Enzyme polymorphisms in the Anopheles gambiae (Diptera: Culicidae) complex related to feeding and resting behavior in the Imbo valley, Burundi

A cellulose acetate electrophoresis system was used to study the Anopheles gambiae complex at 2 villages in Central Imbo Valley and at 1 village in South Imbo Valley (Burundi). In South Imbo, only An. gambiae Giles sensu stricto was present. In the drier Central Imbo, the dominant species was An. arabiensis Patton (97.5%); An. gambiae s.s. represented only 2.5%. Both species were separated readily by Odh and Mpi, because they did not share alleles at those loci. Indoor resting An. gambiae s.s. from South Imbo differed significantly from outdoor resting females at 2 Ioci, Mpi, and Got-2. In Central Imbo, total An. arabiensis did not differ between adjacent villages. Endophagic An. arabiensis significantly differed at loci alpha-Gpd, and Idh-1 between the 2 villages, whereas no difference was observed between exophagic females. Allelic and genotypic frequencies at the locus Mdh-2 were significantly different between indoor and outdoor biting An. arabiensis. Active choice for the best place to bite or to rest seemed to be associated with specific genotypes. The Nei genetic distance values were typical of conspecific populations, ranging from 0.154 to 0.160 between An. gambiae s.s. and An. arabiensis. Even though vector populations were structured at spatial and behavioral levels, they were panmictic, and thus selection of exophilic or exophagic vectors, or both, by insecticide pressure is not likely to occur