Worldwide spread of the tropical fire ant, Solenopsis geminata (Hymenoptera: Formicidae)

The tropical fire ant, Solenopsis geminata (FABRICIUS, 1804), is a well-known pest in many parts of the world, where it is notorious for its potent sting. To evaluate the worldwide spread of S. geminata, I compiled and mapped published and unpublished specimen records from > 2100 sites. I documented the earliest known S. geminata records for 122 geographic areas (countries, island groups, major Caribbean islands, US states, and Canadian provinces), including several areas for which I found no previously published records, e.g., Anguilla, Barbuda, Curacao, Madagascar, Montserrat, Nebraska, Nevis, St Martin, and Vanuatu. Several New World Solenopsis species were once considered junior synonyms of S. geminata (e.g., S. gayi (SPINOLA, 1851), S. saevissima (SMITH, 1855), S. virulens (SMITH, 1858), and S. xyloni McCOOK, 1880). Therefore, I did not map unconfirmed New World S. geminata records published before CREIGHTON'S (1930) revision of Solenopsis from areas where these species occur, because some of these early records were likely to be based on misidentifications. Solenopsis geminata records are common through much of the New World tropics as well as parts of subtropical North America. Whereas S. geminata is certainly native to South and Central America, it may well be exotic to the southeastern US and the West Indies, introduced several hundred years ago. By 1900,S. geminata had also spread through many parts of the Old World, notably tropical Asia and Oceania. In the mid-20(th) century, another invader from the Neotropics, the "unvanquished" fire ant, Solenopsis invicta BUREN, 1974, began to spread around the world. Solenopsis invicta has displaced S. geminata in open and disturbed habitats in many parts of the southern US, leaving only remnant S. geminata populations, primarily in forested areas that S. invicta does not invade. Although S. geminata still has a much broader worldwide range, I expect S. invicta will continue to spread and displace S. geminata in open habitats through many other parts of the tropics and subtropics.