Hunting for natural enemies of the red imported fire ant is paying off for USDA Agricultural Research Service (ARS) scientists. Their latest discovery—a new virus found in fire ants from Argentina—has the potential of becoming a biological control agent against the red imported fire ants infesting the United States.
When the red imported fire ant, Solenopsis invicta, invaded the United States in the 1930s, it left most of its natural enemies behind in South America. The pest quickly spread throughout the southeastern U.S., reaching populations up to 10 times those found in its native country. Today, these ants are a serious threat to human and animal health; the damage that they cause and efforts to control them cost more than $6 billion annually.
“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.”
At CMAVE’s Imported Fire Ant and Household Insects Research Unit, work involves identifying natural enemies—pathogens and parasites—that can be released safely into the United States and used as a natural control that’s sustainable. The biocontrol agents that have been released into the United States were first demonstrated to be specific to fire ants and harmless to other organisms. These agents spread naturally after release and will continue to negatively affect fire ants as long as they have fire ants to infect or parasitize.