Abstract: The insecticidal effect of camptothecin against Nilaparvata Lugens，Brevicoryne Brassicae and Chilosuppressalis Walker was carried out under laberatory and field tests．A bioassay showed that 0．2％ camptotbecin has strong contact toxicity，with LC50 and IC90 values of 0．1—0．6 mg/L and 0．4—5．0 mg/L，respectively．The descending order of activity was：Nilaparvatalugens> Brevicoryne brassicae > Chilo suppressalis．Field tests showed that the survival rate of B．brassieae and N．lugens were between 70％ and 95％，which were not signiticantly different from the 10％ imidacloprid WP control values of 63％ and 98％．The survival and susceptibility of C．suppressalis were 85％ and 88％，respectively，which were not significantly different from the 5％ Regent SC control values of 93％ and 95％, respectively．The results showed that camptotheein has strong insecticidal activity against above three agricultural pests．

Key words: camptotheein, Nilaparvata lugens, Chilosuppressalis walker, Brevicoryne brassicae, new natural insecticide