STUDIES ON MORPHOLOGICAL AND BIOCHEMICAL FACTORS IMPARTING RESISTANCE AGAINST AMERICAN PINWORM, Tuta absoluta (MEYRICK) (LEPIDOPTERA: GELECHIIDAE) AND THRIPS SPECIES IN TOMATO
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Date
2019-12-27
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
Investigations on morphological and biochemical factors imparting resistance
against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) and thrips species in tomato
revealed that egg and larval load of T. absoluta were found to be significantly higher
during summer 2018-19, followed by rabi 2017-18 and kharif 2018-19. Four thrips
species were recorded namely Gynaikothrips uzeli Zimmermann, Scirtothrips dorsalis
Hood, Thrips palmi Karny and Thrips hawaiiensis Morgan from the field screening.
Pheromone trap catches of T. absoluta had significant negative correlation with rainfall
(r = -0.35*) and relative humidity (r = -0.61*) and significant positive correlation with
temperature (r =0.76*). Laboratory bioassays confirmed the resistances of wild
accessions of tomato against T. absoluta and TOSPO vector, S. dorsalis by recording
significantly lower egg load and higher larval mortality as compared to the susceptible
check. Higher acylsugar content had a negative impact on T. absoluta larvae and resulted
in reduced pupal weight. Dense glandular trichomes showed highly significant positive
correlation (R2=0.94*) with acyl sugar content. Total glandular trichomes showed
significant negative correlation with egg load (R2= 0.89*). Wild accessions showed
contrasting differences in their green leaf volatile profile as compared to susceptible
genotypes. Among biochemical parameters, acyl sugar, tannin, phenol, monoterpene and
sesquiterpene contents were found at significantly higher quantity in resistant wild
accessions as compared to susceptible genotype.