Spatiotemporal variation in the microbiome of Aedes vexans from Korea reveals regional markers linked to environmental risk factors.

Aedes vexans is a widespread mosquito species known to carry West Nile virus (WNV); however, our understanding of how its microbiome changes across different regions and seasons, particularly in temperate areas such as South Korea, remains limited. In this study, we examined the microbiome of Aedes vexans collected from 16 locations over 3 consecutive summer months. Using 16S rRNA sequencing, we found that the microbiome was largely made up of Proteobacteria, but the specific genera present, like Dickeya, Spiroplasma, and members of Enterobacterales, varied depending on the location and time of collection. Dickeya, in particular, was more common in inland areas and stayed relatively stable over time, which suggests it could serve as a useful microbial marker. We also observed a significant absence of Wolbachia, a common endosymbiont in mosquitoes, which hypothesizes potential increased risk of WNV transmission. Diversity analyses showed clear differences in microbial communities by region, and we found seasonal patterns in genera like Asaia and Pseudomonas, which were correlated to mosquito abundance and local environmental conditions. These patterns held up when we looked at co-occurrence networks between microbes. Altogether, this is the first study to track Aedes vexans microbiome across both space and time in Korea, and our findings offer new insights into mosquito ecology and the potential use of bacteria in disease control strategies.IMPORTANCEUnderstanding the dynamics of the mosquito microbiome is essential for predicting disease risk and developing targeted vector control strategies. Aedes vexans, a globally distributed species and potential vector for West Nile virus (WNV), has seen a notable population increase in South Korea, yet its microbial ecology remains poorly characterized. This study provides the first comprehensive spatiotemporal analysis of Aedes vexans microbiota across Korea, identifying key microbial taxa that vary by region and season. The absence of Wolbachia, a known antiviral symbiont, and the dominance of Dickeya, a plant-associated genus with potential ecological implications, underscore the need for microbiome-informed surveillance tools. By highlighting native microbial signatures and their environmental drivers, this work lays the groundwork for microbiota-based monitoring of vector populations and opens new avenues for symbiont-based interventions in arbovirus control.