This year, the Florida Department of Health has issued mosquito-borne illness advisories in several counties for diseases like West Nile virus and dengue. With mosquitoes abundant in Florida, some counties have been practicing mitigation strategies against the bugs.
Nathan Burkett-Cadena with the Florida Medical Entomological Laboratory discussed mosquitoes with Tom Hudson on "The Florida Roundup."
Burkett-Cadena said with different areas of Florida getting above- or below-average rainfall this year, the number of mosquitoes varies.
“And we know that mosquito larvae are aquatic, and they rely upon that rainfall for breeding. So wherever there's above-average rainfall, you've got a lot more mosquitoes, and places where you've got less rainfall, you've got a lot fewer mosquitoes. So looking around the state, you can see there's no really uniform pattern,” he explained.
While there are dozens of mosquito species in Florida, Burkett-Cadena noted a few are important as transmitters of human diseases. Some of these species breed in urban areas while others prefer residential zones.
“And so it's really hard to generalize, but there is a lot of mosquito-borne disease transmission going on this year. West Nile virus is particularly hot right now with our sentinel chickens ... a lot of infections around the state,” Burkett-Cadena said.
Blood samples from sentinel chickens are tested for antibodies for mosquito-borne illnesses.
In Lee County, the mosquito control district has tens of millions of dollars in its budget; part of that includes using helicopters to spray scrub bush and salt marshes for the bugs from above.
“If you could picture 1 square foot, so if you picture that in your brain, 1 square foot, we've done research that says in a salt marsh area, you can have as little as 1,000 eggs and up to 39,000 eggs in 1 square foot. That's a lot of mosquitoes,” said Jen McBride, communications director for district.
"And so it's really hard to generalize, but there is a lot of mosquito-borne disease transmission going on this year." Nathan Burkett-CadenaNathan Burkett-Cadena
The female Aedes mosquitoes are the type that bite humans and animals to spread diseases. In the Florida Keys, Monroe County has previously released genetically modified male mosquitoes with a gene that prevents female offspring from surviving. The bugs mate, and female population subsides.
“We did not do any releases this year because we no longer had our permit to do so. But from what we saw in the neighborhoods where we were doing releases in comparison to those neighborhoods that we weren't, we did see a population suppression,” Andrea Leal, executive director of the Monroe's mosquito control district, said.
Mosquito-borne illness in Florida
In 2024, there have been 27 locally acquired dengue cases reported in Florida, according to the Centers for Disease Control and Prevention.
“I'm gonna go out on a limb here, I'm gonna say that it's not related to mosquito activity. What I think it's reflective of, it's what's going on in the rest of the Americas,” Burkett-Cadena said, referring to the surging number of dengue cases throughout Latin America.
He added local Florida cases of the mosquito-borne illness come from residents who travel to other countries and come back infected.
“So the person feels feverish, feels ill, they're being bitten by the mosquitoes that can transmit, and they're transmitting those viruses to their, maybe their neighbors and their family. And so the number of imported cases is very high because of the number of cases that are happening in other parts of the world,” Burkett-Cadena said.
Impacts of mosquito control on other organisms
The effects of mosquito spraying on other flora and fauna has been a concern of mosquito control for decades, according to Burkett-Cadena.
“And I and some of my colleagues here at the Florida Medical Entomology Laboratory have been working with some of the districts that you mentioned, especially Lee County Mosquito Control District, determining whether their practices impact these nontarget pollinators, and so we've done things like going out and collecting butterflies, I hate to say this, but pinning them live onto little lines, and letting mosquito control trucks come by and spray them, putting bees in bags,” he explained.
“For the most part, those organisms are resilient to the applications of adulticides, so there's a lot of variability out there.”
This story was compiled off interviews conducted by Tom Hudson for "The Florida Roundup."
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