December 3, 2008

Invasive Ant Species Spreads Across Europe

Scientists have warned that a recently discovered ant species may soon be colonizing parks and gardens across northern Europe, including the UK.

The Lasius neglectus ant was identified only 20 years ago after finding and established colony in Budapest, but scientists believe the species probably originated in west Asia.

Scientists say a small area can contain between 10 and 100 times more ants than if it bears native European varieties.

"When I saw this ant for the first time, I simply could not believe there could be so many garden ants in the same lawn," said Professor Jacobus Boomsma from the University of Copenhagen, who oversaw the research.

Reminiscent in appearance to the common black garden ant, the invasive Lasius neglectus is very different in its behavior, particularly in the social structure within colonies. Which may be key to understanding why it can invade parks and gardens and exterminate varieties that previously held sway, researchers said.

The colonies now exist in France, Germany, Poland and Belgium and researchers believe the ants were probably transported across Europe in soil used to grow pot plants.

The ant species' origin is unknown, but it is thought to have originated in western Asia.

Species of ants and other social insects differ in the way mates are selected and in what happens to new queens.

Scientists say the Lasius neglectus queens mate within the existing colony rather than leaving and establishing a new one. But over time, it likely limits the mixing of different genetic variants.

But for an invasive species it is a highly advantageous trait. A queen leaving a colony that had been transported to new pastures would find no mates.

When the queen mates with other males from the same colony, it can just expand, with the ever-growing number of ants burrowing through soil and building new nests connected to the old one, until the entire area is populated with one "supercolony".

Lead scientist Dr. Sylvia Cremer, who now works at the University of Regensburg in Germany, said many ant species share this lifestyle, so it is no surprise that a number of them have become invasive pests with giant supercolonies based on the same principles.

The Argentine ant is another invasive species. After arriving in Europe around 1900, by 2002 it had established what was effectively a single supercolony from northwestern Italy round southern France and the Iberian Peninsula to the northern coast of Spain.

So far, Northern Europe has remained free of the species, but researchers believe the invasive garden ant is sure to establish itself further in the region, with the UK unlikely to find itself exempt.


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