Population Genetic Structure ofAnopheles gambiaeandAnopheles arabiensisin Niger

Abstract

The increasing usage of long-lasting insecticide-treated nets allows protection of millions of people from malaria infection. Monitoring studies should be planned during any wide-scale malaria control program integrating insecticide-treated materials, to evaluate their effects and effectiveness on epidemiologically relevant parameters. Such operational control interventions may be challenged by insecticide resistance spread within vector populations, as a result of wide insecticide pressure. A nationwide distribution of long-lasting insecticidal nets was implemented throughout Niger in 2005. We studied the population genetic structure of major malaria vectors across Nigerien Sahel, and investigated potential effects of this large malaria control intervention. Wild-caught Anopheles gambiae sensu lato females from seven villages and two wet seasons were genotyped at 12 microsatellite loci. The genetic diversity within both species appeared homogenous between villages and years. The estimated genetic differentiation among samples was very low within both species, indicating high gene flow across the area. An absence of differentiation was also found between 2005 and 2006 wet seasons, for all samples but one, showing that the net distribution did not impact significantly the genetic diversity and structure of vector populations in a single year. We provide valuable results participating to document effects of large malaria control programs, to maximize the efficiency of available tools in future interventions.

Diversity, Differentiation, and Linkage Disequilibrium: Prospects for Association Mapping in the Malaria VectorAnopheles arabiensis

“…arabiensis within East Africa ( e.g. , Czeher et al 2010; Lee et al 2012; Nyanjom et al 2003) but strong population structure at greater distances ( i.e. , Cameroon and Tanzania) (Donnelly and Townson 2000).…”

Islands and Stepping-Stones: Comparative Population Structure of Anopheles gambiae sensu stricto and Anopheles arabiensis in Tanzania and Implications for the Spread of Insecticide Resistance

“…Observation of absence of genetic differentiation among temporal populations of An. arabiensis have been reported by [23] , [42] , [81] , although a study on temporal population structure of An. gambiae s.s. revealed significant genetic differentiation between successive monthly collections [75] .…”

“…<200 km; [40] ), and in the absence of variation in molecular or chromosomal forms in West African An. gambiae s.s., differentiation is usually low in both species [32] , [40] – [42] , often falling below the limits of detection of the microsatellite marker panels applied. Therefore studies to date partially support a hypothesis of weaker population structure in An.…”