farmer ants fertilize their gardens with bacteria

Wired | “It’s entirely possible that nitrogen-fixing bacteria played a critical role in the evolution of this very different group of ants, with their giant colonies and massive effects on the environment,” said Ted Schultz, a Smithsonian Institute entomologist who was not involved in the study. He and Currie both noted that leafcutters are uniquely complex among fungus-growing ants, but evolved just 10 million years ago, or 40 million years after other fungus growers.

“What humans do for nitrogen is mine it from other sources, and dump it on our crops,” said Schultz. But this leads to waste and pollution, “and the ants accomplish it through microbes. Who knows? Maybe humans could do something similar, and cultivate microbial communities in the soil around our crops.”

And this isn’t the only trick farmers might learn from the ants. In March 2008, Schultz showed that leafcutters also use antibiotic-producing microbes to keep their gardens pest-free.

Currie is studying whether nitrogen-fixing bacteria help break down the ants’ leaf cuttings into a fungally-digestible form. If so, the bacteria may suggest better ways of turning plants into biofuels. “We need to discover new enzymes, new processes, to convert plant cell walls into simple sugars that can be converted into ethanol,” he said. “Ants have been converting plant biomass into energy for millions of years.”

Currie added that leafcutter ants are the subject of thousands of papers authored over the last century, “yet this critical aspect of their success was completely unknown.”

“This is a well-studied natural system, and we’re still learning who the players are,” he said. “What does that say about most of the natural world, where mutalisms and associations haven’t been studied?”