Vector Bionomics and Malaria Transmission Seasonality in Wetland Communities of Bayelsa State, South South Nigeria

Bayelsa State's extensive wetland and mangrove ecosystems create near year-round Anopheles mosquito breeding conditions, with unique vector bionomics that challenge standard seasonal malaria transmission models applied elsewhere in Nigeria. This longitudinal entomological study characterised Anopheles vector bionomics and malaria transmission seasonality across four wetland communities in Bayelsa State. Monthly mosquito collections using Centers for Disease Control light traps and human landing catch methods were conducted over 18 months. Collected Anopheles were morphologically identified, dissected for parity assessment, and tested for Plasmodium sporozoites by ELISA. A total of 4,680 Anopheles mosquitoes were collected, predominantly An. melas (61.2 percent) and An. gambiae s.s. (38.8 percent). Sporozoite rate averaged 5.4 percent with minimal seasonal fluctuation, confirming perennial high transmission. Mean monthly entomological inoculation rate was 24.7 infectious bites per person, among the highest documented in Nigeria's South South zone. Parity rates above 80 percent indicated long-lived vector populations sustaining efficient transmission. Indoor resting densities were highest during tidal flooding events. These findings demonstrate that wetland-adapted vector species sustain transmission patterns distinct from inland zones and call for wetland-specific vector control strategies, including larval source management adapted to tidal cycles, in Bayelsa State. Keywords: vector bionomics, malaria transmission, Anopheles melas, wetland ecology, Bayelsa State.