Metagenomic insights into regional gut microbiota variation of invasive Spodoptera frugiperda across the Gaoligong Mountains

BACKGROUND: The invasive pest Spodoptera frugiperda poses a potential threat to the ecological security of western Yunnan, using the Gaoligong Mountains as an important cross-border corridor and overwintering site. However, the potential role of gut microbiota in the local adaptation of S. frugiperda during its invasion remains poorly understood. METHODS: Adult populations were monitored using sex pheromone traps, and metagenomic sequencing was performed on larval gut microbiota from different regions of the Gaoligong Mountains. The gut microbial composition and functional potential were analyzed, with specific focus on the microbial traits potentially associated with host adaptation and invasion. RESULTS: S. frugiperda populations persisted year-round in the Gaoligong Mountains, with adult activity peaking from January to May. Microbial diversity was highest in southern samples. Enterococcus, typically dominant in S. frugiperda, displayed low abundance in the central and northern regions. In contrast, Providencia emerged as the dominant genus specifically at the Pianma site (PM, along the China-Myanmar border), where the gut microbiota exhibited higher abundance of site-specific functional genes compared to other regions. These genes encoded proteins including type 1 subunit membrane proteins and outer membrane-targeting proteins. Additionally, the PM samples showed a higher relative abundance of genes K07345, K07347, and K15125. Functional annotation highlighted a strong potential for vancomycin degradation and an enrichment of diverse antimicrobial resistance-associated genes, with adeL being the most abundant. CONCLUSIONS: These findings suggest that the PM area may represent an important gateway or a priority monitoring site for the transboundary invasion of S. frugiperda, underscoring the urgency of strengthening local management of invasive pests.