Induction of midgut glutathione S-transferase in Helicoverpa armigera (Hubner) by different hosts and its influence on insecticide metabolism

Effect of different hosts viz., cotton, pigeonpea and chickpea of Helicoverpa armigera on the induction of gut detoxifying enzymes and its effect on insecticide metabolism were studied in the present investigation. Glutathione S-transferase was found to be induced in higher amount in the gut of H. armigera when reared on chickpea as compared to the other studied hosts. Midgut proteins were also found to be influenced by these hosts. Toxicity levels of different insecticides were studied against the H. armigera reared on different hosts. The variability in toxicity was observed among strains i. e. H. armigera reared on different hosts. Strain reared on chickpea showed tolerance against indoxacarb, spinosad and emamectin benzoate, whereas strain reared on pigeonpea showed higher LC50 for lambdacyhalothrin. Cotton fed larvae were found to be comparatively susceptible. Different hosts were found to induce GST and protein in mid gut, which in turn reflected in terms of tolerance against insecticides.