Floral Trait Influence on the Foraging Decisions of a Fly Pollinator

ABSTRACT

Flies foraging for floral resources provide important ecosystem services through the pollination of myriad angiosperms, including many crop species. However, the specific floral cues used by fly pollinators to locate and discriminate among floral rewards and the preferences they may have for specific cues remain poorly understood. In this study, we examined the foraging decisions of the globally distributed fly pollinator Calliphora vicina (Diptera: Calliphoridae) in response to colour and odour cues associated with guiding flower visitation for nectar rewards. Naive C. vicina exhibited (1) a significant preference for yellow over black, green and red, with no significant preference detected between yellow and white, UV yellow or blue; (2) significant attraction to floral odours relative to stem controls in three of the four plant species tested; and (3) altered attraction when visual and olfactory cues were presented together. These findings demonstrate that both unimodal and bimodal cues influence fly foraging decisions. Improved understanding of cue use and attraction may support the development of strategies to enhance fly mediated pollination in agriculture. The preference of naive C. vicina for yellow over less attractive colours suggests that visual cues alone could be exploited to draw flies toward crop flowers, and that incorporating yellow flowering species or those with attractive odours may be a strategy worth testing to enhance fly attraction and pollination services, pending field validation.