Mechanisms of Competitive Displacement of Native Ant Fauna by Invading <I>Myrmica rubra</I> (Hymenoptera: Formicidae) Populations

Abstract

Exotic ants have become invasive in many regions around the world, with variable ecological impacts. Postinvasion, native ant communities are often found to be depauperate, though the causes of this apparent lack of coexistence are rarely well known. Myrmica rubra (L.), a Palearctic Myrmecine ant, is currently expanding its range as an invasive in North America. This aggressive ant forms dense, patchy local infestations and appears to aggressively displace native ant fauna. We measured behavioral interactions and rates of recruitment in experimental Þeld assays pitting native foragers against captive colonies of M. rubra at tuna-jelly or aphid baits in uninfested areas of Mt. Desert Island, ME. Behavioral interactions were idiosyncratic with respect to the native opponent, but M. rubra generally showed signiÞcantly higher levels of recruitment, aggression, and displacement of native foragers. As with other invasive ant species shown to have broken the "dominanceÐ discovery trade-off," M. rubra was consistently faster to discover baits and disproportionately displaced native foragers, providing a plausible proximate mechanism for native ant exclusion. Finally, we surveyed ant recruitment at baits for 24 h in August 2004 at four sites with varying M. rubra abundance but found little evidence of temporal niche partitioning. Taken together, these results indicate competitive superiority by M. rubra with respect to native ant communities of the northeastern North America and suggest direct aggression and competitive exclusion at food resources can lead to local native displacement.

Interactions between seed‐dispersing ant species affect plant community composition in field mesocosms

“…in natural settings (along with laboratory and mesocosm settings, similar to this study; Meadley-Dunphy et al, 2016;Prior et al, 2014Prior et al, , 2015. Garnas et al (2014) found that M. rubra recruited to baits faster than native ant species in its invasive range in Maine. Gammans, Drummond, and Groden (2018) found that M. rubra moved more seeds than the native ant species, M. detrinodis and Crematogaster cerasi, also in forests in Maine.…”

Urbanisation alters ecological interactions: Ant mutualists increase and specialist insect predators decrease on an urban gradient

“…Urbanised areas may serve as habitat and corridors for dry-adapted and heat tolerant species such as ants 39,40 , and such habitats select for opportunistic, highly competitive ant species 41,42 . Lasius niger and Myrmica rubra live in colonies of several thousand individuals, showing aggressiveness and displacement against competitors 43,44 , both species are omnivores with varied diet which consists of honeydew, other invertebrates, pollen, seeds and human waste 45 and are good candidates for benefitting from urban habitats 46 . Indirect interactions between ants and other natural enemies can be complex 47 .…”

Ophiocordyceps myrmicarum, a new species infecting invasive Myrmica rubra in Maine

“…All infestations of this polygynous species are in locations where they will be difficult to eradicate. Myrmica rubra is highly competitive and aggressive in defending resources from other ant species in northeastern United States, and high-density populations can completely displace native ant populations (Garnas et al, 2014).…”