Jan. 28, 2003

Contact: Ranjit Arab, University Relations, (785) 864-8855.

KU researcher's work with ants reveals rare four-way symbiotic relationship

LAWRENCE -- The ant farms that Cameron Currie studies are some of the world's smallest cooperatives.

Currie, assistant professor of ecology and evolutionary biology at the University of Kansas, discovered a rare four-way symbiotic relationship through his research involving the Attine ants of South and Central America. Symbiosis is the state in which two or more species live together in close association.

The leaf-cutting ants not only maintain fungus farms to produce food for their colonies, but they also grow bacteria to ward off an unwanted parasitic weed called escovopsis that feeds on their fungi.

Together, the ants, the two types of fungi they cultivate, the bacteria and the parasite all create one of the most complex symbiotic relationships discovered in nature.

In fact, Currie said, this is the first documented case of a four-way symbiosis.

"We generally think of symbiotic associations involving two mutualists," he said. "This is the only system identified that has four different groups of organisms engaged in direct interactions."

The breakthrough was published in the Jan. 17 edition of the journal Science. Currie led the project, which included collaborations with researchers at KU, the University of Texas at Austin and the Smithsonian Tropical Research Institute in Panama. The National Science Foundation supports the project through a five-year, $2.7 million grant.

To conduct the research, Currie made trips to Panama and brought back samples containing the queen ant, hundreds of workers and the fungi gardens to study in his KU lab. He observed the ants as they built their elaborate farms, busily bringing back leaves or traces of animal manure to cultivate their fungi gardens. The ants also grew bacteria that they rubbed parts of their body against for use as an herbicide against the unwanted parasitic weeds.

Plenty of research already existed on the Attine ants, whose skills as farmers have been well documented. Still, no one had picked up on this four-way symbiosis in the more than 3,000 scientific papers previously published on the ants.

But to the modest Currie, the personal achievement is far less important than its scientific value.

"This was one of the most well-studied biological systems in nature," he said. "If these weren't known in this heavily studied system, what possibilities exist among systems that haven't received a lot of scientific attention?"

Currie said these master farmers also might help us think of new approaches in our own attempts to ward off disease.

"These ants have been cultivating fungus gardens for millions of years and dealing with specialized pathogens," he said. "They may have evolved mechanisms of dealing with the evolution of resistance in the pathogen that may shed light on our own dealings with evolution of resistance in diseases."

But perhaps the most important lesson the ants can teach us is that we're never too big to learn from even the tiniest organisms.

"We think of ourselves as so far beyond -- or removed -- from nature that there really isn't much it can teach us," he said. "These ants appear to have been using bacteria for the production of antibiotics for millions of years -- and that's something we've only discovered in the last 70 years or so."