Scientia Horticulturae 119 (2009) 182–187

Resistance of 57 greenhouse-grown accessions of Lycopersicon esculentumand three cultivars to Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Fabrıcio Alves Oliveira a, Derly Jose Henriques da Silva a, Germano Leao Demolin Leite b,*,Gulab Newandram Jham c, Marcelo Picanco d

a Universidade Federal de Vicosa (UFV), Dep. de Fitotecnia, 36571-000 Vicosa, MG, Brazilb Universidade Federal de Minas Gerais, Nucleo de Ciencias Agrarias, Dep. de Agropecuaria, Caixa Postal 135, 39404-006 Montes Claros, MG, Brazilc UFV, Dep. de Quımica, 36571-000 Vicosa, MG, Brazild UFV, Dep. de Biologia Animal, 36571-000 Vicosa, MG, Brazil

A R T I C L E I N F O

Article history:

Received 25 October 2006

Received in revised form 5 July 2008

Accepted 11 July 2008

Keywords:

Tomato

Leafminer tomato

Plant resistance

Allelochemicals

A B S T R A C T

The aim of this study was to evaluate resistance to Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) by

antixenosis on 57 Lycopersicon esculentum Mill. accessions from the Horticultural Germplasm Bank (HGB)

of Universidade Federal de Vicosa and by the three commercial cultivars (Santa Clara, Moneymaker and

TOM-601) under greenhouse conditions. A randomized complete block design was used with three

replications. Infestations with T. absoluta adults were performed weekly and the following characteristics

were evaluated: number of small, large and total mines/leaf and % of leaves mined at days 60, 75 and 90

after planting. Low infestation occurred at days 60 and 75 but at day 90, infestation was sufficient to

evaluate insect damage. Based on these data it was concluded that only accessions HGB-674 and HGB-

1497 appeared to be the most promising. In addition, to determine possible chemical causes of resistance,

hexane extracts were analyzed at day 90 by gas chromatography/mass spectrometry and the major peaks

identified by a mass spectral database using similarity index. Nine hydrocarbons, viz., hexadecane,

heptadecane, eicosane, tricosane, 2-methyltricosane, tetracosane, hexacosane, octacosane and triacon-

tane were identified in the hexane extracts in many samples. Tricosane, tetracosane and hexacosane

presented significant correlations with the leaves mined. Only tricosane presented a negative correlation

with the number of small mines (r = �0.28), total number of mines (r = �0.27) and % of leaves mined

(r = �0.22). However, tetracosane and hexacosane presented significant positive correlations (r = 0.25

and 0.24, respectively) with the % of leaves mined.

� 2008 Elsevier B.V. All rights reserved.

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1. Introduction

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of themajor pests that attacks commercial tomato (Lycopersicon

esculentum Mill.). It is considered as a limiting factor for tomatoproduction in several Latin American countries (Silva et al., 1998),accounting for about 70% of the losses. The principal method for T.

absoluta control is blanket spraying with insecticides, harmful toboth man and the environment (Picanco et al., 1998).

Some wild species, such as L. hirsutum (Gilardon et al., 2001; Leiteet al., 2001), L. pennellii (Resende et al., 2000) and L. peruvianum (Silvaet al., 1998; Suinaga et al., 1999, 2004a) are known to be resistant tothis pest. However, undesirable characteristics and/or incompat-

* Corresponding author. Tel.: +55 38 21017719; fax: +55 38 21017703.

E-mail addresses: derli@ufv.br (D.J.H. da Silva), gldleite@ufmg.br (G.L.D. Leite),

gulab@mail.ufv.br (G.N. Jham), picanco@mail.ufv.br (M. Picanco).

0304-4238/$ – see front matter � 2008 Elsevier B.V. All rights reserved.

doi:10.1016/j.scienta.2008.07.012

ibility of these species hinder transfer of resistance factors tocommercial tomato. There is no known cultivated tomato varietyresistant to T. absoluta. This fact could be associated with reducedgenetic variability introduced during tomato domestication, leadingto the loss of genes that control the production of allelochemicalsinvolved in plant defenses.

Resistant genotypes are routinely used to breed pest resistantcultivated plant varieties, and also to maintain insect population atan acceptable level (Vendramim and Nishikawa, 2001). The use ofgenetic resources of cultivated L. esculentum maintained in thegermplasm banks is an alternative to recover the lost geneticvariability, to improve plant resistance to pests and diseases.

The agronomic characteristics of tomato accessions at theHorticultural Germplasm Bank (HGB) of Universidade Federal deVicosa (UFV) have been characterized (Abreu et al., 2006), but theirreaction to insect attack are not known. Thus, the following studywas done to evaluate the resistance of the 57 HGB L. esculentum

accessions and three commercial cultivars to T. absoluta through

F.A. Oliveira et al. / Scientia Horticulturae 119 (2009) 182–187 183

antixenosis under greenhouse conditions. In addition, leaf hexaneextracts were analyzed at day 90 by gas chromatography–massspectrometry (GC–MS) to identify compounds possibly related toresistance.

2. Material and methods

The seedling of 57 accessions and the commercial cultivarsSanta Clara, Moneymaker and TOM-601 were raised for 30 days ina commercial substrate in plastic trays and then transplanted to agreenhouse. Initial planting was done in two 20-cm spaced rowsand 70 cm between plots. After 45 days, one plant was removeddue to excessive growth and insufficient spacing between plants.The experiment was laid in completely randomized block designwith three repetitions.

To evaluate antixenosis, 150 T. absoluta adults (female:male ratio2:1) were released weekly in the greenhouse (Picanco et al., 1995;Suinaga et al., 1999). The insects were obtained from a colonymaintained at the Integrated Plant Management Laboratory. Theinsect damage on the whole plant was evaluated at days 60 and 75after planting. In the third evaluation at day 90, three middle leaves,between third and fourth fruit trusses were evaluated. Theparameters evaluated were, number of large mines (diame-ter> 0.05 cm)/leaf, number of small mines (diameter< 0.05 cm)/leaf and percent of leaves mined (Picanco et al., 1995). At day 90, sixmiddle leaves were harvested, hand-macerated, extracted with20 mL hexane, centrifuged for 5 min at 4000 rpm and the super-natant was frozen at �10 8C until analysis.

For GC–MS analysis, the samples were thawed to roomtemperature and 2.0 mL dodecane stock solution (1 mg/mL) wasadded as an internal standard. All data were obtained on a gaschromatograph/mass spectrometer (Shimadzu, Kyoto, Japan, model

Table 1Number of large and small mines/leaf produced by Tuta absoluta on Lycopersicon esculentu

Vicosa and three commercial tomato cultivars, at day 90 after planting, Vicosa 2003

Number of large mines/leaf produced

HGB-2119 2.61 A HGB-216 0.91 B

HGB-218 2.45 A HGB-327 0.91 B

HGB-160 2.36 A HGB-227 0.88 B

HGB-1490 2.35 A HGB-7237 0.79 B

HGB-7236 2.24 A HGB-184 0.78 B

HGB-121 2.26 A HGB-1498 0.71 B

Moneymaker 2.22 A HGB-1988 0.70 B

HGB-226 2.11 A HGB-1993 0.65 B

HGB-1987 2.11 A HGB-1985 0.65 B

HGB-1992 2.06 A HGB-7234 0.63 B

HGB-378 1.88 A TOM-601 0.59 B

HGB-351 1.83 A HGB-225 0.56 B

HGB-616 1.79 A HGB-1485 0.56 B

HGB-7233 1.76 A HGB-1532 0.48 B

HGB-1706 1.63 A HGB-980 0.43 B

HGB-606 1.60 A HGB-1990 0.41 B

HGB-24 1.59 A HGB-168 0.31 B

HGB-243 1.52 A HGB-1989 0.27 B

Santa Clara 1.42 A HGB-406 0.21 B

HGB-185 1.40 A HGB-1282 0.21 B

HGB-224 1.36 A HGB-7235 0.21 B

HGB-349 1.31 A HGB-320 0.19 B

HGB-6860 1.26 A HGB-603 0.19 B

HGB-161 1.24 A HGB-55 0.10 B

HGB-1499 1.18 A HGB-7238 0.10 B

HGB-700 1.17 A HGB-83 0.00 B

HGB-990 1.14 A HGB-1708 0.00 B

HGB-1538 1.13 A HGB-674 0.00 B

HGB-1254 1.07 A HGB-1497 0.00 B

HGB-1991 1.05 B – –

HGB-186 0.95 B – –

Averages followed by same upper case letter in columns do not differ by Skott–Knott

QP 5000 with the software program-Classs-5000, Version 1.2) fittedwith an auto sampler and mass spectral database with 160,000entries (Wiley 229), and a fused-silica capillary column(30 m � 0.25 mm; 0.25 mm film thickness) coated with polyethyleneglycol (Supelco, College Station, PA) as the stationaryphase. The GC-oven temperature was increased from 20 8C to 80 8Cat 20 8C/min and from 80 8C to 250 8C at 8 8C/min. The injector andtransfer line temperatures were maintained at 280 8C and 300 8C,respectively. The split ratio was (1:1) with He as the carrier gas.Electron ionization mass spectra (70 eV) were recorded by scanningthe mass spectrometer from m/z 29 to 320. To obtain representativedata, the mass spectra of all GC peaks (�50 scans) of interest weregrouped and subtracted from the grouped mass spectra of the regionclosest (before or after) to where no compound eluted.

Retention times of peaks with ion current (IC) higher than6 � 104 ions/s were recorded. Ion current ratios were obtained bydividing the IC of the major sample peak by the IC of the internalstandard peak. The compounds were identified using the massspectral database and compounds with a similarity index (SI)greater than 79% were considered as positive identifications.

The resistance characteristics of the accessions were submittedto Lilliefor’s normality test and transformed to

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

X þ 0:5p

foranalysis of variance. Treatment means were clustered by theSkott–Knott test (p = 0.05) that ranked from highest to lowestattack level. Spearman correlation coefficients (p = 0.05) wereestimated between the resistance characteristics and the ICproduced by the peaks.

3. Results

The insect damage evaluated at days 60 and 75 after plantingdid not differ significantly (p = 0.05) among genotypes due to low

m accessions in the Banco de Germoplasma de Hortalicas of Universidade Federal de

Number of small mines produced

HGB-351 4.07 A HGB-603 0.76 C

HGB-160 3.81 A HGB-606 0.68 C

HGB-2119 3.15 A HGB-327 0.65 C

HGB-24 2.87 A HGB-1490 0.62 C

Moneymaker 2.51 A HGB-1985 0.62 C

HGB-378 2.50 B HGB-1706 0.59 C

HGB-218 2.40 B HGB-83 0.56 C

HGB-121 2.28 B HGB-1989 0.56 C

HGB-226 2.25 B HGB-0320 0.56 C

HGB-7236 2.20 B HGB-0227 0.53 C

HGB-243 2.18 B HGB-1254 0.50 C

HGB-216 1.80 B HGB-1485 0.50 C

HGB-1987 1.77 B HGB-406 0.48 C

HGB-1992 1.75 B HGB-7238 0.48 C

HGB-7233 1.75 B HGB-168 0.48 C

HGB-980 1.58 B HGB-161 0.43 C

HGB-7237 1.58 B HGB-1708 0.31 C

HGB-186 1.33 B HGB-349 0.31 C

TOM-601 1.32 B HGB-1991 0.31 C

HGB-185 1.07 B HGB-700 0.27 C

HGB-1988 1.05 C HGB-55 0.21 C

HGB-225 1.05 C HGB-1990 0.19 C

HGB-1498 1.05 C HGB-1532 0.19 C

HGB-184 1.03 C HGB-616 0.10 C

HGB-1993 1.03 C HGB-1282 0.10 C

HGB-6860 0.98 C HGB-674 0.00 C

Santa Clara 0.98 C HGB-990 0.00 C

HGB-224 0.98 C HGB-1497 0.00 C

HGB-7234 0.98 C HGB-1499 0.00 C

HGB-1538 0.87 C – –

HGB-7235 0.82 C – –

test (5% probability).

Table 2Percentage of leaves mined and total number of mines/leaf produced by T. absoluta on L. esculentum accessions in the Banco de Germoplasma de Hortalicas of Universidade

Federal de Vicosa and three commercial tomato cultivars at day 90 after planting, Vicosa 2003

% Leaves mined Total number of mines produced

HGB-378 100.00 A HGB-186 54.93 A HGB-160 6.17 A HGB-1988 1.75 B

HGB-700 88.42 A HGB-990 54.93 A HGB-351 5.90 A HGB-161 1.68 B

HGB-351 88.42 A HGB-1992 53.39 A HGB-2119 5.76 A HGB-349 1.62 B

HGB-218 88.42 A HGB-616 53.39 A HGB-218 4.86 A HGB-7234 1.62 B

HGB-24 88.42 A HGB-168 53.39 A Moneymaker 4.73 A HGB-225 1.61 B

HGB-7236 88.42 A HGB-1538 53.39 A HGB-7236 4.54 A HGB-1254 1.57 B

HGB-121 88.42 A HGB-1985 53.39 A HGB-121 4.54 A HGB-327 1.56 B

HGB-1987 88.42 A HGB-1254 50.79 A HGB-24 4.47 A HGB-700 1.45 B

HGB-184 77.31 A HGB-606 50.79 A HGB-378 4.39 A HGB-227 1.42 B

HGB-1490 77.31 A HGB-1498 43.82 A HGB-226 4.37 A HGB-1991 1.36 B

HGB-1485 77.31 A HGB-980 43.82 A HGB-1987 3.88 A HGB-1985 1.27 C

HGB-6860 77.31 A HGB-1991 43.82 A HGB-1992 3.82 A HGB-1499 1.18 C

Santa Clara 77.31 A HGB-603 41.35 B HGB-243 3.70 A HGB-990 1.14 C

HGB-226 77.31 A HGB-7235 39.91 B HGB-7233 3.51 A HGB-1485 1.07 C

HGB-327 77.31 A HGB-1989 39.91 B HGB-1490 2.97 A HGB-7235 1.03 C

HGB-349 77.31 A HGB-225 39.91 B HGB-216 2.72 A HGB-603 0.95 C

HGB-2119 77.31 A HGB-227 33.33 B HGB-185 2.47 B HGB-1989 0.83 C

HGB-243 75.61 A HGB-406 31.00 B Santa Clara 2.42 B HGB-320 0.75 C

HGB-7233 75.61 A HGB-1532 31.00 B HGB-7237 2.37 B HGB-168 0.70 C

Moneymaker 75.61 A HGB-320 31.00 B HGB-224 2.35 B HGB-406 0.69 C

HGB-1993 66.66 A HGB-1990 31.00 B HGB-186 2.29 B HGB-1532 0.67 C

HGB-224 66.66 A HGB-1499 27.37 B HGB-606 2.28 B HGB-1990 0.60 C

HGB-160 65.04 A HGB-1708 21.28 B HGB-6860 2.25 B HGB-7238 0.58 C

HGB-185 65.04 A HGB-55 21.28 B HGB-1706 2.23 B HGB-83 0.56 C

TOM-601 65.04 A HGB-1282 21.28 B HGB-980 2.02 B HGB-55 0.31 C

HGB-216 65.04 A HGB-7238 21.28 B HGB-1538 2.01 B HGB-1282 0.31 C

HGB-7237 65.04 A HGB-83 19.13 B TOM-601 1.91 B HGB-1708 0.31 C

HGB-1706 65.04 A HGB-674 0.00 B HGB-616 1.89 B HGB-674 0.00 C

HGB-1988 60.71 A HGB-1497 0.00 B HGB-184 1.82 B HGB-1497 0.00 C

HGB-7234 60.71 A – – HGB-1498 1.76 B – –

HGB-161 54.93 A – – HGB-1993 1.76 B – –

Averages followed by same upper case letters in columns do not differ by Skott–Knott test (5% probability).

Table 3Ratio (ion current generated by each of the nine hydrocarbona/ion current generated by the internal standard dodecane) obtained on gas chromatographic–mass

spectrometric analyses of the leaf hexane extracts of the 57 L. esculentum accessions of the Banco de Germoplasma de Hortalicas of Universidade Federal de Vicosa and three

commercial tomato cultivars at day 90 after planting, Vicosa 2003

Genotype Ratio Genotype Ratio

1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9

Moneymaker N.D. N.D. 4.42 N.D. N.D. N.D. N.D. N.D. N.D. HGB-674 0.17 0.22 1.11 N.D. 0.27 0.12 N.D. 0.26 N.D.

Santa Clara 0.30 0.25 1.71 N.D. 0.3 0.26 N.D. 0.48 N.D. HGB-700 0.10 0.2 1.52 N.D. 0.29 0.24 N.D. 0.41 N.D.

HGB-24 0.23 0.34 2.23 N.D. 0.58 N.D. N.D. 0.59 N.D. HGB-990 N.D. 0.23 1.33 N.D. 0.37 0.16 N.D. 0.3 N.D.

HGB-55 0.25 0.80 2.01 N.D. 0.64 N.D. N.D. 0.51 N.D. HGB-1254 N.D. N.D. 2.05 N.D. N.D. N.D. N.D. N.D. N.D.

HGB-83 N.D. 0.20 1.37 N.D. 0.18 0.16 N.D. 0.30 N.D. HGB-1490 0.18 0.35 1.76 N.D. 0.50 0.22 0.19 0.41 N.D.

HGB-121 N.D. 0.28 2.12 N.D. 0.41 0.23 N.D. 1.02 N.D. HGB-1497 N.D. 0.28 1.92 N.D. 0.29 0.22 N.D. 0.49 N.D.

HGB-160 N.D. N.D. 0.31 N.D. 0.09 N.D. N.D. N.D. N.D. HGB-1498 N.D. 0.2 1.36 N.D. 0.53 0.22 0.15 0.34 N.D.

HGB-161 0.22 0.34 1.58 N.D. 0.61 0.19 0.07 0.38 N.D. HGB-1499 N.D. N.D. 1.37 N.D. 0.20 0.20 N.D. 0.41 N.D.

HGB-168 N.D. 0.23 1.93 N.D. 0.61 0.38 N.D. 1.00 N.D. HGB-1532 0.10 0.24 1.93 0.10 0.36 0.21 0.10 0.49 N.D.

HGB-185 N.D. 0.24 1.47 N.D. 0.40 N.D. N.D. 0.40 N.D. HGB-1538 N.D. 0.82 0.64 N.D. 0.24 0.1 N.D. 0.21 N.D.

HGB-186 N.D. 0.18 1.68 N.D. 0.25 0.27 N.D. 0.51 N.D. HGB-1706 0.21 0.27 1.98 N.D. 0.38 0.28 N.D. 0.56 N.D.

HGB-216 0.20 0.49 2.04 N.D. 0.51 0.24 N.D. 0.57 N.D. HGB-1708 N.D. N.D. 1.55 N.D. 0.36 N.D. N.D. 0.59 N.D.

HGB-218 N.D. 0.22 1.35 N.D. 0.38 N.D. N.D. 0.30 N.D. HGB-1985 0.12 0.33 2.04 N.D. 0.39 0.22 N.D. 0.56 N.D.

HGB-224 N.D. 0.18 1.43 N.D. 0.29 0.18 N.D. 0.40 N.D. HGB-1988 0.23 0.28 1.23 N.D. 0.55 0.14 0.10 0.28 N.D.

HGB-225 N.D. N.D. 1.77 N.D. 0.30 0.27 N.D. 0.63 N.D. HGB-1989 N.D. 0.13 1.91 N.D. 0.10 0.34 0.11 0.63 N.D.

HGB-226 0.23 0.34 2.23 N.D. 0.58 N.D. N.D. 0.59 N.D. HGB-1990 0.25 0.73 3.00 0.20 0.62 0.77 N.D. 0.85 0.57

HGB-227 N.D. N.D. 1.33 N.D. 0.24 0.26 N.D. 0.15 N.D. HGB-1991 0.19 0.28 1.63 N.D. 0.47 N.D. N.D. 0.38 N.D.

HGB-243 N.D. 0.31 3.46 N.D. 0.73 0.45 0.19 0.9 N.D. HGB-1992 0.17 0.29 1.41 N.D. 0.57 0.18 0.17 0.32 N.D.

HGB-320 0.16 0.24 1.54 N.D. 0.50 0.19 0.17 0.44 N.D. HGB-1993 N.D. N.D. 1.79 N.D. N.D. N.D. N.D. N.D. N.D.

HGB-327 N.D. 0.28 1.18 N.D. 0.33 0.19 N.D. 0.27 N.D. HGB-2119 0.16 0.32 2.00 N.D. 0.49 0.23 0.11 0.51 N.D.

HGB-349 N.D. N.D. 1.54 N.D. 0.45 0.25 N.D. 0.44 N.D. HGB-6860 0.09 0.16 1.23 N.D. 0.17 0.16 N.D. 0.27 N.D.

HGB-351 N.D. 0.31 0.60 N.D. N.D. N.D. N.D. N.D. N.D. HGB-7233 N.D. N.D. 1.48 N.D. N.D. N.D. N.D. 0.41 N.D.

HGB-378 0.00 0.00 2.11 N.D. 0.48 0.21 N.D. 0.41 N.D. HGB-7234 0.14 0.26 1.96 N.D. 0.35 0.29 N.D. 0.59 N.D.

HGB-406 0.25 0.2 1.63 N.D. 0.37 0.29 N.D. 0.38 N.D. HGB-7235 N.D. 0.51 4.03 N.D. 0.80 0.57 N.D. 0.76 N.D.

HGB-603 0.21 0.29 1.72 N.D. 0.53 N.D. N.D. 0.42 N.D. HGB-7236 N.D. 0.39 3.70 N.D. 0.61 0.48 N.D. 0.97 N.D.

HGB-606 0.14 0.38 1.76 N.D. 0.53 0.36 N.D. 0.46 N.D. HGB-7238 0.25 0.56 2.68 N.D. 0.47 0.41 N.D. 1.17 N.D.

N.D.: not determined as the corresponding hydrocarbon peaks in the samples were absent.a Peaks 1–9 were identified as hexadecane, heptadecane, eicosane, tricosane, 2-methyl tricosane, tetracosane, hexacosane, octacosane and triacontane, respectively.

F.A. Oliveira et al. / Scientia Horticulturae 119 (2009) 182–187184

Fig. 1. Representative partial reconstructed gas chromatogram obtained on analysis

of the hexane extract (access BGH-1990) along with the internal standard

(dodecane). Peaks were identified as (1) hexadecane, (2) heptadecane, (3) eicosane,

(4) tricosane, (5) 2-methyltricosane, (6) tetracosane, (7) hexacosane, (8) octacosane

and (9) triacontane.

F.A. Oliveira et al. / Scientia Horticulturae 119 (2009) 182–187 185

infestation (data not shown). However, significant differenceappeared on the third evaluation date (Tables 1 and 2).

The accessions could be clustered in two groups for the numberof large mines/leaf (Table 1), with mean of 1.73 mines (range 1.07–2.61) in the most infested group, and 0.46 (range 0.00–1.05) in theleast infested group. Based on the number of small mines/leaf, theaccessions were classified into three groups. In the most infestedgroup, the average number of small mines/leaf varied from 2.51 to4.07 with a mean of 3.28; in the intermediate group it varied from1.07 to 2.40 with a mean of 1.88, while in the least attacked group itvaried from 0.00 to 1.05 with a mean of 0.57.

For % of leaves mined, the accessions could be divided into twogroups (Table 2). In the most damaged group, the damaged leavesvaried from 43.82 to 100% with a mean of 69.87% in contrast only0.00 to 41.35%, averaging 26.46% in least damaged group. Alsobased on the total number of mines/leaf, accessions could bedivided into three groups. In the most attacked group, the averagenumber of total mines varied from 2.72 to 6.17 (mean 4.39); in theintermediate group it varied from 1.36 to 2.47 (mean 1.89), whilein the least attacked group, it varied from 0.0 to 1.27 (mean 0.68).No leaf of the accessions HGB-674 and HGB-1497 was mined(Tables 1 and 2).

Although nine peaks were detected in many samples on GC–MSanalysis, the ratios of IC generated by the hydrocarbons in sample/IC generated by the internal standard varied (Table 3 and Fig. 1).For example, among the 57 accessions, the highest ratio (0.25)generated by hexadecane (peak 1 with SI of 95%) was obtained inaccessions HGB-55, HGB-406, HGB-1990 and HGB-7238. Of thenine peaks detected in the hexane extracts, only tricosane (peak 4)presented a significant negative correlation (p < 0.05) withnumber of small mines (r = �0.28), total number of mines/leaf(r = �0.27) and % of leaves mined (r = �0.22). Peaks 6 and 7(tetracosane and hexacosane, respectively) presented significantpositive correlations with % of the leaves mined (r = 0.25 and 0.24,respectively).

4. Discussion

Tomato plants are cultivated in the state of Minas Geraisprincipally during winter when temperatures can be quite low.Considering little information available in the literature on T.

absoluta, we decided to obtain information under low and hightemperatures. Thus, were conducted evaluations on days 60 and75, when temperatures were low (average approximate tempera-ture 8 8C) as well as on day 90 when the temperature was quitehigh (average approximate temperature 25 8C). Low infestationoccurred on days 60 and 75 (data not presented). However, on day90, infestation was relatively high and sufficient insects were

obtained for evaluation. Since one of our objectives was todetermine possible chemical causes of resistance of the tomatoaccessions, it appeared more interesting to conduct chemicalanalysis when insect damage occurred. Thus, GC–MS analyseswere carried out only on day 90 after planting. This period alsoseemed more interesting since plants were mature, containingflowers, fruit and leaves, representing better plant physiology. Thenumber of insects utilized in this study was based on our previouswork (Suinaga et al., 2004a). Middle leaves were used for chemicalanalysis since T. absoluta attacks the intermediate part of the plantmost intensely (Picanco et al., 1995).

Of the 57 genotypes and three cultivars, only accessions HGB-674 and HGB-1497 were not infested (Tables 1 and 2). In addition,tricosane associated with susceptibility was not found in theseaccessions. Resistance of these genotypes could be related to polarcompounds, which were not evaluated in this study. In theseaccessions, less than 20% of the leaves were mined. This attacklevel is considered to be below control level (Picanco et al., 1998).

Of the four characteristics evaluated, the number of largemines/leaf and % of leaves mined may reflect the degree ofresistance/susceptibility of the accessions to T. absoluta. A lowernumber of large mines may suggest plant resistance throughantibiosis and antixenosis. A lower number of mines may reflectlower oviposition rate or higher mortality of T. absoluta during leafmesophyll feeding (Suinaga et al., 1999, 2004a; Ecole et al., 2000,2001). On the other hand, a low % of leaves mined suggestsantixenosis for oviposition. A lower number of large mines/leaf and% of leaves mined was found in accessions HGB-55, HGB-83, HGB-225, HGB-227, HGB-320, HGB-406, HGB-603, HGB-674, HGB-1282,HGB-1497, HGB-1708, HGB-1532, HGB-1989, HGB-1990, HGB-7235 and HGB-7238, suggesting lower preference of T. absoluta.These could be the principal accessions resistant to T. absoluta byantibiosis and antixenosis. Tricosane, which showed a significantnegative correlation to T. absoluta resistance, was detected only inHGB-1532 and HGB-1990. This suggests that such a resistancecould be related to the presence of this compound.

The number of small mines/leaf does not necessarily suggestgenotype resistance to T. absoluta. A high number of small minesmay suggest that the insect could not find an adequate food sourceon the host plant (Leite et al., 2001). Suinaga et al. (2004b) found ahigh number of small mines but a low number of large mines in theresistant accessions of L. pennellii and L. hirsutum, as compared tosusceptible L. esculentum cultivars, and suggested that, whenconsidering resistance, the number of small mines should beevaluated together with the number of large mines. Similar resultswere reported by Ecole et al. (2000, 2001) in the resistant varietyLA 1777 L. hirsutum f. typicum, compared to the more susceptibletomato cultivars Santa Clara and IPA-5. The authors concluded thatresistance was related to the presence of insect feeding deterrents.Accessions HGB-186, HGB-216, HGB-980 and HGB-7237 and thevariety TOM-601 behaved similarly. Hence, they were grouped asmore resistant, based on the number of large mines. However, theywould be classified as having intermediate resistance based on thenumber of small mines. This suggests a slight non-preferredinadequate feeding. However, based on % of leaves mined, none ofthe accessions was classified as resistant. Although in someaccessions, there were some indications of inadequate feedavailability for T. absoluta, a moderate to high correlation(r = 0.65; p < 0.01) was found between the number of small andlarge mines. Thus, mines which were classified as small at the timeof evaluation could have been formed recently. These minesprobably would evolve into larger mines with time, possibly due toabsence of deterrent compounds. Thus, non-preference resistanceobserved in HGB-UFV tomato accessions was probably notassociated to the presence of compounds causing feed deterrence.

F.A. Oliveira et al. / Scientia Horticulturae 119 (2009) 182–187186

Since no difference was found between the number of small andlarge mines, the total number of mines indicates a low ovipositionpreference. A low number of total mines/leaf occurred in thegenotypes HGB-55, HGB-83, HGB-168, HGB-320, HGB-406, HGB-603, HGB-674, HGB-990, HGB-1282, HGB-1485, HGB-1497, HGB-1499, HGB-1532, HGB-1708, HGB-1985, HGB-1990, HGB-1989,HGB-7235 and HGB-7238, suggesting that the mechanism ofresistance in these accessions is antixenosis by oviposition.

Several studies reported that the principal compounds parti-cipating in the substrate selection for T. absoluta female ovipositionare produced in the glandular trichomes of some wild tomatovarieties. The principal compounds identified were 2-tridecanone(2-TD) and 2-undecanone (2-UD) (Maluf et al., 1997; Giustolin andVendramim, 1996; Magalhaes et al., 2001), sesquiterpenes (Freitaset al., 1998) and acylsugars (Resende et al., 2000). Thesecompounds present in leaf trichomes as cuticular lipids couldoffer both physical and chemical barriers to insects and pathogens(Farrar and Kennedy, 1991; Bianchi, 1995; Eigenbrode and Espelie,1995; Justus et al., 2000; Picoaga et al., 2003). Other compoundshave also been associated to resistance. In L. esculentum,chlorogenic acid in the glandular trichomes was reported to bethe resistance factor to Heliothis virescens (Fabricius) (Lepidoptera:Noctuidae) (Stamp and Osier, 1998). Alpha-Tomatin and rutin inthe leaf lamela are toxic to some insects, e.g., Helicoverpa zea

(Boddie) (Lepidoptera: Noctuidae) and Spodoptera exigua (Hueb-ner) (Lepidoptera: Noctuidae) (Stamp and Osier, 1998).

None of the compounds reported in the wild tomato varietiesresistant to T. absoluta were identified in the accessions evaluatedin this study. Of the L. esculentum varieties known to contain 2-TDin the stem, Moneymaker was found to be susceptible, based onthe evaluated parameters. We did not identify 2-TD in this variety.Chatzivasileiadis et al. (1999), studying Moneymaker’s resistanceto Tetranychus urticae (Koch) (Acari: Tetranychidae), reportedaccumulation of methyl ketones. Thus, if the Moneymaker’sresistance factor (2-TD) was indeed present in the stem, its leavescould be attacked by T. absoluta. Since only the leaves wereevaluated in this study, this probably could explain why Money-maker was found to be susceptible to T. absoluta. The hexaneextract of TOM-601 could not be analyzed due to problemsencountered in this study. This variety was classified in theresistant group based on the number of large mines/leaf and in theintermediate group based on the number of small mines/leaf.However, it was classified in the susceptible group based on the %of leaves mined. Moreira et al. (2005) reported a higher resistanceof these varieties to T. absoluta. Thus, the resistance factors ofMoneymaker and TOM-601 to T. absoluta have yet to be identified.

Identification of compounds based on mass spectral databasesmust be carefully used since relative ion intensities used foridentification are data processing dependent. We took care toobtain representative background subtracted mass spectra.Average mass spectra of the peaks were obtained by scanningthe entire GC peak from which the background was subtracted. Theregion to subtract the background was carefully chosen.

Nine chromatographic peaks were identified in most of thehexane extracts by GC–MS analysis (Fig. 1). Mass spectra of thesepeaks indicated that they were linear hydrocarbons. Identificationbased on mass spectral database was quite reliable as highlyreproducible SI was obtained (�90%). No synthetic standards wereused for confirmation. Of all the compounds identified, onlytricosane presented correlation with T. absoluta. An increase in theconcentration of this compound reduced the number of smallmines (r = �0.28), total mines/leaf (r = �0.27) and % of leavesmined (r = �0.22). Since tricosane was not detected only in theaccessions HGB-1532 and HGB-1990, resistance seemed to berelated to absence of this compound. Low correlations were also

used in some literature studies to explain plant resistance. Grayet al. (1999) reported an r value of �0.33 to correlate the degree ofT. absoluta to leaf 2-TD. Suinaga et al. (1999, 2004a) also attributedresistance of L. peruvianum accessions to 4-methyl-2,6-di-t-butylphenol with an r value of �0.29.

In some accessions, a positively significant correlation wasobserved between the tetracosane and hexacosane concentrationsand susceptibility to T. absoluta attack. The accessions HGB-7236and HGB-243, with a higher % of leaves mined presented highesttetracosane concentrations, suggesting their susceptibility to T.

absoluta. Suinaga et al. (1999) also attributed partially L.

esculentum susceptibility to T. absoluta to tetracosane. Similarly,a higher hexacosane concentration was also correlated with highersusceptibility in the accessions HGB-243 and HGB-1490. Yang et al.(1993) identified this compound in corn leaves but did not explainits participation in resistance to Spodoptera frugiperda (J. E. Smith)(Lepidoptera: Noctuidae). Although octacosane was not correlatedto any resistance characteristics in this study, it was reported to bethe susceptibility factor in L. peruvianum to T. absoluta (Suinagaet al., 1999, 2004a). Suinaga et al. (1999) demonstrated thatheptadecane was the principal compound associated with reducednumber and viability of T. absoluta eggs in L. peruvianum. However,we did not find any significant correlations for HGB-UFV tomatoaccessions to resistance characteristics with heptadecane (SI 95%,peak 2). According to Yang et al. (1993), the effect of suchcompounds in the leaves could be influenced by the presence ofother compounds. It must be emphasized that the results of thisstudy were preliminary and other identification techniques(nuclear magnetic resonance, high resolution mass spectrometry,etc.) are necessary.

Thus, we conclude that the resistance factors found in the wildtomato varieties and other resistant L. esculentum leaves are notpresent in the tomato accessions studied. However, it was possibleto identify hydrocarbons in these accessions, which could explainthe resistance and or susceptibility of some accessions. Thesefindings may be important in breeding programs aiming to developvarieties resistant to T. absoluta. In addition, we demonstratedgenetic variability in the accessions and found different levels ofantixenose in T. absoluta. Although promising results wereobtained, further studies must be carried out. Out of the 57accessions and three varieties studied, only HGB-674 and HGB-1497 appeared to be the most promising. Transfer of resistancefactors from these accessions to commercial tomato could lead todevelopment of tomato cultivars more resistant to T. absoluta

attack and, consequently, reduced use of synthetic pesticides.

Acknowledgements

Financial support from the Brazilian governamental agencies(CNPq—Conselho Nacional de Desenvolvimento Cientıfico eTecnologico and FAPEMIG—Fundacao de Amparo a Pesquisa doEstado de Minas Gerais) is acknowledged. We also thank Dr. O.D.Dhingra for correcting the English revision.

References

Abreu, F.B., Silva, D.J.H., Marim, B.G., Carneiro, P.C.S., Juhasz, A.C.P., Luca, C.A.C.,Valente, R.F., Guimaraes, M.A., 2006. Minimum number and best combinationsof harvests to evaluate accessions of tomato plants from germplasm banks.Genet. Mol. Biol. 29, 112–116.

Bianchi, G., 1995. Plant waxes. In: Hamilton, R.J. (Ed.), Waxes: Chemistry, MolecularBiology and Functions. Oily Press, Dundee.

Chatzivasileiadis, E.A., Boon, J.J., Sabelis, M.W., 1999. Accumulation and turnover of2-tridecanone in Tetranychus urticae and consequences for resistance of wildand cultivated tomatoes. Exp. Appl. Acarol. 23, 1011–1021.

Ecole, C.C., Picanco, M., Moreira, M.D., Magalhaes, S.T.V., 2000. Componentes quımicosassociados a resistencia de Lycopersicon hirsutum f. typicum a Tuta absoluta(Meyrick) (Lepidoptera: Gelechiidae). An. Soc. Entomol. Bras. 29, 327–337.

F.A. Oliveira et al. / Scientia Horticulturae 119 (2009) 182–187 187

Ecole, C.C., Picanco, M.C., Guedes, R.N.C., Brommonschenkel, S.H., 2001. Effect ofcropping season and possible compounds involved in the resistance of Lyco-persicon hirsutum f. typicum to Tuta absoluta (Meyrick) (Lep., Gelechiidae). J.Appl. Entomol. 125, 193–200.

Eigenbrode, S.D., Espelie, K.E., 1995. Effects of plant epicuticular lipids on insectherbivores. Ann. Rev. Entomol. 40, 171–194.

Farrar, R.R., Kennedy, G.G., 1991. Relationship of leaf lamellar-based resistance toLeptinotarsa decemlineata and Heliothis zea in a wild tomato, Lycopersiconhirsutum f. glabratum, PI 134417. Entomol. Exp. Appl. 58, 61–67.

Freitas, J.A., Cardoso, M.G., Maluf, E.R., Santos, C.D., Nelson, D.L., Costa, J.T., Souza,E.C., Spada, L., 1998. Identificacao do sesquiterpeno zingibereno, aleloquımicoresponsavel pela resistencia a Tuta absoluta (Meyrick, 1917) na cultura dotomateiro. Cien. Agrotec. 22, 483–7238.

Gilardon, E., Pocovi, M., Hernadez, C., Olsen, A., 2001. Papel dos tricomas glandularesda folha do tomateiro na oviposicao de Tuta absoluta. Pesq. Agropec. Bras. 36,585–588.

Giustolin, T.A., Vendramim, J.D., 1996. Efeito dos aleloquımicos 2-tridecanona e 2-undecanona na biologia de Scrobipalpuloides absoluta (Meyrick). An. Soc. Ento-mol. Brasil 25, 417–422.

Gray, L., Collavino, G., Gilardon, E., Hernandez, C., Olsen, A., Simon, G., 1999.Heredabilidad de la resistencia a la ‘‘polilla del tomate’’ (Tuta absoluta Meyrick)y su correlacion genetica con caracteres de calidad, en descendencias de cruzasinterespecificas del genero Lycopersicon. Investigacion Agraria. Prod. Protec.Veg. 14, 445–451.

Justus, K.A., Dosdall, L.M., Mitchell, B.K., 2000. Oviposition by Plutella xylostella(Lepidoptera: Plutellidae) effects of phylloplane waxiness. J. Econ. Entomol. 93,1152–1159.

Leite, G.L.D., Picanco, M., Guedes, R.N.C., Zanuncio, J.C., 2001. Role of plant age in theresistance of Lycopersicon hirsutum f. glabratum to the tomato leafminer Tutaabsoluta (Lepidoptera: Gelechiidae). Sci. Hort. 89, 103–113.

Magalhaes, S.T.V., Jham, G.N., Picanco, M.C., Magalhaes, G., 2001. Mortality of second-instar larvae of Tuta absoluta produced by the hexane extract of Lycopersiconhirsutum f. glabratum (PI134417) leaves. Agric. Fores. Entomol. 3, 297–303.

Maluf, W.R., Barbosa, L.V., Costa Santa-Cecılia, L.V., 1997. 2-Tridecanone-mediatedmechanisms of resistance to the South American tomato pinworm Scrobipal-puloides absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) in Lycopersiconspp. Euphytica 93, 189–194.

Moreira, G.R., Silva, D.J.H., Picanco, M.C., Peternelli, L.A., Caliman, F.R.B., 2005.Divergencia genetica entre acessos de tomateiro infestados por diferentespopulacoes da traca-do-tomateiro. Hortic. Bras. 23, 893–898.

Picanco, M.C., Silva, D.J.H., Leite, G.L.D., Mata, A.C., Jham, G.N., 1995. Intensidade deataque de Scrobipalpula absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) aodossel de tres especies de tomateiro. Pesq. Agropec. Bras. 30, 429–433.

Picanco, M., Leite, G.L.D., Guedes, R.N.C., Silva, E.A., 1998. Yield loss in trellisedtomato affected by insecticidal sprays and plant spacing. Crop Prot. 17, 447–452.

Picoaga, A., Cartea, M.A., Soengas, P., Monetti, L., Ordas, A., 2003. Resistance of kalepopulations to lepidopterous pests in northwestern Spain. J. Econ. Entomol. 96,143–147.

Resende, J.T.V., Maluf, W.R., Cardoso, M.G., Goncalves, L.D., Naves, F.O., Azevedo,S.M., Andrade Junior, V.C., Benites, F.R.G., 2000. Heranca dos teores de aci-lacucares em genotipos de tomateiro obtidos a partir do cruzamento inter-especıfico (Lycopersicon esculentum � Lycopersicon pennellii). Hort. Bras. 18,626–627.

Silva, C.C., Jham, G.N., Picanco, M., Leite, G.L.D., 1998. Comparison of leaf chemicalcomposition and attack patterns of Tuta absoluta in three tomato species. Agron.Lus. 46, 61–71.

Stamp, N.E., Osier, T.L., 1998. Response of five insect herbivores to multipleallellochemicals under fluctuating temperature. Entomol. Exp. Appl. 88, 81–96.

Suinaga, F.A., Picanco, M., Jham, G.N., Brommonschenkel, S.H., 1999. Causas quı-micas de resistencia de Lycopersicon peruvianum (L.) a Tuta absoluta (Meyrick)(Lepidoptera: Gelechiidae). An. Soc. Entomol. Bras. 28, 313–321.

Suinaga, F.A., Picanco, M.C., Moreira, M.D., Semeao, A.A., Magalhaes, S.T.V., 2004a.Resistencia por antibiose de Lycopersicon peruvianum a traca do tomateiro.Hortic. Bras. 22, 281–285.

Suinaga, F.A., Casali, V.W.D., Picanco, M.C., Silva, D.J.H., 2004b. Capacidade combi-natoria de sete caracteres de resistencia de Lycopersicon spp. a traca do toma-teiro. Hortic. Bras. 22, 242–248.

Vendramim, J.D., Nishikawa, M.A.N., 2001. Melhoramento para resistencia a insetos.In: Nass, L.L., Valois, A.C.D., Melo, I.S., Valadares-Inglis, M.C. (Eds.), RecursosGeneticos e Melhoramento-Plantas. Fundacao MT, Rondonoplis, MT.

Yang, G., Wiseman, B.R., Isenhour, D.J., Espelie, H.E., 1993. Chemical and ultra-structural analysis of corn cuticular lipids and their effect on feeding by fallarmyworm larvae. J. Chem. Ecol. 9, 2055–2074.