Flies to Combat Pesky Fire Ants
W A S H I N G T O N, Nov. 17, 2000 -- The South’s newest weapon against the dreadedfire ant sounds like something out of a sci-fi thriller: An insectwhose larvae eat the heads off their prey.
The Agriculture Department plans to release hundreds ofthousands of tiny ant-eating flies in Georgia, across the South andpossibly in California, where the fire ants have now spread. USDAsays the gnat-like phorid flies, imported from Brazil, pose no harmto anybody or anything other than fire ants.
“It is a self-sustaining biocontrol,” said Richard Brenner,who leads a USDA research team in Florida. Releasing flies at 12sites per state could blanket the region within five years, hesaid.
Ants Panic and Flee
The flies don’t kill enough of the ants to destroy colonies, butthey cause enough panic to keep the ants in check, Brenner said.The ants, which have an innate fear of the flies, stop foraging andflee when they spot them, giving native ants a chance to move backinto the territory.
Fire ants can make life miserable for homeowners and gardenersand cause billions of dollars in damage every year to airconditioners, electrical equipment and farms, experts say. The antscan blind and even kill livestock and wildlife, and their sting isoccasionally fatal to humans.
The ants, which are native to South America, have no naturalenemies in the United States. Chemical treatments are onlytemporarily effective.
The phorid fly helps keep the ants under control in Brazil andArgentina, where infestation levels are far lower than they are inthe United States.
Larvae Decapitate, Eat Brain
The flies hover over ant mounds before darting down andinjecting a torpedo-like egg into the ants. After the egg hatches,the maggot decapitates the ant by eating the brain and othercontents of the head. The maggot later turns into a fly and thecycle is repeated.
Some scientists are skeptical that there are enough native antsin the South to compete with the fire ants, even with the help ofthe flies. The native ants have either been poisoned by humans ordriven away by fire ants.
“You’ve got to have a really good competing ant population forthe phorid flies to have an effect,” said Brad Vinson, anentomologist at Texas A&M University.
Scientists also are studying other biological enemies of thefire ant, including a microorganism and a parasitic ant.
“Anything that will take care of these fire ants will be finewith me, as long as it doesn’t hurt anything else or theenvironment,” said Kym Bell, a Cottondale, Ala., woman whose5-year-old daughter missed several days of kindergarten this fallbecause of repeated ant bites on her school playground. The stingsleft welts the size of a half dollar on her skin.
The Agriculture Department started studying the flies in 1993 tosee if they could harm anything other than fire ants. Nothing otherthan the fire ants would attract them, including animal dung orhuman waste, so the government is confident they will be completelysafe for the environment, Brenner said.
Trial Run Still Being Studied
The flies were released at four sites near Gainesville, Fla.,three years ago and now have spread to 700 square miles. USDAscientists are now studying the area to see how the flies haveaffected ant populations.
As part of the federal project, Florida’s agriculture departmentwill begin mass-rearing the flies next spring and will ship them tofield sites in Alabama, Arkansas, Florida, Georgia, Louisiana,Mississippi, North Carolina, Oklahoma, South Carolina, Tennesseeand Texas.
The project will cost USDA about $100,000.
Discussions also are under way about releasing the flies inCalifornia, where parts of the Los Angeles area are under a federalquarantine intended to keep the ants from spreading.