Abstract

Invasive species have become a growing ecological concern caused by the increase in frequency of global human transportation. An important step in studying biological invasions is identifying the ecological niche a new species will occupy in its environment. in an effort to predict its expansion and its effect on native ecosystems. The effective range of a species consists of habitats in which a species is able to complete its life cycle, to sustain its population. The European Common Blue (Polyommatus icarus) is a non-native species established in Quebec since 2005, its only known distribution in North America to date and its first occurrence outside of its native range. As a species that forms mutualistic interactions with ants, i.e., a myrmecophilous species, this butterfly represents an opportunity to study the role of mutualistic interactions in the role of invasion success. The following research questions were investigated:
1. Whether myrmecophilous interactions persist in the new range of P. icarus.
2. Which factors drive adult abundance and oviposition decision, among host preference, plant structures and habitat structure?
Myrmecophilous interactions, adults and oviposition were surveyed through a field study in the area of Montreal, Quebec. A novel myrmecophilous interaction between the native ant species Lasius neoniger and P. icarus was documented in the summer 2019. Adult presence was positively correlated with the abundance of Lotus corniculatus, Trifolium pratense and Medicago lupulina. More adults and eggs were found in sites with shorter vegetation. T. pratense and M. lupulina. Eggs were laid as a function of host availability, without any significant preference for a particular species, and preferably in shorter vegetation. This field study gives support for the importance of vegetation structure in habitat selection in P. icarus, and suggests that this species will likely occupy disturbed or artificial habitats in North America.