Study on insecticidal activities of six plants against Helicoverpa armigera

In order to screen an environment friendly and highly effective insecticide,the insecticidal activities of plants were detected in this paper.Growth and developmental effects of the powder of six plants on the larvae of Helicoverpa armigera were tested by diet-incorporated method.The results showed that the powders of the six plants had effect on the larvae of H.armigera,and Herba ephedrae showed the best effect,whose growth inhibitory rate reached 90.3 % at the 5th day after treatment.Compared to the control it had much effect in the fertility of adult: the egg laying period was 3.7 days shorter and the number of eggs-laid was reduced by 623.The H.armigera all died in the larval stage if the treatment diet of H.ephedrae powders did not renew with the normal diet at the 5th day.In the extracts of H.ephedrae by 7 different solvents,the ethanol extract had highly inhibition of growth on the H.armigera and the inhibitory rate of weight was 82.2%,but no significant difference between the different concentrations of ethanol was observed.