Alien Invasive Arthropods of Malta and Sicily

Abstract Most invasive species, particularly those originating from subtropical regions, tend to follow a similar distributional pattern: they first establish themselves in the Mediterranean and/or Macaronesian regions before gradually expanding northward. Once they take root in a new territory, these biological invasions pose threats to native biodiversity and can jeopardise economically significant crops. Sicily and Malta are no exceptions to the phenomenon of biological invasions and the combined count of terrestrial and freshwater alien arthropods in either of these regions exceeds 600 species. It’s worth noting that this number is likely an underestimate because many arthropod groups remain inadequately studied. A significant portion of these organisms were inadvertently introduced during historical times and has since become nearly ubiquitous in distribution, establishing themselves as native to these territories (autochthonous). Throughout this work, new insights into alien invasive species found in either Malta, Sicily, or in both islands, were acquired. Whenever possible, data for each of the 101 selected alien invasive species discussed herein is included. For each species, data is provided on their native origins, global distribution and the dates of their introductions where available. Synonyms and common names are included where relevant and initial interceptions in Malta and Sicily are highlighted and referenced. Each organism is accompanied by photographs to aid field identification, along with a brief description, ecological information, preferred invading habitat and other relevant biological details. The invasive status and the potential threats that these organisms pose to biodiversity and agriculture are also discussed.