Abstract: 【Aim】 The aim of this study is to clarify the effects of Vip3Aa11 toxin on the Asian corn borer, Ostrinia furnacalis, and its parasitoid Macrocentrus cingulum. 【Methods】 The indirect effects of Vip3Aa11 protein on M. cingulum were assessed by the bioassay with the artificial diet containing 6 μg/g azadirachtin used as the positive control. The mortality and parasitism of O. furnacalis larvae parasitized by M. cingulum were recorded at 10 d after feeding with a diet containing 100 μg/g Vip3Aa11 protein, and the cocoon weight of M. cingulum and the emergence number per O. furnacalis larva after pupation and emergence of M. cingulum were investigated. The direct effects of Vip3Aa11 protein on M. cingulum were assessed by the bioassay with 20% honey solution containing 100 μg/g azadirachtin used as the positive control. The mortality of M. cingulum adults daily after feeding with 20% honey solution containing 100 μg/g Vip3Aa11 protein, and the mortality and parasitism rate of O. furnacalis larvae at 10 d after being parasitized by M. cingulum adults from different treatments were recorded. The cocoon weight of M. cingulum and emergence number per O. furnacalis larva of next generation of M. cingulum were recorded after pupation and emergence. 【Results】 The bioassay results showed that the average mortality and average inhibition rate of body weight of O. furnacalis larvae were 50.7% and 77.1%, respectively, at 7 d after exposure to 100 μg/g Vip3Aa11 protein. In the bioassay of indirect effects, the mortality of O. furnacalis larvae significantly increased when they were fed with the artificial diet containing Vip3Aa11 protein after parasitized by M. cingulum, and the cocoon weight and the number of M. cingulum progenies produced per host decreased; however, the toxin had no effect on the parasitism rate and longevity of M. cingulum adults. In the bioassay of direct effects, the longevity and parasitism rate of M. cingulum adults, the mortality of O. furnacalis larvae, and the cocoon weight, the number of progenies produced per host and the adult longevity of next generation of M. cingulum were not affected when M. cingulum adults were fed with 20% honey solution containing 100 μg/g Vip3Aa11 protein. 【Conclusion】 This study assessed the potential effects of Vip3Aa11 toxin on M. cingulum from the indirect and direct aspects through bioassay system. The results demonstrate that M. cingulum is insensitive to Vip3Aa11 protein at the concentrations exceeding those encountered in Bt crop fields. Vip3Aa11 protein has no direct adverse effects on M. cingulum, and the indirect detrimental effects detected in the bioassay may be due to poor host quality.

Key words: Macrocentrus cingulum, Ostrinia furnacalis, insecticidal protein, Vip3Aa11, bioassay, parasitism