Antifeedant and mortality effects of neem oil (0.03% Azadirachtin) against III instar grubs of Oryctes rhinoceros L. (Coleoptera: Scarabaeidae)

A commercial formulation of neem oil EC (Nimbex, 0.03% A²) was tested at different concentrations viz. 25, 50, 75 and 100 ppm for feeding deterrence and mortality effects against grubs of Oryctes rhinoceros at laboratory conditions. The results clearly indicated that neem oil, deterred feeding in terms of per cent reduction in body weight at or above 25 ppm. But significant feeding deterrancy was observed in higher concentrations (50, 75 and 100 ppm). In feeding toxicity tests, neem oil at concentrations of 50, 75 and 100 ppm caused greater than 20%, 45% and 90% mortality, respectively on exposer upto 96 hand 100 ppm caused 90.67% mortality of O. rhinoceros grubs through feeding and contact tests.