A preliminary prioritized list of Italian alien terrestrial invertebrate species.
Invasive alien species (IAS) are considered one of the largest drivers of biodiversity loss worldwide and the negative impacts of IAS can also affect human health and economy. More than 12,000 alien species occur in Europe. Terrestrial invertebrate species are the largest proportion of alien animal species and represents one of the most impacting groups in Europe. The most important European policy against alien species is the EU Regulation 1143/2014, which provides for the development of priority lists of IAS of relevant concern aimed to allow the optimization of intervention measures. Italian policy implemented the EU Regulation with the Legislative Decree No 230/2017 that provides the adoption of a list of IAS of national concern. Aim of this work is to present a preliminary prioritized list of alien terrestrial invertebrate species (ATIS) present in Italy, thus providing an useful tool to identify species to be included in the list of IAS of national concern. We defined criteria for assessing the species and ranking them in a prioritized list on the basis of the magnitude of their potential impact on wild native biodiversity. We identify 233 relevant ATIS, among the 1126 species included in the Italian Alien Terrestrial Invertebrate Database, on which the evaluation process started. After the evaluation process, 109 ATIS with considerable impacts on biodiversity were selected and prioritized. We ranked the species in four priority categories by matching their distribution in Italy with the magnitude of their possible impact on biodiversity.