The European Fire Ant, Myrmica rubra (Hymenoptera: Formicidae) in the Credit River Valley Watershed

The European fire ant, Myrmica rubra (Linneaus) (Hymenoptera: Formicidae) is an ant species native to Europe that is invasive in the northern United States and Canada. M. rubra has proven very hard to control once it has invaded an area, and preventing the further spread of the species has become important for limiting its negative effects. Knowing what environmental factors are associated with high abundance of M. rubra can help to inform where efforts at limiting future spread should be aimed, but for most areas this information is lacking. In this study, pitfall traps were used to sample M. rubra abundance at ten sites managed by Credit Valley Conservation (CVC), in the Credit River watershed in southern Ontario. These data were combined with environmental data gathered by CVC and used to determine whether the surrounding urban cover of sites, the disturbance level of sites and the wetness of sites are associated with M. rubra abundance. The surrounding urban cover of a site emerged as the most important predictor variable of M. rubra abundance, with more surrounding urban cover having higher M. rubra abundance. Higher wetness and disturbance also both predicted higher M. rubra abundance in the Credit River watershed. This information can be used to help target prevention and management efforts at sites that may be particularly vulnerable to future M. rubra invasion.