The European hornet, Vespa crabro L. (Hymenoptera: Vespidae), is a eusocial insect native to Eurasia that was accidentally introduced in the island of Sardinia (Italy) in 2010. This alien generalist predator could impact on native insect species through predation or competition by modifying interspecific relations in sensitive island ecosystems. As part of the Interreg project ALIEM, the present work regarded the first monitoring activity of the European hornet conducted in Sardinia by means of verified citizen science. The main goals of this study were to define the distribution area of the wasp in 2018 and evaluate the profile and the performance of citizen scientists. Our results showed that V. crabro is mainly located in north-eastern Sardinia and that the hotspot was probably the commercial port of Olbia. Furthermore, data provided by contributors were very accurate and none of the parameters considered to define the participants (age, gender, education level, job category) was a true predictor of a volunteer’s ability to recognise the wasp. In conclusion, this small-scale study suggests that citizen scientists could be a valuable aid to monitor already-established alien species and could be part of a surveillance network for early detection of other potentially invasive alien species not yet introduced in Sardinia, such as the yellow-legged hornet, Vespa velutina, which is already present in northern Italy.

The pine tortoise scale, Toumeyella parvicornis, is an insect native to the Nearctic region that is able to infest several Pinus species. It can cause weakening, defoliation and, at high infestation levels, tree death. After its first report in Italy in 2015, the pest spread rapidly over the surrounding areas and was reported in France in 2021. Due to the threat that this pest poses to pine trees, the suitability of European Mediterranean basin areas for T. parvicornis at different spatial scales was estimated by constructing species distribution models (SDMs) using bioclimatic variables. Our results showed that several coastal areas of the Mediterranean basin area could be suitable for T. parvicornis. Based on performance assessment, all the SDMs tested provided a good representation of the suitability of European Mediterranean non-native area for T. parvicornis at different spatial scales. In particular, most of the areas with a medium or high level of suitability corresponded to the geographical range of distribution of different Pinus spp. in Europe. Predicting the suitability of European Mediterranean areas for T. parvicornis provides a fundamental tool for early detection and management of the spread of this pest in Europe.

We evaluated the potential use of ants as a powerful tool for environmental monitoring, together with the applicability of the functional group approach as an alternative method for studying ant communities in cork oak woodlands. Variations in ant community composition, diversity and functional groups were studied in two cork oak forested sites across the Mediterranean region. Ants were sampled using pitfall traps placed along linear transects at 12 sites located in the main cork districts of Italy and Morocco (Gallura in Sardinia, and Maâmora, east of Rabat). A total of 13.501 specimens were collected, belonging to 38 species (five shared species). A distinct separation in the NMDS plots between Gallura and Maâmora ant assemblages was clearly visible. Ant species composition was widely different between the two districts and significant differences were detected within the Gallura district at the species level. Opportunist species were well represented in Gallura (about 27% of average Bray-Curtis similarity) as well as cryptic species (over 23%). In the Maâmora forest, generalized Myrmicinae, hot climate specialists and opportunists contributed equally to the average similarity (together about 53%). Multi-scale ant diversity showed that the true turnover was higher in Gallura than in Maâmora. These findings support the idea that the functional group approach, rather than species diversity per se, could be considered as a valuable tool to detect the response of the ant community to environmental changes in Mediterranean cork oak woodlands. Using ants as bioindicators could help not only in detecting early warning signs of habitat disturbance, but also in defining a useful management strategy to increase the resilience of agroforestry systems under future global change scenarios.