“They’re Advancing Much Faster Than Anticipated,” Hybrid Fire Ant Threat Heats Up In Virginia

A strange invader is marching across the United States, born of two different species. Red fire ants and black fire ants have both been imported to the US, and now they’ve teamed up to create a hybrid that’s more aggressive and more resilient than either of its parents. Meet Solenopsis invicta × richteri.

The hybrid ants are already established in East Tennessee, plus parts of Kentucky and North Carolina, writes Case Keatley for Virginia Tech News – and now they’re descending on Southwest Virginia. New mounds are reportedly being found weekly, and the spread is likely due to a perfect storm of hybridization hardiness and changing environmental conditions.

“When two different species interbreed, they can ‘borrow’ genes from one another,” said Scotty Yang, assistant professor in the Virginia Tech Department of Entomology, told Virginia Tech News. “If those borrowed genes happen to be useful – say, for surviving cold winters – they may stick around and give the hybrid a leg up in adapting to its environment.”

It seems Solenopsis invicta × richteri is enjoying the best of both worlds as it combines the traits of its parents to be able to thrive in cooler conditions than a pure-bred ant might prefer. Then, we have climate change to think about.

Fire ants live it up in the southernmost states of the US because they like heat, but areas they would’ve once found a bit chilly are getting warmer year on year. Virginia is no exception, experiencing milder winters and hotter summers since the hybrid ants first appeared in the region around 25 years ago. As the trend continues, it’s expected the hybrid ants will march on more states across the country.

“They’re advancing much faster than anticipated,” said Yang. “While it’s hard to say exactly when fire ants will establish themselves permanently in the New River Valley or Roanoke, given this rapid movement, it could happen as soon as the next few years.”

Hardy as they are, a fire ant is still an ant – but they’re able to make some serious distance by hitchhiking in bales of hay and firewood, traveling on vehicles. The issue is so pressing that the Virginia Department of Agriculture and Consumer Services and the US Department of Agriculture have established quarantines specifically for these hybrids, but there is concern the ants have already breached these areas.

It might seem like a lot of fuss over an insect, but the introduction of an unusually aggressive swarming insect armed with venom can have devastating effects in regions that aren’t accustomed to them. Fire ants have been connected to calf deaths in livestock, and they can be a nasty surprise for unsuspecting humans too, capable of causing anaphylactic shock in an unlucky few.

“People need to be educated on these ants so they can prepare,” said Amy Byington, who partners with the Virginia Department of Agriculture and Consumer Services in locating and treating hybrid fire ant mounds. “They are dangerous for populations not used to dealing with them and who initially treat them like normal ants.”  

For more information on avoiding stings, visit the Virginia Cooperative Extension website.

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