Leaf-cutters switch jobs to ensure efficiency

WASHINGTON - It seems humans could take a cue from leaf-cutter ants to remain productive for the society and know when to quit to make room for someone else to take over.

Researchers from the University of Oregon have found that when their razor-sharp mandibles of the leaf-cutter ants wear out, they change jobs.

Leaf-cutter ants slice leaves, carry pieces back to the underground nest for further processing and, like tiny mushroom farmers, grow an edible fungus on the resulting substrate.

“Cutting leaves is hard work. Much of the cutting is done with a V-shaped blade between teeth on their mandibles that they use like a tailor who holds a pair of scissors in a fixed V shape to slice through cloth,” said lead author Robert Schofield, of the University of Oregon.

Over time, though, their mandibles slowly dull. It takes longer and requires more energy to get the job done. When it takes an ant about three times as much time and energy to cut out a leaf disc than it would have taken when her blades were sharp, behaviour changes, the researchers reported. The cutting ants rest their blades and join the delivery staff, carrying the discs cut from the leaves into their nest.

The findings have supported the idea that wear and fracture are big problems for smaller animals. The researchers estimate that, because of wear, the colony spends twice as much energy cutting leaves as it would if all ants had sharp mandibles.

This cost should have resulted in an evolutionary pressure to develop materials that resist dulling, the research team noted. The cutting blades are indeed made of a zinc-rich biomaterial that the researchers suspect is wear resistant.

The findings were published in the journal Behavioral Ecology and Sociobiology. (ANI)