Selectivity in the exploitation of floral resources by hoverflies (Diptera: Syrphinae)

Adults of the Syrphinae subfamily display no strong flower preferences but exploit pollen and nectar produced by native plants having large inflorescences and flat corollae (e.g. Apiaceae, Asteraceae. Ranunculaceae and Rosaceae). Seven foraging guilds are defined according to the dietary patterns of hoverflies, reflecting mainly a sequential exploitation of flowers at different times of the year and in different habitats. The majority of species live in forests where they form highly diversified communities. Few Syrphinae colonize successfully open and anthropogenic habitats, such as field margins and fallow areas. Episyrphus balteatus, Melanostoma mellinum, Eupeodes corollae, Sphaerophoria scripta and Platycheirus spp. are dominant in the communities of Syrphinae from open habitats, all over western Europe. These species are highly polyphagous and characterized by elongated mouthparts as well as a long and slender body. They have access to pollen and nectar in flowers with small and tubular corollae. It is suggested that their polyphagy is an important asset for colonizing open and ephemeral habitats.