草地贪夜蛾作为新近入侵我国的重大农业害虫，对我国粮食生产安全构成了严重威胁。转Vip3A玉米对草地贪夜蛾防治效果良好，具有广阔的应用前景。但草地贪夜蛾对转Vip3A玉米的田间抗性已在巴西等地报道，抗性的产生也将是制约我国转Vip3A玉米长期种植的重要因素。靶标害虫Bt抗性机理的解析将为Bt抗性监测与治理提供重要的理论指导。项目组在前期通过连续多代筛选，已获得了一个可稳定遗传的草地贪夜蛾Vip3A抗性品系，在此基础之上利用抗性/敏感品系杂交后的F2群体对Vip3A敏感性的差异，通过分离群体混合测序的方法定位与抗性相关的基因，利用基因编辑技术验证其功能，并对其介导抗性的分子机制进行初步探索。研究成果不仅有助于推动Bt抗性机制的揭示，也可为我国转Vip3A玉米田间抗性监测提供靶标位点，相应的研究方法对其他昆虫重要性状的定位也具有借鉴价值。

Spodeptera frugiperda, a major agricultural pest that has recently invaded China, which poses a serious threat to the national food production security of China. Vip3A is an insecticidal protein secreted by Bacillus thuringiensis, which has a good effect on controlling S. frugiperda. However, field-resistance of S. frugiperda to transgenic corn expressing Vip3A has been reported in Brazil and USA. The emergence of Bt resistance will also be an important factor restricting the long-term cultivation of transgenic Vip3A corn in China. The analysis of Bt resistance mechanism of target pests will provide important theoretical guidance for Bt resistance monitoring and management. Our team has obtained a stable inheritance of S. frugiperda Vip3A resistant strain through successive multi-generations screening in the early stage. Based on the difference of sensitivity, we will identify and cross the Vip3A resistant DH-R and sensitivity strain to obtain F2 population. The genes related to Vip3A resistance will be located by bulked segregation analysis of F2 population, and fine map the candidate gene. The function of the genes will be verified by gene editing technology, and preliminarily explored the molecular mechanism of resistance. These results are not only helpful to reveal the mechanism of Bt resistance, but also are expected to be applied for monitoring and controlling of Bt resistant pests. The corresponding research methods could also be useful for studying other important characters of insects.