Does arbovirus emergence in humans require adaptation to domestic mosquitoes?

In the last few decades, several mosquito-borne arboviruses of zoonotic origin have established large-scale epidemic transmission cycles in the human population. It is often considered that arbovirus emergence is driven by adaptive evolution, such as virus adaptation for transmission by ‘domestic’ mosquito vector species that live in close association with humans. Here, I argue that although arbovirus adaptation to domestic mosquito vectors has been observed for several emerging arboviruses, it was generally not directly responsible for their initial emergence. Secondary adaptation to domestic mosquitoes often amplified epidemic transmission, however, this was more likely a consequence than a cause of arbovirus emergence. Considering that emerging arboviruses are generally ‘preadapted’ for transmission by domestic mosquito vectors may help to enhance preparedness toward future arbovirus emergence events.