High level of population structuring within the West-African malaria vector Anopheles melas

Anopheles melas is a brackish-water breeding mosquito that is a member of the An. gambiae complex, with a distribution that is limited to coastal marshlands from Senegal to Angola. Because of its limited distribution it is not considered a primary vector, although it is frequently an important vector locally, as is the case in several locations on Bioko Island, Equatorial Guinea. These Anopheles melas populations are subject to intensive vector control efforts under the Bioko Island Malaria Control Program II in support of the National Malaria Control Program of Equatorial Guinea. Understanding the population structure and migration patterns of this species is therefore important, because it can inform vector control efforts. We are analyzing An. melas populations throughout its range using microsatellites markers and a portion of the mitochondrial ND 4 and 5 genes to provide insight into the population structure of this species. We are particularly interested in estimating migration between the mainland and Bioko Island, as well as the effect of An. melas' patchy distribution on its population structure. Our results thus far suggest that An. melas is a highly structured species. Although Anopheles melas on Bioko Island belong to a single larger population, they appear to be isolated from mainland populations. Additionally, An. melas populations from The Gambia and Central Africa are highly differentiated and show little evidence of gene flow based on mtDNA. We are incorporating additional samples and populations in our data set, which will provide a detailed picture of the population structure of this malaria vector.