Invasive ants in Australia: documented and potential ecological consequences

A growing number of species are being transported and introduced by humans to new locations and are establishing self-sustaining populations outside their native ranges. Since ants play many ecological roles, introduction of an invasive ant species, and subsequent disruption of Australia's rich and abundant native ant fauna, has the potential for numerous adverse consequences. Over 6700 ants representing 105 species from 73 genera have been intercepted at Australian ports of entry in the last 20 years and all six of the world’s most destructive invasive ants have become established in the country. Here we review the current and potential consequences of these ants on Australia's natural and agricultural environments. To date, several studies, most involving the big-headed ant, Pheidole megacephala, and the Argentine ant, Linepithema humile, have documented a decline in native ant species richness. The displacement of native ants by these invaders could have multiple consequences for the native flora and fauna. Since few of these have been investigated in Australia, we combine knowledge from invasions elsewhere, the ecology of the interactions, and data on current and predicted geographic ranges of introduced ants to hypothesize about likely indirect effects of invasive ants in Australia. Further investigations that are aimed at testing these predictions will also aid in justifying and prioritizing national prevention and control efforts, and will contribute to some of the long-standing questions about ant invasions globally.