Insights from genetics into the fine-scale ecology of common and scarce bumblebees

Bumblebees are important pollinators of food crops and wild plants, but their populations are in decline. Although bumblebees have been well-studied in some respects, fundamental aspects of their ecology remain unknown. We are using a novel combination of molecular genetics, intensive field studies and landscape modelling to determine the fine-scale spatial genetic structure of nest-founding queens and foraging workers, as a tool for predicting the impact of habitat structure on foraging range and dispersal. Here we present results from two of our five study species: B. hortorum which remains common and B. ruderatus which is nationally scarce in the UK. Using microsatellite markers, we reconstructed sibships for workers collected across a varied agricultural landscape. We detected lower colony densities in the rare B. ruderatus but greater colony-specific foraging distances than in B. hortorum. We discuss the implications of our findings for the targeting of strategies such as agri-environment schemes for reversing bumblebee declines. This project is funded under the UK Insect Pollinators Initiative.