Ants Smell Cheaters and Assault Them, Study Finds

By Rebecca Carroll
for National Geographic News
January 9, 2009

If a worker ant dares to reproduce in the presence of the queen, her sisters will smell her attempt and attack, according to a new study.

Typically, only queens produce offspring in an ant colony, and males die after mating. The sons and the daughter queens fly away, with hopes of reproducing elsewhere, while the worker daughters stay on to build the colony and care for the next generation.

These worker ants are biologically capable of a type of parthenogenesis, the process that allows a female to produce offspring without a mate. When they try, however, they produce chemicals called pheromones that their sisters detect with antennas.

"It's basically smell, but not the smell we know," said study co-author Jürgen Liebig of Arizona State University.

If the colony lacks a queen, workers are permitted to have their own babies, Liebig explained.

But when a queen is present, only she is allowed to produce the pheromone that signals fertility status. If a worker tries to "cheat," her sisters will physically restrain the disobedient ant from successfully reproducing.

(Related: "Ants Practice Nepotism, Study Finds" [February 26, 2003].)

The research was published online January 8 in the journal Current Biology.

Scent of a Woman Ant

Previous studies showed a correlation between ant's reproductive policing behavior and these pheromones, Liebig said, so there was strong reason to believe the chemicals were tipping them off.

"The problem was that nobody could ever show it," he said.

Liebig's team studied the ant species Aphaenogaster cockerelli because it uses a simple version of the compound that the scientists could easily obtain.

Continued on Next Page >>


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