Released November 6, 2009

FAYETTEVILLE, Ark. - That three-legged doo-dad that comes with your delivery pizza is part of a tool insect researchers are using to gauge the success of the phorid fly, a natural enemy of the red imported fire ant.

Research conducted this fall found the phorid fly, introduced to Arkansas to provide biological control over red imported fire ants, is gaining ground in the Natural State, according to Kelly Loftin, extension entomologist for the University of Arkansas Division of Agriculture.

The phorid flies are being studied by the Division of Agriculture, in cooperation with U.S. Department of Agriculture. Three species have been released: Pseudacteon curvatus, Pseudacteon tricuspis and Pseudacteon obtusus.

From 1998-2009, phorid flies were released in 11 counties: Bradley, Clark, Drew, Garland, Grant, Jefferson, Miller, Perry, Pike, Polk and Sevier. Loftin and University of Arkansas graduate student Jake Farnum found that the phorid flies had expanded their presence to 16 counties, having survived the Arkansas winter. The counties were chosen because of several factors including density of fire ant colonies and the presence of willing local cooperators: landowners, county agents and others who could help with research followup.

Phorid flies also have been released in surrounding states troubled by imported fire ants.

Thirty-four Arkansas counties are included in the state's fire ant quarantine. In addition to the red imported fire ants, three counties have isolated populations of black imported fire ants, Loftin said.

The flies are parasites on fire ants, laying eggs in the worker, which eventually hatch, killing the ant and providing food for the fly larva.

"The long-range goal is to affect the ability of the imported fire ant to forage, cutting the food supply and therefore the colony size," Loftin said. "It's hoped that by reducing the size of the imported fire ant colonies, native fire ants will be able to compete again."

Farnum made three separate trips to monitor the flies' progress in western, southeastern and southwestern Arkansas. He relied on a device called the Improved Puckett Trap to see just how many flies there were.

"The Improved Puckett Trap consists of three parts: A plastic Petri dish lined on the inside rim with a chemical slippery to insects, a trap - which was a pizza tri-stand covered in a super sticky/tacky substance, and a flag to mark the location, which also has a tag that explains what the trap is and who to contact for questions," he said.

Part of his survey technique included kicking over the mounds.

"The ants, furious, would crawl into the dish and would not be able to get back out," Farnum said. Those ants would attract the flies, which would stick to the glue, allowing him to determine the species of phorid fly trapped.

Unfortunately, dealing with fire ants is its own occupational hazard.

"No matter how diligent I was at picking them off me, I accumulated many stings throughout the day," he said.

One aspect of the study is how well the phorid flies will survive Arkansas' winters.

"Initially, we were concerned about winter survival," Loftin said. "The most northern release, Perry County, drew the most concern, but one species, P. curvatus, survived. We're still not sure about P. tricuspis."

Because P. obtusus was only released last year, Loftin said it will be a while before its success can be assessed.

Meanwhile, the fire ants, natives of South America, are adapting to Arkansas' less-than-tropical climate as they spread northward.

"Modeling suggests that the imported fire ant will survive up to about the northern one or two tiers of Arkansas counties," Loftin said. "Imported fire ants will take advantage of heat ‘sumps' by forming colonies near parking lots, sidewalks and structures that radiate heat.

"Often in newly infested areas that have colder winters than in south Arkansas we find a majority of colonies on south facing slopes," he said.

For more information about controlling fire ants at your home or farm, see http://www.uaex.edu/Other_Areas/publications/PDF/MP426.pdf, "Managing Imported Fire Ants in Urban Areas," or http://www.uaex.edu/Other_Areas/publications/PDF/FSA-7052.pdf, "Twenty Questions about Fire Ants," or http://www.uaex.edu/Other_Areas/publications/PDF/FSA-7036.pdf, "Fire Ant Control in Two Easy Steps."

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http://www.uaex.edu/news/november2009/1106phorid.htm

Editor: Elizabeth Fortune, (501) 671 - 2120, efortune@uaex.edu