Insecticidal Activities of Extracts from Acorus graminues Rhizome against Mythimna separata Walker

Six extracts from Acorus gramnues rhizome were conducted for the insecticidal activities against Mythimna separata Walker. The results showed that methanol extract possessed high effectiveness of anti-feeding, contacting and growth inhibition. The anti-feeding rate of methanol extract against 4 th larvae of Mythimna separata Walker was 91.89% in no-choice tests. In growth inhibition tests, given the treated diet with methanol extract for 24h to 4 th larvae and after 3 days treatment, the weight of the tested larva was lower than that of the first day. And all the tested lava died at 4 days. Methanol extract also possessed some contacting activity with the mortality of more than 60%. In this study, the anti-feeding activity of petroleum extract was only lower than that of methanol extract, but the growth inhibiting activity was lower than that of methanol, chloroform and ethyl acetate extracts. Among the six extracts, the effectiveness of water extract against Mythimna separata Walker was the least.