Monitoring research on the resistance gene frequency of field populations of Spodoptera frugiperda to Bt toxin in Yunnan

The wide application and industrialization promotion of transgenic Bt crops not only effectively contained the large-scale outbreak of pests, significantly reduced the application amount of chemical pesticides, but more importantly, alleviated the resulting problems of pesticide residues and environmental pollution. In order to monitor the resistance of S. frugiperda to Bt toxin in Yunnan Province, this study investigated the field populations of fall armyworm in Xundian County, Yunnan Province; diagnostic dose test in the F₂ generation was performed. The research systematically assessed the level of resistance of fall armyworm populations in this area to Bt toxins. Detection results showed that only three single female lines had low-frequency resistance to Cry1Ab (resistance allele frequency of 0.006), but remained highly sensitive to Vip3Aa. This study indicated that the fall armyworm population in Yunnan has not yet developed obvious resistance, providing an important scientific basis for the sustainable promotion of Bt transgenic crops in this area and suggesting the need for long-term resistance monitoring and resistance management strategies.