Suitability assessment of three Trichogramma species in the control of Mythimna separata (Lepidoptera: Noctuidae)

Mythimna separata (Walker) is a serious cosmopolitan pest. Trichogramma species have been used worldwide as biological control agents of lepidopteran pests. However, no data on the control efficiency of Trichogramma species on this pest have been reported. We evaluated the suitability of M.separata eggs for three Trichogramma species, Trichogramma dendrolimi Matsumura, T.ostriniae Pang et Chen and T.japonicum Ashmead, and compared the suitability with that of Corcyra cephalonica (Stainton) eggs. The parasitism rate, development time, emergence rate, female proportion, body size and egg load of female offspring indicated that the M.separata egg is a suitable host for the three Trichogramma species. On the other hand, the non-emergence rate and the relationship between egg load and body size reflected that M.separata eggs are less suitable for the three Trichogramma species than C.cephalonica eggs. Egg resorption occurred in T.japonicum 4days after emergence.