Don’t forget the flies: dipteran diversity and its consequences for floral ecology and evolution

The attention of the global pollination community has been drawn to food safety and other ecosystem services provided by pollinators, in light of decline in social bee populations. Despite intensified research on bees, recent studies have revealed important contributions of flies to pollination success, reproductive isolation and floral diversification. Diptera is a highly diverse insect order, comprising over 125,000 described species in 110 families and representing a broad spectrum of ecological niches beyond the well-known agricultural pests and blood-feeding vectors of human and animal diseases. Flies are most appreciated as generalized pollinators in alpine habitats (anthomyiids and tachinids) and as specialized pollinators in brood-site deceptive plants that mimic fungi (drosophilids), feces (muscids) or carrion (sarcophagids and calliphorids). Syrphid and bombyliid flies visit many of the same flowers as bees and butterflies do, but with different impacts on plant fitness. Guilds of South African plants have evolved specialized relationships with long-tongued nemestrinid and tabanid flies, thanks to geographic isolation and climatic stability. Studies in Japan highlight the evolution of another plant guild, pollinated by sciarid and mycetophilid fungus gnats, whereas Zygothrica flies (Drosophilidae) pollinate mushroom-like Dracula orchids in Andean cloud forests.