FLOWER USAGE BY BUMBLEBEES - A BASIS FOR FORAGE PLANT MANAGEMENT

1. Flower visits by bumble-bees were recorded in a national survey throughout Britain in 1987 and 1988. 2. To avoid misidentifications, recorders were asked to name bumble-bees in terms of five colour groups. Each group included one or two common and widespread species, which are probably responsible for major patterns of flower usage, and several rarer forms. 3. A simple selectivity score ranks plant taxa in terms of the visits they receive from bumble-bees of each colour group. High scores may be due to high local flower abundance or to preference by the bees, and indicate plant taxa that may be worth encouraging to enhance bumble-bee populations locally. 4. A group-specific selectivity score highlights differences between bumble-bee groups in flower choice. It could be used to indicate which bumble-bee groups visit particular crops, and to plan vegetation management to favour particular bumble-bee species selectively. 5. Bumble-bees allocate a disproportionately high percentage of their visits to perennial plants of later successional stages. Annual plants of newly disturbed land receive relatively few visits. The implications for management are discussed.