures between 12.78 and 15.56~ were extremely slow. A grain temperature of 21.1 oC was considered to be the danger line for insect infestation, above which there were high percentage losses of wheat in storage. Temperatures below 15~ are considered as safe for quality preservation of wheat. (P)

Quality Conservation of Paddy Stored Under Gastight Seal Outdoors in the Philippines

S. Navarro, 1 EM. Caliboso, 2 G.C. Sabio and 2 E.J. Donahaye 1 1Dept. of Stored Products, ARO, The Volcani Center, Bet Dagan 50250, Israel

[Fax: +972-3-9604428] and 2National Post Harvest Institute for Research and Extension, Ma~oz, Nueva Ecija, Philippines

Paddy stacks with capacities ranging from 13.4 to 31.9 tons were stored in flexible enclosures, outdoors, for 78 to 183 days. Paddy quality was compared with that of three control stacks (5.3-5.6 tons capacity) held under tarpaulins in the open for 78-117 days. The trials were conducted at the NAPHIRE compound, Nueva Ecija, the Philippines.

The enclosures consisted of heavy-duty PVC-based sheeting, sufficiently gastight to control insect infestations. They were designed in Israel for stacked bag storage ('Volcani cubes') and weld-mesh supported silos in which the paddy is stored in bulk. The upper layers of both storage systems were covered with a layer of rice hulls aimed at reducing temperature gradients, while plastic sheeting placed between this insulating layer and the grain, served to prevent moisture transfer to the top grain layer. Moisture content, grain temperature and gas concentrations were measured throughout the trials.

Initial and final samples were taken to determine changes in paddy quality. Insect infestation, fungal infection, milling recovery, head rice, yellow kernels, brokens, germination and weight loss were analyzed. Percent milling recovery and levels of yellowing in the gastight stacks showed no significant change. The levels of head rice and brokens were preserved in seven out of nine stacks. A decrease in percent of head rice in two stacks was attributed to the biological aging phenomenon. The two control stacks showed decrease in head rice and increase in brokens. Rice yellowing was very pronounced in one of thecontrol stacks. (L)

Potential for the Storage of Cereal Grains under Sheeted Bag Stacks in Ghana t

K.A. Dzisi 1 and W.O. Ellis 2 1Dept. of Agricultural Engineering and ~ Dept. of Biochemistry, University of Science and

Technology, Kamasi, Ghana [Fax: +233-51-60137]

t Paper not presented at the Conference.

222 Meetings

A comparative study was carried out of the storage of cereal grains in a warehouse in sheeted and unsheeted bag stacks. Temperature and moisture content changes were monitored, microbial examinations were conducted and chemical composition was analyzed during the storage period and compared. Temperature and moisture content changes in both stacks did not vary considerably over the storage period. Microbial examination of the grains revealed that viable bacterial counts and mold and yeast counts were much higher in the sheeted than in the unsheeted stack. Observations also showed that the percentage of damaged grains in the samples increased faster in the sheeted than in the unsheeted stack.

We examined the potential for the storage of cereal grains under sheeted cover in Ghana based on the results of the initial study and weather conditions in different parts of the country. Climatographs of four different agro-climatological zones were presented, with suggestions on the possibility of siting strategic sheeted bag stack storage facilities where storage conditions are best. (L)

Use of Controlled Atmospheres in Storage of Small Coconut Fruits t

Ana Maria Estevez, Ljubica Galletti, T. Fichet and E. Oteiza Centro de Estudios Postcosecha, Facultad de Ciencias Agrarias y Forestales, Universidad de Chile,

Casilla 1004, Santiago, Chile [Fax: +56-2-6785700]

Chilean palm fruit (Jubaea chilensis (Mel) Baillon) is a small coconut with a high lipids content (ca 59%). For this reason they are very susceptible to oxidative rancidity. Oxygen and high temperatures are predisposing factors to oxidative reactions. Research was conducted to study the effect of two storage temperatures and two controlled atmospheres on the quality of small coconuts. Fruits harvested in May were shelled and stored for 8 months under six different conditions: two storage temperatures, 0 ~ and 12~ two controlled atmospheres (C.A.), 5% O2/0% CO2 and 5% O2/10% CO2; and two controls, run at 0 ~ and 12~ at normal atmosphere. Coconuts were analyzed for moisture content, peroxides and tannins. Moisture content ranged between 3.0% and 5.6%; the lower values were those of the fruit kept in C.A. 5% 02/0% CO2. Peroxides development (oxidative rancidity) was significantly lower in all the C.A. studied, as compared with the level observed in both controls. Coconuts stored at 0~ had the lowest level of peroxides. Tannin content did not show changes in small coconuts stored under different temperature and C.A. conditions. C.A. storage at 0~ preserved small coconut quality for at least 8 months. (P)

Effect of Storage in Controlled Atmospheres on Chestnut Quality t

Ana Maria Estevez, L.A. Lizana and M.X. Gonzalez Centro de Estudios Postcosecha, Facultad de Ciencias Agrarias y Forestales, Universidad de Chile,

Casilla 1004, Santiago, Chile [Fax: +56-2-6785700]

Maintenance of chestnut fruit (Castanea sativa, var. 'Miller Gard') at room temperature lessens quality losses; under refrigeration, fruit is subjected to dehydration, which reduces its processing capacity. Research was carried out in order to evaluate the effect of storage under controlled and modified atmosphere conditions, upon the quality of chestnuts for preparation of 'marron glac6'.

Chestnuts harvested in April were stored for 9 months at 0~ and 95% r.h. under the following conditions: controlled atmospheres (C.A.) 5% 02/0% CO2 and 5% O2/20% CO2; and modified atmospheres (M.A.) in two types of films, namely: 'Cryovac' impermeable to CO2, 02 and water vapor, and 'Cryovac' impermeable to 02 and water vapor but semi-permeable to CO2. Every 2 months chestnuts were analyzed for moisture content, total sugars, reducing sugars and starch. Also 'marron glac6' was prepared and subjected to sensory evaluation for color, texture and overall acceptability.



The moisture content of chestnuts under all the above storage conditions was considered good at the end of the conservation period. Nuts stored under C.A. lost the highest amount of starch (from 75% to 52%); when stored under M.A., total sugar increased significantly but reducing sugars decreased by the fourth month, followed by a slow rise. Chestnuts conserved in the totally impermeable film produced 'marron glacC with the best texture, color and acceptability. (P)

Control of Beeswax Moths Using Carbon Dioxide in Flexible Plastic and Metal Structures

B. Yakobson, 1 S. Navarro, 2 E.J. Donahaye, 2 A. Azrieli , 2 Y. Slavezky 3 and H. Ephrati 3 1Kimron Veterinary Institute, Bet Dagan 50250 [Fax: +972-3-9681721]; 2Dept. of Stored Products,

ARO, The Volcani Center, Bet Dagan 50250; and 3Agricultural Extension Service, Ministry of Agriculture, haQirya, Tel Aviv 61070, Israel

The building structure of bee hives is based on the wax cells produced by the bees. Of the species that attack beeswax, the most important is Galleria mellonella, the greater wax moth, and protection of stored combs against this pest is of high priority, especially in hot climates. A new approach in controlling this pest has been to replace the traditionally used chemical methods such as fumigation with EDB, by environmentally sound methods. We propose the controlled atmosphere methodology using CO,, for insect control and subsequent protection of honey supers during storage. The results of field tests using mixtures of CO2 in air at concentrations ranging from 50% to 75%, over a range of exposure periods, were presented. The tests were undertaken using plastic enclosures of 12 m 3 capacity, and specially sealed 20-foot freight containers of 34 m 3 capacity. Both methods enabled complete control of the wax moths and subsequent protection from reinfestation. The containers had the inherent advantage of their rigid structure, which provided better protection from rodents and pilfering. However, each container requires specific sealing procedures followed by sealing tests. The plastic enclosures were found to be suitable for smaller enterprises, had the advantage of ease of portability and installation at the storage site, and the structural seal was checked during manufacture. They have been under continual use for 5 years. (L)

Influence of Fumigation on Quality of Stored Products in Morocco: Investigation of Alternatives t

E1-H. Bartaly Dept. of Agricultural Engineering, Institute Hassan H of Agronomy and Veterinary Medicine, Rabat

Institute, Rabat, Morocco [Fax: +212-7-670303]

Individual farms do not have easy access to the purchase and use of phosphine in their storage structures. This is justified by the hazards associated with the application of the product. Phosphine is generally sold only to grain storage cooperatives which have appropriate licenses. In order to investigate alternatives to be used for grain protection on farms, a study was conducted of polyethylene-lined farm silos between 1992 and 1994 with funds provided by the Moroccan Ministry of Agriculture. Alternatives considered in this investigation include: (a) the use of a local plant, hot pepper, for its insect-repellent properties; this plant is available on farms or can be obtained at affordable prices; (b) no treatment, since the polyethylene bags used to line the interior of the silos provide improved airtight conditions, particularly for underground silos.

Barley and fava beans were stored over a period of 2 years in underground silos and aboveground reed silos, respectively. During this period, temperature and relative humidity were


224 Meetings

monitored using data loggers and a portable microcomputer and the grain characteristics, including specific weight, grain damage and dry weight loss, were determined in the laboratory.

Influence of Fumigation on Seed Quality: Prospects and Review t

R.K. Kashyap CCS Haryana Agricultural University, Hisar 125 004, India [Fax: +91-1662-32120]

Healthy and viable seed is the first requisite for increased crop productivity. Seed stocks are fumigated for effective protection from insect-pest infestation during storage. Deterioration of seed quality is more pronounced at the farmers' level, since storage facilities are not sound, particularly in tropical and subtropical regions. Deleterious effects of EDB fumigation on seed quality, viz., germination and seedling vigor index, have been reported in several crops. Differential reaction of cultivars as regards deteriorating seed quality, due to phosphine and methyl bromide fumigation, have been reported in wheat, barley, oats, rice, legumes and broadbean. A single phosphine fumigation had no effect on the seeds of cereals, legumes, cotton and vegetable crops, although repeated fumigations affected the parameters of seed quality of most crops' seeds. Higher seed moisture content and fumigation dose and longer exposure period contribute significantly toward increased loss of seed viability, chromosomal aberrations and mutagenic effects. This influence of fumigation on seed deterioration has important implications during evaluation of old seed stocks, which are often stored for extended periods in tropical and subtropical regions. Factors associated with efficient fumigation in seed stores without accompanying detrimental effects on seed quality were discussed. (L)

Effect of Phosphine Fumigation on Seed Quality of Vigna radiata

M. Gupta, W.L Kashyap and B.S. Dahiya Seed Technology Centre, CCS Haryana Agricultural University, Hisar 125 004, India

[Fax: +91-1662-32120]

Green gram (Vigna radiata, cv. K-851) seed of 9% and 12% moisture content (m.c.) was fumigated with three doses (0.125, 0.250 and 0.500 mg/l) of phosphine gas for various exposure periods to evaluate its effect on seed quality, i.e., germination, viability and seedling vigor index. An increase in phosphine or repeated fumigations reduced the quality of seeds at 12% m.c. The standard germination of seeds at 9% m.c. and exposure to 0.500 mg/l phosphine was equal to the seed lot at 12% m.c. and exposure to 0.125 mg/l phosphine. Seed viability and seedling vigor index were influenced by repeated fumigations and also by the combination of exposure period and seed moisture content. The study highlighted the possible problems with phosphine fumigation at different doses and seed moisture contents, and has implications in the evaluation of old, carried- over seed stocks.

Phosphine Residue and Its Dissipation from Some Legumes Fumigated with Quiekphos t

A.K. Dash, J.R. Rangaswamy and R.D. Shroff R&D Laboratory, United Phosphorus Ltd., Vapi 396 195, India [Fax: +91-22-6487523]

Legumes fumigated with Quickphos (aluminum phosphide) dosed at 6 tablets/ton exhibited different levels of free phosphine residue. Green gram (Vigna radiata) dhal had the highest free



phosphine residue (0.096 mg/kg), followed .by green gram (0.071 mg/kg), Bengal gram (Cicer arietinum, 0.061 mg/kg) and Bengal gram dhal (0.028 mg/kg). Green gram dhal, with its smaller surface area, holds more free phosphine residues than Bengal gram dhal, which has a large surface area. Also, after one day of exposure to air, the loss of residue from green gram dhal (87.5%) was more than that from Bengal gram (78.9%). These observations suggest that the free residue and its loss during exposure to air depend more on the phosphine-holding capacity of the legume than on its surface area. During storage, pre-alred Bengal gram dhal had the highest computed phosphine residue (0.13 mg/kg), which persisted for 33 days, followed by Bengal gram (0.124 mg/kg, 11 days), green gram (0.084 mg/kg, 20 days) and green gram dhal (0.04 mg/kg, 10 days). One-day-aired Bengal gram (0.012 mg/kg, 11 days), green gram (0.009 mg/kg, 16 days), green gram dhal (0.005 mg/kg, 7 days) and Bengal gram dhal (0.0039 mg/kg, 12 days) show low levels of computed residue during storage. Amounts of inorganic phosphorus in green gram and Bengal gram dhal were 0.9 and 0.07 mg/100 g, respectively, and zero in Bengal gram and green gram dhat, suggesting that phosphine oxidation is negligible during fumigation and storage. There appears to be no relation between moisture content of the legumes and amount of unspent aluminum phosphide after fumigation (values significant at P<0.00I).

D: PHYSICAL AND CHEMICAL PROCESSES IN THE APPLICATION OF CA AND/OR FUMIGATION

Mathematical Models for Carbon Dioxide Distribution and Loss

D.S. Jayas, 1 W.E. Muir I and N.D.G. White 2 1Dept. of Biosystems Engineering, University of Manitoba, Winnipeg R3T 5V6, MB [Fax: +1-204-2750233]; and 2Agriculture and Agri-Food Canada, Research Centre,

Winnipeg R3T 2M9, MB, Canada

A mathematical model was developed for predicting the distribution of carbon dioxide (CO2) through bulk grains. The model was solved using a finite element method and can be used for any shape or size storage structure, provided that the structure can be discretized into 8-node brick elements and input data can be created for the model. The model was developed in stages. Initially, it was based on pure diffusion of CO2 through bulk grain. In its current form, the model includes diffusion and bulk movement of CO2 within the grain bulk and sorption or desorption of CO2 by grain. The predictions of the model, in its various stages of development, were compared with the experimental data on distribution of CO2 from three pilot-scale bins (ca 1.5 m in diameter and 1.5 m high). The details of the model and the results of the comparison of the predictions with the measured data were given in the paper. In addition, two mathematical models reported in the published literature were evaluated using experimental data for their capability to predict the loss of CO2 from storage structures. The results of this evaluation were included in the paper. The use of the mathematical models as an engineering design tool, and the need for further research in the development of mathematical models, were discussed. (L)

Sorption of Carbon Dioxide by Wheat

S. Navarro Dept. of Stored Products, ARO, The Volcani Center, Bet Dagan 50250, Israel

[Fax: +972-3-9604428]

Sorption of CO2 by soft red winter wheat was tested in 1-I jars containing 700 g grain of 12.9% moisture content and filled to 93% of the jar's capacity. In the first series of experiments, the jars

226 Meetings

of wheat were purged with CO2 to contain an initial concentration of 99.8%. The jars were sealed and pressure changes were recorded periodically at different time intervals. All tests were carried out at temperatures of 15 ~ 20 ~ 25 ~ and 30~ In a second series of experiments different CO2 partial pressures ranging from 30.6% to 98.6% were maintained in the filled jars at 25~

In the first series of experiments the sorption rate changed inversely with temperature of the wheat, the highest sorption being recorded at 20~ The higher the temperature, the shorter the time that was required for the sorption to reach steady state equilibrium. The times required to reach equilibrium varied inversely with temperature and were 65, 80, 95 and 120 h at temperatures of 30 ~ 25 ~ 20 ~ and 15~ respectively. Maximum sorption also varied inversely with temperature and was 260, 297, 331 and 393 mg CO2/kg of wheat at 30 ~ 25 ~ 20 ~ and 15~ respectively. A linear relationship was found between sorption of CO2 and the partial pressure at a constant temperature. This was in accordance with Freundlich's classic adsorption isotherm. Using this equation, the sorption of wheat at 25~ for any given CO2 concentration in the range studied in our tests, can be calculated. (L)

Sorption of Fumigants by Cut Flowers

Gaye L. Weller and J.E. van S. Graver Stored Grain Research Laboratory, CSIRO, Division of Entomology, Canberra, ACT 2601, Australia

[Fox: +61-6-2464202]

A study was conducted of sorption of three fumigants (carbonyl sulphide, methyl bromide and phosphine) by two flower species, field carnations (Dianthus sp.) and kangaroo paw (Anigozanthos hybrid). Flowers were fumigated in stainless steel chambers at concentrations recommended for use on cut flowers or similar commodities: carbonyl sulphide, 15 mg l-1; phosphine, 0.25 mg l-1; and methyl bromide, 32 mg l-1. The sorption profiles were different for each of the three fumigants and were relatively constant across the flower species. The highest sorption was observed with carbonyl sulphide. After 7 h there was no measurable level of carbonyl sulphide in the fumigation chambers (100% loss), a 33% loss of phosphine, and a 5% loss of methyl bromide. Further study is warranted to determine whether the gas loss, particularly with carbonyl sulphide, is due to sorption by the flowers or to hydrolysis of the fumigant. (L)

Penetration of Phosphine among the Corn Grains in a Silo t

Wu-Kang Peng Dept. of Plant Pathology, National Taiwan University, Taipei, Taiwan 106 [Fox: +886-2-7332620]

Before the silo was filled with corn, 4-mm-diameter plastic tubing was installed in the silo at depths of 0, 5, 10, 15 and 20 m from the top. All tubing was led outside the silo to a pump that pumped the gas samples from the silo into a phosphine monitor. One thousand five hundred tablets, each weighing 3 g and containing 57% aluminum phosphide, were applied at the surface of the grain- mass in a silo containing 600 tons of corn. The tablets generated phosphine while reacting with water or moisture in the air. The phosphine penetrated among the grain interstices down to the bottom of the silo and was measured every ca 24 h. Recordings showed that phosphine concentration reached a maximum of 1090 ppm after 24 h at the grain surface, whereas only 45 ppm was measured at the bottom. Gas distribution was reported in detail. (P)



Efficacy of Phosphine Fumigations of Bagged Milled Rice under Polyethylene Sheeting in Indonesia

M. Bengston 1 and E. Alip 2 1 Queensland Department of Primary Industries, Indooroopilly, Qld 4068, Australia

[Fax." +61-73-8969440]; and 2Ministry of Food Affairs, The National Logistics Agency (BULOG), Jakarta, Indonesia

Phosphine fumigation is the major means of pest control in milled rice in government godowns in Indonesia. In the tropical climate, insect infestation is severe and phosphine fumigation is required every 3 months. The predominant pest species are Tribolium castaneum (Herbst) and psocids, chiefly Liposcelis entomophilus (Endedein). The fumigation enclosure comprised a single polyethylene (PE) sheet 0.125 mm thick covering two adjoining stacks, each approximately 300 tons and thus totaling approximately 600 tons of grain. The PE sheeting was sealed to the concrete floor by weighting with fumigation chains around the perimeter of the enclosure. The nominal dosage of phosphine was 2 g/ton plus an allowance of 5% for walkway space, and was applied as tablets containing aluminum phosphide. Phosphine concentrations were monitored throughout the fumigation using portable electronic meters with the capacity to determine carbon monoxide separately. In a 5-day fumigation, the concentration x time product exceeded 150 mg 1-1 h -1. Fumigations involving sheeting in poor condition, fumigation enclosures with two sheets joined only by overlap, or fumigations without chains all produced much lower concentration x time products.

The phosphine concentrations were discussed in relation to the rate of release of phosphine from the aluminum phosphide, the rate of sorption/desorption on milled rice, and the rate of permeation of phosphine through the PE sheet and the woven polypropylene bags. Complete kill of both species is possible in this type of fumigation, but reports of strains from Indonesia of L. entomophilus with enhanced tolerance to phosphine suggest that complete kill is not always achieved in practice. Meters capable of monitoring phosphine concentrations in the field have now been issued to operational staff and should reduce the frequency of fumigation failure. (L)

Influence of Grain Temperature on Efficacy of Fumigation in Leaky Bins

C. Reed Dept. of Grain Science and Industry, Kansas State University, Manhattan, KS 66506, USA

[Fax: +1-913-5327010]

Hard wheat at 20 ~ 25 ~ and 30~ was fumigated with an aluminum phosphide formulation in small cylindrical grain bins of corrugated metal. The bins were provided with sufficient open area to approximate leakage rates commonly encountered in farm- and commercial-scale bins of this type. Fumigant concentration profiles were ascertained over a 10-day period. Leakage and fumigant sorption rates at each temperature were ascertained by comparing the fumigant profiles with those obtained in a sealed barrel fumigated at the same temperatures with and without the same grain.

Grain temperature affects the length of time that stored-grain insects remain in fumigant-resistant stages. Therefore, the effect of temperature on concentration profiles was compared with the effect on insect development. The 25 ~ and 30~ grain temperature conditions appeared to provide the greatest likelihood of a complete kill, since concentrations lethal to early egg stages of Rhyzopertha dominica (Fab.) were observed within 3 days, and concentrations remained lethal after half the egg development time. However, variation in fumigant concentrations was larger at 30~ indicating a greater likelihood of insect survival in underdosed parts of the grain mass. The 20~ condition would excessively prolong the time spent in fumigant-resistant stages, reducing the likelihood of a complete kill. (L)

228 Meetings

Methyl Bromide Emission Control from Commodity Fumigation

J.G. Leesch 1 and G.E Knapp 2 1USDA-ARS, Horticultural Crops Research Laboratory, Fresno, CA 93727 [Fax: + 1-209-4533088];

and 2 GFK Consulting Ltd., San Clemente, CA 92672, USA

A proprietary process to control emissions of methyl bromide (MB) to the atmosphere following the fumigation of commodities is described. The process consists of trapping the MB on an appropriate adsorbent, such as activated carbon, reactivation of the carbon for further use as an adsorbent, thermal destruction of the desorbed MB, and the recycling of its bromide content for reuse in the manufacture of new MB and/or other brominated compounds. Research was undertaken to observe the effects of: temperature; relative humidity (r.h.); trapping speed (i.e., MB concentration in the aeration stream); and carbon type on the amount of MB that could be loaded on the activated carbon. Tests revealed that temperature seems to have the most effect on the loading of each carbon while the loading of various carbons is different, possibly due to the different source material from which each of the carbons tested was made. Temperatures on the activated carbon column rose in response to the adsorption of MB and could be followed down the carbon bed to the breakthrough point reached when the adsorption process reached the bottom of the column. Relative humidity of the in-flowing stream may not be important due to the heating of the column and the simultaneous lowering of the r.h. as it reaches the point of adsorption.

This process offers a procedure which does not interfere with established fumigation schedules used for quarantine purposes. No concern for the sorption of commodity volatiles is necessary because there is no recycling. (L)

E: APPLICATION METHODOLOGY OF CA AND~OR FUMIGATION, INCLUDING USE OF C02 UNDER INCREASED PRESSURE

Siroflo | A Better Way to Fumigate Grain

R.G. Winks 1 and G.E Russell 2 CSIRO, Division of Entomology, 1SCMC Nambour, Qld 4560 [Fax: +61-74-789489] and

2Canberra, ACT2601, Australia

Although phosphine has been used to fumigate grain in unsealed storages for many years, such usage is not an acceptable option in any on-going fumigation strategy. At best it will lead to an illusion of success by killing the mobile stages; at worst it will promote the selection for phosphine resistance. Similarly, methods such as 'trickle-flow' or regular 'top-up' of concentrations in storages that are not sealed, are equally unacceptable.

With the development of Siroflo | a technique designed for both sealed and unsealed storages, the questions concerning fumigation strategies and whether or not some storages should be sealed, have been brought into focus. The choice of fumigation strategy can now be between the use of sealed storages with recirculation or with passive distribution of gas or, alternatively, the use of a positive pressure distribution system in storages that may or may not be sealed. An understanding of the behavior of gases and the factors that give rise to gas loss is a primary consideration in examining this question. Other factors that will influence the choice include the geometry of the structure and the costs of the options available. The relative merits of the alternative strategies were discussed. (L)


The Use of On-Site-Generated Atmospheres to Treat Grain in Bins or Floor Stores

C.H. Bell, S.T. Conyers and L.B. Llewellin Central Science Laboratory, Ministry of Agriculture, Fisheries and Food, Slough, Berks. SL3 7H J,

UK [Fax: +44-1753-824058]

Systems available for on-site generation of low oxygen atmospheres for application to typical storage structures were described. The performance of a propane burner in generating and maintaining an atmosphere lethal to stored grain pests was evaluated for three bins and a small floor store. Under reasonably calm conditions, a flow rate of 4.5 m~/h was required to maintain an atmosphere containing <1% 02 in a bin containing 290 tonnes of grain, compared with 11.5 m3/h for a bin loaded with 810 tonnes of barley and 12 m3/h for a bin containing 1150 tonnes of wheat. The 100-tonne bulk of floor-stored grain was held in a 1% O2 atmosphere by a maintenance flow rate of 9 m3/h. The results were discussed in the context of sealing problems, the effect of interruptions caused by windy weather or wide temperature fluctuations, and application costs. A provisional dosage schedule, based on the current and previous work, was presented. (L)

On-Site Production of Nitrogen for Stored-Product Disinfestation

C.S. Adler, Ch. Ulrichs and Ch. Reichmuth Federal Biological Research Centre for Agriculture and Forestry, Inst, for Stored Product


Controlled atmosphere (CA) treatments for the disinfestation of stored products and materials are considered to be environmentally friendly, residue-free and safe for workers at doses of up to 5000 ppm (CO2) or higher (N2). In some areas of stored-product protection, CAs may replace the use of toxic fumigants or contact insecticides. The use of this alternative, however, is limited to highly gastight enclosures with leakage rates that do not render the treatment uneconomical. While the costs for structural sealing and treatment supervision may not be reduced easily, the costs for gas supply - especially in areas remote from industrial gas production sites - could be cut by flexible on-site production.

A membrane system and a pressure swing absorption (PSA) unit were tested under semi- practical and practical conditions. It was demonstrated that at ~20~ an 02 content of 0.5% was sufficient to kill the granary weevil, Sitophilus granarius, and other stored-product pests within 6 weeks in a very gastight welded steel silo bin. When N with 0.5% residual 02 and a flow rate of 5 m3/h was introduced from below into a grain-filled 188 m 3 concrete silo bin with a pressure half-life of >30 sec, diffusion of 02 into the silo resulted in 02 contents of 3% at the top. It is concluded that membrane and PSA systems are valuable techniques for the on-site production of large or smaller quantities of hypoxic atmospheres, but that the use of N is limited to well sealed silo bins, containers or chambers. Such gastight seals could be achieved by metal covers, glass, plastic

foils or gas-impermeable coatings. (L)

Purging Grain Bulks with Nitrogen: Plug Flow and Mixing Processes Observed under Field Conditions

H.J. Banks and EC. Annis Stored Grain Research Laboratory, CSIRO, Division of Entomology, ACT 2601, Australia

[Fax: +61-6-2464202]

230 Meetings

Many experimental, full-scale applications of nitrogen gas to grain bulks have been extensively monitored. These trials have shown that there are often substantial deviations in practice from the theoretical behavior expected when a gas, such as nitrogen, is used to displace air from a particulate commodity such as cereal grain in storage. In its most efficient form, plug flow in the grain bulk can be expected, followed by dilution of the headspace by the incoming nitrogen. In practice there is some dispersion as the purging front transits the bulk. The degree of dispersion is dependent on several factors, notably the face velocity of the front, with higher velocities reducing dispersion. Dilution of the headspace generally follows the expected logarithmic fall in oxygen content with time. Some areas of grain bulks, in practice, are not effectively purged by disperse plug flow processes, but lose oxygen by dilution, leading to inefficient use of purge gas. These areas are apparently associated with low-pressure gradients or high levels of non-grain material (e.g. grain dust). Examples of various problems encountered in purging grain bulks with nitrogen for controlled atmospheres were presented; all were drawn from full-scale practice. (L)

A Cost-Benefit Analysis of Current Nitrogen Fumigation Technologies in New South Wales, Australia t

R. Allanson GrainCorp Operations Ltd., Sydney, NSW 2000, Australia [Fax: +61-2-3259180]

Use of nitrogen-based technologies to produce low-oxygen atmospheres for grain fumigation was evaluated in a series of trials conducted in New South Wales, Australia. The trials were specifically directed at providing comprehensive cost-benefit appraisals of nitrogen use at a variety of storage locations. The evaluations indicated that particular locations and customer needs dictated which technologies were most cost-effective for grain handling companies and, ultimately, grain end-users. Bulk tanker-fed vessels for silo purging and atmosphere maintenance were found to be most cost-effective for grain silos with high throughput rates, within a nominal radius of commercial nitrogen plants. As a result, the use of nitrogen was competitive with methyl bromide costs at these silos and subsequently replaced methyl bromide for grain fumigation. For silos outside this radius, direct purging from the tanker, plus use of pressure swing absorption (PSA) or membrane nitrogen generators for atmosphere maintenance, was more cost-effective than tanker-fed vessels. While the costs of such treatments were more expensive than those of conventional phosphine fumigation, they were quite acceptable to customers demanding only nitrogen for grain preservation/fumigation. It was concluded that current nitrogen technologies are sufficiently flexible to be customized to individual needs and still remain cost-effective. (L)

Speed of Gas Exchange with Oxygen during Treatment of Compressed Tobacco with Nitrogen or Carbon Dioxide for Pest Control

Ch. Ulrichs, 1 Ch. Reichmuth, 1 R. Tauscher 2 and K. Westphal 3 1 Federal Biological Research Centre for Agriculture and Forestry, Inst. for Stored Product

Protection, D-14195 Berlin [Fax: +49-30-8304284]; 2Technical University Munich, Inst. of Thermodynamics, D-80290 Miinchen; and 3BAT Cigarette Factory GmbH, D-22761 Hamburg,

Germany

Tobacco suffers from infestation by the cigarette beetle Lasioderma serrieorne and the tobacco moth Ephestia elutella. Most of the control measures tend to leave chemical residues. Nitrogen and carbon dioxide are proposed for use as disinfestants. The exposure time required for complete



control depends on the time required for the gas to replace the oxygen, and in large compressed bales the inert gases must diffuse into the center of the bale, where the insects may reside. In laboratory experiments under controlled climatic and fumigation conditions, the diffusion time was determined to achieve complete exchange with air inside the tobacco bale. At room temperature, high concentrations of both gases were reached in the center within ca 6 h, with a corresponding decrease in the oxygen content. (L)

Studies of the Practical Application of Biogenerated Carbon Dioxide from Rice Bran for Stored-Product Insect Control t

S. Mohan, M. Gopalan, P.C. Sumdarababu and V.V. Sree Narayanan Dept. of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore 641003, India

[Fax: +91-422-41672]

Rice bran composted at a moisture content of 80% in a specially designed biogenerator, produced an atmosphere containing approximately 40% carbon dioxide. An average of 1 l of gas was produced from l kg of the substrate, with the gas pressure ranging from 1.23 to 1.45 kg/cm 3. The biogenerated gas completely disinfested a grain bin artificially inoculated with stored-product insects within a period of 28 days, by which time there were even concentrations of CO2 (20.0-20.5%) in all layers of the bin.

Control of Pests in Cocoa Beans and Hazelnuts with Carbon Dioxide under High Pressure

Sabine Prozell, 1 Ch. Reichmuth, 1 G. Ziegleder, 2 B. Schartmann, 3 R. Matissek, 3 J. Kraus, 4 D. Gerard a and S. Rogg 5

1 Federal Biological Research Centre for Agriculture and Forestry, Inst. for Stored Product Protection, D-14195 Berlin [Fax: +49-30-8304284]; 2Fraunhofer Inst. for Food Technology and

Packaging, D-80992 Miinchen; 3Association of German Confectionery Industries, D-51063 Kgln; 4 Carbo Carbon Dioxide Factory, D-53557 Bad Hrnningen; and 5Technical University Berlin, Inst.

for Process Engineering, D-10623 Berlin, Germany

Agricultural raw products in the food processing industry, such as cocoa beans and hazelnuts, require quick disinfestation prior to storage. Such a preventative treatment should not lead to any reduction in quality including buildup of chemical residues. A recently developed effective control method for this purpose is exposure of the commodity to carbon dioxide under pressure of 20--40 bar for a few hours. The experiments consisted of the insertion of 12 species of caged insect pests at their different developmental stages in 1 tonne of bagged commodity in a 3-m 3 chamber. Results showed that at a temperature of ca 10~ under 20-bay of carbon dioxide, the lethal exposure period for treatment was 3 h, which was approximately 1/5 longer than at 20~ Complete control at 30 bar and 37 bar at 20~ was achieved within 1 h and 20 min, respectively. The data were compared with laboratory results. The rate of distribution of the gas depended on the nature and density of the product.

Examination of cocoa beans after all treatments showed that quality had not changed, whereas with hazelnuts there was a tendency for the treated nuts to turn rancid earlier than the untreated ones. (L)


232 Meetings

Carbon Dioxide under High Pressure to Control the Cigarette Beetle, Lasioderma serricorne

Ch. Ulrichs, Ch. Reichmuth and W. Raemann Federal Biological Research Centre for Agriculture and Forestry, Inst. for Stored Product


Pressurized carbon dioxide is able to control most of all important insect and mite pests within a few hours. A quick increase of pressure from a few to 20 bars and a subsequent decrease to atmospheric pressure within a few minutes reduces the lethal exposure time to less than 1 h. This short treatment time renders the method attractive for pest control and especially feasible with high value products such as medicinal products of plant origin, spices, herbs, teas, tobacco, cocoa, beans and nuts. Pressure-tight chambers of up to 30 m 3 capacity are in use for short-exposure pest control, with a carbon dioxide recapture apparatus to reduce gas emission. The lethal effect seems to consist of a combination of increased solution of CO2 in the insect tissues leading to reduction in pH or increase in acidity, as well as rupture of cell membranes following depressurization.

The cigarette beetle, Lasioderma serricorne, causes severe losses in the tobacco processing industry; laboratory and practical results were presented describing the possibility of controlling this pest at various pressures of CO2 at different temperatures. (L)

Gaseous Phosphine - A Revitalized Fumigant

R.E Ryan BOC Gases Australia Limited, Chalswood, NSW 2067 Australia [Fax: +61-2-9928-3919]

Phosphine-generating formulations, commercially available for some 50 years, have made significant contributions to grain protection. A patented non-flammable gaseous phosphine formulation, Phosfume TM, overcomes the flammable hazard associated with quick release of gaseous phosphine from metallic phosphide formulations and offers controlled dosing of phosphine to enable the expansion of traditional phosphine fumigation applications. The gaseous phosphine formulation is a compressed liquid gas mixture of phosphine and carbon dioxide dispensed through innovative equipment to deliver the appropriate gaseous phosphine flow required to satisfy a wide range of concentrations and exposure times (CT) options. Phosfume TM has been adopted by the Australian bulk grain authorities who have successfully treated in excess of 15 million tons of grains using traditional fumigation procedures in sealed storage and flow-through fumigation (Siroflo| in non-gastight structures. International interest is intense, with a number of countries actively planning adoption of this fumigation technique. The ability to deliver high concentrations of phosphine instantly has initiated investigation of the use of phosphine as a replacement for the 'ozone-depleting' methyl bromide in disinfestation treatment. The identification and elimination of contaminants formed by phosphine reacting with atmospheric oxygen, uncovered new aspects of phosphorus chemistry. The recently patented multi-component, non-flammable, compressed gas formulation developed to reduce production and dispensing costs of the liquefied gas mixture, supports gaseous phosphine as the revitalized fumigant. (L)

Study of a Phosphine Fumigation in a High-Walled Horizontal Warehouse Using Circulationi

Ya-Nan Wang Sichuan Province Grain Bureau, Chengdu 610012, PR. China [Fax: +86-661818]

r Paper not presented at the Conference.


Fumigation of a horizontal warehouse 5 m high and 20 m wide poses a difficult problem, particularly for control of pests at the middle or bottom of the grain bulk. With these pre-conditions a new system has been developed, termed high-walled warehouse fumigation with phosphine circulation. The systemcomprises three parts: a phosphine generator, piping for introducing and extracting the air, and a fan. Trial fumigations have shown that: (i) the circulation system produces even concentrations of PH3 throughout the grain bulk, enabling more than threefold prolongation of exposure times; and (ii) contact with PH3 by the operator is reduced, and dosage is decreased, thereby resulting in financial savings. (L)

Economic Feasibility of Phosphine Recirculation Systems in Sealed Silos at U.S. Grain Elevators

R.T. Noyes, 1 P. Kenkel, 1 J.T. Criswell 2 and G.W. Cuperus 3 1Biosystems & Agricultural Engineering Dept. [Fax: + 1-405-7449693]; 2Agricultural Economics

Dept.; and 3Entomology Dept., Oklahoma State University, Stillwater, OK 74078, USA

A closed loop fumigation (CLF), or gas recirculation, system for phosphine fumigation using a low-volume blower/piping system per tank was patented by James Cook in 1980. To make CLF more effective, two large steel tanks (2,000 to 10,000 tonnes/tank) were manifolded to one blower in 1992. The manifolded phosphine recirculation (MPR) system design concept was expanded to include concrete silos in 1995 through an EPA grant. To make concrete CLF systems cost effective as 2,000- 10,000 tonne steel tanks, MPR designs for 3 to 18 silos manifolded to one blower were developed as 1,500-20,000 tonne storage units in 1995. Economic data on sealing, plumbing and blower equipment costs vs fumigated storage volume (cost/unit volume) for these concrete silo installations were compared to the 12-steel-tank MPR systems in the EPA study. Costs of installed MPR systems and operating cost data from MPR systems built from 1991-1995 were also reviewed.

In this CLF system demonstration, Oklahoma State University supplied almost all of the MPR piping systems, including blowers, for all cooperating elevators. Each elevator manager was responsible for construction/wiring costs to install the system. (L)

An Investigation into Safe Disposal of Phosphine-Generating Formulations

R. Allanson, 1 C.J. Waterford, 2 C.P. Whittle s and Jan E. van S. Graver 2 1GrainCorp Operations Ltd., Sydney, NSW 2000 [Fax: +61-2-3259180]; and 2Stored Grain

Research Laboratory, CSIRO, Division of Entomology, Canberra, ACT 2601, Australia

Recommended methods for disposal of phosphine formulations require immersion, combustion or burial, all of which can pose safety hazards to operators. Although burial has been recommended, no clear operating procedures have been defined. This evaluation examined the efficacy and occupational safety associated with burial of blanket and tablet/pellet phosphine- generating formulations, unspent and spent, at two depths in soil. Phosphine generated by the buried formulations was monitored within, and immediately above, the burial site while phosphine levels remained above the 0.3 ppm threshold limit value.

Residual unreacted phosphide in the buried formulations was determined at the end of the investigation. Soil type and conditions were recorded. Worker safety implications of the results obtained from this work were discussed. (L)

A New Product for Short-Term Fumigation

L. Benzing Detia Degesh GmbH, D-69514 Laudenbach, Germany [Fax: +49-6201-708402]

234 Meetings

A new product based on magnesium phosphide for phosphine fumigation targeted for the protection of stored products, has several advantages when compared with the usual products.

The metallic phosphide formulation is contained in bags made of specially impregnated paper (Tyvek), which are permeable only to water vapor. After complete decomposition of the metal phosphide, the fine dust remains in the bags and no residues can reach the fumigated stored commodities. By adding zeolite, a water-absorbing sodium-aluminum silicate, no uncombined phosphine can be detected in the packed product when the tin is opened for use. In addition, all danger of self-ignition is precluded. Furthermore, this adjuvant delays the development of phosphine at the beginning of the decomposition. Thus, there is enough time for the workers to apply the product before diffusion of the fumigant, thereby precluding risk of inhalation of the generating gas. In contrast to similar products based on aluminum phosphide, the new product, 'Detia Gas Ex-B Forte', under normal conditions (20~ r.h.), decomposed completely within 48 h. The residue in the bags contains only traces of magnesium phosphide (0.1%). Because of its prompt decomposition, this product is especially suitable for short-exposure fumigations. This formulation is also remarkable in that it enables fumigations to be carried out at low temperatures (below 5~ without considerable prolongation of the exposure time. Consequently, short-term fumigations in cold weather or in chilled containers are also possible. By using this magnesium phosphide product in bags, new operational areas for fumigation with phosphine might be made accessible. Good results have been achieved already with the quarantine treatment of bananas, red pepper, mangos, etc. (L)

F: SEALING TECHNIQUES AND METHODS OF DETERMINING GASTIGHTNESS

Installation and Sealing of Phosphine Recirculation Systems in Silos at U.S. Grain Elevators

R.T. Noyes, 1 E Kenkel, 1 J.T. Criswell 2 and G.W. Cuperus 3 1Biosystems & Agricultural Engineering Dept. [Fax: +1-405-7449693], 2Agricultural Economics

Dept., and 3Entomology Dept., Oklahoma State University, Stillwater, OK 74078, USA

A closed loop fumigation (CLF), or gas recirculation, system for phosphine fumigation using a low-volume blower/piping system per tank was patented by James Cook in 1980. To make CLF more effective, two large steel tanks (2,000 to 10,000 tonnes/tank) were manifolded to one blower in 1991. In 1995, manifolded phosphine recirculation (MPR) system designs for concrete silos were developed. At five elevators, 3 to 18 concrete silos manifolded to one blower will operate as 1,500- 10,000 tonne storage units. At four elevators, all under-roof external wall vents will be sealed. Gas from all silos flows through open under-roof wall vents between silos to CLF blower suction pipes. Suction pipes will connect to only one end silo. Blower pressure piping manifolds will connect to the base of each silo in a variety of different plumbing schemes. Silo roof vent and silo base sealing problems required a variety of techniques.

CLF-MPR benefits are: (i) smaller work crews, reduced worker exposure; (ii) quicker fumigation response; (iii) lower fumigant cost; (iv) eased compliance with regulations; (v) better efficacy with less fumigant and less management expertise needed; and (vi) mobility of blowers moved from site to site minimizes investment. (L)

Test Methods for Level of Sealing of Grain Stores: Pressure Tests and Tracer Techniques

H.J. Banks Stored Grain Research Laboratory, CSIRO, Division of Entomology, Canberra, ACT 2601, Australia

[Fax: +61-6-2464202]


Verifiable and convenient predictors of success of fumigation or controlled atmospheres (CA) are needed prior to the actual addition of the gas. Two test systems are in use: pressure testing and tracer gas techniques. There are two versions of pressure test: pressure decay (Pt test) and pressure-flow (PQ test). The former is quick and simple but can be less informative than the latter. Both suffer from two defects: they must be conducted with the contents of the structure under test at constant temperature, and they give 'worst case' estimates of suitability for fumigation. Typically, gasholding will be better than predicted so on some occasions a structure may be adequately sealed even though it does not meet a set level. Tracer gas techniques (e.g. with CO) give a more directly applicable test, but require several days of intensive monitoring to obtain a result. The various test results can be related mathematically. A pressure half-life of 5 min from a Pt test in a full structure corresponds approximately to a gas loss rate of less than 5% per day in grain stores. This is an adequate level of sealing for most fumigation and CA processes and corresponds to several national standards. As a special case, a decay time of > 10 sec is adequate for freight containers. Practical examples of test results and their correlation with success or failure of treatments were given, and the appropriate level of test value was discussed with regard to various treatment systems. (L)

Pressure Tests to Determine the Need for Sheeting Loaded Freight Containers before Fumigation

S. Ball 1 and J. van S. Graver 2 1Australian Fumigation Services, Port Adelaide, SA 5015; and 2Stored Grain Research Laboratory,

CSIRO, Division of Entomology, Canberra, ACT 2501, Australia [Fax: +61-6-2464202]

In Australia, compliance with a pressure test standard is mandatory before freight containers, loaded with hay, can be fumigated with methyl bromide. In compliance with the current Australian Quarantine Inspection Service (AQIS) standard, containers that fail to meet the standard must be fumigated under sheets (tarps).

In commercial practice, pressure testing has shown 99% of new ply-floored containers and more than 80% of old ones (3-4 years) meet the standard. However, only 60% of new plank- floored containers, and less than 10% of old (1-2 voyages) plank-floored containers met the standard. Routine pressure testing of freight containers has provided the means for rapid evaluation of the appropriate fumigation regime. This eliminated the need to sheet all containers, increased the number of containers that can be fumigated per day, and reduced the average labor requirement per container treated. (L)

Sealing Efficiency Assessment in Modified Atmosphere Storages

S. Navarro Dept. of Stored Products, ARO, The Volcani Center, Bet Dagan 50250, Israel

[Fax: +972-3-9604428]

The leak area that would permit air infiltration into an experimental silo of 666 I capacity was assessed with constant pressure tests using cross-section areas ranging between 30 mm 2 and 100 cm 2. The relationship between orifice cross-section area and its length, on the variations of the empirical constants that describe the constant pressure test, was also demonstrated. Based on a series of tests, an empirical equation to estimate leak area was proposed.

An experimental silo which was filled to 92% of its volume with ca 500 kg wheat, was tested for carbon dioxide loss using different sized orifices. The measured CO2 concentrations were compared with the calculated values based on equations that consider initial CO2 adsorption by the wheat, diffusion of CO2 through the leak, and variations in temperature and barometric pressure. Under the

236 Meetings

experimental conditions, close agreement between the measured and calculated values was obtained. The influence of temperature and barometric pressure variation on infiltration of air into the silo was also analyzed. The information obtained from the constant pressure tests and from analysis of the weather conditions provided guidelines as to the time that a certain concentration could be maintained in a CO2-treated structure. Leak rates for any structure may be assessed by the method developed in these experiments. (L)

Sealing Outdoor Storage and Fumigation Facilities Using Plastic Sheeting

T. DeBruin Haogenplast, Kibbutz HaOgen 42880, Israel [Fax: +972-9-620642]

Plastic sheeting used for modified atmosphere facilities for storing grain, dried fruits and beehives was discussed. The following aspects in the production of plastic membranes and in ensuring sufficiently sealed facilities were reviewed. The prerequisites for sealed outdoor facilities are as follows: The plastic membrane of the structure should have sufficient physical strength, a low gas permeability rate, and good resistance to UV. The structure should be sufficiently gastight either to allow metabolic processes to create the desired atmospheric composition or to enable modification of the atmosphere by addition of gas. Manufacturers should perform leak tests before the units leave the production plant.

On-the-spot sealing is employed for very large units only, such as bunkers for grain storage of over 10,000 tonnes, or sealed storage of dried fruits containing tens of tonnes, since sealing techniques demand high professional skills, including use of hot air guns and adhesives. Where grain is stored in units of up to 1,000 tonnes, sealing of liner sections with an easily locked plastic tongue and groove zippers is convenient. Prefabricated units have the advantage of lower price (due to a standard manufacturing process) and ease in operation. On-the-spot installations are less cost- effective and testing is rather complicated. Also, each time a fresh commodity is stored, a new sealing process is required.

Tests used for determining air tightness include physical control of seams and weldings, inflation and audio control, inflation and measurement of drop in pressure, inflation with colored smoke, and ultrasound. (L)

Response of the Silo Manufacturing Industry in Australia to the Sealing of Transportable Grain Silos

C.R. Newman Agriculture Western Australia, Industry Resource Protection Program, Forrestfield, WA 6058,

Australia [Fax: +61-9-4531228]

Research in Australia in the 1970s suggested it was possible effectively to seal farm grain storage to create an environment in which fumigation would be effective. The information was communicated to all government advisory agencies across Australia for dissemination to manufacturers and users of grain silos. In Western Australia in 1982 this information was transferred by the Agriculture Protection Board through its extensive network of officers. Sealing standards were recommended to silo manufacturers and advice on how to conduct correct fumigation procedures was communicated to farmers. In the eastern states of Australia the extension network, although comprehensive, relied on individual effort by advisers to create transfer opportunities. The economics of manufacturing and the requirements of purchasers influenced design developments by individual manufacturers. In Western Australia this evolutionary process resulted in the adoption of a narrow range of successful sealing techniques. In the eastern states of Australia, advice was acted on


by some manufacturers and there was some demand for sealed silos from growers. Later campaigns to stimulate interest in the production and use of sealed grain storage on farms in the eastern states created interest in better fumigation techniques. The developments in silo design and the stimuli to change to sealed silos were discussed. (L)

G: INTEGRATED COMMODITY MANAGEMENT METHODS WITH CA

Effectiveness of Ethyl Formate as a Fumigant of Sultanas and Raisins

S.J. Hilton and H.J. Banks Stored Grain Research Laboratory, CSIRO, Division of Entomology, Canberra, ACT 2601, Australia

[Fax: +61-6-2464202]

Ethyl formate is used in the Australian dried fruit industry as a fumigant against insect infestation. The rate of sorption of ethyl formate on sultanas was found to be independent of concentration but greatly increased with filling ratio and moisture content. There was a slight temperature effect. Sorption was initially rapid, with 13% of the gas remaining in the headspace at 12 h in containers 95% full, followed by a more gradual reaction phase. Rate constants per full container for the reaction ranged from 0.077 h to 0.038 h. At typical commercial dosage rates, concentration x time (CT) products of 1493 g h m -3 at 8 h and 3876 g h m -a at 24 h were obtained in sealed containers at 25~ and 60% r.h. These CT products were shown to be greater than those required to control dried fruit pests.

Fumigations at 25~ of mixed aged cultures of six pests showed that 8-h exposures were more effective than 24-h exposures with the same CT product. In 24-h exposures, there was 100% mortality of Oryzaephilus surinamensis, O. mercator, Plodia interpunctella and Carpophilus hemipterus at 765 g h m -z, and Tribolium confusum at 1158 g h m-a; and 94% mortality of T. castaneum at 1158 g h m -3. All pests were controlled at 541 g h m -3, but not at 496 g h m -3 in 8-h fumigations. Ethyl formate appears to have excellent potential as a replacement for methyl bromide in the treatment of durable commodities where not limited by sorption behavior. (L)

Carbon Dioxide Fumigation of Organic Grains Followed by Refrigerated Aeration

B.W. Bridgeman Grainco Limited, Toowoomba, Qld 4350, Australia [Fax: +61-7-6382440]

Organic grain was fumigated with carbon dioxide upon arrival. Concentrations were maintained above 35% for 15 days by topping up by continuous addition via the recirculation system. Integration of this technique with refrigerated aeration has enabled long-term storage without the need for refumigation. This ICM strategy has provided the means to outload insect-free grain in 60-tonne batches over a storage period of 24 months. Results of trapping in the storage area were discussed, and the equipment and operational costs of implementing the strategy were described. (L)

Development of a Decision Support System for the Fumigation of Milled Rice Bag-Stacks in the Tropics

R.J. Hodges, 1 M. Smith, 1 A. Madden, 1 D. Russell I and H. Halid 2 1 Natural Resources Institute, Chatham Maritime, Kent ME4 4TB, UK [Fax: +44-1634-880066];

and ~ Ministry of Food Affairs, The National Logistics Agency, BULOG, Jakarta, Indonesia

A Fumigation Decision Support System (FDSS) was developed that enables pest control operatives in milled rice bag-stores to predict when future fumigations will be required and whether

238 Meetings

previous fumigations were successful. The FDSS consists of an insect monitoring technique, an insect growth model and a pragmatic pest control threshold. The last two elements are contained in a computer program. The growth model, which is central to the system, is specific to Tribolium castaneum, and is valid only for use in the humid tropics.

The FDSS was tested in rice stores in Indonesia and a logistic model of insect population growth was found to perform best. Within the limitations of this test, the predicted time to fumigation on average deviated by only about one week from the actual time to fumigation. The FDSS was also tested by unsupervised pest and quality control staff at two godowns sites in Java, after suitable training. The staff's performance was evaluated. They found the system easy to use and fumigation time predictions were again close to actual time to fumigation, deviating by less than one week. The FDSS is now ready for operational use. (L)

H: POTENTIAL THREATS TO CONVENTIONAL CA AND~OR FUMIGATION, BY INSECT RESISTANCE OR REGULATIONS

Resistance: A Threat to the Use of Controlled Atmospheres for Stored Product Protection?

C.S. Adler Federal Biological Research Centre for Agriculture and Forestry, Inst. for Stored Product


With the very limited number of stored product protection agents available today, the danger of insecticide resistance is a serious threat and increases the need for sound resistance management. Controlled atmospheres (CAs) low in oxygen and/or high in carbon dioxide have been registered for stored product protection purposes in many countries during the last decade. Even though CA treatments require a high degree of gastightness and technical skills, their importance is growing, due partly to the fact that (i) they do not leave residues in the treated product, (ii) minor leaks do not represent a health risk to exposed persons, and (iii) there is no unforeseen environmental risk in the use of N or CO2.

So far there have been no reports of resistance to practical CA treatments. A comparison of eight laboratory and two field strains of the granary weevil, Sitophilus granarius, from six countries revealed no significant variation in susceptibility towards various CAs. However, in a comparison of the strains, medium adult body weight correlated with the relative tolerance to an atmosphere with 95% CO2 (the rest being air). Other lab studies proved that increasing commodity moisture content or increasing residual O2 content correlates with insect survival. At high moisture contents, it is possible to select for individuals tolerant or even resistant to hypoxic or hypercarbic atmospheres.

Lethal exposure periods to secure complete disinfestation at a given temperature and commodity moisture content must be identified for all major pests, in order to minimize the risk of resistance development. (L)

Influence of Resistance on Future Fumigation Technology

J.L. Zettler USDA-ARS, Horticultural Crops Research Laboratory, Fresno, CA 93727, USA

[Fax: +1-209-4533088]

Global dependence on fumigation continues to increase but many constraints on that technology could lead to its extinction. One of those constraints is resistance. Phosphine resistance continues to increase in frequency and in intensity among pest populations but control failures rarely occur.


When they do, however, they can usually be managed by the use of existing alternative methods or technologies. In spite of our ability to control these resistant populations, future pest control operations will become more complex and challenging. New, developing technologies, such as genetic engineering, could threaten our pest control security and undermine our efforts to manage resistance. The presence of transgenic food products will increase in the market place and impact pest management technologies in the future. (L)

Phosphine Resistance of Rhyzopertha dominica in the Philippines

Perlina D. Sayaboc and A.J.O. Gibe National Post Harvest Institute for Research and Extension, Mu~oz, Nueva Ecija, Philippines

[Fax: +63-2-9268159]

Field strains of Rhyzopertha dominica were collected from areas where phosphine fumigation is commonly practiced. These strains were tested for resistance at a range of phosphine concentrations recommended by the FAO. Insects were exposed to phosphine for 20 h inside gastight desiccators. They were then transferred to culture media and mortality was assessed after 14 days. Insect mortality was subjected to probit analysis. A high level of resistance (>500x) was obtained in strains collected from Metro Manila and Cebu. This can be attributed partly to the insects' exposure to poor fumigation practices. Widespread resistance ofR. dominica to phosphine is suspected. (L)

The Current Status of Methyl Bromide and Phosphine Fumigation in Poland

S. Ignatowicz, 1 S. Oboza 2 and C. Slusarski 2 1Dept. of Applied Entomology, Warsaw Agricultural University, 02-787 Warsaw

[Fax: +48-22-471562]; and 2SOLFUM Ltd., 91-734 Lodz, Poland

Insects and mites are common pests of stored products in Poland. They not only cause economic loss of agricultural commodities in storage, but through quarantine their presence restricts the export of grains, dried fruits, mushrooms, vegetables and other products. These losses and restrictions are eased by the application of fumigation treatments. At present, only two fumigants are registered for use in Poland: methyl bromide (MB) and phosphine. While MB is used widely as a fumigant for soils, commodities and structures, it is an effective ozone-depleter, and will be banned in Poland at some future date. Pbosphine will continue to play a major role in the fumigation of agricultural commodities, and Poland is becoming increasingly dependent on this fumigant for stored-product pest control. The following products releasing phosphine are now registered for use in Poland: Phostoxin (tablets), Quickphos (pellets), Delicia-Beutel (bags), Delicia-Gastoxin (tablets), and Degesch plates or strips. For phosphine to remain available as a fumigant, it is essential that any risk that could lead to its removal, such as pest resistance to phosphine, be identified and eliminated. Therefore, a research program has been undertaken to detect and monitor phosphine resistance in Poland. The information obtained will be used to predict the future impact of resistance on storage industries, as well as to develop tactics and strategies aimed at managing or delaying the development of resistance. (L)

Does Underdosing Select for Resistance to Phosphine?

EJ. Collins Plant Protection Unit, Department of Primary Industries, Indooroopilly, Qld 4068, Australia

[Fax: +61-73-8969440q

In eastem Australia farmers are becoming increasingly reliant on phosphine to control insect pests. Many fumigations undertaken on farms and by produce merchants occur in unsealed storages

240 Meetings

of all types. These fumigations vary considerably in the doses achieved and hence in their efficacy. The aim of this work was to determine what effect current small-scale fumigation practices have on selection for resistance to phosphine. Farm fumigations, undertaken in a variety of situations, were monitored to determine typical doses achieved in practice. Meanwhile, the responses to phosphine of adults, eggs and pupae of phosphine-resistant, heterozygous and susceptible Rhyzopertha dominica, Sitophilus oryzae and Tribolium castaneum were measured in the laboratory. Assays were conducted at a range of concentrations of phosphine for exposure periods of 3 and 6 days. The responses to phosphine of each life stage and each species varied considerably, as did the dominance of the resistant phenotype. A wide range of concentration x time profiles was observed in the field fumigations, none of which, however, would have controlled all stages of all species. Analysis of the responses to phosphine showed that any fumigation that does not achieve a dose sufficient to kill all life stages of resistant insects will select for resistance, i.e., underdosing will select for resistance. The significance of this result to the management of phosphine resistance was discussed. (L)

Selection of Tribolium castaneum for Resistance to a Combination of Phosphine Plus CO2 and Biological Observations on the Resistant Strain

F.A. EI-Lakwah, A.A. Darwish, M.M. Khattab and A.M. Abdel-Latif Plant Protection Department, Faculty of Agriculture at Moshtohor, Tukh, Kalyubia, Egypt

[Fax: +20-2-3412445]

The main objective of this work was to study the development of resistance in the red flour beetle, Tribolium castaneum Herbst, to a combination of phosphine plus carbon dioxide, and to investigate some biological characteristics of the resistant strain in comparison with the parental stock.

Adult populations of T. castaneum were exposed in the laboratory for 16 generations to a mixture of 40 ppm PH3 + 46% CO2 for varying exposure periods at 26+1~ and 6+1~ in order to select for a resistant strain. Selection pressure was carried out at the median lethal time (LT) inducing mortalities that ranged from 50-70%. The LT values necessary to obtain a given mortality were significantly higher for the 16th generation at both test temperatures than for the parental strain. At the 16th generation, T. castaneum adults showed a 19.4-fold resistance to the mixture of phosphine + CO2 at 26+1~ and a 18.5-fold resistance at 6-4-1~ when compared with the parental stock at the LTso level. This result indicated clearly that T. castaneum adults have the genetic potential to develop resistance to an atmosphere containing a combination of phosphine + CO2.

The biological characteristics of the resistant strain revealed that this strain laid a significantly higher number of eggs than the laboratory strain. However, no significant differences were found in the average pre-oviposition period and the sex ratio. The average incubation period and the total developmental period were markedly longer for the laboratory strain than for the resistant strain. Larval mortality and average hatching rate of the eggs increased significantly for the resistant strain. The emergence rate of the adults was unaffected and amounted to 100% for the two strains. (L)

A Comparative Study of Phosphine Resistance Levels in Stored-Grain Beetles Collected from Sealed and Unsealed Farm Storages in Western Australia

R.N. Emery Agriculture Western Australia, South Perth, WA 6151, Australia [Fax: +61-9-3683223]

Western Australia has established a reputation as an exporter of residue-flee grain despite having conditions that are more suitable to the development of grain insect pests than many other countries. This has been achieved by the extensive use of sealed storage and phosphine fumigation both in the central handling system and on-farm.


The Western Australian grain industry has been concerned for some time that phosphine resistance may occur on farms through the inefficient use of phosphine in unsealed and poorly maintained sealed storages which result in concentration gradients. In order to monitor this threat, a survey was conducted in 1991 to study the frequency of phosphine resistance in the red flour beetle, Tribolium castaneum (Herbst), rice weevil, Sitophilus oryzae (L.), granary weevil, S. granarius (L.), lesser grain borer, Rhyzopertha dominica (E), and sawtoothed grain beetle, Oryzaephilus surinamensis (L.). From this study, which used a discriminating dose test, it was concluded that there were no significant differences between strains. There is, however, a need to determine whether phosphine resistance levels differ between sealed and unsealed farm storages, and between well maintained and leaky sealed storages.

The paper reported the progress of a series of graded concentration phosphine resistance tests conducted on field-collected strains of grain insects and cultures which have been held since the previous phosphine resistance frequency survey. (L)

There is No Resistance of Stored-Product Moths to Treatment with C02 under High Pressure

Ch. Reichmuth Federal Biological Research Centre for Agriculture and Forestry, Inst. for Stored Product


Several moth species of the pyralid family, such as Ephestia spp. and Plodia interpunctella, regularly infest various stored products. World wide, warehouse keepers and food factories suffer from high losses ranging in the billions of DM annually. Apart from the direct losses, consumers', retailers' and importers' claims lead to financial losses for replacement and disposal. To overcome the problem, current strategy includes intensive hygienic measures and treatment of all raw products on entering the storage structure. The high turnover of trade and production, and in some cases - such as herbs and spices - the high value of the products, requires quick disinfestation procedures without any damage to the goods. A recent new approach is treatment with CO2 under high pressure of ca 20 bars for an exposure period of 1-3 h. Almost none of the developing stages of insect pests and mites survive such a treatment.

Official authorization exists in Germany for the use of CO2 in this field of application according to the plant protection law. The results presented dealt with the possibility of buildup of resistance in eggs of P interpunctella. Eggs of the surviving adults were exposed to an LDso high-pressure CO2 treatment for ten consecutive treatments of following generations. No significant change in mortality occurred during the experiments, which were replicated five times. (L)

Phosphine Measurement at Environmental Levels

S. Pratt and C. Waterford Stored Grain Research Laboratory, CSIRO, Division of Entomology, Canberra, ACT 2601, Australia

[Fax: +61-6-2464202]

The perceived threat of bans on phosphine use has put pressure on the grains industry to show that concentrations in the vicinity of grain stores do not exceed levels about 100 times lower than permitted workplace levels. Trace level phosphine analysis is thus vital to the continued use of this fumigant by the grains industry. This has prompted us to develop reliable field measurement methods.

The proposed Environmental Management Standard (ISO 14000) emphasizes pollution management by industry and open communication with workers and the public, rather than prescriptive regulations. The dynamic tension among regulators, the community and industry hinges

242 Meetings

on the ability to obtain reliable analyses of phosphine in the environment. The grains industry is one of several sources of environmental phosphine. The difficulty in trace analysis of phosphine, coupled with questions of sample instability and interference from other substances, has led to disagreement in the literature.

A major source of error in trace phosphine analysis by gas chromatography is variability of manual injections. In addition, standards can be compromised by breakdown of phosphine at high dilution. We have constructed a repetitive computer-controlled system which samples dilutions of calibrated metered gas flows, affording excellent reproducibility and stability of standards. This also allows peak detection where signal-to-noise ratios are normally too low to measure. Using gas chromatography (GC) with flame photometric or thermionic detection, we equaled reported limits of detection in the picogram (ng l - 1 or ppb v/v) range.

Several auxiliary techniques for detecting low phosphine concentrations have been tested in our laboratory against the standard GC analyses. Some of these involve novel sensors which are used as GC detectors, and others involve amplification of existing electrochemical and optochemical sensors. (L)

Limitations for Infestation Control in Cooled Bulk Grain and a Strategy to Overcome Inherent Sealing and Gas Distribution Problems Using Phosphine Gas

C.H. Bell, A.L. Clifton, K.A. Mills and T.J. Wontner-Smith Central Science Laboratory, Ministry of Agriculture, Fisheries and Food,

Slough, Berks. SL3 7H J, UK [Fax: +44-1753-824058]

The tolerance of five important grain pests to phosphine at 10~ and below was assessed in the laboratory. Older stages of Sitophilus granarius were highly tolerant of the combination of cold and exposure to phosphine and survived exposures of over 3 weeks' duration at phosphine concentrations above 0.7 mg/l at 5-7.5~ As a result, fumigation with phosphine at temperatures below 10~ can be recommended only if S. granarius is absent. The other species tested were all killed by a 12-day exposure to 0.1 mg/l phosphine.

A sensor-controlled automated dosing system originally developed for use with methyl bromide mill fumigations has been modified for use in phosphine fumigations of bulk grain. A new sensor based on an electrochemical cell has been incorporated into the system to monitor phosphine concentrations within the ranges encountered in commercial fumigations. The dosing system has been tested in the laboratory and in one recent field trial on a 470-tonne bulk of grain. The system offers the potential of maintaining adequate gas concentrations of phosphine throughout the long exposure times required for phosphine treatments at low temperatures, by countering gas losses caused by adverse weather conditions and inherent sealing problems. (L)

I: QUARANTINE AND REGULATORY ISSUES PERTAINING TO THE USE OF CA AND/OR FUMIGATION

Managing the Risk of Infestation in Bulk Shipments of Imported Grain: An Australian Perspective t

G. Khair and W.S. Magee Quarantine Operations Branch, Operations Division, Australian Quarantine and Inspection

Service, Canberra, ACT 2601, Australia [Fax: +61-6-2723709]

Australia imported in excess of 500,000 tonnes of grain during 1994/95 to meet shortfalls in grain as a result of the drought in the country. The Australian Quarantine and Inspection Service



developed quarantine conditions, in consultation with the relevant industry groups, to manage the risks associated with imported grain and facilitate the safe entry of grain for end users. Quarantine conditions were directed at minimizing the risk of seedborne disease transmission, and introduction of exotic weeds, and ensuring that shipments were free of stored-product pests prior to discharge. This paper examined the regulatory, technical and commercial requirements necessary to ensure that bulk shipments of grain arrive free of infestation with stored-product and other pests. (L)

A New Approach to Adoption of Potential Alternative Quarantine Treatments Worldwide

R.T. Baker New Zealand Plant Protection Centre - Lynfield, Ministry of Agriculture Quality Management,

Auckland, New Zealand [Fax: +64-9-6279750]

The recent GAIT agreement regarding the way plants and plant products are traded is expected to lead to clearer and more scientifically justified quarantine regulations on a worldwide basis. Following the guidelines set forth by the FAO for the regulation of quarantine specifications and entry conditions, many countries are now starting to develop justifiable import standards. These must be based on the principles of pest risk analysis which demands the production and categorization of pest lists, scientific and realistic assessments of pest risk from both economic and biological viewpoints, and development of clear risk management options. While the initial thrust is to apply the new methods to the trade in fresh produce, it is inevitable that they will be applied to the movement of all forms of plant products, including stored products. Whether the implementation of new technologies is delayed by the actions of quarantine agencies will depend on the quality of scientific research and the clarity with which the justification for new treatments is presented. We illustrated the new challenges to the trade in stored products by describing the approach being taken by New Zealand, in response to the FAO initiatives. (L)

The Present Use of Methyl Bromide as a Fumigant for Stored Products in Developing Countries: Results of a Recent Survey

R.W.D. Taylor Natural Resources Institute, Chatham Maritime, Chatham, Kent ME4 4TB, UK

[Fax: +44-1634-880066]

In 1992, under the terms of the Montreal Protocol Agreement, methyl bromide (MB) was listed as an ozone-depleting substance, with the expectation that a program to control its use would be decided upon in 1995. Although routine use of the chemical for disinfesting stored products has declined in recent years, MB continues to be very important for treatments which need to be completed quickly, such as those undertaken for quarantine purposes. Many developing countries continue to rely upon MB for routine disinfestation programs and in connection with their import and export trade. These countries consider that any controls on the chemical may affect trade adversely. Uncertainties regarding the effect on developing countries of future restrictions on the use of MB were considered to be due partly to a lack of data on the continued importance of the. chemical in those countries. In an attempt to overcome some of these uncertainties, a survey of MB use and potential alternatives was organized by the United Nations Development Programme in three regions. The results obtained in the surveys and their implications for Latin America, Southeast Asia and the Pacific, and for English-speaking Africa, were described. (L)

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Controlled Atmospheres and Other Alternatives to Current Uses of Methyl Bromide in the Netherlands

J. Klijnstra TNO Plastics and Rubber Research Institute, 2600 JA Delft, the Netherlands

[Fax: +31-15-2612834]

Current uses of methyl bromide (MB) in the Netherlands have been restricted to quarantine applications and fumigation of durables and structures since soil sterilization was banned in 1992. In accordance with the Montreal Protocol, the policy of the Dutch government aims at further reductions in the years to come. The baseline for an effective reduction scheme is the availability of reliable use figures. Since 1992 fumigations with MB have been subject to notification at a central registry. From this database the use pattern of MB can be determined. The presentation discussed developments in this pattern over the last few years.

The major guideline for use reduction is the availability of effective alternatives to current uses of MB. Research is focused on identifying suitable alternatives for the Dutch situation; Controlled atmosphere seems to be a promising alternative for products such as cocoa beans and groundnuts. Heat treatment appears to be applicable for disinfesting flour mills.

Control of MB emissions with charcoal filters is attempted at the permanent fumigation facility at the flower auction in Aalsmeer. Chemical analyses have shown a very high removal efficiency. (L)

Impact of Domestic and International Regulatory Controls on the Competitiveness of American Agriculture

R.T. Ross U.S. Department of Agriculture, Animal and Plant Health Inspection Service,

Washington, DC 20025, USA [Fax: +1-202-6904265]

Methyl bromide (MB) produced and used by man is a versatile, highly effective, fast-acting fumigant employed in a number of important ways to kill organisms destructive to plants. A broad spectrum of commodities is treated with MB. The compound is unique in that it provides a wide range of pest control, may be applied to a broad spectrum of both food and non-food commodities, can be used for fumigation of large and small quantities of materials, and, when applied properly, leaves no residues of toxicological significance. Recently, this compound has come under scientific scrutiny and has been identified as a potentially potent ozone-depleting chemical. As a result, countries operating under the Montreal Protocol (MP), an international treaty for regulating ozone- depleting substances, will be restricting its use and, in some cases, eliminating it altogether. For example, the U.S. Environmental Protection Agency (EPA) has proposed a total phaseout of MB by 1 January 2001. Its limited use and/or potential phaseout will have severe economic implications unless there are alternatives which are efficacious, economical and available.

Due to the complexity of researching a wide array of alternatives, the number of steps involved in making efficacious alternatives available, and the limited amount of time at hand, there may be many important uses for which effective alternatives will not be available by the time the phaseout takes effect. The consequences of that eventuality would pose significant competitive disadvantages for American agricultural production and trade. The more stringent provisions of the U.S. Clean Air Act (CAA) vs the MP which governs the regulatory controls in other countries of the world, have come under considerable debate by the U.S. agricultural community and the U.S. Congress, regarding the economic and competitive position of American agriculture. (L)


The Potential of Systems Approaches for Quarantine

K.W. Vick USDA-ARS, National Program Staff, Beltsville, MD 20705, USA [Fax: +1-301-5045987~

A systems approach is a set of safeguards and investigation measures which individually and cumulatively provide a reduction in plant pest risk. This approach to management of plant pest risk provides an alternative to postharvest quarantine treatment for obtaining phytosanitary security. Examples of successful systems approaches for movement of quarantined commodities were discussed in the context of potential elimination of the use of methyl bromide. (L)

Commercial Quarantine Fumigation of Narcissus Bulbs to Control Narcissus Flies

S. Navarro, E.J. Donahaye, R. Diaz, A. Azrieli, Miriam Rindner and M. Kostokovski Dept. of Stored Products, ARO, The Volcani Center, Bet Dagan 50250, Israel

[Fax: +972-3-9604428]

Fumigation trials were carried out in commercial flexible plastic fumigation chambers using methyl bromide (MB) for quarantine control of narcissus flies in narcissus bulbs. The objective was to examine the suitability of existing dosage schedules when fumigation is performed in these chambers, in view of previously recorded damage due to phytotoxicity of MB at the recommended dosage levels. It was found that for the 4-h exposure regime required for quarantine purposes, recirculation was necessary to produce initial uniform concentrations. Also, dosage had to be adjusted to account for the volume of free space within the fumigation chambers and sorption by the bulbs. Since a significant CO2 concentration was generated by bulb respiration during fumigation, MB concentrations registered by thermal-conductivity monitors were affected. An initial dosage of 24 g/m 3 resulted in a uniform concentration of MB (~20 g/m 3) at different heights after I h of recirculation. A stable concentration was maintained throughout the remaining exposure period. (L)

The Efficacy of Methylisothiocyanate against Cydia pomonella on Apple

Val6rie Ducom Ministdre de l'Agriculture, Laboratoire National Denr~es Stock~es, 33150 Cenon, France

[Fax: +33-56-865150]

The biological efficacy of methylisothiocyanate (MITC) at an applied dose of 20-40 g m -a on all stages of Sitophilus granarius has already been demonstrated. Numerous tests of its efficacy on other stored-product pests confirm the interest in this fumigant. The cited application doses are far higher than the actual efficacy of the molecule, but its large capacity for sorption remains a handicap to its diffusion; this problem must be solved before a reduction in dosage can be envisaged.

The subject presented herein concerns the fumigation of apples with MITC, the objective being to satisfy quarantine requirements of certain countries against the codling moth (Cydia pomonella). The method in current use is methyl bromide fumigation followed by a period of cold exposure, for as long as 50 days, to control all egg stages. The aim of this study was to control this stage without the need to immobilize fresh products with long exposure periods. Preliminary tests have shown that MITC is extremely successful in the control of the codling moth egg stages. (L)

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Use of Low-Oxygen Atmospheres in Quarantine Applications to Eradicate Mus musculus, the House Mouse

Julie A. Cassells, 1 J.E. van S. Graver I and R.H. Burton 2 1Stored Grain Research Laboratory, CSIRO, Division of Entomology, Canberra, ACT2601

[Fax: +61-6-2464202]; and ~Cooperative Bulk Handling, Perth, WA 6001, Australia

The feasibility of using low-oxygen atmospheres to eradicate infestations of mice (Mus musculus) to meet quarantine standards was investigated. Drilling equipment and portable buildings were enclosed within standard plastic fumigation sheets, with and without floor sheets. The enclosures (ranging from 45-189 m 3) were dosed with a high nitrogen atmosphere (with 1.5% 02) supplied by a membrane system. Atmospheres containing less than 2.5% 02 were obtained and maintained within the enclosures for a minimum of 6 h. This regime was found to achieve 100% mortality against mice exposed to it. Work is continuing to establish a cost-effective exposure period. The potential application of this treatment as a quarantine measure against rodents was discussed and its costs were compared with conventional disinfestation using methyl bromide. (L)

J: SAMPLING AND TRAPPING IN RELATION TO CA AND~OR FUMIGATION

Sampling to Determine Treatment Efficacy

S. Bhadrikaju, 1 D.W. Hagstrum 2 and R.L. Meagher 1 1Dept. of Entomology, University of Minnesota, St. Paul MN55108 [Fax: +1-612-6255299]; and

2 USDA-ARS, U. S. Grain Marketing Laboratory, Manhattan, KS 66502, USA

Sampling insects infesting stored products provides information necessary for determining if control measures are needed, and if insects have been effectively controlled. Routine chemical applications - especially with fumigants, or controlled atmospheres, are put into practice without a valid pre- and post-treatment density estimation of insects. Therefore, the degree and duration of insect suppression obtained are often unknown. This uncertainty results in unnecessary treatments or in commodity damage because of delayed treatments. Accurate assessment of treatment efficacy requires: (i) the use of appropriate tools for sampling insects, and (ii) characterizing insect distribution based on sampling data to obtain valid estimates of insect density. The selection of an appropriate sampling tool depends on species and stage of the insect being sampled, precision of the density estimate needed, and detection sensitivity of the sampling device. The spatial and temporal distribution of insects must be characterized by fitting probability distribution functions (Poisson, negative binomial, binomial) or Taylor's Power Law to sampling data. This characterization helps in determining the precision and sample sizes required for insect density estimation, and for classifying insect density or damage with respect to an economic threshold. Sampling is an integral component of integrated pest management. The development of an appropriate sampling protocol for determining treatment efficacy is essential for cost-effective management of insects. (L)


Influence of Pitfall Traps and WB Probe II Traps on the Capture of Four Stored-Grain Coleoptera

P. Trematerra and M. Mancini Department S.A. V.A., University of Molise, 1-86100 Campobasso, Italy [Fax: +39-874-98743]

Two commercially available traps, the Pitfall Trap and the WB Probe II Trap, were used in the laboratory to monitor insects in grain (Triticum aestivum) at a temperature of 22-24~ and relative humidity of 65-1-5%. The major coleopteran pests of cereals in Italy: Oryzaephilus surinamensis (L.), Rhyzopertha dominica (E), Sitophilus oryzae (L.) and Tribolium castaneum (Herbst), were added to the grain at 0.9 insect/kg. Trapping revealed significant differences in the numbers of insects collected by the two types of trap. Also, the numbers of individuals of the different species captured differed significantly when compared across trap and treatment types.

The Pitfall Trap, located on the surface and within the grain bulk (15 cm below the surface), indicated by trap capture that T. castaneum migrated in numbers to the surface, whereas O. surinamensis remained within the bulk. The WB Probe II Trap trapped more T. castaneum than O. surinamensis; the species R. dominica and S. oryzae were trapped in fewer numbers. (L)

Effects of Live and Dead Insects in the Trap on the Capture of Tribolium castaneum

P. Trematerra, F. Fontana and M. Mancini Department S.A.V.A., University of Molise, 1-86100 Campobasso, Italy [Fax: +39-874-98743]

The activity of traps baited or not baited with 4,8-dimethyldecenal, the aggregation pheromone of the red flour beetle, Tribolium castaneum (Herbst), is influenced by the presence in the traps of accumulated trapped specimens. This has been observed in traps containing live or dead specimens. Interactions among the different substances produced by adult red flour beetles during their communication are involved in this behavior. The results obtained in the trials suggest that the presence of live insects in traps is attractive to other free specimens. However, under conditions of overcrowding, the quinone secreted by the insects regulates population density by counteracting the effect of 4,8-dimethyldecenal, causing the insect to disperse, or suppressing the aggregation behavior. The presence of dead insects in the traps, whether baited or not baited with 4,8-dimethyldecenal, can repel other free specimens of T. castaneum, this probably being related to the presence of a residual alarm pheromone produced by the specimens before death. (L)

A Comparison of Two Approaches to Detecting Insects in Grain

R. Wilkin and C. van Natto Chalfont St. Peter, Bucks SL9 0EP, UK [Fax: +44-1494-875543]

Detecting insects in grain is a fundamental component in establishing the need for fumigation, in post-treatment assessment, or in comparing the effectiveness of alternative treatments. Despite the. importance of pest detection, few comparative studies between methods have been done. This work compared the testing of samples of infested grain with a Berlese funnel with the Insectomat, which is designed to extract insects from relatively large samples of grain. Samples of grain with a natural infestation of Oryzaephilus surinamensis, Sitophilus granarius and Cryptolestes sp. were used. The Insectomat assessed 5-kg batches, whereas 1-kg batches were used in the funnels. The Insectomat was consistently better than the funnel in detecting all three species of insect in the grain sample. It

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also produced larger estimates of the size of the population. The Insectomat allowed samples to be assessed in approximately 5 min as compared with more than 6 h for the funnel.

The size of sample used by each system would appear to be the key to accurate detection, and the work indicated the potential dangers involved in using small samples taken from larger bulks to estimate insect populations or to determine the effectiveness of treatments. (L)

An Innovative Approach to Monitoring Insect Pests in Silos

V. Stejskal Research Institute of Crop Production, Prague 16106, Czech Republic [Fax: +42-2-365228]

Various traps have been developed for monitoring insect pests in stored grain (e.g. probe trap, PC trap, cup trap). The surface condensation zones of stored grain are critical for initiating infestation. Pitfall traps can be placed easily at the surface of bulk grain, but their use in deep silos/bins could be problematic. Wright (1991) sampled insect pests in empty silos by cardboard traps hung on strings. Hagstrum et al. (1994) used sticky traps placed in the bin headspace.

In the Czech Republic (CZR) half of the annual cereal production is stored in large silos and bins. Monitoring is based on taking samples at the bottom of the silos. Mobile vacuum samplers are considered by most storekeepers to be time consuming for regular monitoring. A new conical metal trap and sampler was developed in the CZR. This trap is hung on a long string and its heavy tip enables vertical application into remote grain surfaces. Removable sets of covers (with holes of various diameter) in the trap allow the entry of insects but not grain. The plain cone without the cover can serve as a probe sampler for taking grain samples for periodic laboratory evaluation (e.g. moisture, biochemical composition, mite infestation). The tool is also proposed for field evaluations of the results of fumigations. Infested grains are enclosed (via the removable cover with small holes) in traps, which are placed in the silos. After fumigation the samples are checked for adult emergence. (P)

The Use of Traps to Monitor Insect Infestations in Cocoa Container Shipments

EM.Cogan Central Science Laboratory ( CSL), Ministry of Agriculture, Fisheries and Food, Slough,

Berks. SL3 7H J, UK [Fax: +44-1753-824058]

Cocoa beans are routinely fumigated with phosphine before shipment in containers to the UK. If, upon arrival, the containers are found to be infested, they are re-fumigated. During 1993 an increase in infestation rate was observed in containers originating from West Africa. To explore the potential of insect pheromone traps as a monitoring tool for infestations in such shipments, as well as to provide information on the effectiveness of the fumigations, traps were placed in containers prior to shipment and examined upon arrival. Initially eight trap locations were used in each of 39 containers to evaluate three trap types: a window trap, a locator trap (both from AgriSense, BCS) and a prototype floor trap from CSL. Results showed the relative effectiveness of the trap types and the most effective placements of the traps. The results also determined that the infestations were the result of a failure in the West African fumigations rather than of post-fumigation re-infestation. Recommendations were made as to the number, placement and type of trap to use for monitoring infestations of moths and beetles within cocoa containers. The traps demonstrated their value to the cocoa trade not only for pinpointing fumigation problems but also as an inexpensive, essential monitoring tool. (L)


M E E T I N G S


THE JOINT INTERNATIONAL CONFERENCE OF FAOPMA - CEPA ON PEST CONTROL IN THE 21ST CENTURY

[Federation of Asian & Oceania Pest Managers Associations - Confederation of European Pest Control Associations]

May 8-12, 1996 Dan Panorama Hotel, Tel Aviv, Israel

A: CONTROL OF PUBLIC HEALTH PESTS

Keynote Address Partners in Public Health: New Roles for Pest Control Firms in a New Century

N.G. Gratz CH-1291 Commugny, Switzerland [Fax: +41-22-7760332]

Since commercial pest control firms went into business, their major occupation was at first with household pest control and later with institutional or industrial pest control. Originally these companies worked to control household pests such as cockroaches, bedbugs and, eventually, fleas, ticks, rodents and termites. As public and official confidence in these firms grew, municipal inspectors who noticed the presence of filth insects or rats or mice on private premises or in food handling establishments, would issue a citation instructing the proprietor to contact a pest control firm to deal with the problem.

Concomitantly, municipal authorities almost everywhere in the world created their own pest control departments, some of them extremely large and costly to the budget. These pest or vector control sections were usually responsible for the control of insect vectors or rodent reservoirs of disease which affected the entire community. In the United States and later in France, Germany and other countries, mosquito abatement districts were created and paid for by voluntary taxes, and charged with the responsibility of controlling mosquitoes or other insect pests.

The control of insect pests or vectors and rodents has become increasingly complex. Insects and rodents have developed resistance to pesticides used against them and, at the same time, a more demanding public (i.e., the taxpayer) calls for higher levels of control of insect pests or nuisance or rodent infestations. However, municipalities are reluctant to hire the more highly trained (and therefore more highly paid) vector control specialists or to establish laboratories for the identification of insect and rodent species and determine their susceptibility or resistance to pesticides. New pesticides and pesticide formulations require greater care in their handling to avoid toxic and environmental hazards that have now become of great concern. Application equipment has become far more efficient, sophisticated and complex than the old hand-held sprayer; however, equipment such as vehicle-mounted ultra-low-volume insecticide sprayers or helicopters carrying spray equipment must be operated and maintained by highly trained personnel and is far too complex for most municipal inspectors to handle.


This has created a great area of opportunity for private pest control firms to take over these operations and responsibilities on a contract basis for municipal authorities. To carry out this work means that the contracting private firms must be ready to acquire highly trained personnel and more complex application equipment; they must also learn more about the problems of public health and the biology and habits of the target species. The private companies must be prepared to maintain a high level of familiarity with new pesticides and pesticide formulations and application equipment. They must also learn how to evaluate insect and rodent population densities in order to demonstrate the effectiveness of their control operations. Finally, they must learn how to work with the authorities on the one hand and with the public on the other.

For firms that are prepared to acquire the trained personnel, laboratories, equipment and knowledge, there is a wealth of new opportunities open to them. If they are successful, municipal authorities will be increasingly prepared to divest themselves of this responsibility of mosquito and rodent control, provided that the pest control firms are prepared to undertake and carry out the work efficiently.

Control of Public Health Pests and Improvement of the Quality of the Environment in Israel

U. Shalom Div. of Pest Surveillance and Control, Ministry of the Environment, Jerusalem 95464, Israel

[Fax: +972-2-6553763]

Measures to control nonagricultural pests in Israel are concerned mainly with cockroaches, mosquitoes, rodents, house flies, ants, sand flies, wasps, fleas, ticks, termites and others. All these pests are restricted to specific locations, and extensive infestations are not found across the country. This is one of the results of continuous environmental improvements in Israel, which were achieved also as a result of pest control measures. An increasing number of operators in Israel are practicing Integrated Pest Management, with careful planning and monitoring to reduce infestations. They are actually improving the environment by changing it, with or without insecticides.

Successful environmental improvement must not end up by creating another environmental problem. Nevertheless, in many cases there is a true conflict in finding the balance between two needs, without a single clear solution to the problem. Thus, the optimal and practical control measures should be examined and executed carefully. This is Good Environmental Practice (GEP). Optimal control measures differ from pest to pest, and also when the same pest exists in different environmental conditions. Following are some examples:

�9 The main mosquito control measure is to reduce the number of larval breeding sites. Reducing breeding sites by drainage of wetlands might harm ecological habitats and thus GEP, in this case, is the optimal control measure that will differ, according to the ecological parameters in the wetland.

�9 The best means of wasp control is to destroy the nests, and the most efficient way to achieve this is by using poison baits. Application of highly toxic insecticides can result in secondary poisoning, and weak insecticides would not be efficient. Thus GEP consists in finding the optimal insecticides which can poison the wasps in the nests without causing secondary poisoning.

�9 'Successful' control measures that induce resistance are mainly short-term environmental improvements that will only develop into much larger problems in the near future. The optimal control measure and GEP here consist of using the optimal insecticides and dose for each operation.

�9 DDT is probably the most efficient insecticide for use in outdoor control of sand flies in Israel. It is known to be environmentally hazardous, and there is always a conflict about how often

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to use it, instead of repeatedly using organophosphorus insecticides. Gerbils may carry the parasite causing cutaneous leishmaniases and, as they are a protected species in Israel, there is always a question of what is the optimal way to reduce the risk of leishmaniases and how much to change the gerbil habitats. Again we must find the optimal means and the correct GEP for each case.

These examples show that pest control operationsAwhich always involve changing the environment, must be done by GEP.

Insect Growth Regulators in Public Health Control in Israel

Hedva Pener Entomology Laboratory, Ministry of Health, Jerusalem 91060, Israel [Fax: +972-2-233168]

Insect Growth Regulators (IGRs), which represent a relatively new category of insect control agents, act principally on embryonic, larval and nymphal development by interfering with metamorphosis and reproduction. Thus, in practice, their application is more limited and necessitates more specific control strategies than conventional insecticides. Moreover, IGRs require good knowledge of the target pests and more time to reduce insect populations than the other insecticides. Consequently, IGRs have been employed in Israel against only a few insect species of public health importance and usually in conjunction with conventional insecticides.

The IGRs include various chemical classes with different modes of action and representatives of all groups are in current use, as follows:

Juvenile hormone analogs or mimics: methoprene and pyriproxyfen are employed in the control of fleas and, to a lesser extent, of mosquitoes and house flies.

Chitin synthesis inhibitors: diflubenzuron (Dimilin) is used in house fly control. Triazine derivatives: cyromazine, the only representative of this group, has been widely used

over the past 10 years in the control of house flies, either by direct application to manure (as Neporex) or as feed-through in poultry (as Larvadex). Initially, the results were very satisfactory. Development of resistance in certain populations of house flies necessitates a re-evaluation, at least of the mode of application, of this compound.

At present, new compounds are being tested and considered for introduction into the IPM of vectors of public health importance.

Integrated Control of Manure and Garbage Breeding Flies in Farming Communities in Southern Israel

A.G. Havron Kibbutz Be'eri, M.P. haNegev 85135, Israel [Fax: +972-7-949437]

Animal husbandry and poultry production provide major breeding sites for house flies (Musca domestica), stable flies (Stomoxys calcitrans), and various other 'garbage flies'. These pests contaminate food and utensils, affect farm workers and livestock productivity, transmit enteric and ophthalmic diseases, affect recreational and tourist businesses, and are the source of endless complaints from institutions and the general public. Space sprays and area treatments with toxic insecticides are neither effective nor acceptable as control measures.

An integrated pest management (IPM) program was described, combining: (i) Improved management of manure and other agricultural refuse by composting; (ii) careful management of animal premises and feed storage facilities; (iii) extensive use of traps and baits; (iv) utilization of selective insecticides such as insect growth regulators as larvicides; (v) selective placement of broad spectrum pesticides, where necessary; and (vi) conserving natural biological control by beetles,


mites, spiders, ants, parasitic wasps, etc., by desisting from space and area spraying. Additionally, municipal garbage and animal carcasses are disposed of by prompt removal and burial. All active control measures are preceded by intensive monitoring of suspected breeding sites and evaluation of the nuisance level requiring such intervention.

The integration of area-wide fly control activities by farmers, municipal authorities, pest control operators, extension personnel and the public is another essential aspect of fly IPM.

The implementation of a fly control program along these lines by the Eshkol Regional Council in the western Negev region led to a considerable reduction of the fly problems in most situations, along with reduced pesticide use, environmental pollution and control expenditures.

Wasps and Their Control in Israel

Z. Klein 1 and H. Adler 2 a Plant Protection and Inspection Services, Ministry of Agriculture, Bet Dagan 50250

[Fax: +972-3-9681507~; and 2The Regional Veterinary Office, Ministry of Agriculture, 'Akko 25212, Israel

Two serious wasp pests in Israel are the Oriental hornet (Vespa orientalis) and the German yellow jacket hornet (Vespula germanica). Both represent a health hazard and nuisance to humans, being attracted to sweets, meats and kitchen waste; their stings pose a danger to allergic individuals. Additionally, both hornets cause serious damage to the bee-keeping industry by attacking and destroying hives, thus reducing honey production and greatly impairing bees' pollination activity. The yellow jacket also can cause severe harm to milk cows by aggressively feeding on the teat area.

The Oriental hornet appears in spring, increasing with pollination in summer and autumn. Of the methods used for Oriental hornet control, we tried: (i) control of queens in the spring, (ii) dusting the nest entrance with insecticide, (iii) use of baited traps and (iv) use of poisoned meat baits. The last was found to be the most effective method. During the 1980s a large-scale screening program for chemicals indicated fluoroacetamide to be best for hornet colony control. However, since this chemical is dangerous to both humans and animals and does not have an antidote, we searched for an alternative chemical control agent. In recent trials, among many chemicals tested the only one that equaled the effectiveness of fluoroacetamide was the commercial formulation of the insecticide acephate (Orthene 750 g a.i./kg SP, Chevron Chemical Co., CA, USA), applied in the poisoned meat baiting method and providing excellent control of the Oriental hornet. As an organic phosphate, acephate is less dangerous to humans and animals and, moreover, it has an antidote. A request has been filed to add this use to the chemical's label.

The German yellow jacket can cause severe damage to milk cows by deep bites to the skin and subcutaneous tissues, on or near the teats. Secondary infections occur, mainly by Staphylococcus aureus. Although long known, this phenomenon has recently reached alarming proportions, affecting up to 25% of cows in certain herds during the summer of 1993. The poisoned meat baiting method, described above as effective for the control of the Oriental hornet, was tried in the autumn of 1993 in a Western Galilee kibbutz herd. After accustoming the hornets to feed on untreated bait, acephate was mixed with ground beef (5 g/500 g beef) and placed in each of nine raised cages located around cowsheds; this was repeated on three consecutive days. The treatment was found to be very effective. Within a few days the pests were almost completely eradicated and within 2 months the teat lesions were cured. It should be stressed that because of this chemical's toxicity, maximum precaution must be exercised in handling it.

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Control of Vertebrate Pests: Looking Towards the 21st Century

S. Moran Plant Protection and Inspection Services, Ministry of Agriculture, Bet Dagan 50250, Israel

[Fax: +972-3-9681507~

A breakthrough in vertebrate damage control techniques has taken place during the last few years. Researchers succeeded in achieving a better understanding of the mode of action of old materials, adapting new active ingredients, and developing non-pesticidal techniques. Some of the prominent achievements are described here.

In field rodent control, compound 1080 (sodium fluoroacetate) had been considered quite hazardous to the environment and to non-target organisms, and it has no antidote. In recent years it was found to be biodegradable in soil and in water, and to be eliminated rapidly from the animal body. The probability of toxic residues in carcasses can be reduced by decreasing the dosage employed in the field, or by diluting the treated bait with an untreated one. It is possible that DFP (1,3-difluoro-2-propanol) will be a favorable alternative to 1080, as it has an effective antidote: 4- methylpyrazole. Research on rodent resistance to anticoagulants is continuing. One of the interesting findings is the possibility that the gene for resistance may persist through the dominant heterozygotic rats. Cholecalciferol (vitamin Da) has not yet become a popular substitute for the anticoagulant rodenticides, but it is assumed that it will play a role in the future.

Bird damage to field crops remains one of the unsolved issues. To date, application of bird repellents has been problematic, as they were more or less toxic. The development of the food- grade ingredients D-pulegone, methyl anthranilate and o-aminoacetophenone as bird repellents which are friendly to crop and consumer, as well as to the environment, may enable the direct application of these ingredients on food crops. To obviate the use of toxicants, as demanded by the public, it is possible to use multiple bird traps, sometimes old models which have been used by pest control operators and farmers for decades. Some of them, especially pigeon traps, are manufactured commercially. Various models are modifications of the Australian crow trap, mainly for corvids, starlings and parakeets, and they have proved to be as effective as toxic control measures. Another way to overcome the bird problem, in urban as well as rural environments, is by exclusion. This technique became inexpensive with the development of plastic bird nets, which are useful in excluding fruit-eating birds from orchards, and pigeons from structures. These nets can be useful for the exclusion of mammals: hares and gazelles have been effectively and economically excluded by fences constructed of the same material. Recorded stress calls are broadcast to repel effectively and completely some flocking species of birds. They scare away starlings from urban roosts, fields and cow sheds, and lark focks from sprouting fields, thus becoming a perfect non-toxic means of bird damage control.

These are some of the milestones in the development of vertebrate pest control techniques friendly to the environment. During the next few years, as we approach the 21st Century, we can expect other advanced methods, and further development of the existing ones.

B: CONTROL OF STORED-PRODUCT AND FOOD INDUSTRY INSECTS; FUMIGANTS

Problems of Insect In fes ta t ion in Food and Food Factories and M e thods o f

Control and Prevention

A. Wilamowski 1 and R. Amichai 2 1Entomology Laboratory, Ministry of Health, Jerusalem 91060 [Fax: +972-2-233168]; and

2Nationwide Exterminating Ltd., Ramat Gan 52002, Israel


Food factories in Israel provide the optimal conditions necessary for the development of insect populations: excess food, high temperature "and appropriate humidity. Some of the plants are surrounded by cultivated vegetation, others are located in rural areas; these sites are natural foci for the development of insect populations which invade factories. Moreover, the lights of night-operating plants attract a wide range of flying insects. The results of surveys carried out since 1975 by the Entomology Laboratory at the Ministry of Health, Jerusalem, monitoring the presence of insects in food and in food plants, indicated four groups of insects infesting food factories. (i) Stored- product insects, which live and develop in dried food, may develop from populations in the factory or warehouse, or may reach the factory in the raw materials. Generally, 6-8% of the samples examined each year are infested with insects from this group. (ii) Insects which live permanently in the factory (mainly cockroaches), causing severe sanitation problems. (iii) Insects which invade the factory from outside foci, either flying or crawling (such as Musca domestica, other flies, moths, beetles, etc.). (iv) Insects which are attracted to a specific food produced in the factory (e.g. Drosophila spp., flesh flies, etc.).

The strict food standards in Israel, as in many other countries, compel factories to take preventative and extermination measures in order to produce uncontaminated food. The measures are interconnected, complicated to carry out, and require extensive expertise. The exterminators must operate according to certain basic factors such as the building structure, how well it is sealed, the level of its sanitation, etc. The goal of this joint work of the Entomology Laboratory and Nationwide Exterminating is to demonstrate a model of integrated pest management by preventative and extermination methods, the aim of which is to prevent insect infestation using a minimal amount of insecticides. The model, which has been employed successfully in a number of food plants in Israel, is based on the following principles: (i) All the measures should be carried out in full cooperation with factory representatives suitably trained in monitoring and identification of infestation foci. (ii) Daily monitoring in the factory. (iii) Monitoring should be conducted using species-specific traps. A large amount of information can be obtained from the traps: identification of the insects; level and duration of infestation; whether the infestation is temporary or continuous; and the point of invasion into the factory, and the infestation foci. (iv) Mapping of the factory, correct placement of the traps at sensitive points, and the daily collection of information are carried out by a computer program (Prog. to Kill) which enables the correct analysis of the results and the institution of immediate control procedures.

By employing this model, a significant reduction in the use of insecticides was achieved. For example, in a large factory specializing in the production of several types of dry food, there was a decrease from 40 insects per trap per day and 40 liters of insecticide per month to one insect per trap per day and 14 liters of insecticide per month. The use of insecticides is recommended only when there is no alternative, and only on specific foci.

The Practical Use of Pheromones

D.K. Mueller Insects Limited Inc., Indianapolis, IN46280, USA [Fax: +1-317-8469799]

A means for determining the presence or absence of potentially harmful pest insects is needed where stored commodities are held for extended periods of time. Pheromone-baited traps are an excellent tool for this purpose. Not all pheromone traps are created equal: traps for moths may act differently from beetle traps. One cannot treat all stored pests the same when it comes to recommending an effective trapping program. Long-lived insect adults (e.g. Tribolium sp.) tend to be less attached to pheromone traps than short-lived insect adults. A Tribolium adult that lives for 12 to 18 months does not react like an Indianmeal moth (Plodia interpunctella) adult that may live in this stage for only 1 or 2 weeks.

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It is important to recognize that there is only one type of trap that is optimal for use in a pest monitoring program. One must match the specific trap to the environmental conditions in each particular situation, such as dusty areas vs areas that are not dusty, hot vs cold temperatures, and outdoor vs indoor use.

Trapping for stored-product insects around the outside of a facility can offer several advantages in an overall pest management strategy. By placing pheromone-baited traps along the outer perimeter of a storage facility, potentially destructive insects can be intercepted early and lured away from stored food and grain. A common misconception in a strategy used to manage stored products employing pheromone-baited traps is that there is a set numerical threshold for action or reaction. There is no magic number for determining action. A trained pest management inspector must weigh all factors before a decision is made. Population growth is a key to making a judgment. The use of pheromone-baited traps to determine the presence or absence of a pest population in storage facilities is an exciting new step toward a total pest management program. The practical application of pheromone traps to alter insect behavior and prevent reproduction provides the pest control operator with a gauge to determine the presence or absence of insect pests.

Update on the Status of Methyl Bromide in Connection with the Ozone Issue

M. Spiegelstein Health, Safety and Environment Division, Bromine Compounds Ltd., Be'er Sheva 84101, Israel

[Fax: +972-7-297832]

Methyl bromide (MBr), a unique, broad-spectrum fumigant, was added to the Montreal Protocol list of ozone-depleting substances (ODS) in November 1992, after a long and heated debate. The scientific basis for this decision was very weak, with many data gaps and assuming an estimated ozone depleting potential (ODP) of 0.7. When new scientific findings (1994/95) are considered, the ODP of MBr can drop as low as 0.3, with a lifetime of approximately one year.

Chlorine and bromine derivatives were implicated as being involved in stratospheric chemistry that destroys ozone molecules. The sources of these ODS were identified as man-made chemicals - chlorofluorocarbons, hydrochlorofluorocarbons, Halon, chlorinated solvents and, recently, MBr. Of these, MBr is the only compound that is predominantly a natural product, produced, stored and released by ocean biomass activity. Other sources of MBr are biomass burning, emission from combustion engines, and emission from fumigation (primarily soil fumigation).

The regulatory status of MBr was recently decided in the Vienna meeting of the parties to the Montreal Protocol as follows:

�9 Developed countries (OECD): 25% reduction in 2001, 25% reduction in 2005, phaseout in 2010 (base year: 1991)

�9 Developing countries will freeze consumption by 2002, to the average consumed from 1995- 1998.

�9 Uses for quarantine and preshipment are exempted from any controls.

�9 Critical agricultural uses will be defined and discussed in 1997.

It is recognized by the parties to the Montreal Protocol that viable alternatives to MBr exist only for a very limited number of its activities. Due to pressure from agricultural groups, the Methyl Bromide Technical Option Committee will define critical agricultural uses shortly. Fumigators for non-agricultural uses have to come forward with advanced technologies to reduce/prevent MBr emissions in order to preserve its use.


Plant Volatiles as Alternatives for Methyl Bromide for the Control of Stored-Product Insects

E. Shaaya and M. Kostjukovski Inst. of Technology, ARO, The Volcani Center, Bet Dagan 50250, Israel [Fax: +972-3-9684428]

The fumigant toxicity of a large number of essential oils obtained from various spices and herb plants was assessed against several major stored-product insects. Three types of tests were performed to evaluate the activity of the oils: (i) space fumigation in glass chambers to select the most active oils; (ii) the highly active oils were then assayed in small fumigation chambers filled to 20% and 70% by volume with grain; and (iii) pilot tests were carried out in simulation columns filled to 70% volume wtih grain, under conditions similar to those present in grain bulks. Tribolium castaffeum (Herbst) was found to be the most resistant to most of the essential oils tested, compared with Sitophilus oryzae (L.), Rhyzopertha dominica (E) and Oryzaephilus surinamensis (L.). Of the highly active oils, a concentration of 1.4--4.5 #l/l air and an exposure time of 24 h were enough to obtain an LCg0 to all the insects in the space tests. In columns filled with 70% wheat, a concentration of 50 #l/1 and a 7-day exposure were needed to obtain 94-100% kill of insects.

Volatiles extracted from oilseed of crucifers were also found to possess high activity against stored-product insects. Of the highly active volatiles, a concentration of 5 #l/l air and an exposure time of 3 h were enough to obtain 100% kill of all insects tested. In columns filled with 70% wheat, a concentration of 15 #l/l and a 1-day exposure were needed to obtain 100% kill.

The high activity of these essential oils makes them potential substitutes for methyl bromide, identified as a major contributor to ozone depletion, which casts doubts on its future use in insect control.

EPILOGUE

Extended Summary The NPCA's Fact-Finding Mission to the Galapagos Islands

N. Cooper Rye, NY10580, USA[Fax: +1-914-698885~

Last year the National Pest Control Association's (NPCA) President appointed a committee to explore the feasibility of NCPA involvement in a long-term biodiversity conservation program in the Galapagos Islands. This was a challenge to our industry. The islands' unique ecosystem is a high-profile opportunity to provide professional pest control expertise and an ideal forum to garner favorable worldwide publicity for our industry. It was decided that the NPCA Galapagos Conservation Mission would not offer solutions but act solely as a fact-finding mission on a voluntary basis.

The Galapagos Islands are a UNESCO preserve which was declared a Natural World Heritage Site by UNESCO in 1978, underscoring its universal value. Although the flag of Ecuador flies over these islands, the site is really the heritage of the entire world. This volcanic archipelago in the Pacific lies 900 km west of Ecuador. 95% of its reptiles, 75% of the insects, half the birds and nearly a fifth of all the fish appear nowhere else on earth. The Galapagos Islands were the incubation laboratory for Charles Darwin's theory of evolution.

The giant tortoise has become a symbol of endangered species. It has few natural enemies but is threatened with extinction by humans and the animals we have introduced. Rats introduced by ship have been responsible to a great extent for the extinction and threatened extinction of several

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subspecies. For example, on Pinzon Island, in recent years rats had eaten every tortoise which hatched. The endemic race of giant tortoises had not successfully bred on that island for over 100 years as a result of depredation on the eggs and newly hatched young by the black rat (Rattus rattus). From the several hundred thousand tortoises that roamed these islands before man's recent arrival, only a small fraction survive today and far fewer would exist if it were not for the efforts of the Charles Darwin Research Station. The workers in the station's tortoise rearing programs have been successful in gathering tortoise eggs, incubating them and, after hatching, rearing them to sustainable size and repatriating them to their islands of origin.

Mice (Mus musculus) and black rats have been in the Archipelago since the 1800s but the brown rat (Rattus norvegicus) is believed to have been introduced in 1983 and has become firmly entrenched on two islands. Among the victims of these introduced predators are flightless cormorants, iguanas, dark rumped petrels and giant tortoises, not to mention man.

From 2,500 inhabitants living on the islands in 1980 the population increased to 15,000 people living there now; moreover, there is a huge increase in tourism. The human population explosion is severely endangering the delicate ecological balance of the Galapagos.

The Director of the National Galapagos Institute, the agency primarily responsible for the development of populated areas, its residents and their pets, identified their most serious problems as rats, public education regarding the need for sanitation and pest control and feral animals. We visited a municipal garbage dump, an area which is burned and bulldozed once a month; however, no pest control services are presently rendered at this site.

Although the Galapagos Islands are volcanic, the island of Santa Cruz has highlands, rich soil for farming, rain, and seven temperature zones. The primary problems facing the farmers are rats - mostly black rats, but recently brown rats have been spreading. The rats eat fruit, seeds and chickens. The farmers currently use their own mixtures of Racumin (coumatetralyl), sugar cane, oil and corn. Compound 1080 is widely available and used. It is also readily available to townspeople with little instruction in its use. Reportedly there are very few cases of non-target poisoning.

It has been estimated that the dark rumped petrel, which exists only in Hawaii and the Galapagos Islands, will be extinct in Hawaii before the end of this decade, and is seriously threatened with total global extinction in the Galapagos Islands as a result of rat depredation. Rat-baiting programs have been undertaken in the past few years by the Ecuadorian Park Service and are credited with raising the survival rate of petrel chicks to 80% as compared with 20% prior to the rat-baiting program. There are problems regarding the spread of cockroaches, fire ants and also of non-native wasps.

Some of the mission's priorities which were examined and need to be addressed include:

�9 Stemming the emigration to the Galapagos Islands

�9 Boat inspection, waste disposal, fumigation protocols

�9 Freighter quarantine

�9 Control of introduced fire ants

�9 Eradication of introduced wasps

�9 Elimination of rat nesting sites

�9 Information exchange

�9 Educational and public relations

�9 Community education

�9 Landfill and recycling specifications

�9 Limitations on tourism

�9 Hotel, restaurant and tour boat regulations.


By title only

The proper use of baits to control German cockroaches - S. Clark

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M E E T I N G S


T H E 2ND I N T E R N A T I O N A L A G R O - E C O L O G Y S Y M P O S I U M ON I N T E G R A T E D PEST M A N A G E M E N T :

FROM T H E D R A W I N G BOARD TO T H E M A R K E T (within the framework of "Agritech Spring '96", the 13th International Agricultural Exhibition)

May 15, 1996 Tel Aviv Convention Center, The Israel Trade Fairs Center, Tel Aviv, Israel

Principles of Integrated Pest Management

M. Coil Dept. of Entomology, The Hebrew University of Jerusalem, Faculty of Agriculture,

Rehovot 76100, Israel [Fax: +972-8-9466768]

In intensive agricultural systems, the introduction of high-yielding genetically uniform crops and the use of fertilizers, irrigation, monocultures, and dense planting favor pest epidemics. In most systems, crops are protected simply by the unilateral application of a single control tactic, mainly pesticides. The rapid increase in the appearance of pesticide-resistant pests and the growing environmental and health concerns demand a more sophisticated approach - Integrated Pest Management (IPM). IPM programs act to minimize the use of harmful pesticides and employ a mix of several pest control tactics, based on economic and safety criteria. A central principle of this approach is that potentially harmful species will continue to exist at tolerable levels of abundance. IPM efforts manipulate the environment to lower the density of key pests to levels below the economically damaging ones. This reduction in pest densities could be accomplished using three major strategies, singly or in combination: (i) introduction of predators and parasites in areas where they do not occur; (ii) utilization of pest-resistant crop varieties; and (iii) modification of the crop-habitat to decrease the reproduction, development, and survival of the pest and to increase the effectiveness of its natural enemies. To reduce pesticide use and conserve natural enemies, pest populations are routinely monitored and remedial measures, such as the use of pesticides that cause minimal ecological disruption, are taken only when pest populations are to exceed the economic threshold. Clearly, the development of effective and long-lived IPM programs depends on a sound, research-generated biological, ecological, environmental, as well as economic understanding of the system at hand.

The Role of Commercial Biological Control in IPM

S. Steinberg Biological Control Industries and Bio-Bee, Sede Eliyyahu, M.P. Bet She'an 10810, Israel

[Fax: +972-6-580908]

Commercial biological control is a key component of IPM. It encompasses augmentative releases of mass-reared natural enemies, which are economically competitive to chemicals in solving pest


problems. Augmentative releases of beneficial organisms take the form of seasonal inoculative introductions, mainly in protected crops (e.g. greenhouse vegetables) and to some extent in citrus orchards. Inundative introductions are applied in field crops, chiefly corn. The current and future role of commercial biological control in modern IPM was discussed in light of incentives (promoting factors) and disincentives (limiting factors) which may be considered by the potential users. The incentives are: (a) resistance to pesticides; (b) consumers' environmental concern which leads to reduction of pesticides on the one hand, and promotion of 'eco-product' labels on the other hand; (c) increasing availability of natural enemies, expressed in multi-species biocontrol systems; and (d) the use of bumblebees for natural pollination. The disincentives are: (a) relatively high costs of natural enemies; (b) complicated application; (c) zero tolerance status of some key pests; and (d) objective growing conditions. The extent to which IPM in general, and commercial biological control in particular will be utilized in various agricultural crops, is basically an economic, market- driven matter.

Integrated Pest Management Programs in Israel: The Clean Arava Project

E. Ravins Arava Research and Development, Sapir Center, M.P Arava 86825, Israel [Fax: +972-7-581235]

The Arava Region stretches for 180 km from the Dead Sea in the north to Elat on the coast of the Red Sea. Positioned along the Afro-Syrian rift, the Arava clearly defines a geographical area, ecologically isolated from the rest of the country. The arid climate, with a very hot, dry summer and dry, cold winter nights, contributes to natural eradication of pests and pathogens. The Clean Arava project was designed to take advantage of the unique isolation of the region, by employing integrated methods to achieve a pest-free area.

The seven settlements in the Central Arava Region taking part in the project are widely separated, thus allowing for the success of the sanitation measures which are dictated by the project. The 2400 residents of this region, most of whom support themselves with family farms, produce 50% of Israel's total vegetable export, and almost 20% of Israel's flower export.

During the 1983-85 seasons, an outbreak of viruses led to the initial steps towards sanitation between seasons. The experience accumulated over the years pointed to the possibility of area wide IPM (only one main road crosses the area), and analysis of word market trends indicated its necessity. The project was initiated in 1991 by the Minister of Agriculture and the Chief Scientist of the Ministry of Agriculture with a series of surveys and field experiments.

The main goals of the project are: increasing awareness and enforcing sanitation bylaws in the region, expanding agricultural export into countries with phytosanitary barriers, reducing the use of chemicals, producing chemical-residue-free vegetables, and greater profitability for farmers, while increasing the total amount of export products.

IFP - How It is Being Done in the South Tyrol

W. Waldner South Tyrolean Advisory Service for Fruit and Winegrowing, Lana 39011, Italy

[Fax: +39-473-564220]

The South Tyrol is one of the most intensively cultivated fruit-growing areas in the world. On 17,600 ha approximately 8,000 orchard owners produce 700,000-800,000 tons of apples every year. 10% of the European apple crop is grown here.

In order to overcome resistance problems the South Tyrolean Advisory Service for Fruit and Winegrowing developed an integrated pest management program which paved the way for integrated fruit production (IFP). A working group for IFP was founded in the South Tyrol in 1988. It includes

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the main local organizations concerned with fruit production, marketing, research, extension service, and the local government. In January 1989 the first guidelines were published. IPM is only one of 15 chapters in our IFP guidelines. The IFP program was started in 1989, since when approximately 70% of the orchard owners have taken part in the program each year.

The packing houses are interested in being supplied with the largest possible quantity of IFP- fruit, because in that way they can be sure that this part of the apple production has no or very little pesticide residues. In order to motivate the orchardists, most of the packing houses are willing to pay 15-16 Italian Lire/kg more for IFP fruit than for conventionally produced apples.

IFP is a guarantee for less residues on fruits and improves our ability to meet the competition in the domestic and foreign markets. It also helps to open up new markets. The term IFP and the label with the ladybird are regarded favorably by the consumers, even if they do not know their exact meaning. For all these reasons IFP will be an integral part of our future fruit production.

Integrated Pest Management in Deciduous Fruit Orchards in Israel

R. Ausher Ministry of Agriculture and Rural Development, Extension Service, Tel Aviv 61070, Israel

[Fax: +972-3-6971664]

Reduction in the use of pesticides through IPM practices is a government-mandated policy supported by research, extension and farmers. Deciduous fruit crops - pome fruits and grapes - have been the first ones to be covered by the program, followed by stone fruits (peaches, nectarines, plums, apricots). The program relies on a regional network of local pest scouts, who monitor the pest populations on a weekly basis. Their work is coordinated by regional scouts and supported by the coordinator of the regional fruit growers' association. At the top of the regional pyramid are the crop protection extension specialists working in close collaboration with the crop husbandry extension specialists. At state-level, the program is coordinated by a steering committee consisting of research, extension and growers' representatives. By now, the program can be found in all the fruit- growing regions of the country and almost 30% of the cropping area is covered by it. The research thrust is aimed at the disruption of insect-pest populations through pheromone release, the promotion of selective and environment-friendly pesticides, and of beneficial insects, and the improvement of pesticide application techniques. In the domain of fungal and bacterial diseases, the technical objectives are the promotion of early warning and forecasting programs aimed at sophistication of the fireblight control on apples, pears and loquats; downy mildew of grapes; and apple scab. The extension-advisory component is responsible for the implementation of the field activity, the training of growers and scouts, the publication of training material, warnings, collection of scouting data and its processing, economic evaluation, and release of information about the program to the public at large. The amount of pesticides used on the project plots has been reduced by an average of 30%.

IPM and the Citrus Industry in Israel

Y. R6ssler The Israel Cohen Institute for Biological Control, Citrus Marketing Board of lsrael,

Bet Dagan 50250, Israel [Fax: +972-3-9683838]

IPM is, inter alia, the production of environmentally friendly fruit. The term 'friendly' should apply to the production process and the end product. Three circles of environments are involved: the grove and the farmer; the immediate ecosystem to which the production process is of primary concern; and the consumer, who is concerned mainly with the quality of the end product. IPM should cater to all three environments, and provide the solution to both the production process and


the quality of the end product. The citrus industry in Israel has been implementing components of IPM, such as the utilization of biological control, the use of selective pesticides, and establishment of monitoring systems for the major citrus pest (the Mediterranean fruit fly) for many years. Biological control of citrus pests in Israel began in 1912 and since then numerous projects of classical biological control have been launched. The unofficial IPM of citrus in Israel has benefited the three environmental circles, but no attempts have been made to declare IPM as a national or even industry- wide policy. To do so, the following points have to be adopted and implemented. It should be recognized that: (i) The object of IPM is the process and the end product. (ii) The means and guidelines should be clearly defined. (iii) The participation of the farmer should be voluntary but binding. (iv) A continuous quality control procedure of the process and the end product should be maintained. (v) A clear understanding of the activities during the production process is essential. (vi) A label of quality for IPM produce should be adopted on a national scale.

The time has come to institutionalize these efforts and institute a national IPM project, based on the accumulated achievements of the industry. Such a project will require the cooperation of research institutes, the extension services and, above all, the growers themselves.

Pest Management: Examples from Horticulture and Viticulture

H. Denzer Pessl & Berger Consultants GesmbH & Co. KEG, 8160 Weiz, Austria [Fax: +43-317-2552123]

The occurrence, the date of occurrence, and the severity of pests and diseases in perennial crops are determined by the hibernation of primary inoculum, the weather during the season, and the susceptibility of the host. The influence of these three factors varies among different pests and diseases. Even for one disease, the influence of these factors can vary during the season. For Plasmopara viticola, Uncinula necator, Botrytis cinerea and Venturia inaequalis, primary inoculum is present every year in most European growing areas. For P viticola, U. necator and V. inaequalis, the form and quantity of primary inoculum influence the disease severity at the beginning of the epidemic. Damages due to B. cinerea are related only to weather conditions.

The propagation of some pathogens, such as P viticola and V inaequalis is determined by a sequence of different weather conditions. Meteorological observations give us detailed information about the different propagation cycles of the disease. But there is a large group of diseases such as all powdery mildews, which are able to spread during a wide range of weather conditions. They are favored by one or two climatic factors. Therefore, meteorological observations can only lead to an assessment of the propagation ability of these fungi. Insects are influenced mainly by temperatures during their different stages. Hence, unfavorable climatic conditions can lead to noncoincidence between host and pest. There are only a couple of insect pests for which climatic conditions are related directly to propagation rate and severity of damage.

Pheromones as an Important Component of IPM

E. Dunkelblum and M. Kehat Inst. of Plant Protection, ARO, The Volcani Center, Bet Dagan 50250, Israel

[Fax: +972-3-9683647]

Sex pheromones are natural nontoxic compounds usually produced by female insects to attract conspecific males. Pheromones of most key insect pests have been identified and synthesized during the last 20 years, enabling their use in IPM programs.

In practice, pheromones are used for two main purposes: (i) monitoring of insect pests by trap catch of male moths and (ii) control of pests. Both aspects are important components of IPM, although problems have been encountered occasionally. The successful application of pheromones

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for monitoring and for direct control of major pests, in particular, will reduce significantly the use of harmful insecticides.

Monitoring: We have optimized the parameters of male attraction for several cotton and orchard pests. The most important pests which are monitored with pheromone traps in Israel are the spiny bollworm (Earias insulana), the cotton bollworm (Heliothis armigera), the pink bollworm (Pectinophora gossypiella) and the cotton leafworm (Spodoptera littoralis) in cotton fields, and the peach twig borer (Anarsia lineatella), the honeydew moth (Cryptoblabes gnidiella), the codling moth (Cydiapomonella) and the European vine moth (Lobesia botrana) in orchards and vineyards. Israeli- made rubber septa have been introduced and optimal doses of pheromones have been determined for most key pests. These lures are at least equivalent to and in some cases better than the commerciaI lures (due to higher trap catch and prolonged longevity). Dry funnel traps are being used instead of the sticky traps which are messy, are not suitable in the dusty Israeli environment, and become quickly saturated with captured moths.

Mating disruption: Control of moth pests can be achieved by pheromone-mediated mating disruption. The main problem with this method was the development of long-lasting, efficient pheromone formulations. At present, several formulations are available, some of which are commercial and others at an experimental stage. In Israel, pheromones are applied commercially to control the pink bollworm in cotton fields and the codling moth in apple and pear orchards. Experimental mating disruption tests are carried out against the peach twig borer and European vine moth in orchards and vineyards and against the cotton bollworm and the spiny bollworm in cotton fields. Some of these tests are at an advanced stage and others are at an early one. The performance of the various formulations is evaluated in the field by comparing trap catch, infestation and damage in pheromone-treated plots with the same parameters in control plots. Mating tables are also used to evaluate the efficacy of new pheromone formulations for mating disruption.

We have used in recent years mainly Shin-Etsu ropes and BASF ampoules. Our results indicate that the success of mating disruption depends on the quality and longevity of the formulation, on proper application and evaluation, and not too high population densities of pests at the start of work. Initial high population densities of pests must be reduced by early insecticide sprays before pheromones can be applied satisfactorily. Lately, we have started testing new formulations produced by AgriSense, Concep and Troy Bioscience in order to find the optimal one for each of the important pests.


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