Floral signal complexity as a possible adaptation to environmental variability: a test using nectar-foraging bumblebees, Bombus impatiens

► We tested whether a floral scent backs up a floral colour signal during bumblebee foraging under low light. ► Foraging accuracy under low light improved when scent was added to a colour signal. ► Rate of visits slowed under low light regardless of the presence of scent. ► A backup function for accuracy was supported but seems to be context dependent.