Bumblebees do not prefer consistent floral scents over variable ones

Abstract

To attract pollinators, flowering plants evolve diverse 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, including across flowers of the same plant species. Yet, it is unclear whether scent variability influences bee flower choices, and thus whether plants would be under selection to minimise variation in their scent composition. Since bees typically avoid variability in rewards, we hypothesised they would favour flowers with more consistent scents. To test this, we trained individual bumblebees (Bombus terrestris) on two equally rewarding flower arrays: one with a consistent scent blend across flowers, and the other with variable scent blends between flowers. Contrary to expectations, bees showed no preference for scent consistency. They readily foraged from both arrays across bouts and did not favour either flower type in the binary choice test. To the best of our knowledge, this is the first study to examine how bees respond to scent variability. A better understanding of scent profile preferences in pollinators could offer new insights into their co-evolution with plants and the development of floral traits. More broadly, further research is needed on how pollinators respond to variability and unpredictability in neutral cues like scent or colour, a largely overlooked aspect of foraging decision-making.