Is Aedes aegypti adapting to colder climates? Implications for future range expansion

FISCHER, SYLVIA

La Plata

Congreso; II Congress of the Latin American Society for Vector Ecology; 2022

Universidad Nacional de La Plata

The mosquito Aedes aegypti, vector of dengue and other arboviruses, has recentlyexpanded its distribution in Argentina towards colder climate regions, where lowwinter temperatures limit the development and reproduction of this species. Thisobserved range expansion might be favored by adaptations of the populations to thethermal conditions of the recently colonized environments. In this presentationwe will address two hypotheses regarding possible adaptations of Aedes aegypti to colder climate regions:1) populations from temperate regions have an increased tolerance of immaturestages to low temperatures, which might favor that individuals complete theirdevelopment (and eventually reproduce) during an extended period of the year,avoiding an excessive mortality at the beginning and the end of the cold season;2) populations from temperate regions have a better adjusted hatching responseto environmental conditions like low temperatures and short photoperiods, whichallows for a reduction in larval mortality due to untimely hatching of the eggs.Different studies performed during the last decade with Aedes aegypti from Argentina assessing these two hypotheses will bepresented and discussed. The results provide evidence of: 1) an ongoingadaptation of immature stages to lower temperatures; 2) an ongoing adaptationof the hatching response at low temperatures; and 3) the induction of embryonicdiapause in response to short photoperiods (observed for the first time in thisspecies). These findings might explain the expansion and successful persistenceof Aedes aegypti in increasinglycolder areas of Argentina, and further range expansions of this species shouldbe expected.