Not all pollen are created equal

Are bumblebee populations able to change their diet with shifting host plant distributions and how might that affect colony development?

GBIF-mediated data resources used : 3,000 species occurrences
Large red-tailed bumblebee (Bombus lapidarius)

Large red-tailed bumblebee (Bombus lapidarius) by Bruno Durand. Photo via iNaturalist licensed under CC BY-NC 4.0

Exclusively relying on pollen for survival, bees may be facing population declines due to to changes in host plant availability and quality. Some generalist species, however, have remained stable for many years. In this study, researchers assessed potential changes in pollen diets for five bumblebee species in northwestern Europe, using GBIF-mediated occurrences to test if such changes were related to shifts in suitable habitats of host plants. They find evidence that four out of five species tend to forage on pollen from plants with expanding distributions. Chemical analysis of the quality of the pollen revealed no differences in nutrient composition between past and recent diets. Finally, using an experimental setup of queen-less microcolonies of Bombus terrestris, the researchers find no difference in pollen collection, however, productivity was higher in colonies fed diets of newly integrated resources, showing a clear impact of changing diet on colony development.

Roger N, Moerman R, Carvalheiro LG, Aguirre-Guitiérrez J, Jacquemart A-L, Kleijn D, Lognay G, Moquet L, Quinet M, Rasmont P, Richel A, Vanderplanck M and Michez D (2016) Impact of pollen resources drift on common bumblebees in NW Europe. Global Change Biology. Wiley-Blackwell 23(1): 68–76. Available at doi:10.1111/gcb.13373.