Florida State To Test Evolution Theory On Fire Ants

TALLAHASSEE, Fla. - Walter R. Tschinkel is out standing in his field of fire-ant research.

Tschinkel (pronounced "CHINK-ehl"), a professor of biological sciences at Florida State University, is leading a team of researchers who are studying fire ants in a pasture at SouthWood, Fla.

They are testing part of the theory of evolution, which describes how populations evolve. The theory suggests that traits that help populations survive or reproduce are more likely to be passed along to the next generation.

Tschinkel is trying to understand and prove how the theory applies to social-insect colonies, including fire ants.

Thousands of individual "workers" are sterile, so their traits are not passed on directly. Yet fire-ant populations, he said, continue to evolve.

Some people may think the best fire ants are dead ones, but Tschinkel disagrees. He says ant colonies are fascinating and deserve to be understood rather than eradicated.

"They're cool," he said. "I could go on and on (about them)."

In a pasture near Tallahassee, Tschinkel, research assistant Joshua King and technician Kevin Haight have set up what look like tepees for a tribe of Lilliputians.

They are putting up 100 of the polyester tents, held up by a PVC pipes. The tents are used to funnel breeding fire ants (called sexuals or alates), which can fly, into traps at the tops of the tents.

About 250,000 fire ants live in a typical mature mound. Most of them are worker ants, which cannot reproduce. Each colony has a single queen, which produces new ants.

Worker ants vary in size, with some larger ants being about four times the size of the smaller ones. The researchers are trying to determine whether the proportion of larger ants to smaller ants affects the production of the breeding ants that produce new colonies.

Colonies of social insects continue to evolve by adapting new traits even though the individual workers do not reproduce, Tschinkel said.

"The colony is the reproductive output," he said. "It is the colony that is evolving."

Both large and small fire-ant workers play important roles in maintaining colonies, Tschinkel said.

The larger worker ants, which on average are about four times the size of smaller ants, are better at killing insects, which are an important food source for ant larvae.

Smaller worker ants care for the larvae, passing along the food and providing grooming. Large worker ants do not appear to play a role in the production of new ant colonies.

But Tschinkel theorizes that the larger ants play a role in colony reproduction that hasn't been proved. Otherwise, according to the theory of evolution, colonies would not continue to produce large ants, he said.

Tschinkel and the other researchers are introducing additional larger ants into some mounds and additional smaller ants into other mounds. They also are introducing a combination of both sizes to some mounds to serve as a control group.

He says the study is the first to try to determine whether traits in sterile individuals contribute to reproductive success.

Fire ants, which were accidentally brought to this country from Brazil in the 1930s, are hated by homeowners, landowners and naturalists. They use water and chemicals to try to kill the ant mounds that arise in golf course fairways, highway medians and yards.

Tschinkel has a suggestion for those who rudely tell him they want to kill fire ants. And his suggestion isn't meant to be practical.

"I tell them I got a sure-fire way to kill ants," Tschinkel said. "I say, 'You get yourself a brick. You get yourself a hammer. You put the fire ant on the brick and hit it with a hammer. It works every time.'"

Killing fire-ant colonies isn't effective, Tschinkel said, because new, small colonies quickly move in to replace the large colony that has been killed. They thrive on land that has been cleared or mowed.

"That's why I say mankind is a fire ant's best friend," he said.

Instead of trying kill them, Tschinkel suggests people try to understand that fire ants are interesting. They are social like humans, but their societies are structured very differently.

"They certainly have a fascinating biology - a colony of 250,000 individuals that work toward a common goal," he said. "It's mind-expanding."

Source: Tallahasee Democrat