Parasitism performance of the parasitoid Trichogrammadendrolimi on the plum fruit moth Grapholitha funebrana

Abstract

The egg parasitoid Trichogramma dendrolimi Matsumura is one of the most widely used agents in sustainable crop protection to manage many lepidopteran pests in China, especially via inundative releases. It has been used as an important biocontrol agent in Integrated Pest Management (IPM) programs for the control of the plum fruit moth Grapholitha funebrana Tr. However, accurate knowledge of the parasitoid’s biology and ecology is needed to optimize its practical application in pest management. In the current study, the effect of key factors on T. dendrolimi effectiveness as biocontrol agent, including host age, exposure time, parasitoid density and, host density was evaluated under laboratory conditions. The parasitoid showed a higher parasitism rate on younger over older G. funebrana eggs. When host egg density increased, the number of eggs parasitized by the parasitoid also increased, but parasitism rates decreased. The functional response of T. dendrolimi on G. funebrana eggs fitted the Holling type II Model ( N _t = 0.932 N/(1+0.112 N)). When parasitoid density and exposure time of hosts to parasitoids increased, the parasitism rate of T. dendrolimi also increased. In addition, previous exposure of host eggs to ultraviolet (UV) light did not affect parasitism rate. All aforementioned factors did not influence the emergence rate of the parasitoid offspring. Our results would provide references for optimizing the application of T. dendrolimi inundative releases in large-scale management of G. funebrana in orchards.