A history of accidental widow spider (genus Latrodectus ) introductions on the island of Ireland with a new irish record for Latrodectus hesperus (Chamberlin and Ivie, 1935), and additional records of Latrodectus geometricus (C.L. Koch, 1841).

Abstract

The widow spiders of the genus Latrodectus (Araneae: Theridiidae) have a well-documented global medical significance due to the potent venom many of them possess. This medical importance partially stems from the global range expansion the genus has undergone, facilitated in part by human trade. This expansion has had an impact on human health in countries where Latrodectus spiders establish populations. Ireland has a detailed report history of accidental widow spider introductions, spanning over 30 years, which assists in understanding the potential such species have for establishing. Here we present three additional cases: a second and third record of Latrodectus geometricus (C.L. Koch, 1841) and the first record of Latrodectus hesperus (Chamberlin and Ivie, 1935). We also review all published reports of Latrodectus introductions in Ireland and discuss the potential for populations to establish. While case histories suggest that L. hesperus and L. geometricus can survive Irish winters, it is not certain that they can complete an egg-to-egg life cycle or even reproduce. Nevertheless, it seems possible they could do so in favourable micro-habitats in anthropogenic habitats such as hot houses. Identification of instances of Latrodectus introductions into Ireland is essential to prevent potential establishments that could lead to envenoming cases.