Picnic from hell: the invasive nature of European fire ants

fire ant fire ant stinger

Biology instructor Ken Naumann’s first encounter with the subject of his Langara research project has all the elements of a 1950s sci-fi thriller – with a little Stephen King and Alfred Hitchcock thrown in for good measure.

“It was about 15 years ago,” Naumann recalls. “A classmate of my daughter was having a birthday party, and they wanted to celebrate in a park next to the Fraser River. It’s a beautiful spot with lots of room to run and play and have a birthday picnic.

“We all drove there. Van doors slid open, squealing girls jumped out and headed for the tall grass, while parents were left to set up the food.”

Cue ominous music...

Suddenly, there were screams coming from a section of tall grass. Parents dropped half-filled bowls of potato salad and ran for the source of the commotion.

Girls were screaming, running in every direction, patting their pants, and hitting their legs. Within seconds, parents were doing the same thing. Everyone was being stung by tiny red ants.

Not just any ants. These were European fire ants (Myrmica rubra). They are aggressive and will defend their nest vigorously if disturbed. The girls had obviously disturbed a nearby colony.

Naumann was fascinated. With the help of a $3,000 Langara RSAF grant, he began studying these ants three years ago.

“These guys are packing,” says Naumann. “Their sting hurts. It’s like getting a face full of vinegar. The injury site will usually swell up, which can be a serious problem for anyone who is allergic. And unlike bees, fire ants don’t die after they sting.”

Fire ants were introduced to the east coast of North America in the 1900s, and became newsworthy in BC in 2010. How they crossed the continent is one of the questions Naumann and co-researcher Mario Moniz de Sa, chair of Langara’s Biology department, hopes to answer. The European fire ant is considered the “big box retailer” of the insect world.

Ants can be easily transported through infested soil, mulch, garden materials, and even potted plants. Naumann considers the European fire ant to be the “big box retailer” of the insect world. Once they move into a neighbourhood, they displace all other ants by virtue of sheer numbers.

Naumann and Rob Higgins, a co-researcher from Thompson Rivers University, have established that biodiversity in an area drops dramatically with the presence of fire ants. They simply overwhelm all other ant species.

“Fire ants are also comfortable with very high population densities,” Naumann says. “Each colony can have several queens, not just one. These queens often establish their own colony less than a metre away from the original. It’s called ‘colony budding’.”

Recent developments in gene sequencing have revealed more fire ant secrets. Using behavioural assays and DNA extracted from various colonies, Naumann, Moniz de Sa, and several students have found genetic links between colonies that are geographically miles apart yet somehow linked. The research team is looking forward to further study of these “super colonies.”