Communication between ants is generally thought to be chemical in nature, however, more and more evidence is being gathered showing that sound is also very important in the life of an ant. Unfortunately for the ants…this can be exploited.
In the European ant Myrmica shencki, queens produce a distinctive sound that makes workers treat them as royalty. This means the queens get cleaned and fed more than the workers and brood.
Like everywhere in nature, there is an animal that exploits this relationship between the queen and workers. However, this parasite is not an ant, but a butterfly!
It has been long known that the Mountain Alcon Blue butterfly (Maculinea rebeli) parasitizes on ants. Their larvae get carried into ant nests, where the ants treat these larvae as one of their own. Once the larva pupates and ecloses as a butterfly, the ants suddenly realize something is wrong, and the newly emerged butterfly has to get out of the nest before it is killed by the ants.
However, one thing was not known yet…why do ants treat these butterfly larvae even better than their own larvae? They don’t smell very different at all! The answer might lie with acoustic communication. Francesca Barbero and colleagues show that the butterfly larvae produce a sound that is very similar to that of the queen! This makes the ants treat the caterpillars even better than their own larvae, and ensures that the caterpillar grows up to be a healthy butterfly, which in its turn can produce a new generation of larvae to parasitize on the ants!
Barbero, F. et al. (2009) Queen ants make distinctive sounds that are mimicked by a butterfly social parasite. Science 323: 782-785