Alien Terrestrial Invertebrates of Europe

Unlike other groups of animals and plants, no checklist of alien terrestrial invertebrates was available in any of the European countries until recently. Since 2002, such checklists were successively provided by Austria (Essl and Rabitsch 2002), Germany (Geiter et al. 2002), the Czech Republic (Šefrová and Laštů vka 2005), Scandinavia (NOBANIS 2007), the United Kingdom (Hill et al. 2005), Switzerland (Wittenberg 2006) and Israel (Roll et al. 2007). However, most European regions remained uncovered and, furthermore, comparisons between the existing lists were inherently difficult because they used different definitions of alien. Thus, estimating the importance of terrestrial alien invertebrates at the European level remained impossible, mostly because of poor taxonomic knowledge existed for several groups. By gathering taxonomists and ecologists specialised on most invertebrate taxa together with collaborators working at the national level in 35 European countries, the DAISIE project intended to fill this gap. However, a lack of European expertise in some taxonomic groups did not allow coverage of all the terrestrial invertebrates with the same level of precision. Data on insects were more reliable than those of other taxa, and consequently the analyses presented below will mostly refer to this group.