The role of Crithidia bombi and commercial bumblebee colonies in pollination

Callum Martin

Research output: ThesisDoctoral Thesis

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Bumblebees provide crucial pollination services to crops and wild plants. They also play host to a variety of parasites. It is not known whether such parasites impact upon the pollination services that bees are providing. Commercially-reared bumblebee colonies, which are used around the globe to supplement crop pollination, have been shown to harbour high levels of parasites, which can spread to wild-bee populations. Despite such negative impacts, commercial bees are widely used on many different crop species. However, for many of these crops, the benefit commercial colonies provide has not been assessed. Furthermore, we do not have a full understanding of the role that commercial colonies play in the parasite epidemiology of wild bee populations. In this thesis I begin to fill these knowledge gaps.

My results show that the common bumblebee parasite Crithidia bombi did not affect the olfactory learning ability and foraging activity of the bumblebee Bombus terrestris. However, I was unable to conclude whether this parasite impacts upon pollination services. In addition, I demonstrated that commercial colonies improve the quality and value of a strawberry crop on a farm setting, but that this benefit is only observed at certain times of the year. These same colonies became infected with parasites likely to have been acquired from wild-bee populations, and the prevalence of these parasites was also found to vary temporally. Finally, I showed that altering the concentration and availability of the commercial bumblebees’ nectar reservoir can significantly affect their foraging activity.
The results have important implications for the use and management of commercial bumblebees and could help reduce environmental damage caused by commercial colony use. I have also further increased our knowledge on the impacts of C. bombi on B. terrestris, and gained novel insights of the parasite prevalence in commercial colonies in a farm setting.
Original languageEnglish
Awarding Institution
  • Royal Holloway, University of London
  • Brown, Mark J F, Supervisor
  • Fountain, Michelle T, Supervisor, External person
Thesis sponsors
Award date1 Mar 2019
Publication statusUnpublished - 2019


  • bumblebee
  • Bombus terrestris
  • commercial bumblebee
  • parasite
  • Crithidia bombi
  • pollination
  • ecology
  • strawberry
  • bee
  • Fragaria x ananassa
  • Apicystis bombi
  • Nosema bombi
  • ecosystem services
  • pathogen spillover
  • pathogen spillback
  • agroecology
  • fruit quality
  • behaviour
  • overpollination
  • applied ecology
  • flower visitation
  • pollinators
  • insects
  • Malling Centenary
  • Flair
  • colony activity

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