Genetic structure of Aedes albifasciatus (Diptera: Culicidae) populations in central Argentina determined by random amplified polymorphic DNA-polymerase chain reaction markers.

The floodwater mosquito, Aedes albifasciatus (Macquart), is the main vector of western equine encephalomyelitis virus in Argentina. Previous studies on the genetic structure of this species using allozymes showed low levels of polymorphism, absence of subpopulations at distinct habitats, and moderate differentiation among localities separated up to 500 km. To examine gene flow using other genetic methods, we analyzed random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) polymorphism in 28 presumptive loci of Ae. albifasciatus from 6 populations in central Argentina. Allele frequencies were estimated assuming that RAPD products segregate as dominants and that genotype frequencies at those loci are in Hardy-Weinberg equilibrium. Expected heterozygosity ranged between 0.19 and 0.31, approximately 3 times the value obtained on the basis of the 16 allozymic loci studied previously. Four of the populations formed a single panmictic unit. Allele frequencies in populations occupying different phytogeographic regions gave significant FST values at 5 loci. Effective migration rates among populations estimated from FST ranged from 2.3 to 9.0. The results support the existence of a north-south cline.