Population genetic diversity in the annual breeding area of the Spodoptera frugiperda in China

= -0.033). Guangxi emerged as a gene flow hub, exhibiting higher haplotype diversity likely due to continuous influx from the China-Vietnam border. Furthermore, significantly positive Tajima's D values (3.08-3.94) in Chinese populations, coupled with field-observed population fluctuations, support an invasion model characterized by rapid expansion from a limited number of founders. This study provides critical insights into the population genetic dynamics of fall armyworm in its newly invaded range, which are essential for forecasting its spread and formulating sustainable management strategies.