Antifeedant and Toxic Activity of Melia azedarach Seed Extracts against Helicoverpa armigera (Lepipoptera. Noctuiuae)

Melia azedarach seed extracts were investigated in the laboratory against Hellcoverpa armigera (Hubner). The extracts exhibited significant antifeedant and growth disruption activity. The toxic symptoms of the poisoned larvae included reduction in weight gain and mortality of farvae and pupae, larvallpupal intermediates and malformed adults. Methanol extract with Al₅₀ of 0.085% was more effective than neem oil (0.11%) in causing antifeedance that tesulled in 50% of larval weight gain reductton at 0.09% concentration on 3 DAT. The cumulative larval mortality in insects was maximum with the methanol extract (LC₅₀ 1.65%) followed by hexane extract (1.94%) and ethyl acetate extract (3.17%). At the highest concentration, the pupal weight reduction was predominant with methanol extract (39.4%) followed by hexane extract (38.2%). Methanol extract was also found effective at 0.09% concentration, inhibiting 50% of normal adult emergence from the treated larvae.