Newly introduced butterfly could spread to Canada

This summer, if you see a butterfly with blue wings on top with orange spots underneath, you may have come across a common European blue male (or Polyommatus icarus), a species newly introduced to Canada.

Could it be a fluke? Probably not, according to a group of researchers at the University of Ottawa who have taken a close look at this captivating blue creature. They are indeed the first to study its ecology.

“The results of our study suggest that the Polyommatus icarus (P. icarus) could become more widespread in the future since it prefers urban areas, ”said Stéphanie Rivest, doctoral student at the University of Ottawa, who is the first author of the article“ Human disturbances promote abundance of a newly introduced butterfly, the common European blue (Polyommatus icarus; Lepidoptera: Lycaenidae), in Canada ”published in the Canadian Journal of Zoology.

“It can reach extremely high densities and its caterpillars depend on a ubiquitous host plant in Canada.

A new house

Commonly found in Europe, P. icarus was discovered near Montreal, Quebec in 2005. Its introduction provided the Rivest team with a rare opportunity to study a non-native insect during the early stages of its colonization and to better understand the progression of an invasion.

“The rate of introduction of animal and plant species beyond their home ranges is increasing globally, but only a few of these species will become invasive, meaning that they are widespread, abundant and have negative effects on ecological communities, ”explained Rivest. “This is why it is so important that newly introduced species are studied, as we have done here, so that we can better understand and predict which introduced species are likely to become invasive.”

Predict the spread

“We found that P. icarus is most abundant in urban areas and where its favorite food plant for caterpillars, trefoil trefoil (Lotus corniculatus) is found, Rivest said. Province.”

“Our study also shows that P. icarus can reach extremely high densities compared to native butterflies and is a weak to moderate disperser, meaning adults don’t fly very well, ”explained Rivest.

This butterfly might not win a flying contest, but it could still spread to Canada.

“Based on our initial assessment of P. icarus, we need future studies to model the predicted trajectory of range expansion and to investigate other potentially important factors, ”added Dr. Heather Kharouba, Associate Professor in the Department of Biology at the University of Ottawa and head of the laboratory where the research was conducted. .

A growing population

At the start of the study in 2017, the common European blue (Polyommatus icarus) is only found in southwestern Quebec. This is where Rivest and his colleagues conducted their field investigations. They collected information on butterfly communities and their habitat at several sites, and then measured the ability to P. icarus adults to fly. To do this, they scored as many P. icarus individuals as possible with a permanent marker.

“Each individual was given a unique marking on their wing so that if they were ever picked up we could measure the distance they traveled,” Rivest said. “We have captured and tagged an incredible number of individuals, 4,629 to be exact!”

These butterflies have now found their way outside of Quebec.

“Since the start of our study in 2017, there has been an increase in the number of P. icarus observations on citizen science websites like eButterfly and iNaturalist, ”said Stéphanie Rivest. “These observations suggest that P. icarus has expanded its range as individuals are now found in Toronto, more than 400 km from our study area. “

“We encourage the public to contribute to the monitoring of P. icarus by uploading their observations on this easy-to-identify butterfly species. ”