A biography of an invasive terrestrial slug: the spread, distribution and habitat of Deroceras invadens

Abstract

The article reviews distribution records of Deroceras invadens (previously called D. panormitanum and D. caruanae), adding significant unpublished records from the authors' own collecting, museum samples, and interceptions on goods arriving in the U.S.A. By 1940 D. invadens had already arrived in Britain, Denmark, California, Australia and probably New Zealand; it has turned up in many further places since, including remote oceanic islands, but scarcely around the eastern Mediterranean (Egypt and Crete are the exceptions), nor in Asia. Throughout much of the Americas its presence seems to have been previously overlooked, probably often being mistaken for D. laeve. New national records include Mexico, Costa Rica, and Ecuador, with evidence from interceptions of its presence in Panama, Peru, and Kenya. The range appears limited by cold winters and dry summers; this would explain why its intrusion into eastern Europe and southern Spain has been rather slow and incomplete. At a finer geographic scale, the occurrence of the congener D. reticulatum provides a convenient comparison to control for sampling effort; D. invadens is often about half as frequently encountered and sometimes predominates. Deroceras invadens is most commonly found in synanthropic habitats, particularly gardens and under rubbish, but also in greenhouses, and sometimes arable land and pasture. It may spread into natural habitats, as in Britain, South Africa, Australia and Tenerife. Many identifications have been checked in the light of recent taxonomic revision, revealing that the sibling species D. panormitanum s.s. has spread much less extensively. A number of published or online records, especially in Australia, have turned out to be misidentifications of D. laeve.

An invasion from Germany: Deroceras invadens (Pulmonata: Agriolimacidae) and other synanthropic slugs in the southwest corner of Poland

“…The first finding in Poland was from the botanic garden in the centre of Wrocław in 2001(WiktoR 2001. This population was still extant in 2013(hutChinson et al 2014), but we are not aware of any subsequent findings from elsewhere in Poland (A. WiktoR, pers. comm., July 2015).…”

“…However, in 2014 we found D. invadens at two sites in Hrádek nad Nisou, a small town in the Czech Republic just over the border from both Germany and Poland (Fig. 2;hutChinson et al 2014). This stimulated us to examine whether the species had also spread into the adjacent towns in Poland.…”

“…It was first found in Germany in 1977, but the first record from an area at all close to the Polish border was in 1991 (Reise & bACkelJAu 1994, hutChinson et al 2014. This was from the town of Görlitz, which sits directly on the opposite bank of the river Neisse (Nysa) from the Polish town of Zgorzelec.…”

“…Deroceras invadens Reise, Hutchinson, Schunack et Schlitt, 2011 (previously known as Deroceras pa normitanum (Lessona et Pollonera, 1882): Reise et al 2011) is a slug that has spread from southern Italy across much of the world over the last century (hutChinson et al 2014). However, in central Europe it has been slow to colonise further east than Germany.…”

“…1), although not as ubiquitous as it can be further west in Europe (e.g. noRth & bAiley 1989, hutChinson et al 2014). The first finding in Poland was from the botanic garden in the centre of Wrocław in 2001(WiktoR 2001.…”