Amazing Leafcutter Ants: Part 1

Jan 22, 2011 By Arati Rao
Arati Rao's picture

An ant that farms. An ant that cures. An ant that lives in a society almost as intricate as the human society.  Meet the Leafcutter ant. Endemic (that is, not found anywhere else) to South and Central America and parts of southern United States, this ant is one fascinating creature.

Farmer Ants

If the first human farmers appeared 11,000 years ago, these ants have been farming for over 50,000 years! They have a crew that goes out to cut up leaves and a crew to spirit those leaves back to their underground colony. In these mounds, the ants chew up these leaves and lets fungus grow on them. In other words, they “farm” fungus. This fungus feeds the whole colony and also becomes the place where they live. This mutually beneficial behavior between the ant and the fungus is called “mutualism.”

How large is a colony – well in some cases, it could spread across 30m and hold over a million individuals! Yes, these societies rival human societies. Leafcutter ants keep cutting and bringing back fresh leaves to feed the fungus and keep the fungus growing for the colony. Then there is another crew that is in charge solely of keeping the colony clean. These ants carry rotten or waste matter to a “dump site.”

The crew that cuts the leaves has to have very sharp mandibles. When they start out, these mandibles are apparently as sharp as the sharpest man-made blades! As these mandibles wear out, the cutting crew changes! The new fresh mandibled-ants take over the cutting and the older ants save themselves up for only carrying the cut leaves to the colony.

Think about it!

Have you ever tried cutting a piece of paper suspended in air with a cutter? Can you do it easily? A-ha! Then how do you think these ants cut the shaky leaves they are on? Well – their mandibles vibrate. And these vibrations balance out the movement caused by the force of the mandibles on the leaves! So the leaves are almost still and the razor sharp mandibles cut them out cleanly. Can you think of another implement that works like the mandibles? [Ans: BreadSlicer with serrations (teeth) that vibrate when you move it back and forth, making it easy to cut soft bread]

Doctor ants

So the leafcutter ants farm fungus and eat it. But – if there is a pathogen (bad microbes or fungus) detected in the colony, the ants all get to work. Scientists noticed that they produce a white substance on their bodies and when they observed it closely, they saw that it was bacteria. This bacteria, called an actinobacteria produces over 80% of the antibiotics we use! So these ants are “curing” the fungal infection with bacteria that they are growing on their bodies. How much more ingenious can these little creatures get?

Well, there’s more. You’ll have to wait for the next installment of the Leafcutter Ant Story to learn what other wonders they have in store for you! We leave you with a short video from the San Diego Zoo -- next time you are there, don't forget to check these little creatures out.