Consequences of a cryptic invasive ant (Pachycondyla chinensis): Local extinctions mediated by behavior?

Invasive species and in particular ants are one of the most important threats for biodiversity, but are mostly restricted to human disturbed environments. Invasive species remain rare in most undisturbed habitats. The Asian ant, Pachycondyla chinensis, was introduced no fewer than 75 years ago to the United States. Recently it was noticed that this species in increasing in abundance and expanding into not only disturbed but also undisturbed forest ecosystems of the southeastern US. We evaluated the impact of this species on the native ant communities in four forests in North Carolina and in paired sites in the species native range in Japan. We also conducted behavioral observations of P.chinensis and native species. Our results show that P. chinensis has a strong negative impact on most of the native species, with apparent local extinction, but has at some density a positive impact on a few other species. We speculate that these effects are mediated by aspects of the behavior of P. chinensis and offer speculation as to what these might be.