Invasive Garden Ants As New Pest Insects In Europe

Northern Europe has so far been free from invasive pest ants, but it seems just a matter of time until Lasius neglectus, a new ant that was discovered
in 1990, will reach these latitudes and wreak havoc in parks and gardens of Northern Germany, Scandinavia and the British Isles.



A new study, published in the online, open-access journal PLoS ONE, illuminates where this ant comes from, how it organizes its supercolonies, and how
it attained its pest status. The study provides a wake-up call for closer monitoring of urban ecosystems to eliminate infestations before they become
problematic.



Invasive pests are an increasing problem for the preservation of natural biodiversity. Among the insects, ants are disproportionally well represented
among the world's 100 worst invasive pests. The red imported fire ant causes about US$ 750 million of damage in the US every year, and the Argentine
ant has spread along 6000 km of coastline in southern Europe while exterminating the natural insect fauna. Several of these pest ants have been
studied in parallel during recent years, which has given surprising insights in their evolutionary development.



"We found that invasive garden ants developed from species in the Black Sea region that have natural populations with small networks of
interconnected nests with many queens that mate underground and don't fly. It is now becoming clear that rather many ant species share this
lifestyle, so that it is no surprise that a number of them have become invasive pests with giant super-colonies based on the same principles," says
Dr. Sylvia Cremer, the lead author of the new publication.



An international team of 20 researchers, coordinated from the Centre for Social Evolution (CSE) at the University of Copenhagen, Denmark, started this
study more than five years ago. Dr Sylvia Cremer, initially a Marie Curie Fellow at CSE, later moved to the University of Regensburg, Germany to
continue her studies of the invasive garden ant, Lasius neglectus, in cooperation with Drs Jes S. Pedersen and Jacobus J. Boomsma in Copenhagen.



As the ant's name aptly illustrates, the species was overlooked until it was described in 1990, when it already had infested an entire neighbourhood
in Budapest, Hungary. Since then it has been found in more than 100 locations across Europe, where it prefers parks and gardens and quickly
exterminates the native ant fauna. It resembles the common black garden ant but the number of workers crawling around is around 10 to 100 times
greater.



"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", says Professor Boomsma,
one of the co-discoverers of Lasius neglectus almost 20 years ago.



The invasive garden ant is able to thrive in the temperate climate zones of Europe and Asia, and is therefore the first pest that will be able to make
it to the colder temperate regions of Europe and Asia, unless we stop it from doing so. So far, it has reached Jena in Germany, Ghent in Belgium, and
Warsaw in Poland.
















The work by Dr. Cremer and colleagues clearly suggests that the preconditions for developing invasive ant syndromes develop naturally in the ants'
native range. This is no problem as long as the ants are kept in check by their natural enemies, because the natural tendencies of these non-flying
ants to spread are very limited. However, when their colonies infest large potted plants and humans start moving these around across borders, such
introductions can get out of control.



"The future will therefore see many more ants become invasive, so it is about time we understand their biology and this study is a major step in
that direction", says Jes S. Pedersen, who coordinates the invasive ant program in Copenhagen.



A distribution map of the invasive garden ant is available online here.



Citation:
" The Evolution of Invasiveness in Garden Ants. "

Cremer S, Ugelvig LV, Drijfhout FP, Schlick-Steiner BC, Steiner FM, et al. (2008)

PLoS ONE
3(12): e3838. doi:10.1371/journal.pone.0003838

Click here to view article online


About PLoS ONE
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