How many and which ant species are being accidentally moved around the world?

Human transportation facilitates the dispersal of exotic ants, but few studies have quantified the magnitude and geography of these movements. We used several non-parametric indexes to estimate the number of species successfully introduced to or established in new regions. We also compared their source biogeographic realms to assess the importance of the geographical origin in determining the likelihood of establishment after introduction. Data on exotic ants derive from studies of three temperate regions. Our results suggest that the numbers of introduced or established ants may be much larger than the numbers so far documented. Ants introduced or established in new regions tend to arrive from the same or neighbouring realms, as would be expected if exotic species tend to match climates and if arrival/establishment is dependent upon higher trade rates from neighbouring countries.