Mosquito diversity and arbovirus circulation at the Taï National Park, western Cote d'Ivoire

Understanding the ecological and virological dynamics of mosquito populations across different landscapes is essential for predicting and mitigating the risk of arbovirus spillover. From December 2021 to September 2022, we conducted an entomological and molecular survey across sylvatic, transition, and urban zones in the Tai region of western Cote dIvoire. We collected 4,414 mosquitoes, representing 29 taxa, and grouped them into 1,553 pools of the same taxa for virus detection and identification. While Eretmapoditis sp. were dominant across all zones, their species composition varied between the zones, with Er. fraseri being most abundant in the sylvatic and urban zones. In the transition zone Er. quinquevittatus was the dominant species. Abundance of other species also varied across zones. Aedes aegypti and Anopheles sp. were most frequent in the urban zone with An. gambiae s.l. and An. paludis being the most common ones. Molecular screening revealed flavivirus RNA being present in multiple pools, with the highest detection rates in the transition zone. We were able to assemble three flavivirus contigs, including Cimo flaviviruses II and VIII, known as insect-specific flaviviruses that can influence vector competence. Notably, Anopheles sp. had the highest estimated infection rates in the sylvatic and transition zones, suggesting a potential role in arbovirus ecology. Our findings suggest that Eretmapodites sp., particularly Er. fraseri, may serve as key bridge vectors due to their widespread presence, mammalian feeding behaviour and potential virus competence. The transition zone emerged as a hotspot for arbovirus diversity and vector-host interactions. This study provides the first comprehensive ecological and molecular characterization of mosquito communities in the Tai region since more than twenty years and underscores the importance of longitudinal and habitat-specific surveillance for anticipating spillover risks. Author summaryMosquitoes are important to study because they can carry viruses that spread to humans and animals. These viruses, known as arboviruses, often come from wildlife and can spill over into people, especially when natural and human environments overlap. From late 2021 to 2022, we collected and studied mosquitoes in western Cote dIvoire, across forest, village-forest edges, and towns. We wanted to understand which mosquito species were present, how their populations varied across different landscapes, and whether they carried any viruses. We found that one group of mosquitoes, called Eretmapodites, was common in all areas, with different species dominating in different zones. We also found that some mosquito groups, including Anopheles, carried viruses that could potentially affect humans or influence how diseases spread. The area between forest and town, the transition zone, showed the greatest variety of viruses and mosquitoes. Our work helps show how changes in land use and mosquito ecology can affect the risk of disease outbreaks. By understanding where and when mosquitoes are most likely to carry viruses, we can improve surveillance and better prepare for future disease emergence. This is especially important in regions where people and wildlife live close together.