Superparasitism and Ontogeny of Two Trichogramma Species on Corcyra cephalonica (Stainton)
The egg-laying and ontogeny of Trichogramma dendrolimi Matsamura and T.ostriniae Pang et Chen were investigated in the laboratory with eggs of Corcyra cephalonica (Stainton) as host.The two Trichogramma species laid more than one eggs in one host egg and T.ostriniae laid more eggs per host egg than T.dendrolimi did.The wasp offspring number per host decreased to less than two when the wasps developed to pupae.However,the number of T.dendrolimi in the host eggs was less than that of T.ostriniae at all observation times after parasitization.The mode of ontogeny of the two Trichogramma species was similar,individual size increased after parasitization but decreased at 72 h and 144 h since parasitization,which corresponds to the stages from larva to prepupa and from pupa to adult,respectively.Furthermore,the larva molt two times,one happened at hatching and the other one at pupating,and there is only one stadium within whole larva developmental stage.