Host preferences, Bloodmeal sources, and Gonotrophic cycles of Anopheles gambiae complex mosquitoes in Rural Southwestern Nigeria.

Background objectives: Malaria remains a major public health challenge in sub-Saharan Africa, with the Anopheles gambiae complex, comprising An. gambiae s.s., An. coluzzii, and An. arabiensis, as the principal vectors. These sibling species exhibit diverse ecological and behavioural traits that significantly influence malaria transmission dynamics. Understanding their host preferences, blood-meal sources, and gonotrophic cycles is vital for designing effective vector control strategies. This study investigated the feeding behaviour, blood meal sources, and exophilic tendencies of An. gambiae complex mosquitoes in Igbo-Ora and Idere communities, southwestern Nigeria.

Methods: Indoor-resting mosquitoes were collected using pyrethroid spray collections (PSC) during the rainy season of 2022 over three months. Specimens were identified morphologically and confirmed molecularly. Data on abdominal conditions, feeding behaviour, gonotrophic cycles, and blood-meal sources were analysed. Human blood index (HBI) and exophily degree (DE) were calculated using standard protocols.

Results: A total of 298 An. gambiae complex mosquitoes were examined. Fully fed mosquitoes accounted for 77.2%, while 12.4% were gravid, and 5.4% were half-gravid. An. coluzzii in Idere exhibited the highest feeding rate (84.6%), followed by An. arabiensis in Igbo-Ora (77.8%). The gonotrophic cycle was longer in Idere (5-6 days) compared to Igbo-Ora (3-4 days). Blood-meal analysis of 421 specimens identified humans as the predominant host (45.8%), with mixed blood meals indicating opportunistic feeding. The highest HBI was recorded in An. gambiae (0.69) in Idere and An. arabiensis (0.96) in Igbo-Ora.

Interpretation conclusion: The findings reveal significant ecological and behavioural variability within the An. gambiae complex, including their strong anthropophilic tendencies and opportunistic feeding behaviour. These characteristics underscore the species' pivotal role in malaria transmission and highlight the need for localized, species-specific vector control interventions targeting feeding and reproductive behaviours.