Relative effect of various extracts of Melia azedarach (Linn) leaf against Helicoverpa armigera (Hübner) and their comparison with seed extracts

Melia azedarach leaf extracts were investigated for their antifeedant and insect growth regulatory activity against H. armigera by leaf dip method in the laboratory. Amongst the various extracts of M. azedarach leaves, the maximum percent antifeedance was caused by methanol extract that ranged from 76.75 to 25.83. None of the extracts caused the larval mortality more than 50.00 per cent. The cent adult emergence inhibition by various extracts of M. azedarach leaves at the highest concentration was in the order of methanol (70.00) > hexane (63.33) > ethyl acetate (56.67) > aqueous (53.34) = butanol extract (53.34). Melia azedarach seed extracts proved statistically superior over their respective leaf extract in causing antifeedance and IGR activity. The various seed extracts of M. azedarach viz., hexane, methanol, ethyl acetate, aqueous and butanol were 6.16, 5.73, 9.45, 7.63, 7.63 times more effective than their respective leaf extracts in exhibiting antifeedant effect (Also). All the extracts of M. azedarach leaf required higher dose to inhibit the 50.00% larval weight gain than the seed extracts at 3 and 7 DAT, respectively. In addition to antifeedant and IGR activity, the hexane, methanol and ethyl acetate extracts of M. azedarach seed exhibited toxic effects against H. armigera larvae, the LC_so values being 1.94, 1.65 and 3.18%. None of the leaf extract caused significant larval mortality. The dose required for inhibition of 50.00% normal adult emergence by the hexane, methanol, ethyl acetate, aqueous and butanol extract of M. azedarach seed was 22.73, 22.81, 15.80, 15.89 and 10.21 times more than their respective leaf extracts.