Antifeeding Acting of Larvae of Pieris rapae to Chloroform Extracts of Litsea populifolia Gamble

Litsea populifolia Gamble was investigated for its antifeedant activity against the third instar larvae of Pieris rapae by using the method of selective antifeedant and complete antifeedant.The result indicated that chloroform extract of Litsea populifolia Gamble appeared strong antifeedant activity.The middle Antifeeding Concentration(AFC50) of selective antifeedant activity in 24 h,48 h,72 h were 54.13 mg/L,170.97 mg/L,143.51 mg/L respectively while its AFC50 of complete antifeedant activity were 784.07 mg/L,382.75 mg/L,259.76 mg/L.The growth of Pieris rapae's was seriously influenced by the experiment.From the results both selective antifeedant and complete antifeedant had high antifeedant rate,which approximately reached 100%.With the concentration of 125 mg/L selective antifeedant was higher than 50%, but complete antifeedant is lower than 10%.