“This is a dynamic species that is changing rapidly as it adapts to human activities,” Powell said. For instance, Aedes aegypti apparently survives colder winters in Washington DC by entering sewers, which it does not do in other habitats.
In California, the drought may have driven mosquitoes to more populated areas with water sources such as swimming pools. The species often hitchhikes on products such as ornamental plants or used tires, which are shipped to other parts of the world.
A more benign and close genetic cousin found mostly in sub-Saharan Africa appears to be interbreeding with its more aggressive relative, increasing the risk for the spread of yellow fever in those areas, researchers said. Powell and colleagues at Yale are studying genetics of the mosquitoes to pinpoint their source of origin.
“We are getting warmer and it won’t take much before mosquitoes expand their northern limits,” Powell said. The research was published in the journal Science.