Climate-associated variation in mosquito abundance and species composition in Jeollanam-do, Republic of Korea, 2021-2024.

Mosquito communities in temperate-subtropical transition regions are highly sensitive to climatic variability. This study investigated temporal variation in mosquito abundance and species composition in Jeollanam-do, Republic of Korea, from 2021 to 2024, and evaluated the associations between mosquito abundance and temperature, relative humidity, and precipitation. Female mosquitoes were collected from urban areas, bird sanctuaries, and a cattle shed. Mosquito pools from urban areas and bird sanctuaries were screened for medically important flaviviruses using real-time reverse transcription PCR (RT-qPCR). A total of 108,498 female mosquitoes representing 15 taxa across eight genera were collected. Mosquito species composition varied substantially across years and collection environments. Aedes vexans was the most abundant species overall, whereas the relative abundance of Culex tritaeniorhynchus increased markedly in 2024. The temperature intervals associated with the highest observed mosquito abundance shifted progressively upward over the study period. In a zero-truncated negative binomial generalized linear mixed model, mosquito abundance was significantly lower in 2022, 2023, and 2024 compared to 2021. Temperature was positively associated with mosquito abundance, yielding a 14.4% increase in abundance per 1°C rise (IRR = 1.144, 95% CI: 1.096-1.195, p < 0.001), whereas relative humidity and precipitation were not significantly associated with abundance. Although collections were largest in the cattle shed, cross-environment comparisons require cautious interpretation due to differences in trap types and sampling frequencies. No flavivirus RNA was detected in 774 mosquito pools from urban areas and bird sanctuaries. These findings demonstrate substantial temporal variation in mosquito abundance and species composition, underscoring the necessity of sustained, standardized, and climate-informed surveillance in temperate-subtropical transition regions.