They say every cloud has a silver lining and it appears to be true for hurricane cloud as well. Researchers battling fire ant infestations in Louisiana have found that the heavy salt water flooding from Katrina has wiped out quite a bit of the fire ant population:

Fire ants are normally very adaptive to the environment. When it floods in their native ranges in South America, they will create a floating “ball” in hopes some will survive, Hooper-Bui said. Essentially, some sacrifice their lives so their fellow ants can float on top of their carcasses.

In checking populations after the storms, researchers from the Red Ant Laboratory at LSU found a dearth of fire ant mounds in flooded areas. “We just didn’t expect to see no fire ants,” Hooper-Bui said. “We thought it might be saltwater.”

Some experimentation found the “ball” survival reaction to flooding doesn’t seem to work when the water is salty.

They’re still not sure for the exact reason why salt water makes the ant’s survival trick useless, but they have confirmed it with experiments.

Undergraduate researchers Andy Fulks said he has found that in concentrations of 3 percent or greater salt in the water (typical of seawater), the fire ant ball reaction doesn’t seem to work. The ants will ball, but not for long. They slowly sink and drown. Lower concentrations of salt act slower, Fulks said.

“That’s pretty dramatic,” Hooper-Bui said as she watched a ball of fire ants floating in a bucket of salty water quickly disintegrate, sink and drown. In a freshwater bucket next to it, the ball was still working.

They’re hoping to take advantage of the lower populations in the area to apply some treatments to try and keep the ants numbers from returning to previous levels.