Genetic differentiation and population structure of Anopheles funestus from Uganda and the southern African countries of Malawi, Mozambique, Zambia and Zimbabwe.

BACKGROUND

Anopheles funestus (s.s.) is a primary vector of the malaria parasite Plasmodium falciparum in Africa, a human pathogen that causes almost half a million deaths each year. The population structure of An. funestus was examined in samples from Uganda and the southern African countries of Malawi, Mozambique, Zambia and Zimbabwe.

METHODS

Twelve microsatellites were used to estimate the genetic diversity and differentiation of An. funestus from 13 representative locations across five countries. These were comprised of four sites from Uganda, three from Malawi and two each from Mozambique, Zambia and Zimbabwe.

RESULTS

All loci were highly polymorphic across the populations with high allelic richness and heterozygosity. A high genetic diversity was observed with 2-19 alleles per locus and an average number of seven alleles. Overall, expected heterozygosity (H) ranged from 0.65 to 0.79. When samples were pooled three of the 12 microsatellite loci showed Hardy-Weinberg equilibrium. Unsupervised Bayesian clustering analysis of microsatellite data revealed two clusters with An. funestus samples from Mozambique, Uganda and Zambia falling into one group and Malawi and Zimbabwe into another. The overall genetic differentiation between the populations was moderate (F = 0.116). Pairwise differentiation between the pairs was low but significant. A weak but significant correlation was established between genetic and geographical distance for most populations.

CONCLUSIONS

High genetic diversity revealed by the loci with low to moderate differentiation, identified two clusters among the An. funestus populations. Further research on the population dynamics of An. funestus in east and southern Africa is essential to understand the implications of this structuring and what effect it may have on the efficient implementation of mosquito vector control strategies.