Rob Plowes, a research associate at the University of Texas, said fire ants first emigrated from Argentina to Mobile, Alabama, in early 1930s, probably on an agricultural-produce boat, then began moving through Texas around 1950.
"They're still spreading," Plowes said.
There's a "huge history of efforts to remove the ants, ranging from physical removal to pesticides and, most recently, biological control," Plowes added.
Though one phorid species didn't take hold, two others have expanded to cover almost half the U.S. fire ant range and will probably make it the rest of the way in the next several years, the USDA's Porter said.
Ludwig and his colleagues released the foraging-ant-attacking species, Pseudacteon obtusus, last year in southern Texas, though the species has failed to spread.
This year the researchers will release P. obtusus in two new locations—one near previously released species in southern Texas so that, hopefully, the different species' ranges will one day overlap, resulting in a multipronged attack on the ants.
The second set is headed to eastern Texas, where no other phorid flies have yet been released. Eastern Texas is moister than southern Texas, making the east more conducive to phorid survival, the researchers hope.
Besides the phorid flies, several labs are working to develop fire ant-fighting fungi and viruses—perhaps to be delivered via phorid fly eggs.
"It will take a community of natural agents to control them," Porter said.
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