Take it or leaf it: bees learn leaf shape as a cue when flower colour is easily learned
Abstract
Over a century of research has demonstrated that pollinators, such as bees, associatively learn diverse flower cues, including tactile, visual and olfactory cues, to find food rewards. However, floral cues are not always reliable, as flowers of different plant species often differ in terms of the qualities of their food rewards, even when flower types resemble each other. At the same time, some nonfloral traits, such as leaf shape, can differ among plant species and might be associatively learned by bees to improve foraging success. In this laboratory study, we tested whether generalist bees (Bombus impatiens) can (1) associatively learn differences in leaf shape to discriminate rewarding from unrewarding flowers and (2) rely more on differences in leaf shape when a flower colour cue is harder to discriminate. We therefore assigned bees to either of two treatments: in one treatment, rewarding and unrewarding artificial targets (‘flowers’) differed greatly in petal colour, and in the other treatment, they differed little; each treatment's targets differed in leaf shape in the same way. As expected, bees learned significantly faster when flower petal colours were more dissimilar and thus relatively easier to discriminate. These bees also learned and recalled the correct combination of petal colour and leaf shape. Yet when petal colours differed relatively little, bees had a much harder time learning petal colour and did not show evidence of having remembered leaf shape. Our results demonstrate that leaf shape is a cue that foraging bees can learn to associate with a pollen food reward. However, leaf shape may be learned secondarily to, or only in combination with, floral cues (such as petal colour). We discuss evidence of compound learning and overshadowing and implications of our results for pollinator-mediated selection on nonfloral plant traits.
Department(s)
Biology
Document Type
Article
DOI
10.1016/j.anbehav.2026.123509
Keywords
bumble bee, cognition, floral display, floral reward, flower, foraging, leaf shape, learning, memory, pollen
Publication Date
4-1-2026
Recommended Citation
Castagna, Anthony Moth T.; Burrow, Jenny K.; Stewart, Ciara G.; and Russell, Avery L., "Take it or leaf it: bees learn leaf shape as a cue when flower colour is easily learned" (2026). Faculty Scholarship. 12.
https://bearworks.missouristate.edu/articles00/12
Journal Title
Animal Behaviour
