To understand the species composition, density, seasonal fluctuation of mosquitoes and the virus-carrying situation in Tianjin from 2019 to 2023, and to provide a reference for reducing mosquito density and controlling mosquito-borne diseases.

According to the “Monitoring Work Plan for Vector Control in Tianjin”, from April to November each year, the number of adult mosquitoes was monitored in 16 districts of Tianjin using the mosquito-attracting lamp method. Habitats such as residential areas, parks, hospitals, livestock sheds, and rural households were selected as monitoring sites. In addition, from June to October, adult mosquitoes or mosquito larvae were captured using methods such as the mosquito-attracting lamp method and the mosquito-and-egg trap method. Reverse transcription polymerase chain reaction (RT-PCR) technology was used to detect the presence of Japanese encephalitis virus and dengue virus in the samples.

From 2019 to 2023, a total of 12 641 mosquito-attracting lamps were deployed in Tianjin, and 54 870 female mosquitoes were captured, with an average mosquito density of 0.72 mosquitoes/(lamp·h). Among them, 52 569 were Culex pipiens pollens (accounting for 95.81%),followed by 1 402 Aedes albopictus (accounting for 2.56%). From 2019 to 2023, the overall mosquito density showed a downward trend. The mosquito density was the highest in July each year, showing a single-peak distribution. Among different habitats, the mosquito density was the highest in livestock sheds, reaching 1.45 mosquitoes/(lamp·h), followed by rural households at 0.96 mosquitoes/(lamp·h), and the lowest in hospitals at 0.42 mosquitoes/(lamp·h). Culex pipiens pollens was the dominant mosquito species in all habitats. Neither Japanese encephalitis virus nor dengue virus was detected in Culex pipiens pollens or Aedes albopictus.

The dominant mosquito species in Tianjin is Culex pipiens pollens, and the key period for mosquito density control is from June to September. Priority should be given to improving the environmental conditions of livestock sheds, and targeted mosquito- vector control strategies should be implemented according to the mosquito population distribution, density changes, and seasonal fluctuation patterns.