Insecticidal Activities of the Non-alkaloid Extracts fromTripterygium wilfordii against Piers rapae L.

The non alkaloid contents were extracted from the root bark of Tripterygium wilfordii Hook. The results of bioassy showed that the non-alkaloid extracts has abviously insectidal activities to imported cabbage worm (Pieris rapaeL.).LC50 values of poisoning to the 5th instarts of Pieris rapae is 7.23 mg·L-1 . The values of medium antifeeding concentration (AFC50 ) of the non alkaloid extracted against the 5th larval of Pieris rape is 11.34 mg·L -1 . Median narcosis dose (ND50 ) is 15.54 μg/g.Median contact dose (LD50 ) is 3.1079 μg/head. The non-alkaloid extracts have no fumigant to insect. The main poisoning symptoms are that the tested insect showed paralysis and the epiderm of the larval turns black, the larval are dead at last.