Exotic and native plant species and their role attracting native pollinators

Facing continuous losses of natural habitats, botanical gardens seem to pop up as important centre to sustain insect communities. Actually, what distinguishes many of these areas is the fact that the preserved plants are often exotic and that, in the case of Angiosperms, there is a wide variability of flower anthesis and morphology in a restricted area. The role of exotic plant species in attracting floral visitors in such environments, is little known yet. We addressed the question of how successful native and exotic plant species within the same environment were in attracting insects. In summer 2016 and 2017 we performed pollinator surveys at all flowering plants species at the Ghirardi’s botanical garden at Garda Lake (N 45°38’ 21,61’’, E 10° 36’ 40,33’’), Brescia, Italy. Network analysis of plants and native pollinators were performed by distinguishing the origin of plants in two groups, native and exotic. Thus, we assigned the role of each plant group in attracting the bee community. Furthermore, we grouped all bees by functional traits (tongue size) to address the question if bee-plant interactions were driven by plant origin (native/exotic) or by compatibility between tongue size and floral traits. Our results added a novel paradigm in bee-plant interactions in urban areas where, according to our results, exotic species seem to play an important role in network interactions.