Global invasions of fire ants can be traced back to the southern United States where the nuisance insect first gained a hold in the 1930s, researchers say.
Scientists at the University of Florida say the ant, native to South America, had been contained there and in the southeastern United States before turning up in faraway places in the last 20 years, including California, China, Taiwan, Australia and New Zealand, a university release reported Thursday.
Their findings could prove helpful in finding new ways to control the invasive species, Solenopsis invicta. The United States spends more than $6 billion a year to control the ants and offset damage they cause, including medical expenses and $750 million in agricultural losses.
"Fire ants are very annoying pests, and they cause people to suffer," researcher Marina Ascunce said. "People who are allergic can die (from ant stings)."
The research team used genetic markers to trace the origins of ants in nine locations where recent invasions occurred and traced all but one of the invasions to the southern United States.
The scientists were surprised by the findings, Ascunce said.
"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 United States," she said.
The study results show the problematic side of a robust global trade and travel network, the researchers say.
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