Antifeedant Activities of Different Plant Extracts Against Plutella xylostella

The antifeedant activities of the methanol extracts of 10 plants against 3rd instar P.xylostella were determined by leaf-dipping method in laboratory in order to seek new insecticidal plants.The results showed that the methanol extracts from Terastrocmia gymnanthera,Gordonia acuminate,Tutcheria brachycarpa,Tutcheria hirta,Eurya chinensis had high antifeedant activity against 3rd instar P.xylostella.Their 48 h antifeedant rates were more than 70% when the concentration reached 10 g/L.The methanol extracts from T.gymnanthera had the highest antifeedant activity,the antifeedant rates of 48 h was 81.48%.Secondly,they were G.acuminate(77.25%),T.brachycarpa(74.99%),T.hirta(70.52%),E.chinensis(70.51%).The other five plants had low antifeedant activities,with the antifeedant rates being below 60%.