Environmental factors affect the communities of avian Plasmodium in two species of Culex mosquitoes.

Understanding vector-borne pathogen transmission is a priority due to its impact on human and animal health. While mosquitoes are key hosts of avian malaria, most studies focus on birds. This study examines how environmental factors influence Plasmodium communities in Culex pipiens and Culex perexiguus and compares lineage composition and spatial patterns. Mosquitoes were collected from 16 sites in southwest Spain over two years. Plasmodium detection was performed using nested PCR, and lineages were identified by SANGER sequencing. Linear mixed models tested environmental effects on Plasmodium communities, and correspondence analysis and Mantel tests explored interspecific and spatial relationships. In Cx. pipiens, Plasmodium prevalence increased with NDVI, while lineage richness declined with land surface temperature. In Cx. perexiguus, prevalence and lineage richness increased with minimum temperature, and diversity decreased with land surface temperature. Plasmodium communities differed between mosquito species, with community similarity correlating with geographical distance only in Cx. pipiens. These findings suggest that environmental factors shape Plasmodium communities in mosquitoes, and that vector identity influences lineage structure and distribution. Integrating vector ecology and environmental context is essential to better understand avian malaria transmission dynamics in changing environments.