Vector competence across Aedes aegypti populations shaped by host-preference adaptation and host-pathogen interactions.

Aedes aegypti is the principal vector for yellow fever, dengue, Zika, and chikungunya viruses. Although this mosquito continues to expand its global range, its intrinsic ability to acquire, support the replication of, and transmit specific viruses-known as vector competence (VC)-varies across populations. A mechanistic understanding of this variation is a key goal of vector biology and is central to devising interventions to contain epidemics. In this review, we examine how evolutionary history fundamentally shaped VC in the sylvatic and human-adapted subspecies of Ae. aegypti. We discuss how the physiological processes underlying arbovirus infection define transmission potential and synthesize our understanding of the global heterogeneity in VC for the principal arboviruses transmitted by Ae. aegypti. Finally, we evaluate emerging insights into the molecular mechanisms that may drive this variation, with emphasis on the mosquito virome and the antiviral RNA interference pathways, and how these, in turn, help shape the genetic architecture associated with the intrinsic capacity to transmit arboviruses.