Vol. 11, Special Issue 1 (2022)

Author(s):
Rakesh Kumar, Suresh Nebapure, Bishwajeet Paul, SR Sinha, RK Sharma and Rekha Kumawat

Abstract:
The present investigation was aimed at identification of herbivore induced plant volatiles from okra and their possible implications in insect pest management through target specific attraction of natural enemies in okra agro-ecosystem. Findings of the present investigation revealed that mechanical damage and larval feeding of Earias vittella F. induced, albeit differently, the plant volatile production in okra. A total of 64 and 46 volatile compounds were identified from headspace compositions of okra plant and okra fruits, respectively. Mechanical damage and larval feeding of Earias vittella F. induced the plant volatile production in okra. A total of 64 and 46 volatile compounds were identified from headspace compositions of okra plant and fruits, respectively. Isoxazole, 5-chloro-4-(2-phenylethyl)- (8.01%), hexatriacontane (6.88%), tetratriacontane (4.32%), decane, 3,3,4-trimethyl- (4.11%), 3-hydroxypropyl palmitate, TMS derivative (2.92%), m-Ethylacetophenone (2.65%) and D-limonene (2.44%) were emitted in highest quantities from okra plant. While, mesitylene (10.01%), butanediol (5.51%), azulene (3.33%) and D-limonene (2.64%) were emitted in highest quantities from okra fruits. Shoot and fruit borer, Earias vittella antennae responded to the volatile stimulus by depolarization. Fresh fruits, mechanically damaged and undamaged plant elicited strong antennal responses from both sexes of E. vittella. In addition herbivore damaged fruits and mechanically damaged fruit plant elicited strong antennal (EAG) responses from E. vittella male only. In behavioural bioassay both sexes of egg parasitoid Trichogramma chilonis Ishii preferred headspace volatile blends from herbivore damaged plant, herbivore damaged fruit and larval excreta over the control. Whereas, volatile blends from mechanically damaged plants were only preferred by T. chilonis females. This is the first study which shows the importance of role of herbivore-induced plant volatiles in the indirect defense of okra against Shoot and fruit borer, Earias vittella.