Supercolony of ants found
16apr02 The Associated Press
A SUPERCOLONY of ants has been discovered stretching more than 5,000km from the Italian
Riviera to north-west Spain.
It is the largest co-operative unit ever recorded, according to Swiss, French and Danish
scientists, whose findings appear in the latest issue of Proceedings of the National
Academy of Science.
The colony consists of billions of Argentine ants living in millions of nests that
co-operate with one another.
Normally, ants from different nests fight. But the researchers concluded that ants in the
supercolony were all close enough genetically to recognise one another, despite being from
different nests with different queens.
Co-operating allows the colonies to develop at much higher densities than normally would
occur, eliminating some 90 per cent of other types of ants that live near them, said
Laurent Keller of the University of Lausanne, Switzerland.
The Argentine ants were accidentally introduced to Europe around 1920, probably in ships
carrying plants, Keller said.
Richard D Fell, an entomologist at Virginia Polytechnic Institute in the US, said
Argentine ants have been known to form large colonies - the size of several city blocks,
for example - but he had not heard of any as large as that cited in the new report.
"It may be that certain ant colonies will bud off, form satellites and remain
connected with one main colony," he suggested.
The European researchers said that in addition to the main supercolony of ants, they found
a second, smaller but also large colony of Argentine ants in Spain's Catalonia region.
When ants of the two supercolonies were placed together they invariably fought to the
death, while ants from different nests of the same supercolony showed no aggression to one
another.
"It is interesting to see that introduction in a new habitat can change social
organisation," Keller said of the behaviour of Argentine ants that had been relocated
to Europe.
"In this case, this leads to the greatest co-operative unit ever discovered."
However, in the long run, the very co-operation that seems to make the ants successful
could lead to the supercolony's self-destruction, he suggested.
That is because in such a giant colony many workers are unrelated to the queens they help
to raise.
END
OF REPORT
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