Characterisation of Anopheles gambiae Complex Species in Relation to Malaria Transmission in Kano Metropolis

The Anopheles gambiae complex comprises multiple sibling species with differing vectorial capacities and insecticide susceptibility profiles, and accurate species characterisation is critical for informed vector control decision-making in Northwest Nigeria. This study characterised the species composition and bionomics of the Anopheles gambiae complex in Kano Metropolis, Northwest Nigeria. Adult female mosquitoes were collected over 12 months using Centers for Disease Control and Prevention light traps, pyrethrum spray catches, and clay pot collections from urban, peri-urban, and rural transects. A total of 2,840 Anopheles gambiae complex specimens were identified morphologically and a subset of 600 specimens were genotyped by PCR for species differentiation. Sporozoite rates were determined by ELISA for circumsporozoite protein. Anopheles arabiensis was the dominant sibling species at 71.4 percent, with An. gambiae sensu stricto at 28.6 percent and no An. coluzzii detected. Sporozoite rates were significantly higher in An. gambiae s.s. (4.1 percent) than An. arabiensis (1.8 percent). Insecticide resistance to deltamethrin was documented in 79.4 percent of An. arabiensis and 62.1 percent of An. gambiae s.s. specimens tested. The dominance of An. arabiensis with its outdoor biting behaviour has critical implications for indoor vector control effectiveness and calls for evaluation of outdoor interventions in Kano. Keywords: Anopheles gambiae complex, species characterisation, malaria transmission, insecticide resistance, Kano.