State prone for mosquito season ripe with painful behemoth
Published: Tuesday, March 5, 2013 at 6:38 p.m.
Last Modified: Tuesday, March 5, 2013 at 6:38 p.m.
When Tropical Storm Debby hit Florida last summer, the torrential waters unleashed a swarm of mosquitoes, among them the gallinipper — a big, biting mosquito that is native to Florida.
The storm also set up the perfect breeding ground for the mosquito to regenerate if Florida experiences heavy rainfall again this summer.
"The entire basis of mosquito populations of this type are weather-driven, and so if we end up with a tropical hurricane, that's what drives it," University of Florida entomologist Philip Kaufman said.
The gallinippers tend to congregate in low-lying areas containing still water, such as cattle pastures, Kaufman explained. They lay their eggs in soil, and the eggs can lie dormant for years until heavy waters effectively help hatch them.
"Because of the events last year, and the eggs laid, we can expect large numbers of these mosquitoes again," Kaufman said, adding that it will take "something like a tropical storm" for them to populate.
The gallinippers don't pose much of a threat to urban areas.
"Down near Paynes Prairie, you are more likely to have more numbers than Main Street Gainesville," Kaufman said.
They also have been more prevalent in Central and South Florida, even though they have lived throughout the state for hundreds of years, Kaufman said.
"When you read the historical accounts of the first European settlers in the Southeast and they talked about gigantic mosquitoes, this was one they were talking about," he said.
The gallinipper is big — with a wingspan of 6-7 millimeters — and colorful. Its bite also hurts.
"It is quite capable of biting through my shirt," Kaufman said. "We suggest people wear long-sleeve pants and shirts. Just doing that may not be enough for this type of mosquito; you're going to have use one of the insect repellants to dissuade them from landing."
And like most mosquitoes, the gallinippers are most active at dusk and dawn, Kaufman added. To help people better understand the breed, Kaufman and colleagues created a document on the IFAS website: http://edis.ifas.ufl.edu/in967.
‘Rough summer' possibly ahead
Whatever the mosquito type, locals could be destined for "a very rough summer," said Paul Myers, administrator for the Alachua County Health Department.
The area's mild winter spared mosquitoes from the hard freezes that would have killed many of them, he said, adding that major rainfall would amplify the problem. Two-thirds of the county's population lives in areas with mosquito spraying, but the rest lives in unincorporated Alachua County, where the County Commission has opted not to spray because of concerns about the cost and effectiveness of the treatment, as well as its environmental impacts, Myers said.
The county also has a surveillance program that detects cases of mosquito-borne illnesses such as West Nile virus, partly by checking with area physicians and veterinarians for suspected or confirmed cases of such diseases. It also checks county-maintained retention basins to determine if they have become mosquito breeding grounds and treats those that have.
Resurgent yellow fever mosquito
Meanwhile, Florida's most common backyard mosquito — a species known as the Asian tiger — appears to be facing evolutionary competition from the female yellow fever mosquito, according to a recent UF study published in the Proceedings of the National Academy of Sciences.
The yellow fever mosquito was introduced to the U.S., and the Southeast in particular, 500 years ago during the slave trade. When the Asian tiger mosquito landed in the Southeast via Texas in the mid-1980s, it reduced the yellow fever population, through the trickeries of courtship. The Asian tiger males rendered the yellow fever females sterile in a process called "satyrization," in which two different species mate but don't produce offspring and the male transmits a chemical to the female that sterilizes her.
But female yellow fever mosquitoes have begun to spurn the Asian tiger males.
"They seem to be recognizing what the wrong kind of male is," said Irka Bargielowski, a post doc at the Florida Medical Entomology Laboratory in Vero Beach who worked on the study. How exactly they do this is unknown and the subject of future study, Bargielowski said.
But the implications resonate with natural selection, said Dr. Philip Lounibos, an entomologist at the Vero Beach Lab and another author of the study.
"Since Darwin's time, sexual selection has been a very potent evolutionary force," Lounibos said. "(The mosquitoes) are going to use everything within their grasp to select for avoidance."
The practical consequence of a resurgence of yellow fever mosquitoes, however, might mean more transmission of dengue, a viral infection causing flu-like symptoms in humans. Lounibos said dengue has been problematic here only in the Florida Keys because of unsuccessful control efforts.
He said he suspects that dengue won't become an issue in other parts of the state, such as Jacksonville and Volusia County, where the resurgent yellow fever mosquito populations have been sighted.
Bargielowski said: "If you looked at other places in the world — maybe certain places in South America or in Asia where the two species are and dengue is endemic — then I think you could get a better outbreak. Obviously Florida is a nice study laboratory for us to work relatively safely."
Staff writer Morgan Watkins contributed to this story. Contact Kristine Crane at 338-3119 or firstname.lastname@example.org.