 |
||||||||
 |
||||||||
|
||||||||
|
Flying enemies unleashed on fire ants
By ALICIA CALDWELL, Times Staff Writer
Fred Santana swats at the insects perfunctorily, and continues squatting in the field, stirring sand with a stick. This is, after all, serious scientific work. Santana, a Sarasota County coordinator of pest management, is on the front lines of a government-backed biological war against fire ants. On this warm afternoon, Santana has released hundreds of Brazilian decapitating flies, whose mission in life is to zoom in on fire ants like smart bombs. The fire ants do not, of course, take kindly to this air raid on their world and fight back, emitting alarm pheromones and attacking the flies as best they can. Think Godzilla versus Rodan, but on a microscopic level. This drama, played out behind a fire station in Sarasota, is the latest chapter in a joint venture between Florida and federal scientists who are trying to knock down the population of exotic fire ants, which are now established on more than 310-million acres in the South. Being stung by fire ants is one of Florida's initiation rites. You come here, you get stung. And once you have experienced those itchy welts that turn into nasty pustules, you make sure you never again stand on a dry, sandy patch of earth for more than three seconds without checking your ankles. The problem had not gone unnoticed by scientists, who have been researching ways of attacking the fire ant problem without using more pesticides to kill them. Enter the phorid fly, Pseudacteon tricuspus, a mortal enemy of imported fire ants. Scientists first released the flies in Gainesville in 1997. They prospered. The gnat-sized fly went after fire ants, and only Solenopsis invicta, the South American species accidentally introduced to the United States in the 1930s. The fire ant's demise is gruesome in detail. The female fly latches onto a fire ant and injects an egg into it that turns into larva and crawls into the ant's head. The head falls off and provides a cocoon for the developing fly. Releases in Gainesville and in the Naples area appear to have been successful, said Sanford Porter, research entomologist with the U.S. Department of Agriculture's (USDA) research service in Gainesville. The flies are reproducing on their own. "They're expanding widely," Porter said. "We believe they've gone coast to coast and almost to Georgia." In the past two years, the flies were released in six other Southern states. The Sarasota release occurred over 10 days in mid November. Porter, who has studied the fly-ant relationship for years, said that he would expect the flies to make it to St. Petersburg in three to five years. Porter said the flies have been studied extensively. The first question that people have when hearing about them is what will the flies do if the ant supply runs low? Will they go after something else -- plants, humans or animals? The answer, Porter said, is no. "There's no way they're a problem to parakeets or people or butterflies," Porter said. "We can't get them to develop in anything but fire ants. These flies are extremely specific." Nevertheless, whenever a new pest is introduced, there's always the risk of unanticipated results, said John Randall, director of the Nature Conservancy's wildland invasive species team. "It's a balancing of risks," Randall said. "What if we do get an agent that attacks native insects? It suddenly becomes a huge curse." Randall said he was somewhat familiar with the phorid fly project and that it seemed scientifically sound. Most biocontrol efforts gone bad were species introduced decades ago by farmers as a knee-jerk reaction to a problem at hand, not a result of research, he said. An example is the introduction of cane toads. They were brought to Hawaii from Puerto Rico in 1932 to control sugar cane beetles and other insects. They also were released in Florida, U.S. Virgin Islands and other places around the world. The voracious toads did little to reduce the beetle population, but decimated a number of native species. The toads have few enemies because they are so well protected by toxic skin glands and have reproduced vigorously. Porter is well aware of the cane toad debacle and said that "never should have been done." The fly situation is far different, he said. Their interest in fire ants is well-documented and very specific, he said. The program is primed for expansion, said David F. Williams, USDA research leader for imported fire ant research. A lab in Gainesville is producing 6,000 flies a day. Santana, Sarasota's pest management coordinator and a medical entomologist, received 4,100 fly larvae from the Gainesville lab. Over 10 days, he hatched them and brought them to a sandy field in eastern Sarasota County. Then he dug up fire ant nests to bring the angry pests to the surface. Disturbing the ants is important because agitated ants emit fly-attracting pheromones. He released the flies over the ant nests and began a two-hour vigil, walking from nest to nest, stirring up the ants with a stick and blowing on them. The flies live about two hours, just long enough to inject their eggs. Santana, who has closely followed the fly research, has great hopes for the biocontrol method. He said that in Sarasota, there is strong interest in finding pesticide alternatives in combatting the destructive and pervasive ant. "This is the first attempt to tip the balance back in our favor," Santana said. "The tide has always been in their favor."
 © 2006 • All Rights Reserved • St. Petersburg Times
490 First Avenue South • St. Petersburg, FL 33701 • 727-893-8111 
|
From the Times state desk
From the state wire
|
