Invasive Matters

Following on the heels of my previous article, there is another invasive invertebrate in our midst that deserves greater attention.

The European Fire Ant, formerly thought to be strictly a coastal species, was confirmed to occur in the Naramata area in 2013 by Dr. Robert Higgins of Thompson Rivers University.

It is an aggressive, swarming ant that can deliver a painful sting when disturbed. In some cases, the reactions can be much more severe.

In fact, B.C.’s first case of anaphylaxis attributed to European Fire Ant stings was confirmed this past summer in the Lower Mainland.

The European Fire Ant is native to Europe and Asia and was first introduced to eastern North America in the 1900s.

While Dr. Higgins first confirmed the ant’s existence in B.C. in 2010, he believes it could have lived in the province without drawing attention for 20 years.

Over the last four years, fire ant infestations have been confirmed in 25 locations in the province. It is now found in virtually every municipality in the Lower Mainland, from Chilliwack to the North Shore and on Vancouver Island (in Victoria and Courtenay).

Talking to local residents, it appears that the ants may have been in Naramata for close to a decade. As far as we know, Naramata is the only location in the Southern Interior where the ant is found.

The most likely method of introduction and spread is through the movement of

infested garden and landscape material such as soil, mulch and potted plants. They nest in lawns, raised garden beds, under rocks or in wood debris.

Colonies can reach densities of up to four nests per square metre, rendering gardens, lawns and parks unusable for normal

activities.

The ant also has the potential to impact agricultural crops and has been shown to displace native ants in their

natural environment. They

establish their nests in the root zone of vegetation, so there is no obvious mound which can be typical of some ant species in our region.

In 2015, Dr. Higgins trialled an experimental technique in Naramata in an attempt to

rid the community of this

unwanted invader.

The process required locating nests, digging them up and treating the soil with a synthetic pesticide called permethrin. While the treatments proved effective, Dr. Higgins reports that this technique is “too slow” for the area in Naramata, other than spot cleaning where ant activity might be high.

As well, these treatments cannot be applied in the riparian area along Naramata Creek. This begs the obvious question of where do we go from here?

Unfortunately we are unable to answer this question, but continue to seek

guidance from provincial experts.

Reports of fire ants elsewhere in the Okanagan are likely native ants. B.C.’s

native ants do bite and about half of the ants we’re used to seeing have stingers, but don’t use them on humans. Dr. Higgins

explains that fire ants are tough to identify and many people confuse them with

thatching ants which are native and tend to bite, not sting.

Thatching ants are quite good for the environment especially by removing pests from trees, but their aggressive nature and fairly large size can cause concern for some people.

For more information on European Fire Ant and to view a video we helped to

produce in the Naramata area, visit

Dr. Higgins website: faculty.tru.ca

/rhiggins/myrmica_rubra_index.htm

For information on invasive species go to our website: www.oasiss.ca or contact the Program Coordinator for the Okanagan-Similkameen, Lisa Scott, at 250-404-0115.

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