Alien ants (Hymenoptera, Formicidae) on a quest to conquer Greece: a review including an updated species checklist and guidance for future research

Biological invasions represent one of the main drivers of biodiversity loss with adverse impacts on human societies, economies and public health. More than 500 ant species have been transported outside their native range with the help of humans, while the majority of them have managed to establish viable populations in the wild. Nevertheless, data from the Mediterranean region suggest that most alien ants occupy anthropogenic habitats with little spread in semi-natural and natural habitats. Research on biological invasions of ants in Greece had previously identified a total of 15 alien ant species. In this article, an extensive literature investigation and material examination provide a revised checklist of the alien myrmecofauna of Greece. Although the number of alien ant species remains the same, the checklist’s composition is largely altered to provide an up-to-date overview of the country’s alien myrmecofauna in order to enhance management decisions and future research. The presence and distribution of alien ants within Greek administrative divisions, NATURA 2000 sites and Corine Land Cover types are analysed and presented. In particular, the species richness of alien ants seems to be highest in the Aegean Archipelago (Crete and Southern Aegean Islands) probably due to uneven collecting efforts and increased climatic suitability. Alien ant species are mostly associated with anthropogenic habitats including urban and agricultural areas, although a significant percentage has managed to spread into forest and semi-natural areas, including protected NATURA 2000 sites. Future research directions enhancing the monitoring of alien ants and their impacts are indicated to safeguard native ant biodiversity and conservation efforts of rare and endemic taxa.