The red colored fire ants, which arrived in the United States in the early 1930s, are now akin to a plague in areas of the country like Virginia and California. They are sighted in places like ranches, open pastures, croplands as well as urban lawns. Known scientifically as Solenopsis invicta , humans and livestock fear them for their stinging bites.
The massive fire ant colonies destroy crops, damage farm and electrical equipment and hasten soil erosion. Fire ants have been detected in 13 states and covering an area of 320 million acres. With no natural predators to keep them in check, fire ants have spread across the U.S., where their numbers are now 10 times greater than in their native South America.
Yet researchers of the US Department of Agriculture say that they have finally discovered the nemesis of fire ants- a virus found in some fire ant fields and which can break down their colonies in about 3 months.
Bob Vander Meer, the leader of the USDA research team is naturally excited about the discovery. He was quoted: "Certainly, we are excited about it.
"I think the virus has great potential. No question about it."
Yet the researchers agree that eradication is out of the question. What they are aiming for and what is eco- friendly, is pest management and not pest elimination. "Sustained control is what we're trying to achieve," says 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 is documented to eliminate a colony within three months.
This makes the researchers believe the virus has potential as a viable biopesticide. The virus, which occurs naturally in fire ants, nevertheless needs a stressor before it becomes deadly and starts replicating within a colony.
The researchers believe that integrating the virus into ant baits could offer a tool to the pest-control industry, agricultural producers and harvesters, consumers and others for whom fire ants are a persistent problem.
The virus is not the sole one in the fight against the fire ant. In South America, there are dozens of natural enemies. Yet, researchers are unsure of whether these predators could be introduced in America.
One such bioparasite 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 we really don't know how effective these phorid flies are going to be in North America," says Mike Merchant, an extension entomologist in the cooperative's Dallas office.
Some Texans may have thought the fire ant problem was improving. Drought conditions across much of the state in recent years have only driven them deeper under ground.
"One thing you can thank the dry weather for is it keeps the fire ants down," says Merchant.
This year, as wet conditions have returned, it is believed the pests' visibility would be increased.
"I think those fire ants are waking up," says Bart Drees, an entomologist with the Texas Cooperative Extension in College Station.
The fire ant is not totally a farmer's enemy. 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 opines. "The good that they do is far outweighed by the negative."