Solitary bees (Hymenoptera, Apoidea) as connectors in pollination networks: the case of Rhodanthidium

Bees (Apoidea) are the main pollinator group in Mediterranean ecosystems, having a dominant role as connectors of modules (groups of species tightly linked in pollination networks), but little is known about the role of particular species. Here, we analyse data from four Iberian networks, and we pay special attention to the role played by the solitary snail-shell bee Rhodanthidium sticticum (Fabricius, 1787) in shaping network modularity. Our results show that R. sticticum is a pollination generalist that acts as an important connector of modules, strongly influencing the topology of its networks. We also examined 51 networks from all over the world to determine the modular role of other Anthidiini species. Anthidiini were present in 14 of these networks and another Rhodanthidium species, but also two Anthidium species, played a role as connectors in their respective networks.