Ecological connectivity of bee communities in fragmented areas of Volcano Etna (Sicily, Italy) at different degrees of anthropogenic disturbance (Hymenoptera, Apoidea, Anthophila)

The present study analyses the ecological connectivity of four bee communities in fragmented areas in the foothills of Volcano Etna (Catania province, Sicily, Italy). The surveys were carried out in four sites under different land management regimes from 2007 to 2010. The selected areas include two different urban parks in the city of Catania (Parco Gioeni and Parco degli Ulivi), a Nature Reserve (Complesso Immacolatelle e Micio Conti, San Gregorio di Catania), and an agroecosystem (a citrus orchard, Aci Catena). The well-known bee community of a suburban park (Timpa di Leucatia, north of Catania) was considered as a control site. The bee communities include 163 species, belonging to the families Colletidae (10 species), Andrenidae (27 spp.), Halictidae (31 spp.), Melittidae (1 sp.), Megachilidae (49 spp.), and Apidae (45 spp.). Comparative zoocenotic analyses have been carried out, by calculating the main diversity indices and different methods of multivariate analysis. The ecological connectivity was evaluated through cartographic instruments by mapping the level of biopermeability of the foothills of Etna, to highlight how the level of naturality and ecological corridors could affect bee diversity. Furthermore, the degree of environmental fragmentation was evaluated through the biogeographic model of islands under the linear regression species-area, considering the examined sites as “ecological islands”. The data obtained highlight that reliable conservation strategies should consider firstly the maintenance of adequate ecological connectivity among environmental patches as well a high degree of local biodiversity, especially a high diversity of flowering plants.