ALABAMA A&M and AUBURN UNIVERSITIES
ALABAMA A&M and AUBURN UNIVERSITIES |
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Auburn, Aug. 7--- Death and taxes are two things in life that can't be avoided. In the Southeast, add to that list imported fire ants.
Fire ants have been a bane for Southerners ever since the stowaway South American insects jumped ship in Mobile Bay earlier this century and steadily began moving in every direction.
Until now, virtually nothing has stood in their way. But the fire ant's longstanding reputation as the No. 1 pest in the Southeast may be ended within the next few years, thanks to a series of new biological control methods developed by U.S. Department of Agriculture entomologists in conjunction with land-grant university and state entomologists in the Southeast.
One reason fire ants are such a nuisance in the Southeast is the lack of natural enemies. Having no natural enemies also enables the fire ants to out compete every other ant species.
As a result, fire-ant density runs between 40 and 80 mounds an acres in the Southeast, whereas the typical rate in the fire ant's native habitat, South America, is roughly 10 mounds an acre.
Until recently, insecticides have been the only toolsavailable.
"Insecticides work against fire ant colonies, but that's not the problem," says Dr. Kathy Flanders, an Alabama Cooperative Extension System entomologist. "The problem is keeping ants from returning to areas that already have been treated. They're able to come back in and start new colonies."
So, entomologists have decided to lend nature a hand by introducing into the Southeast one of the fire ants predators: the phorid fly. Entomologists already have introduced the flies into selected fire ant mounds in Talladega County.
"Most of the time, the flies just terrorize the ants, attacking in squadrons like bombers," Flanders says. "This forces the ants to curl up into a ball for protection. So the theory behind it is that it will prevent the fire ants from foraging from food, thereby allowing other ants species to compete in the same area."
Exposure to the flies results in a gruesome death for between 5 and 10 percent of worker ants. In a process bearing an eerie resemblance to the movie Aliens, the flies first lay their eggs on the ants.
"Afterwards, the larvae hatch and crawl into the heads of the ants," Flanders says. "As the larvae continue maturing, this causes the ants' heads to fall off.""But even then they continue maturing inside the decapitated heads until they emerge as flies. Then thecycle is repeated."
Even with these potent predators as an ally, Flanders says fire ants never will be eradicated completely. In fact, the most Flanders and other entomologists are hoping for is to reduce the density of fire ant mounds to levels comparable to South America.
"We don't want to eliminate the fire ants completely, because we then would open up the areas to be re-infested with new, incoming fire ants," Flanders says. "Our aim is to maintain a balance, keep a few of the fire ants there to defend the territory so that density is lower than what we currently have."
Although the phorid flies and other biological control strategies look promising, Flanders cautions against too much optimism. The new strategy, she believes, will be used with other control strategies, which include both insecticides and other biological control methods.
"This isn't going to be a quick fix," she says. "In fact, it may be as long as six years before we begin seeing any results."