Objective To analyze the population composition, density distribution, and seasonal fluctuation pattern of mosquitoes in Tongzhou District of Nantong City from 2022 to 2024, and to provide a basis for the prevention and control of mosquito-borne infectious diseases.

Methods From 2022 to 2024, mosquito lamp trap methods were used to monitor five kinds of habitats in Tongzhou District, including urban residential areas, parks, hospitals, rural residential areas and livestock sheds, to calculate mosquito density and mosquito species composition ratio and analyze the seasonal fluctuation trend based on monthly data.

Results A total of 11 471 female mosquitoes were captured from 2022 to 2024, with the mosquito densities of 24.88, 20.98, and 17.87 mosquitoes·(light·night)^-1, respectively, and an average mosquito density of 21.24 mosquitoes·(light·night)^-1. Culex pipiens pallens was the dominant mosquito species (64.61%), followed by Culex tritaeniorhynchus (19.97%) and Anopheles sinensis (7.12%). The differences of mosquito species composition ratio in different years were statistically significant (χ²=517.75, P<0.001), and the differences of mosquito density in different mosquito species were statistically significant (F=20.05, P<0.001). Culex Pipiens pallens had the highest density at 13.72 mosqutoes (light·night)^-1, followed by Culex tritaeniorhnchus at 21.24 mosquitoes (light·night)^-1. The differences of mosquito density among different habitats were statistically significant (F=10.98, P<0.001), with the highest density of mosquitoes in livestock shed 41.22 mosquitoes·(light·night)^-1, and the differences of mosquito species composition ratio across different habitats were statistically significant (χ²=763.99, P<0.001). The seasonal fluctuation of mosquito density displayed a single peak distribution, with the peak from June to September and the highest density concentrated in July.

Conclusion The density of mosquitoes in Tongzhou District overall showed a downward trend, and Culex pipiens pallens was the dominant mosquito species. Rural areas, especially livestock sheds, could be key areas and places for prevention and control; June-September was the peak period of mosquito activity, and scientific prevention and control measures should be carried out according to the habitat distribution and seasonal fluctuation of mosquitoes.