Worldwide spread of Alluaud's little yellow ant, Plagiolepis alluaudi (Hymenoptera: Formicidae)
biogeography, Biological invasion, exotic species, Invasive species
Abstract Plagiolepis alluaudi EMERY, 1894 is a tiny Old World ant that has spread to many parts of the world through human commerce. To examine the worldwide distribution of P. alluaudi, I compiled and mapped published and unpublished specimen records from > 450 sites. I documented the earliest known P. alluaudi records for 46 geographic areas (coun- tries, island groups, and US states), including several areas for which I found no previously published records: Anguilla, Barbados, Comoros Islands, Grenada, Guadeloupe, Îles Eparses, Martinique, Nevis, St. Kitts, St. Lucia, and St. Martin. Plagiolepis alluaudi is a primarily tropical species, apparently native to Madagascar and neighboring islands. It has be- come a pest on Pacific islands and in European greenhouses. Before the present study, the only published reports of P. alluaudi in the New World were several records from Bermuda and one record from California. Recent surveys in Ber- muda and California have produced no additional reports of P. alluaudi. My new records of P. alluaudi from nine tropical islands in the West Indies indicate a substantial New World invasion. It may be that the tropical climate of the West Indies is more suitable for P. alluaudi than the subtropical climates of Bermuda and California, where it may have died out.