South Florida Hosts New Disease-Carrying Mosquito Species

The mosquito species Aedes scapularis was first observed in larval form in the Florida Keys 75 years ago.  A new study by Lawrence Reeves and colleagues has discovered that Aedes scapularis is now established on mainland Florida in Miami-Dade and Broward counties.
Photo:  Lawrence Reeves.

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.

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

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 in,

Establishment of Aedes (Ochlerotatus) scapularis (Diptera: Culicidae) in Mainland Florida, With Notes on the Ochlerotatus Group in the United States

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. 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.

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“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 told 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.”

Aedes scapularis mosquito biting.

Reeves and his colleagues published a second paper, this one in Insects aptly titled:  
Potential Distribution of Aedes (Ochlerotatus) scapularis (Diptera: Culicidae): A Vector Mosquito New to the Florida Peninsula

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.

Environmental suitability range of Aedes scapularis mosquito

In South America, the species has been found infected with pathogens such as yellow fever virus and Venezuelan equine encephalitis virus. Reeves told 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, as well.

Map of Broward and Miami-Dade Counties, Florida, United States, indicating localities where Aedes scapularis were collected in 2006–2020. White points indicate collections of single specimens; gray points indicate collections of 2–19 specimens; black points indicate collections of 20 specimens. Inset on right shows location of Broward and Miami-Dade Counties within the Florida Peninsula (shaded). Star indicates location of Vaca Key (Monroe County), the collection site of three Ae. scapularis larvae in 1945 and the only records of Ae. scapularis in Florida prior to 2006.