USDA Agricultural Research Service (ARS) scientists latest discovery—a new virus found in fire ants from Argentina—has the potential for becoming a biological control agent against the red imported fire ants infesting the United States.
The Red Imported Fire Ant (RIFA) arrived in the United States in the 1930s, likely in ballast in cargo ships docking in Alabama. From there the ants quickly spread throughout the southeastern United States, reaching populations up to 10 times those found in its native country, Argentina. Today, these ants are a serious threat to human and animal health; the damage that they cause and efforts to control them cost over $6 billion annually. One of the worst things about the ant is its aggressiveness combined with a sting that feels like fire.
Fire ants have done so well in the U.S. because they left most of their natural enemies behind. “In Argentina, the fire ant is not really a problem because it has many natural enemies there,” says entomologist Steven Valles, with ARS Center for Medical, Agricultural, and Veterinary Entomology (CMAVE) in Gainesville, Florida. “But in the United States, this ant is a serious problem because populations are growing unchecked. There’s nothing to constrain them.”
But that could change with the discovery of a new virus: Solenopsis invicta virus-5 (SINV-5). Valles and his Argentine colleagues found the virus by studying 180 native Argentinian colonies and using genetic techniques to isolate SINV-5. (Read the full paper here.) Valles and his team are testing the virus to find out what it does to the U.S. fire ants. The photo below shows the before and after results after inoculation with SINV-5. The virus infects the worker ants, altering normal foraging behavior. Workers stop collecting food for the colony and the brood dies as a result. The queen also stops producing eggs because she becomes malnourished. The result is a dead colony in about 8 to 12 weeks. (Photo by Steven Valles)
Researchers are also working on other biological controls including additional viruses and a parasitic phorid fly. These flies inject an egg into the fire ant which kills the ant when it hatches. Scientists shipped Florida fire ants infected with fly larvae to Coachella Valley sites in California. The test seems to have worked as both male and female flies have been collected at one of the test sites and flies have been found as far as one-eighth mile from that site.
This is not our first attempt to rid ourselves of fire ants. The Museum of Novel Fire Ant Control Methods and Products shows the lengths we’ve gone to. From insecticides, to specialty crushing tools, to grits (which don’t work at all) to microwaves and machines that deliver electrical shocks, inventors have tried all kinds of things to get rid of fire ants. The McCoy Ant Stomper Windmill is one of my favorites:
This article was drawn in part from a story on USDA’s Tellus website.
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