Breeding site salinity tolerance in the Aedes aegypti mosquito (Diptera: Culicidae)

Despite their small size, mosquitoes continue to have a massive impact on public health worldwide due to their role as pathogen vectors. The yellow fever mosquito, Aedes aegypti, is a carrier of pathogens that cause diseases such as dengue virus, Zika virus, and yellow fever virus, and is of particular concern because of its ability to be exceptionally invasive. Originally native to sub-Saharan Africa, the Ae. aegypti mosquito has since migrated to tropical regions surrounding the equator globally. This is in stark contrast to a related mosquito, Aedes togoi, which have an incredibly narrow coastal range across the Pacific Northwest (including Vancouver) and Asia. Paradoxically, Ae. togoi can survive much harsher environmental conditions as compared to Ae. aegypti. Of note is their ability to tolerate highly variable water salinity from freshwater up to three times that of seawater. While Ae. aegypti is primarily a freshwater mosquito, the recent discovery of a brackish water adapted population of Ae. aegypti in Jaffna, Sri Lanka provides an interesting opportunity to probe the limits of salt tolerance in this species. To elucidate how Ae. aegypti respond to and survive in fresh and brackish water, we bred five generations while selecting for survival and oviposition preference under different salinities. A combination of genetic and behavioral tests will shed light onto potential explanations for this phenotypic plasticity and the mechanisms by which mosquitoes can alter their salt tolerance, with implications for understanding the potential of some mosquitoes to become invasive species.