Alien scale insects of Europe: an updated checklist

An inventory of all alien terrestrial arthropods to Europe was established in 2010 through a consortium of researchers of biological invasions in Europe (DAISIE : Delivering Alien Invasive Species Inventories for Europe). The alien arthropod fauna is highly diverse with a total of 257 families but only 11 of these families contribute more than 30 species, including Scale Insects (Hemiptera: Coccomorpha) which constitute the second group in number of species. For obvious reasons, such information requires regular updates to reflect the dynamic nature of biological invasion. Based on a literature survey, an additional species list of alien scale insects is given here and main biogeographic patterns are presented. Alien scale insects in Europe belong mainly to three different families (Diaspididae, Pseudococcidae, and Coccidae). They come mainly from Asia, Central and South America but for about one third the origin remains unknown. Two European countries present a particularly high number of alien species (France, and Italy) lagging far behind Spain, Great Britain and Portugal. Some alien scale insects are phytophagous and often harmful for crops, some others are only present on ornamentals. Some monophagous species are only known in botanical gardens or strictly associated with their host-plant. Global trade is the major pathway of introduction and the main habitats colonized are cultivated lands, greenhouses, gardens and parks.