New Horizons in Insect Science Towards Sustainable Pest Management

Redesigning Research on Crop Resistance to Insects: Experiences with Tomato 297

Antixenosis and/or antibiosis mechanisms of
resistance operating in insect resistant/tolerant
crop varieties may be attributed to the biophysi-
cal and/or biochemical factors of resistance. Vari-
ous biophysical parameters of resistance name-
ly trichome density, calyx area, thickness and
toughness of the fruit rind, fruit sepal thickness,
seed: pulp ratio were examined among which,
trichome density was found to exert a significant
negative correlation with larval feeding (Fig. 2 ).
Trichomes or plant hairs on the foliage of Lyco-
persicon spp. have been categorized as types I–
VII (Luckwill 1943 ). Among these, types I, IV,
VI, and VII are glandular and types II, III, and

V are non-glandular. In this study, the selected

accessions had two non-glandular (III and V) and

three glandular types (I, VI, VII) (Selvanaray-

anan 2011) (Fig. 3 ). Though the trichome density

exerts a negative influence on pest species, it also

negates the role of natural enemies as inferred

earlier by Kennedy ( 2003 ).

Various biochemical factors of resistance name-

ly, reducing sugars, non-reducing sugars, total sug-

ars, amino acids in the foliage and fruits; acidity,

ascorbic acid, lycopene in the fruits; total phenols,

O. D. phenols and chlorogenic acid in the foliage

were estimated. Among them, phenol content of

the foliage and acidity of the fruits exerted a sig-

Table 5 Reports on resistance in tomato against serpentine leaf miner, L. trifolii
Plant spp. (variety/accession/line/
cultivar)

Reports on resistance Reference

L. hirsutum accessions L. hirsutum f. typicum, L. hirsutum f.
glabratum

Farrar and Kennedy 1992

Wild accessions and cultivars LA 1663 found resistant Eigenbrode et al. 1993
cv. Pusa Ruby and six hybrids Hybrid Abinash susceptible to leaf miner
but tolerant to whitefly

Chaudhuri et al. 2000

10 tomato accessions cv. Varalakshmi found less susceptible Tandon and Bakthavatsalam 2003
Hybrid derivatives Hybrid derivatives of Varushanadu
Local tolerant

Muthukumaran 2004

Backcross generations (PKM1 × VL) × PKM1 (BC 1 ) tolerant Manikandan 2012

Table 6 Reports on resistance in tomato against S. litura/ S.littoralis
Plant spp. (variety/accession/line/cultivar) Reports on resistance Reference
Wild accessions High level of resistance Juvik et al. 1982
Cultivars and wild accessions Fruit skin toughness Juvik and Stevens 1982
Wild accessions and cultivars Antibiosis in wild lines Eigenbrode and Trumble 1993
Five L. pennellii accessions and two
cultivars

L. pennellii found resistant Berlinger and Dahan. 1987

Hybrid derivatives Hybrid derivatives of Varushanadu
Local tolerant

Muthukumaran 2004

Backcross generations (PKM1 × VL) × PKM1 (BC 1 )
tolerant

Manikandan 2012

Table 7 Criteria used to determine resistance ratings of 321 tomato accessions under glasshouse and field conditions.
(Selvanarayanan 2000 ; Selvanarayanan and Narayanasamy 2006 )
Rating Glasshouse Field
Percent foliage
damage

Percent fruit damage Number of larvae/

plants

Percent fruit damage

Highly resistant (HR) < 10.0 < 15.0 0.0–0.30 < 15.0
Moderately resistant (MR) 10.1–25.0 15.1–30.0 0.31–0.60 15.1–30.0
Susceptible (S) 25.1–40.0 30.1–45.0 0.61–0.90 30.1–45.0
Highly susceptible (HS) > 40.0 > 45.0 > 0.90 > 45.0