Researchers Use 'Decapitating' Flies to Create 'Zombie' Fire Ants

Texas researchers across the state are finding a solution to fire ants and it is coming from South America.

The Phorid fly is a parasitic breed that finds its host in fire ants. This breed is nicknamed the "decapitating fly" for its effect on its host, and its host is nicknamed the "zombie fire ant."

"The current studies are the results of Don Henne, a Ph.D. student from LSU," said Robert Puckett, assistant research scientist at the Texas A&M AgriLife Research and Extension Center for Urban and Structural Entomology. "With what he determined, we have been releasing these flies into the U.S. in hopes of suppressing fire ant populations."

There are more than 20 species of the Phorid fly, but four are being studied. There are approximately 7 million acres of Texas where the flies are being released and observed.

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The female fly is capable of laying 30 to 35 eggs, one egg per ant. Each egg is injected into the thorax of a fire ant worker.

As the larva develops inside the ant, it gradually moves into the head of the fire ant, secreting enzymes that dissolve the connecting tissues of the head and thorax.

This causes the fire ant's head to fall off, thus appropriating the nickname "the decapitating fly."

"As the larva is consuming the ant from the inside, the ant slowly loses its body functions," said Paul Nester, a program specialist for Texas AgriLife Extension Service. "Thus you can say it is the living dead, aka zombie."

The ant continues to attempt normal ant life but the larva presence hinders performance until the ant's body fails completely, which takes anywhere from 10 days to two weeks, Nester said.

"This is not the silver bullet since the multiple queen fire ant colonies can have between 100,000 to 500,000 workers," said Kimberly Scholfield, a program specialist for Texas AgriLife Extension Service. "However, the fly makes the fire ant go into a panic mode so that it forgets to look for food and takes cover instead."

The panic experienced by a fire ant in the presence of a phorid fly costs the colony food and keeps other fire ants from being alerted.

Many people ask about the danger of the flies instead of the fire ants, Puckett said.

"In fact, I have never seen a fly unless I was attracting it to something," he said. "They don't congregate like gnats, they appear to be nectar feeders so they are not attracted to decaying organic matter [such as maggots]."

The "decapitating fly" and "zombie ant" are not threatening species, Nester said.

"They are not anything to fear, they are not magical, they do not cause more damage, they are not genetically modified to be more ferocious," Nester said. "[The nickname 'zombie ant'] is just a name given to a fire ant that is slowly dying, and its actions are not typical of the way a healthy fire ant acts."

Puckett, Nester and Schofield said the phorid flies are one of the most promising biocontrol strategies available, and will hopefully prove useful in reducing fire ant populations.

"It will take time to see results, and it's not a rapid, fast solution," Puckett said. "But for every fly you know, there was an ant killed in result, and if you can shut down the foraging efficiency by introducing these flies, then this will allow the native ant assemblages to compete with fire ants."

This story originally appeared in The Battalion at Texas A&M University.