The value of information in floral cues: bumblebee learning of floral size cues

Lay Summary In many plant species, flower size acts as a cue informing pollinators which of a plant's flowers produce the most rewards. We found that bumblebees learn to prefer large artificial flowers when they are more rewarding than small ones while ignoring flower size when it does not provide information about floral rewards. However, the bees do not prefer an artificial flower type that gives them information about floral rewards over one that does not.In many plant species, larger flowers offer larger or higher quality rewards to visitors, and flower visitors preferentially visit these larger, more rewarding flowers. Limited evidence suggests that plants in which flower size provides more reliable information about reward value have higher reproductive success than plants in which flower size offers less reliable information. We tested whether bumblebees could learn to respond to flower size when it was an informative reward cue while simultaneously learning not to respond to it when it was not informative. We also tested whether bees would develop a preference for a flower type that provided reward cues over one that did not. Bees were allowed to forage on an artificial array containing 2 flower types, each with a unique color and scent. In the informative flower type, large flowers contained sucrose rewards, whereas small flowers contained quinine solution (a deterrent). In the uninformative flower type, both flower sizes were equally likely to contain sucrose or quinine. Bees learned to prefer large flowers in the informative flower type and to be indifferent to flower size in the uninformative type. However, contrary to expectations, bees did not develop a preference for the informative type. These results suggest that although bees may benefit from floral cues that give information about rewards, plants offering these cues may not receive more flower visits than plants that do not.