What role are ants playing in the spread of the Thesium in Fish Creek National Park? This was the question that Dr. Mary Ann McLean, Associate Biology Professor at St. Mary’s University, had after observing ants carrying seeds of the invasive species during the summer of 2017.

This query led Dr. McLean to reach out to Christine Sosiak, then a student-teacher at the University of Calgary and one of the leading experts on ants, and the two collaborated to develop a research program evaluating possible vectors for the spread of the invasive Thesium ramosum plant species.

“The basic concept behind ants spreading Thesium is that in a thesium seed there is a structure called a lysosome that is attractive to ants,” explained Sosiak. “A plant will normally grow this on a seed in order for the ants to find it then the ants will transport the seed further away and that’s how the plant spreads.”

“Here, since the plant is invasive, native ant species are starting to spread the seed.”

Within a lab on campus at St. Mary’s, McLean, Sosiak and some St. Mary’s biology students conducted seed removal trials and food preference trials to establish if ants want to eat the seed at all and to observe how the seed traverses through the nest.

“The theory behind this is that the ants will eat the lysosome and put the seed out into a nutrient rich area and whether or not that has any bearing on the germination.”

The food preference trials were utilized to observe if the ants species’ in Fish Creek Provincial Park preferred native food items from the park and how much they preferred the Thesium seeds.
It was observed that the ants do seem to prefer the Thesium over any other types of seeds provided in trials.

The ability to utilize Fish Creek Park as a laboratory for field study was extremely beneficial to the program and allowed St. Mary’s students to observe what the ant species’ natural behaviour looked like as well as if any other species in the park carry the seed as well.

To Dr. McLean, having Fish Creek Library adjacent to St. Mary’s is a wonderful resource. “We have collaborations with park staff, we’re collecting data and we share long-term data,” explained McLean. “It gives the students a chance to see real world problems.”

“One of things we’ve learned to do is spot the ants and identify the species,” said McLean. “We’re learning tons of information and the whole process has been quite interesting.”

The research program has allowed St. Mary’s students to delve into the relationship that ants have with the Thesium, as well as the role that humans play in the germination of the invasive species.

“All of the projects that we have been observing are going to be extremely important ecologically, some will most closely tie to management issues within the park itself,” said McLean. “It’s fabulous to see the students develop in ways that I never expected, and I’m really pleased.”

“To share some of the data with other people working on insects in the province will be very cool.”