'Bad news' for fire ants: Phorid flies feeling at home in North Texas
Life from now on will be harder for red imported fire ants in some North Texas communities, say experts with the Texas AgriLife Extension Service.
The fire ants' natural enemies--phorid flies--have been introduced in Red River County, and established populations have spread through areas of Denton County.
"We've been hoping that two species of the flies would take hold in Red River County after being released there nearly two years ago," said Kim Schofield, an AgriLife Extension program specialist in Dallas. "We're glad they're finally established."
After two releases since 2004 in Denton County, the phorid flies have spread as far as 30 miles from the original release site at Ray Roberts Lake State Park, about 45 miles northwest of Dallas, Schofield said.
"That's bad news for fire ants," she said.
It's good news, however, for residents of Red River County who are happy for another helpful tool in fighting off red imported fire ants, said AgriLife Extension agent Lynn Golden, based in Clarksville.
"The flies as a biological control hold promise for suppressing red imported fire ants," he said. "They don't promise to eradicate the ants. They're just another way to help control them."
Phorid flies are native to South America where they and other predators keep red imported fire ants in check, Schofield said. The female flies attack the ants and lay eggs in their bodies. Larvae eventually hatch and burrow into the ants' heads. There, they grow and release enzymes that cause the heads to fall off. Mature flies eventually emerge from the decapitated heads, and the cycle starts over.
"The flies attack and eventually kill the ants, but their real impact is that they stalk the fire ants when they're foraging," Schofield said. "That reduces foraging activity which, in turn, helps limit food within the fire ant colony."
The Clarksville project is Extension's latest and northernmost release of phorid flies in a long-running battle against fire ants in the state, said Dr. Bart Drees, a Texas A&M University professor and AgriLife Extension entomologist.
"In the late 1990s, researchers began to see these as potential biological control agents," said Drees, who is based in College Station. "And since that time the flies have been imported to the United States, mass-produced and released."
Test releases began in 1997 to determine whether the flies would populate designated areas and to make sure they posed no threat to anything other than fire ants, he said.
In 2000, a governmental initiative brought several agencies together to raise and release large quantities of phorid flies in southern states, Drees said.
The initiative involves AgriLife Extension, the University of Texas at Austin, U.S. Department of Agriculture's Agricultural Research Service, the USDA's Animal and Plant Health Inspection Service and the Florida Department of Agriculture and Consumer Services.
Phorid fly populations have spread to 97 counties in Texas, Drees said.
A new species of phorid fly was released in East Texas in April where AgriLife Extension entomologists hope they will eventually establish themselves as the others did near Dallas. The species has already been established in 10 sites in southern and central Texas.