Temporal Assessment of Entomological Indices of Indoor Resting Malaria Vectors in Delta State, Nigeria

Malaria remains a major public health burden in Nigeria, sustained by the widespread presence of efficient vectors such as Anopheles gambiae s.l. This study investigated the entomological indices of An. gambiae s.l. in three malaria endemic communities of Delta State; Egbudu-Akah, Aghalokpe, and Owhelogbo, between July 2024 and March 2025. Mosquitoes were collected using Pyrethrum Spray Catch (PSC), molecularly assayed, and examined for feeding characteristics, indoor resting density, human biting rate, and seasonal variations in relation to temperature and relative humidity. A total of 820 An. gambiae s.l. mosquitoes were collected and molecularly confirmed as An. coluzzii. Egbudu-Akah recorded the highest abundance, followed by Aghalokpe and Owhelogbo. Blood fed mosquitoes predominated across sites, while gravid females were more common in Aghalokpe and Egbudu-Akah. Indoor resting density and human biting rate peaked in the wet season months, with July showing the highest values. Correspondence analysis revealed that relative humidity positively influenced blood feeding, biting rates, and resting densities, particularly in March, July, and September. The study highlights the seasonal and ecological dynamics of An. coluzzii populations anthropophilic tendencies and the role of climatic factors in malaria transmission. It also provides critical insights for enhancing malaria surveillance and tailoring vector control strategies to local ecological contexts in Delta State.