In southern Texas these days, there is more wildlife than cattle. For ranchers that are increasingly turning to hosting deer and quail hunts as a sideline on their properties, red imported fire ants (Solenopsis invicta) are threatening their businesses to the tune of an estimated $1.2 billion in damage in Texas annually.
One group of wildlife-oriented ranchers, the Bee County Wildlife Management Association, decided to take action. Rather than continue a chemical control route, they looked up Larry Gilbert, a biology professor and director of Brackenridge Field Laboratory at the University of Texas at Austin. Gilbert and his team have successfully introduced a natural predator of fire ants, the phorid fly, into more than 6 million acres of Texas Hill Country over the past few years. The demise of a fire ant is rather graphic: A fly lays eggs in the chest cavity of an ant, and the larvae eat their way into the head of the ant to pupate.
“The association called me in March 2005, wanting to obtain some of the flies,” Gilbert says, noting he had to explain how the flies weren’t something one could just purchase, release and watch the ant population crash. “I told them it was kind of like a caterpillar eating the leaves off a woody weed — while it can do damage, it’s not getting at the roots and change may be slow. Specific sets of phorid flies attack specific fire ant species, but only the non-reproductive workers.
“What was cool was, they said they didn’t care if they didn’t live to see results,” he adds. “They just wanted to do something about the situation.”
The group called a community meeting in Bee County, and Gilbert made the three-hour trek south from Austin to attend. He was amazed at the level of enthusiasm: More than 250 people showed up.
“I thought: ‘well, people helped spread fire ants, they might as well spread their enemies,'” he quips.
The next step was to hold a workshop and teach the citizens how to dig up fire ant mounds and introduce the phorid flies by infecting ants where phorids thrive, then returning them to home colonies. However, the process was not exactly smooth.
What started with enthusiasm dwindled to a core few: “One had a heart attack digging up ants; another broke his leg. Plus, Bee County had the worst drought in its history,” he recalls. While one release of phorids succumbed to drought, one rancher’s irrigation system allowed a successful naturalization of a phorid population a rare success in arid South Texas.
The collaboration of volunteers and scientists led National Geographic to air a television special on the project in 2006. Gilbert eschews the attention: “They made me kind of look like the Lone Ranger riding in to save the day — it was a little embarrassing.” But he’s glad it’s drummed up some attention for the role of natural predators in pest management.
Gilbert foresees a time when phorid flies could be integrated into a traditional chemical treatment program for fire ants. Multiple species combinations of flies may eventually be of use in chemical-sensitive areas or as a long-range economical option for ranchers and other large-acreage property owners.
“Right now, it’s not something I would go into business with — it would lose a lot of money,” he adds. “But research is continuing, and so far this project has had some success.”
You can reach Gooch, a Cleveland-based freelance writer, at heather@goochandgooch.com.
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