Interspecific aggression and resource monopolization of the invasive ant Anoplolepis gracilipes in Malaysian Borneo

*[We describe interactions between the invasive ant Anoplolepis gracilipes (Smith) & resident ant species in disturbed habitats in NE Borneo. We measured interference competition abilities of A. gracilipes by performing arena bioassays between 2 A. gracilipes colonies & 7 local ant species, & measured its effective resource competition at baits within supercolonies & at supercolony boundaries. We compared ant species diversity & composition at baits among core areas of A. gracilipes supercolonies, supercolony boundaries, & outside supercolonies. Anoplolepis gracilipes was behaviorally dominant over most ant species, except Oecophylla smaragdina. Within supercolonies, A. gracilipes discovered all food baits first, & monopolized the vast majority throughout the course of the experiment. At supercolony boundaries, A. gracilipes discovered baits later than resident ant species, but subsequently monopolized half of the baits. Furthermore, the activity & diversity of the ant community within A. gracilipes supercolonies was lower than at its boundaries & outside supercolonies, & the ant communities differed significantly between infested & noninfested areas. Our study supports the hypothesis that successful establishment of A. gracilipes in anthropogenically disturbed habitats may negatively affect resident ant communities through high levels of direct interspecific aggression and almost complete monopolization of resources within high-density supercolonies.]