European fire ants may wreak havoc on North American ecosystems

The European fire ant, Myrmica rubra, is an invasive ant species that is becoming increasingly common in eastern North America. It not only infests people’s yards and has a nasty sting, but also helps spread invasive plant species.

This type of ant is extremely effective at dispersing invasive plant seeds, researchers from the University of Toronto wrote in the journal Proceedings of the Royal Society B. Their study suggests that they could wreak havoc on North American ecosystems.

Co-author Megan Frederickson said:

“Ecologists think invasive species might help each other to spread, but there are few good examples. They talk about ‘invasional meltdown,’ because ecosystems could be very, very rapidly taken over by invasive species if invaders help each other out. Our results suggest that invasional meltdown could be happening right under our noses, here in Ontario.”

The study was carried out at the University of Toronto’s field station, the Koffler Scientific Reserve at Jokers Hill. Ms. Frederickson and team created mesocosms – artificial ecological communities – within 42 small plastic kids’ swimming pools.

Each pool was filled with soil and four species of spring wildflowers were planted – three native species (bloodroot, Canadian wild ginger, and sharp-lobed hepatica), and one invasive species (greater celandine).

The 4-mm reddish European Fire ant (Myrmica rubra) can form huge colonies and lives in forests, parks and backyards. (Photo: J. G. Sanders)

The researchers then added colonies of either native woodland ants or European fire ants to the mesocosms.

The insects picked up and moved these plant species seeds while the scientists observed what happened.

Co-author Kirsten Prior said:

“The pools with the invasive ant were overrun by the invasive plant, but pools with the native ant had lots of native plants.”

The European fire ants moved lots of seeds of all the four plant species, but the invasive plant took advantage of being spread about more than the other species and recruited in very large numbers, the authors explained.

Ms. Prior said:

“Unfortunately, as a result of humans rapidly moving species around the globe through trade and traffic, most ecosystems are now home to numerous invasive species. Our finding that multiple invasive species can accelerate invasion and cause ecosystems to become dominated by invasive species is a troubling one. Invasive species are a leading threat to natural ecosystems, and can have impacts on society.”

“Research on how ecosystems become invaded and the consequences of invasion is important. It sets us on the right path to develop solutions to reduce the spread and impact of these harmful species.”

The research was financed by the Ontario Ministry of Economic Development and Innovation and the Natural Sciences and Engineering Research Council.

Citation:

“Mutualism between co-introduced species facilitates invasion and alters plant community structure.” Kirsten M. Prior, Jennifer M. Robinson, Shannon A. Meadley Dunphy, Megan E. Frederickson. The Royal Society Proceeding B. DOI: 10.1098/rspb.2014.2846Published 24 December 2014.