Abstract
BACKGROUND: Culex quinquefasciatus mosquitoes can be found in almost every major city of Brazil and are vectors of filariasis and several arboviruses. Microsatellite markers have been widely used to uncover the genetic structure of various groups of insect populations. The aim of this study was to glimpse the genetic structure of Cx. quinquefasciatus in Brazil. METHODS: Nine populations were sampled across Brazil (one of them from a laboratory colony - COL) and another one from Argentina and process regarding the variability of six microsatellite loci. RESULTS: The analyzed loci revealed moderate population genetic structure (mean Fst = 0.12). Dendrograms of genetic distances evidenced two major population clusters, respectively corresponding to the northern and southern populations. The hybrid population Cx. pipiens/quinquefasciatus (from La Plata, Argentina) and the colony population fell outside the major clusters. Those clusters were substructured and there was a significant correlation between genetic and geographic distances and environmental variables (r = 0.51; p > 0.001 and r = 0.46; p > 0.004). CONCLUSIONS: Multilocus cluster Bayesian analysis confirmed that populations are mutually distinct, and the set of results point to genetic differences among populations. The presumable low gene flow among them may be due to the large geographic distances (>1000 km) and to the environmental heterogeneity of the sampled areas. The genetic structure observed in this study may lead to the best understanding of Cx. quinquefasciatus demographical diversity as well as their genetic variations patterns in Brazil so far unknown.