Antifeedant Effect of Plant Extracts for Management of Rice Weevil, Sitophilous oryzae L.

Rice weevil (Sitophilus oryzae L.) is one of the major pest of stored connodities. In this study the extracts from n-Hexane, dichloromethane (DCM) and methanol leaf and seed/fruit of Karanja, Pongamia pinnata (L.); Mahogany, Swietenia mahogani Jacq.; Neem, Azadirachta indica A. Juss and Urmoi, Sapium indicum Willd. at 2.0, 4.0, 6.0, 8.0 and 10.0% (w/v) concentrations were evaluated for their antifeedant effect against rice weevil, Sitophilus oryzae. The experiment was conducted with Completely Randomized Design with three replications at the Entomology Division, Bangladesh Institute of Nuclear Agriculture (BINA). All the extracts had moderate inhibitory effects on the feeding activities of rice weevil. Among the four plant extracts tested, urmoi possessed the highest feeding deterrent effect (126.52) whereas neem possessed the least deterrent effect (89.20). Mahogany and urmoi had the same and high level of efficacy (+++), whereas karanja and neem had same but low level of efficacy (++). The fruit extract had the highest total feeding deterrent effect (110.44) and the leaf extract had the least total feeding deterrent effect (98.68). The results showed that the fruit extracts were better than leaf extracts. Among the three solvents, the highest total coefficient of deterrency was observed in methanol extract (116.83). The coefficient of deterrency increased proportionally with the increase of doses. The results of this study shows that 10% urmoi plant extracts able to protect rice weevil in storage condition for their strong antifeedant effect.