Learning to be unfaithful – preferences and flower constancy of Eristalis tenax (Syrphidae) decrease with experience

Pollinators exhibit preferences and flower constancy (i.e. the proportion of visits to the same plant species) toward particular floral traits, which drive their decisions while foraging between flowers. Furthermore, pollinators adjust their preferences and flower constancy based on their experience with the flower reward, shaping their foraging behaviour and consequently pollen transfer. However, while evidence of the pollinators learning from foraging is well known for bees, evidence for hoverflies is only slowly increasing although they represent one of the most abundant pollinator groups in temperate zones. We compared the preferences and flower constancy of flower naive and experienced individuals of the drone fly Eristalis tenax in controlled, full-factorial experiments using artificial flowers differing in colour and size. Our results show that previous experience with flowers in an environment rich in flowering species decreased flower constancy and changed the preferences of E. tenax. We discuss the effect of changes in preference and constancy on E. tenax foraging among flowering plants.