Foraging responses of bumblebees to rewardless floral patches: Importance of within-plant variance in nectar presentation

Nectar-foraging pollinators respond flexibly to the reward condition of floral patches. In a new study published in AoB PLANTS, Nakamura and Kudo compared foraging behaviours of bumblebees between naturally rewarding and artificially rewardless (i.e., nectary removed) patches in aconite populations, with the aim of evaluating the effects of an unrewarding experience. They found that bees increased their movements between inflorescences instead of leaving the patches when they faced rewardless flowers. Because the nectar reward was highly variable among flowers within plants in the aconite populations, they could be rewarded by the adjacent inflorescences even after unrewarding experiences. Completely rewardless plants might be pollinated successfully in rewarding populations if surrounding plants provide a highly variable nectar reward.