Control Fire Ants, Save Crops

Associated Press reported 7 May that researchers have pinpointed a naturally occurring virus that kills fire ants, and the U.S. Department of Agriculture is now seeking commercial partners to develop the virus into a pesticide to control fire ants.

Imported red fire ants have plagued farmers, ranchers and others for decades. They arrived in the U.S. in the 1930s and now cause $6 billion in damage annually nationwide, including about $1.2 billion in Texas. The massive fire ant colonies destroy crops, damage farm and electrical equipment and hasten soil erosion. Humans and livestock are particularly vulnerable to the insect's stinging attacks.

"Sustained control is what we're trying to achieve," said Steve Valles, an entomologist in the Gainesville research lab. "Eradication is not going to happen."

In the laboratory, the virus, SINV-1, has proven to be self-sustaining and transmissible. Once introduced, it can eliminate a colony within three months. That's why researchers believe the virus has potential as a viable biopesticide to control fire ants, known to scientists as Solenopsis invicta. Although it occurs naturally in fire ants, the virus needs a stressor before it becomes deadly and begins replicating within a colony, Valles said.

The virus isn't alone in the fight against the fire ant. In South America, they have dozens of natural enemies. But researchers don't know whether those predators could be introduced here.
Among them is the small phorid fly, which seeks out fire ants and lays its eggs on them. The eggs hatch into tiny maggots that bore into the heads of their host and feed on its brains.
The problem is no one knows how effective these phorid flies are going to be in North America.

The fire ant isn't all bad. As omnivores, they eat just about anything and can reduce tick populations in pastures and yards. Also, cotton and sugarcane growers see them as helpful. The ants munch on boll weevils, caterpillars and sugarcane borers. "But on balance they're an ecological disaster," Merchant said. "The good that they do is far outweighed by the negative."