CROP RESEARCH

Effect of different hosts viz., cotton, pigeonpea and chickpea of H. armigera on the induction of carboxylesterase and cytochrome p-450 en2ymes was studied in the present investigation. Pigeonpea was found to be good inducer of CarE. Less induction of CarE activity was observed in larvae reared on cotton. Different isozymes were observed which showed significant difference in expression on PAGE. Pigeonpea strain showed maximum number of bands with dark intensity, followed by chickpea strain than by cotton strain. Microplate assay results showed higher expression of p-450 in pigeonpea strain than chickpea strain. Less activity was shown by the cotton strain. Toxicity of different insecticides was tested against the H. armigera reared on different hosts. The variability in toxicity was observed, 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.