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KNOXVILLE – University of Tennessee research is playing an important role in the U.S. Department of Agriculture fight against fire ants.

The USDA announced plans Wednesday to release hundreds of thousands of tiny Brazilian insects known as phorid flies to combat fire ants across the South. The fly larvae eat fire ants, which have caused billions of dollars in damages to electrical equipment and farm livestock, and can injure humans and animals.

Dr. Roberto Pereira, UT assistant professor of entomology and plant pathology, said UT received USDA grants totaling $27,000 as part of the project.

UT released the fly last August at test sites in Bradley County and the UT Ames Plantation sites in Hardeman County, and in September in Monroe County.

The flies have spread successfully at USDA test sites in Florida, but scientists are unsure whether they can thrive in Tennessee, Pereira said.

“We hoped to see a second generation of flies grow from those we have released,” Pereira said. “Unfortunately we have not seen establishment of the fly in any of the sites.

“That doesn’t mean that it has not occurred. Now that temperatures are low, the flies are not flying about and it is hard to pinpoint where they are. They are very small and difficult to detect.”

As part of the USDA project, the flies will be mass-produced in Florida and shipped to field sites in Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee and Texas.

The flies invade ant mounds and inject their eggs into the ants. The larvae hatch and eat tissue inside the ant’s head.

Pereira said weather, soil and variations in fire ant species affect the flies’ survival here. UT researchers hope to see establishment of the fly by next spring and a significant impact on fire ant populations within five years, he said.

Pereira and Dr. Karen Vail, also a UT assistant professor of entomology, said they hope to enhance the flies’ survival chances by importing them from Argentina where the weather is more similar to Tennessee.

Instead of simply releasing flies near fire ant hills, they are digging up fire ants, infecting them with flies, and returning them to their colonies, Pereira said.

“The flies are very small and delicate,” Pereira said. “We think the fly would have a better chance to survive if we first infected the ants and then release them back to the colony.”

“If you depend only on the natural abilities of these flies to spread, it would take too long. But if you can produce them in the lab and set them in areas infested by fire ants, the chances of establishment are very good.”