Worldwide spread of the little fire ant, Wasmannia auropunctata (Hymenoptera: Formicidae)

Abstract

Native to the Neotropics, Wasmannia auropunctata has spread to numerous other tropical and subtropical areas, where it is can reach extremely high densities and threaten the local biota. To evaluate the worldwide spread of W. auropunctata, I compiled published and unpublished specimen records from > 1700 sites. I documented the earliest known W. auropunctata records for 53 geographic areas (countries, island groups, major West Indian islands, and US states), including many with no previously published records: Anguilla, Antigua, Barbuda, Caicos Islands, El Salvador, Guam, Montserrat, Nevis, St Kitts, St Martin, and Texas. In the New World, W. auropunctata has a seemingly continuous distribution from central Argentina to southernmost Texas, suggesting that it may be native throughout this expanse. Wasmannia auropunctata has also spread throughout the West Indies and to peninsular Florida, though it is unclear which West Indian islands may constitute part of its native range. The earliest Old World reports of W. auropunctata, in the 1890’s, came from West Africa: Sierra Leone and Gabon. Although no additional records have come from Sierra Leone, W. auropunctata has spread broadly across Gabon and into neighboring countries, where it is a serious pest. In Oceania, the earliest records of W. auropunctata date to 1972 from New Caledonia and 1974 from the Solomon Islands. Pacific populations of W. auropunctata are actively spreading within these islands and to many other island groups. In the past decade, first records of W. auropunctata have been reported from several Old World areas, including the Central African Republic, Papua New Guinea, Australia, Guam, Italy, and Israel. Wasmannia auropunctata appears to still have much potential for future spread in the Old World.