Worldwide spread of the longhorn crazy ant, Paratrechina longicornis (Hymenoptera: Formicidae)

The longhorn crazy ant, Paratrechina longicornis (LATREILLE, 1802), is a ubiquitous agricultural and household pest throughout much of the tropics and subtropics and a pervasive indoor pest in temperate areas. I compiled specimen records of P. longicornis from > 2100 sites worldwide and analyzed historical, ecological, and evolutionary information to evaluate its known distribution, geographic origin, and potential future spread. I documented the earliest known P. longicornis records for 181 geographic areas (countries, major islands, island groups, US states, and Canadian provinces), including many for which I found no previously published records, e.g., Anguilla, Argentina, Austral Islands, Bahrain, British Indian Ocean Territory, Cayman Islands, Comoro Islands, Dominica, East Timor, El Salvador, Gambia, Ghana, Gibraltar, Guatemala, Iles Eparses, Kenya, Maldives, Mali, Montserrat, Nepal, Nevis, Pakistan, St. Kitts, St. Lucia, Turks and Caicos Islands, Tuvalu, Maryland, Missouri, and Virginia. Paratrechina longicornis is arguably the most broadly dispersed of all ant species, distributed widely across the Old World and New World in both the northern and southern hemispheres. The successful worldwide spread of P. longicornis relates to its ability to flourish in highly disturbed and artificial environments, including ships at sea. Whereas P. longicornis records are most frequent near major commercial waterways, I expect that with the increasing importance of air transport, P. longicornis will spread to more inland areas as well. Many P. longicornis records, including most if not all records from temperate latitudes, come from inside or near buildings. Because P. longicornis can live indoors anywhere that humans live, there is no limit to the latitude where it could thrive. The worldwide distribution records of P. longicornis and two species-specific symbionts provide ambiguous clues to the original native range of P. longicornis. However, the distributions of three closely related Paratrechina species offer good evidence that P. longicornis is native to Southeast Asia and Melanesia.