Dominance of a highly invasive ant is limited to the nesting territory of its supercolony

Abstract

1. Ant invasions represent a serious threat to biodiversity, agriculture and publichealth. Highly invasive ant species exhibit a very high abundance within its introducedrange and cause severe impacts on native ant communities. This scenariotends to be different within the native range, where competitor ants may limit itsaccess to food sources, thus its abundance.2. Here, we evaluated the competitive ability of a typical clonal and supercolonialnative population of Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae)in Argentina. We used a combination of pitfall traps and food baits to study the antinteractions within an assemblage where W. auropunctata coexists with anothergreat invader, Solenopsis invicta (Buren) (Hymenoptera: Formicidae).3. The studied assemblage presented 56 ant species/morphospecies. AlthoughW. auropunctata was the most abundant numerically, its ability to discover baitswas intermediate, and its ability to recruit workers massively and monopolise baitswas low. Wasmannia auropunctata was not successful defending baits nor attemptingto usurp baits dominated by other species.4. Moreover, it lost all contests against S. invicta, one of the most ecologically dominantspecies in this assemblage. Wasmannia auropunctata dominated food sourcesonly when they were located within the nesting territory of its supercolony.5. Within the native range, clonality and supercoloniality may favour the local numericalabundance of a highly invasive ant but may not be enough to achieve ecologicaldominance. This study sheds light on the important role of biotic interactions as akey factor that may limit the dispersal of invasive species.