STUDY ON THE ANTIFEEDANT AND INSECTICIDAL EFFECTS OF SOME NEEM (Azadirachta indica A.Juss) SEED KERNEL EXTRACTS ON RICE MOTH (Corcyra cephalonica St.)

Abstract

Four neem seed kernel extracts (ethanol, hexane, methanol and aqueous extracts) were prepared and screened for their antifeedant and insecticidal effects in comparision with Indian neem oil on rice moth. It was seen that all these neem products affected rice moth as antifeedant and insecticidal agents. The methanolic extract strongly deterred feeding by larvae of rice moth form the first to the fifth instars with antifeedant coefficients 180,7; 159,9; 150,5; 148,7 and 102,8, respectively. Whereas the hexane extract had the lowest antifeedant activity with antifeedant coefficients of larvae form the first to the fifth instars respectively 106,6; 100,3; 86,7; 85,2 and 76,0 %. Fumigation with these extracts caused mortality of rice moth in various development stages. All extracts had the highest toxicity against the fifth instar larvae and adults with LD50 values respectively 817,9 and 608,6 ul. Insecticidal effect trended downwards to the fourth instar larvae, egg, the third instar larvae and pupae with LD so values respectively 1404,7; 1543,1; 2008,0 and 2754,7 pl. Whereas the tested extracts had the lowest toxicity against the first and second instar larvae.