History

Discovering A Supercolony of Ants in Europe

Researchers have discovered an enormous "supercolony" of these ants that extends across 6,000 kilometers (3,728 miles) of Southern Europe.

All the ants within this supercolony, even those from different nests, seem to behave amicably toward each other. By contrast, in Argentina, ants from different nests are particularly belligerent and fight to the death, says Laurent Keller, an entomologist from the University of Lausanne, Switzerland, who led a study on their behavior.

Keller's team captured about 5,000 ants from 33 separate nests in Italy, France, Spain, and Portugal and transported the insects back to his laboratory. Once in the lab, the scientists arranged ant fightsÑpitting ants from one nest against ants from the other 32 nests. Over the span of a year, the scientists conducted almost 1,100 ant fights.

What they discovered was that all the ants were members of either one of two enormous supercolonies. A supercolony is a remarkable structure because it involves hundreds of billions of individuals. Ants from 30 of the nests belonged to the main supercolony, which stretches from northern Italy along the Mediterranean coastline past France and Spain and curves around the Iberian Peninsula past Portugal. Ants from three Spanish nests represented a smaller Catalonian supercolony.

What is extraordinary is that ants from nests separated by thousands of kilometers did not show any aggressive tendencies towards each other; ants from Portugal, Spain, Italy and France all got along, says Keller.

A possible explanation was that the entire supercolony arose from a very small number of founders, which would mean that the ants within the colony are genetically very similarÑhence their surprising tolerance of ants from distant nests.

Keller's work is published in the April 16 issue of the Proceedings of the National Academy of Sciences.

It is said that the Argentine ants invaded Europe in 1920. Argentine ants are a particularly aggressive invasive species. Away from their homeland they tend to displace or eradicate the local ant populations as well as spiders and insects.