Foraging activity of bumblebees ( Bombus) in relation to flower resources on arable land

Abstract

Increasing interest in combining agricultural and nature conservation goals has focused on the potential beneficial role of remnant biotopes on farmland. This study examines the role of field boundaries and a small habitat island within cereal fields in providing a source of forage for bumblebees ( Bombus Latr.), throughout one season. Transect techniques were used to assess bumblebee use of common types of boundary vegetation between crops and semi-natural habitats, and along a footpath within a small woodlot, in southeastern Norway. There were seven species of bumblebee in these habitats, which used only a small fraction of the total number of flowering plant species available to any extent; only nine out of a total of 78 flowering plant species received more than five visits. All bumblebee species had a preference for perennial herbs as forage resources. The quantity of floral resources, their spatial pattern and temporal constancy varied among sites with the least disturbed and open habitats being of greatest value to bumblebees. Length of field boundary and single date surveys are poor indices of the value of field boundaries to bumblebees.