A new mosquito species called Culex lactator has migrated from the tropics and settled in at least three Florida counties since 2018. It is unclear whether this species will contribute to the transmission of mosquito-borne viruses in the state, but scientists are worried about the increasing rate of new mosquitoes arriving in Florida. The findings were published in the  Journal of Medical Entomology.

Lead study author Lawrence Reeves, an assistant professor and mosquito biologist at the University of Florida’s Institute of Food and Agricultural Sciences Research Center in Vero Beach, stated that there are about 90 mosquito species living in Florida, and the list is growing as new species are introduced from other parts of the world.

Culex lactator, a member of the Culex group of mosquitoes, which includes species that transmit the West Nile and St. Louis encephalitis viruses, was first discovered in southern Miami-Dade County in 2018 and is now in Collier and Lee Counties. Reeves believes it may have spread elsewhere in the state.

Using DNA analysis and other tools, Reeves and his team identified Culex lactator among more than 3,600 types of mosquitoes found worldwide. Florida faces challenges every year from mosquito-transmitted diseases like West Nile virus, eastern equine encephalitis virus, dengue virus, and chikungunya virus.

“Introductions of new mosquito species like this are concerning because many of our greatest mosquito-related challenges are the result of nonnative mosquitoes, and in a case like this, it’s difficult to anticipate what to expect when we know so little about a mosquito species,” Reeves noted.

Reeves said that it is too early to know whether Culex lactator will worsen the existing challenges, but the implications are often difficult to predict because not all mosquito species are equally capable of transmitting a particular virus or other pathogen. He emphasised the need for vigilance for new mosquito species, as each introduction comes with the possibility that the introduced species will facilitate the transmission of a mosquito-borne disease.

Reeves said that Culex lactator looks like other more common mosquito species in Florida, making its presence in an area easy to miss. As many as 17 nonnative mosquito species are established in Florida, and detections of nonnative mosquito species are becoming increasingly frequent, with 11 of 17 nonnative species first reported in the past two decades. Six were detected in only the past five years.

Reeves added that the mosquitoes Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus are all nonnative species, introduced from the tropics and among the most important disease vectors in the United States. He believes that climate change may improve the chances of tropical mosquito species becoming established in Florida if the state becomes warmer, and increasing storm frequency and intensity could blow in more mosquitoes and other species from the Caribbean, Central America, and elsewhere.