Red Clover Pollination by Bumble Bees: A Study of the Dynamics of a Plant- Pollinator Relationship

Abstract

(1) A 3-parameter probabilistic model provided a good fit to data relating seed set to the number of florets visited on red clover inflorescences by bumble bees. (2) The model, incorporated as a component in a computer simulation of bees foraging on a patch of red clover plants, was used to compare the pollinating efficiency of bees with different behavioural specifications with respect to the number of florets they visit per inflorescence. (3) Insects which visited only a few florets on each inflorescence were found almost always to cause lower seed set than those which based their decision to leave on the reward status of the inflorescence, even though the rate of inter-inflorescence transitions was greater for the former behavioural specification. Since the second type of behaviour is characteristic of real bumble bees and always returns a higher profit to the insect, it is concluded that the co-evolutionary relationship between Bombus and red clover is adapted to maximize the self-interests of both partners.