New Horizons in Insect Science Towards Sustainable Pest Management

Redesigning Research on Crop Resistance to Insects: Experiences with Tomato 299

nificant negative correlation with larval feeding
(Table 8 ). In addition to phenols, other secondary
metabolites on wild tomatoes were reported to
confer insect resistance. The type VI glandular tri-
chomes of L. hirsutum f. glabratum were reported
to possess methyl ketones such as 2-tridecanone
and 2-undecanone, (Farrar et al. 1992 ) while that of
L. pennelli possess acyl sugars (Juvik et al. 1994 ).

Exploiting Insect Resistance in

Selected Tomato Accessions Through

Hybridization

Realizing the value of the selected accessions,
they were subjected to intercrossing by conven-
tional hybridization (emasculation and pollina-

tion). Among the many intercrosses, Varushana-

du Local x Ac 238; Varushanadu Local x Roma

and Ac 238 x Roma yielded Hybrid 1, Hybrid 2

and Hybrid 3 respectively. The selected acces-

sions and their hybrid derivatives were evaluated

for insect resistant traits, both in the glasshouse

and field, in comparison with a susceptible check

against fruit worm, H. armigera (Dhakshin-

amoorthy 2002 ), serpentine leaf miner, L. trifolii,

whitefly, B. tabaci, and leaf caterpillar, S. litura

(Muthukumaran 2004 ). Though the hybrids re-

corded tolerance to many of the pests at the field

level, a wider variation was observed among

them with regard to population of H. armigera,

S. litura and B. tabaci, besides fruit and leaf dam-

age (Table 9 ). Similarly, under glasshouse condi-

tions also, preference of these insects toward the

Table 8 Biochemical constituents of the foliage of selected tomato accessions
Name of the Phenol (mg/g of dry leaf) Chlorogenic Acidity
accession O.D. Phenol Total Acid (mg/g) (% citric acid)
Roma 0.103 0.190 0.010 0.62
Ac 238 0.096 0.185 0.010 0.67
PT 4287 0.140 0.198 0.017 0.80
Seijima Jeisei 0.142 0.184 0.012 0.78
Varushanadu local 0.146 0.202 0.016 0.83
I 979 (Susceptible check) 0.082 0.172 0.007 0.60
C.D. ( p = 0.05) 0.02 0.02 0.00 0.08
Correlation coefficient (r) − 0.79 − 0.77 − 0.88 − 0.85
Each value is a mean of five replications
Significant at 5% level

Table 9 Field screening of selected tomato accessions and their hybrid derivatives against major insect pests

Accession Helicoverpa armigera (Hubner) Spodoptera

litura Fab. larval

population/plant

Percent leaf dam-

age by Liriomyza

trifolii Blan

Population of

Bemisia tabaci

Genn./plant

Larval

population/plant

Fruit damage (%)

Ac 238 0.53 17.65 (24.84) 0.38 19.17 0.56

Roma 0.77 16.81 (24.20) 0.16 19.44 0.00

Seijima Jeisei 0.42 15.50 (23.18) 0.06 19.96 0.36

Varushanadu

Local

0.50 12.48 (20.69) 0.30 19.89 0.56

HY1F1 0.66 6.20 (14.42) 0.22 19.81 0.08

HY2F1 0.42 5.70 (13.81) 0.26 18.78 0.44

HY3F1 0.32 5.35 (13.37) 0.06 3.48 0.00

HY1F2 0.52 7.40 (15.79) 0.06 20.54 0.62

HY2F2 0.45 6.75 (15.06) 0.28 19.61 0.18

HY3F2 0.36 5.80 (13.94) 0.08 5.14 0.00

I 979 1.83 32.24 (34.60) 0.42 25.20 0.86

C.D. ( p = 0.05) 0.18 3.56 0.07 4.41 0.1 1

Each value is a mean of five replications

Values in parentheses are arcsine transformed