Saturday, January 10, 2009
Worker ants in colonies with a queen are physically attacked by their peers if they try to reproduce, a study says
In ant society, workers normally give up reproducing to care for the queen's offspring, who are also their brothers and sisters. The researchers found that chemicals produced by the sneaky ants gave away their fertility status. The findings by a US-German team of researchers are published in the journal Current Biology. To test the idea, scientists applied a synthetic compound typical of fertile individuals to non-reproductive worker ants belonging to the species Aphaenogaster cockerelli. In colonies where a queen was present, the workers with the hydrocarbon chemical applied to them were attacked by other ants. The researchers reported that deceitful ants were bitten, pulled and held by their peers. But this was not the case in colonies without a queen ant, where workers were free to reproduce. Co-author Jurgen Liebig of Arizona State University in Tempe, US, said the hydrocarbon chemicals produced by the cheating ants were an "inherently reliable signal". This "reproductive policing" plays an important role in maintaining harmony in the ant world, Dr Liebig explained. "The idea that social harmony is dependent on strict systems to prevent and punish cheating individuals seems to apply to most successful societies," he said. For cheating to be a successful strategy for some ants, the researchers say, two conditions would need to be satisfied. Firstly, worker ants would need to suppress the hydrocarbon signals on their bodies. Secondly, they would need to continue to express the signal on their eggs, so that their offspring could not be distinguished from those of the queen. Some ant species are known not only to attack cheating workers, but also to destroy their eggs.