Species Composition and Feeding Behaviors of Vector Mosquitoes of Avian Infectious Diseases at a Wild Bird Rehabilitation Facility in Japan.

Although wild bird rehabilitation facilities are important for the conservation of wild species, individuals may be kept within the facilities for long periods, consequently posing a risk for the bird to be infected with pathogens to which they are not naturally exposed. In turn, novel pathogens may be introduced through rescued migratory species. Avian malaria and West Nile fever are important avian diseases transmitted by mosquitoes. To understand the transmission dynamics of such diseases at rehabilitation facilities, the ecology of vector mosquitoes, including species composition, seasonality, and feeding behaviors, were explored. Mosquitoes were collected at a wild bird rehabilitation facility and wildlife sanctuary in Japan from 2019 to 2020 using mouth aspirators, sweep nets, and light traps. A total of 2,819 mosquitoes of 6 species were captured, all of which are potential vectors of avian diseases. Culex pipiens pallens and Cx. pipiens form molestus were the dominant species (82.9% of all collected mosquitoes). Density and seasonality differed between sampling locations, presumably because of differences in mosquito behaviors including feeding preferences and responses to climatic factors. Blood-fed Culex mosquitoes fed solely on birds, and many mosquito species are thought to have fed on birds within the facility. Particularly, Cx. pipiens group probably fed on both rescued and free-living birds. The rehabilitation facility may be an important site for the introduction and spread of pathogens because 1) numerous mosquitoes inhabit the hospital and its surroundings; 2) blood-fed mosquitoes are caught within the hospital; 3) there is direct contact between birds and mosquitoes; 4) both birds within the hospital and wild birds are fed upon. Furthermore, blood-fed Cx. pipiens form molestus were observed in the winter, suggesting that pathogens might be transmitted even during the winter when other mosquito species are inactive.