Abstract: 【Aim】 Evaluating the efficacy of transgenic Bt maize for resistance to target insect in the laboratory is a key part of the research and development and the environmental safety assessment of insect resistant transgenic maize. 【Methods】 The expression levels of Cry1Ab/Cry1Ac fusion protein in fresh whorl leaves of transgenic cry1Ab/cry1Ac maize ZZM030 were quantified by using enzyme-linked immunosorbent assay (ELISA). The survival rates of neonates of the susceptible strain (ACB-BtS), Cry1Ab-resistant strain (ACB-AbR) and Cry1Ac-resistant strain (ACB-AcR) of the Asian corn borer (ACB), Ostrinia furnacalis, fed on whorl leaves of the transgenic maize ZZM030 and non-transgenic maize X249 were determined by using laboratory bioassays. 【Results】 The expression levels of Cry1Ab/Cry1Ac fusion protein in the whorl leaves of the transgenic maize ZZM030 at the 4-leaf stage and 8-leaf stage were 10.62 and 2.94 μg/g FW, respectively. The survival rates of ACB-BtS neonates fed on whorl leaves of the transgenic maize ZZM030 for 2 d and more than 4 d were only 23.6% and 0, respectively, while the survival rate of ACB-BtS neonates fed on the non-Bt control maize X249 for 4 d was 93.1%. The survival rates of ACB-AbR and ACB-AcR neonates fed on whorl leaves of the transgenic maize ZZM030 for 6 d were 11.1% and 12.5%, respectively, whereas those fed on whorl leaves of non-Bt maize X249 for 6 d were 81.9% and 77.8%, respectively. 【Conclusion】 The highly expressed Cry1Ab/Cry1Ac fusion protein in transgenic cry1Ab/cry1Ac maize ZZM030 has an excellent control efficacy against ACB neonates.

Key words:  Ostrinia furnacalis, transgenic cry1Ab/cry1Ac maize, control efficacy, protein expression level, laboratory bioassay