Supplementary material for: Bumblebees show no preference between flowers with consistent and variable scent blends when rewards are identical

ABSTRACT To attract pollinators, flowering plants have evolved a range of sensory traits into compelling signals. Floral scent, in particular, plays a key role in drawing bees from a distance and shaping their foraging choices. Scent composition varies widely, even between flowers of the same species, but it is unclear whether such variability influences bee flower choices and thus whether plants are under selection to minimise it. Since bees typically avoid variability in rewards, we hypothesised that they would favour flowers with more consistent scent profiles. We trained individual bumblebees (Bombus terrestris) on two equally rewarding flower arrays offering scented nectar made with artificial flavourings. One array had a consistent scent blend, while the other featured variable ratios of a different blend across flowers. Contrary to expectations, bees foraged equally from both arrays and showed no preference in a binary choice test. A control experiment revealed that bees could not discriminate between the airborne scent ratios, so both arrays may have appeared equally variable. These findings suggest that bees may not readily perceive variations in floral scent composition, and thus plants might not be under strong selection to minimise inter-flower scent variability. To our knowledge, this is the first study to directly examine bee responses to scent variability independent of reward differences, highlighting the need for further research into how bees respond to variation in neutral floral cues.