Antifeeding Effects of Extracts from Cynanchum mongolicum on Spodoptera litura

The antifeedant activities of extracts of Cynanchum mongolicum against Spodoptera litura fabricius larvae were tested.The results are as follows: the extract rate is 0.164%,the extracts had very strong activities against the 3rd instar and 5rd instar larvae,and the antifeedant activities was increasing with concentration,the larvae stop feeding while the concentration was above 0.5mg·ml-1.The non-selective AFC50 for the 3rd and 5rd instar larvae were 0.0246mg·ml-1 and 0.0439mg·ml-1 respectively after treated for 24 hours,the selective AFC50 were 0.0097mg·ml-1 and 0.0309mg·ml-1 respectively.The conclusion provided basis for the research and development of the plant insecticide.