Antifeeding Activities of Alcohol Extracts from 10 Species of Plants on the Larvae of Plutella xylostella and Pieris rapae

: The antifeeding activities of alcohol extracts of 10 plants which belonged to 4 families against 4th instar larvae of Pieris rapae and Plutella xylostell were measured. The results showed that the alcohol extracts of Coriaria japonica, Comnyza canadensis,Xanthium sibiricum and Castanea mollissima had higher antifeeding activities against 4th instar larvae of Pieris rapae.The antifeeding effects were all more than 80% after 24 hours and 48 hours.The alcohol extracts of Artemisia anmua had the highest antifeeding activitiy against 4th instar of Plutella xylostella.The antifeeding effect were 95.55% after 24 hours and 91.83% after 48 hours.