Abstract The fall armyworm ( Spodoptera frugiperda ), a globally invasive pest, has established persistent populations in China since its invasion in late 2018, posing a continuous threat to agriculture due to its potential for rapid adaptation and insecticide resistance evolution. To elucidate the genetic underpinnings of its invasion success in China’s annual breeding area, this study systematically analyzed the genetic diversity, differentiation, and population structure of fall armyworm (FAW) populations across four provinces (Yunnan, Guangdong, Guangxi, and Hainan) using a dual-marker system combining mitochondrial COI and nuclear Tpi genes. Our analyses revealed significantly reduced genetic diversity (haplotype diversity: 0.47–0.56; nucleotide diversity: 0.007–0.009) in Chinese populations compared to putative source populations in India (0.942 and 0.014, respectively), indicating a strong genetic bottleneck effect. All individuals were identified as the corn-strain, with 22.7% classified as heterozygous corn-strain based on Tpi genotyping. Population differentiation analysis highlighted the Himalayas as a substantial barrier ( F st = 0.294 between Yunnan and India), while the South China Sea monsoon facilitated genetic fusion between Guangdong and Hainan ( F st = -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.
Lin et al. (Thu,) studied this question.