Habitat heterogeneity and seasonal dynamics structure mosquito community composition and vector niche differentiation in an intra-urban landscape of southeastern Gabon

Abstract Background Mosquito-borne diseases remain a major public health concern in sub-Saharan Africa, yet the ecological drivers of mosquito community structure in intra-urban environments are poorly understood. This study aimed to assess how habitat heterogeneity, seasonality, and environmental gradients shape mosquito communities in Franceville. Methods A longitudinal survey was conducted from July 2023 to July 2024 using 10 CDC light traps deployed weekly for three consecutive nights. Mosquitoes were identified morphologically and environmental, climatic, and urban variables were recorded. Community structure was analysed using diversity indices, principal component analysis (PCA), canonical correspondence analysis (CCA), and Variation Partitioning (VarPar). Species sensitivity to environmental gradients was quantified, and variation partitioning was used to assess the relative contributions of predictor groups. Results A total of 6794 mosquitoes representing 24 species across 7 genera were collected. Community composition varied significantly across habitat and season, with higher diversity in forest-associated habitats and more even assemblages in savannah environments. Multivariate analyses revealed distinct ecological responses among genera: Anopheles species showed high sensitivity to environmental gradients, whereas dominant Culex species exhibited broad ecological tolerance. Aedes aegypti was associated with savannah habitats and the rainy periods, while Ae. albopictus displayed marked ecological plasticity. Variation partitioning indicated that environmental variables explained a larger share of community variation than climatic and urban predictors, with additional effects from their interactions. Conclusions Mosquito communities in southeastern Gabon are primarily structured by fine-scale habit heterogeneity and seasonal dynamics. These findings highlight the importance of integrating ecological complexity and species-specific responses into vector surveillance and control strategies in rapidly urbanising African settings.