Aedes aegypti oviposition dynamics in towns with low human population density in yungas and dry chaco, Salta, Argentina.

We assessed the presence of Aedes aegypti in five ecorregions of Salta province and compared the oviposition activity of Ae. aegypti using ovitraps in towns of two contrasting ecoregions (yungas and Chaco dry forests) in the province of Salta, Argentina, a major contrast in these ecoregions are rain patterns and altitude. Our aim was to estimate how oviposition activities were associated with the ecoregion and site scale local environmental variables. Mosquito oviposition activity was monitored weekly during the summer using ovitraps. Predictor variables were ecoregion, town, and meteorological variables. The effect of the predictor variables was measured on the response variables using multi-model inference. Besides yungas, the presence of Aedes aegypti was confirmed in towns of dry Chaco and High Monte. The only factor that had a significant effect on the presence of eggs in the ovitraps was the ecoregion, with the frequency of positives being higher in yungas. For the number of eggs, the ecoregion, the night temperature of the first week and the NDVI would explain said variable. Overall, results indicate that the variations between towns would be more related with their ecological and climatic characteristics than with the more immediate meteorological variations.

Genome-Wide Screening of Aedes aegypti (Culicidae: Diptera) Populations From Northwestern Argentina: Active and Passive Dispersal Shape Genetic Structure.

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.