Science Daily: Ants Use Bacteria to Make Their Gardens Grow.
ScienceDaily (Nov. 24, 2009) — Leaf-cutter ants, which cultivate fungus for food, have many remarkable qualities.The New York Times: Fossil Shows Ants Evolved Much Earlier Than Thought
Here's a new one to add to the list: the ant farmers, like their human counterparts, depend on nitrogen-fixing bacteria to make their gardens grow. The finding, reported Nov. 20 in the journal Science, documents a previously unknown symbiosis between ants and bacteria and provides insight into how leaf-cutter ants have come to dominate the American tropics and subtropics.
What's more, the work, conducted by a team led by University of Wisconsin-Madison bacteriologist Cameron Currie, identifies what is likely the primary source of terrestrial nitrogen in the tropics, a setting where nutrients are otherwise scarce.
"Nitrogen is a limiting resource," says Garret Suen, a UW-Madison postdoctoral fellow and a co-author of the new study. "If you don't have it, you can't survive."
Indeed, the partnership between ant and microbe permits leaf-cutters to be amazingly successful. Their underground nests, some the size of small houses, can harbor millions of inhabitants. In the Amazon forest they comprise four times more biomass than do all land animals combined.
Researchers have found seven ants in amber that are among the oldest ever found, making it clear that what may be the world's most populous terrestrial creatures were underfoot and already diversifying when dinosaurs trod the earth.
A team from the American Museum of Natural History, led by Dr. David Grimaldi, curator of entomology, found seven ants that were about 92 million years old when they excavated a muddy site in New Jersey that is rich in amber, the researchers reported today in the journal Nature. The ants are of four species.