Effect of industrial palm plantation on the ecological patterns of Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae) in high arboviral risk areas, southeastern Côte d'Ivoire.

Large-scale industrial oil-palm monocultures homogenize habitats, alter mosquito community composition, and often favor arbovirus vectors. We assessed how oil-palm plantations reshape the ecology of Aedes aegypti (Linnaeus, 1762) and Culex quinquefasciatus (Say, 1823) and arboviral risks in Bingerville, southeastern Côte d'Ivoire. We collected mosquitoes in two villages located within and two villages ≥5 km from palm plantations. We sampled larvae and pupae from containers and adults using BG-Sentinel traps and Prokopak aspirators among houses, from August 2023 to July 2024. Abdomens and ovaries were examined. Biodiversity, Stegomyia indices, blood-meal status and parity were compared by villages. Oil-palm areas harbored significantly fewer species (11 vs 18; χ2 = 8.73, P < 0.001) and 39% fewer specimens. Ae. aegypti adults were almost absent (0.03 female/trap/day) and showed a fivefold lower resting density in oil-palm areas. Cx. quinquefasciatus adults exhibited comparable host-seeking rates (≈2.5 female/trap/day), and higher resting densities (41 female/house/hour) and parity (82%) in oil-palm areas. Ae. aegypti pupal productivity was dominated (>80%) by tires in oil-palm, and small containers in non-oil-palm areas. Epidemic risks were uniformly high in both areas (Density figure: 5-7 vs 5-8), but vector-specific productivity and parity revealed a shift from Aedes-driven dengue/yellow fever risks to potential Culex-mediated West Nile risks in oil-palm areas. Effective vector control, therefore, requires landscape-tailored interventions: removal/treatment of functional containers in oil-palm areas, domestic-focused waste reduction in non-oil-palm settlements. Integrating conventional pupal productivity and parity surveillance could improve risk assessment and mitigation of arboviral threats in expanding oil-palm regions.