Diversity and Characterization of Larval Habitats of Anopheles Mosquitoes in Urban Areas in Benin: Influence of Physicochemical and Bacteriological Factors on Larval Density

Background: The implementation of antilarval strategies in the fight against malaria vectors requires fundamental knowledge of their oviposition sites. This study aimed to assess the spatial and temporal distribution of Anopheles breeding sites as well as the influence of abiotic and biotic factors on the proliferation of larvae in urban and non-urban environments in Benin. Methods: : Larval surveys were carried out during the rainy and dry seasons in urbanized and non-urbanized areas in the cities of Parakou, Natitingou, Bohicon and Cotonou in Benin. The Anopheles larval breeding sites were georeferenced and characterized by their nature, typology, physicochemical (pH, temperature, dissolved oxygen, conductivity, turbidity, salinity) and biological attributes (larval density and coliform density). Results: : A total of 198 different types and positive breeding sites for Anopheles larvae were identified. These include 163 (82.3%) breeding sites during the rainy season and 35 (17.7%) during the dry season. Out of these habitats, 61.9% were located in urbanized areas with a predominance of puddles. The Principal Component Analysis (PCA) revealed a high positive correlation of larval density with temperature, dissolved oxygen and salinity in the coastal zone (Cotonou). In addition, the cross-analysis of the microbiological results with the larval density has generally shown a significant negative correlation between the larval productivity of anopheles breeding sites and their faecal coliforms load. Conclusion: This study showed multiple larval habitats of Anopheles in urban environments due to several anthropogenic factors and larval adaptation to unusual ecosystems.