Genome-wide screening of aedes aegypti (Culicidae: Diptera) populations from northwestern argentina: Active and passive dispersal shape genetic structure

Abstract

Aedes aegypti is the primary vector of arboviruses of great impact on human health. Our goal was to assess the spatial genetic structure of Ae. aegypti at the regional and local levels in Northwestern Argentina, an area with high prevalence of dengue fever. We analyzed 59 Ae. aegypti individuals collected from six locations in Northwestern Argentina using nuclear genome-wide Single Nucleotide Polymorphisms (SNPs) generated with double digest Restriction-site Associated DNA Sequencing. We also performed an entomological survey in 70 households in the cities of Orán and Tartagal. An analysis at the regional level indicated that the populations of Ae. aegypti in Northwestern Argentina are spatially structured and present a significant IBD pattern. Our results suggest that passive transport of eggs/immature stages, in both northward and southward directions, plays an important role in structuring Ae. aegypti populations at a regional scale and also as a source for the introduction of novel genetic variants through migration events into established populations. At a local level, we found neither spatial genetic structure nor significant isolation by distance (IBD) in Tartagal, indicating high gene flow within the city and active dispersal. In contrast, samples from Orán formed two clusters with a significant IBD pattern, although weaker than that at a regional level. Both populations showed signs of recent bottleneck events, probably coincident with past eradication campaigns. The entomological survey revealed a high prevalence of Ae. aegypti in both cities, although significantly higher in Tartagal.