Disease-Carrying Mosquito Species Returns to Florida

Aedes scapularis is already established on the peninsula, and researchers predict that its population will continue to spread.

Shawna Williams
Shawna Williams

Shawna was an editor at The Scientist from 2017 through 2022. She holds a bachelor's degree in biochemistry from Colorado College and a graduate certificate and science communication from the University of California, Santa Cruz.

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Aedes scapularis
lawrence reeves

A species of mosquito that can spread several diseases to humans has been found for the first time on mainland Florida, researchers reported in November in the Journal of Medical Entomology. Aedes scapularis, a species commonly found in south Texas, multiple parts of South America, and the Caribbean, had last been seen in Florida in 1945, when specimens were collected in the Keys, but no one had reported observations in the state since then.

That changed in 2019, when the University of Florida’s Lawrence Reeves collected members of the species near Everglades National Park, NPR reports. He later followed up by collecting and examining mosquitoes from more sites in southern Florida, and found Ae. scapularis at multiple sites in Miami-Dade and Broward counties. 

“The central finding of the manuscript is that Aedes scapularis, a non-native mosquito and potential pathogen vector, is now established in the southern Florida Peninsula,” Reeves tells Entomology Today. “The Florida Strait was likely a geographic barrier for the species, and now that it has crossed that barrier, Aedes scapularis could potentially spread further northward and westward to fill any contiguous areas that are environmentally suitable.”

A map showing areas a study found are more likely (red) or less likely (blue) to host Aedes scapularis in the future

Reeves and his colleagues published a second paper, this one in Insects earlier this month, that forecasts where Ae. scapularis might spread to based on environmental suitability. They found habitat for the species could extend along much of coastal Florida and along the Gulf coasts of Louisiana and Texas. 

In South America, the species has been found infected with pathogens such as yellow fever virus and Venezuelan equine encephalitis virus. Reeves tells Entomology Today, “It’s hard at this point to say how Aedes scapularis might become involved in the transmission of these or other pathogens in Florida, but the species is ecologically well positioned to be a vector because it feeds readily from humans: some populations are well adapted to human-dominated habitats, they feed from a broad range of hosts, and they feed readily from humans.”  

The species’ propensity to feed on both wildlife and people could potentially foster future spillovers of pathogens into the human population, Reeves’s coauthor Lindsay Campbell tells NPR.

Correction (March 17): The word “novel” has been removed from the final paragraph, because, according to Campbell, although Ae. scapularis could hypothetically transfer novel pathogens into the human population, it’s more likely that such spillovers from wildlife to people would involve existing human pathogens.