Host‐plant finding and recognition by visual and olfactory floral cues in an oligolectic bee

Abstract

Summary1. Bees use floral cues, such as odour, colour, size and shape, to discriminate and recognize flowers. The interplay between visual and olfactory cues in social as well as in solitary bee species is poorly understood.2. In this study we tested the host finding and recognition behaviour in a specialized (oligolectic) bee species,Hoplitis adunca(Megachilidae), which collects pollen exclusively on flowers ofEchium(Boraginaceae) species. We determined the importance of visual (especially floral colour) and olfactory cues ofEchium vulgareflowers in host‐plant finding and recognition, as well as in the discrimination of non‐host plants (Anchusa officinalis), by foraging‐naïve and ‐experiencedH. aduncafemales.3. Our investigations showed that the interplay between visual and olfactory cues ofE. vulgareflowers is essential for host‐plant finding and recognition byH. aduncafemales. The finding suggests that the blue colour of the flowers attracts the bees, while the olfactory cues, which areEchium‐specific, are used by the bees to recognize their host plant and discriminate it from non‐host plants.4. Our results show that different modalities of floral cues need to be studied in a combined approach in order to understand the communication in bee–flower interactions and the cues used by bees to find and recognize their host‐plants.