Does the introduced bumblebee, Bombus terrestris (Apidae), prefer flowers of introduced or native plants in Australia?

Abstract

Proponents of importation of the European bumblebee, Bombus terrestris (L.), into Australia for pollination of commercial greenhouse crops argue that this species will have little impact on Australian native ecosystems because it prefers to forage on flowers of introduced species of plants rather than Australian native plants. However, data presented as evidence of preference for introduced plants have been equivocal. This study compared the attractiveness of introduced and Australian native plants to free-foraging B. terrestris in a garden at the interface between an urban area and native vegetation in the Australian island of Tasmania, where a feral population of B. terrestris had been established for over 10 years. No evidence was found to support the proposal that B. terrestris forages on flowers of introduced plants in preference to those of Australian native plants. The numbers of B. terrestris seen foraging per 1000 flowers did not differ significantly between introduced plants and Australian native plants, and the preferred food sources of B. terrestris included flowers of both introduced and Australian native species. Because B. terrestris forages frequently on many species of both introduced and native plants, assessments of its ecological impacts must include the effects of altered pollination on recruitment rates in both introduced weeds and native plants, and reduced quantities of nectar and pollen of native plants on recruitment rates of dependent fauna.