Yet Another Toehold for Phorid Flies

Auburn, June 4, 2003 -- With a helping hand from science, phorid flies, the mortal enemies of fire ants, have gained yet another toehold in Alabama. 

Phorid flies were first introduced into Alabama in 1998 as part of a regional project aimed at controlling fire-ant populations throughout the South. The project is the brainchild of Dr. Sanford Porter, a Florida-based USDA researcher who spent years studying phorid flies in South America. 

(Right: Cullman County Extension Agent Charles Pinkston inspects a container of tiny phorid flies -- in this case, Pseudacteon curvatus flies, which appear to be better suited to the hybridized fire ants prevalent throughout north Alabama.)

Like a scene out of a sci-fi thriller, the phorid flies attack the ants in the goriest way imaginable – injecting their eggs into the ants’ bodies with strikes lasting only a tenth of a second.

Over time, the emerging larva makes its way into the fire ant’s skull and begins eating out the inside of the head. Eventually, the head falls off and from it a new fly emerges – small wonder these tiny insects are often called decapitating flies.

This time, though, there is a slightly different twist to the saga. As part of an ongoing project in Cullman, scientists are working with a different kind of phorid fly better suited to the type of fire ants prevalent in northern Alabama, where colder winters preclude the permanent presence of the more aggressive red imported fire ant common in much of the rest of the state.

True, from the standpoint of numbers, fire ants are every bit as bad in north Alabama as they are in the rest of the state. But unlike other parts of the state, north Alabama is populated by a very unique kind of fire ant – one not seen even in South America, where fire ants originated.

Black imported fire ants were the first of two South American ant species to become established in Alabama after their accidental release into the Port of Mobile in the early part of the last century. But within only a couple of decades, the more aggressive red imported fire ants, newcomers to the state as well, pushed their black counterparts out of much of the state except for the northwestern corner of the state, where black ants were better equipped to survive the harsher winters. 

Over time, though, in other parts of north and central Alabama, something unexpected happened. The two species somehow crossed.

“They don’t hybridize in South America, where both species originated, because they’re so geographically separated,” says Dr. Lawrence C. “Fudd” Graham, manager of the Alabama Fire Ant Management Project.

Black imported fire ants, in fact, originated in the cooler temperate region around Buenos Aires, while the red imported fire ants came from farther north in tropical South America along the banks of the Parana River.

No one knows for sure how the ants became hybridized.

What is known is that the phorid flies used to combat red imported fire ants common in central and southern Alabama simply don’t work as well with the hybridized ants in north Alabama. 

Instead, then, of the Pseudacteon tricuspis phorid flies commonly used against red imported fire ants, Graham and other scientists use a smaller species known as Pseudacteon curvatus against the hybridized ants.

Still, there’s one hitch: Even though they appear to be better suited to the hybridized ants, curvatus phorid flies have proven much harder to introduce into fire-ant mounds. Whereas tricuspis flies actually can be inserted directly into the mounds, ants earmarked for curvatus flies first have to be shipped to a USDA facility in Starkville, Mississippi, where they are directly exposed to the flies in a laboratory environment and then returned to the mounds.

The Cullman release, which took place May 22 at the St. Benedictine Abbey in Cullman, was spearheaded by Cullman County Extension Agent Charles Pinkston and funded by the Cullman County Agplex Committee.

“Fire ants are a serious problem across the state,” Pinkston observes. “And as it turns out, Cullman was the first county in the state with a documented death from fire-ant stings.”

Members of the Cullman County Commission witnessed the release of the flies – an event that was also covered by print and broadcast reporters throughout the region.

(Sources: Dr. L.C. “Fudd” Graham, Coordinator, Alabama Fire Ant Management Project, 334-844-2563; and Charles Pinkston, Cullman County Extension Agent, 256-737-9386.)

 Article in MS Word

 Article in Text