Herbivore-Induced Pulse Crop Phytochemicals: Role in Deterrent Effect of Volatiles Against Whitefly, Bemisia Tabaci (Gennadius)

Abstract

Volatile profiles induced by whitefly [Bemisia tabaci (Gennadius)] in four pulse crops in comparison with profiles of un-infested plants were studied, using dynamic volatile trapping unit and GC-MS analyses to characterize and identify useful volatiles for management of whitefly. Major hydrocarbons present commonly in four plant volatiles were identified based on the per cent area occupied by the volatiles in the profiles. Repellent activity of major volatiles against whitefly was studied, using no-choice and choice tests. Significantly higher number of volatiles were detected in whitefly-infested pulse seedlings than un-infested. Among the hydrocarbons, synthetic form of squalane and eicosane at 200 ppm when used to treat soybean seedlings in no-choice test significantly reduced the settlement of whitefly adults for feeding by 55.9% to 57.6% at 24 hr and 52.5% to 54.2 at 48 hr after treatment. In choice test, squalane and eicosane at 200 ppm reduced the alighting of whitefly adults on treated soybean seedlings by 74.34% to 83.5% at 24 hr and 42.62% to 45.29% at 48 hr after treatment, respectively. When these two compounds were validated by third party institutions, the reduction in settlement of whitefly adults on cowpea seedlings was 67.65% to 67.65% at 24 hr and 32.39% to 35.35% at 48 hr after treatment and 54.37% to 76.69% at 6 hr after treatment in French bean seedlings. Alkanes including eicosane and squalane induced by whitefly in pulse crops have been found to repel whitefly adults which can be explored for its management.

Keywords: Pulse crops, Bemisia tabaci, pVOCs, characterization, feeding deterrent, identification and validation, management