Red imported fire ant invasions around the globe in recent years can now be traced to the southern U.S., where the nuisance insect gained a foothold in the 1930s, new University of Florida research has found.
Native to South America, the ant had been contained there and in the southeastern U.S. before turning up in faraway places in the last 20 years — including California, China, Taiwan, Australia and New Zealand.
The team’s findings could prove helpful in finding new ways to control the invasive species, Solenopsis invicta, said Marina Ascunce, co-author of the study and a postdoctoral associate at the Florida Museum of Natural History on the UF campus. Americans spend more than $6 billion a year to control the ants and offset damage they cause, including medical expenses and $750 million in agricultural losses.
The research team used several types of molecular genetic markers to trace the origins of ants in nine locations where recent invasions occurred. They traced all but one of the invasions to the southern U.S. The exception was an instance where the ants moved from the southeastern U.S. to California, then to Taiwan.
Ascunce said the scientists were surprised by the findings.
“I thought that at least one of the populations in the newly invaded areas would have come from South America, but all of the genetic data suggest the most likely source in virtually every case was the southern U.S.,” she said.
The study results show the problematic side of a robust global trade and travel network.
DeWayne Shoemaker, a U.S. Department of Agriculture scientist affiliated with UF’s Institute of Food and Agricultural Sciences who was senior author and lead investigator on the grant that funded the study, said pinning down precise origins for the ants is a huge win because it helps scientists know where to look to find the most effective biological control agents, such as phorid flies.
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