Urban bees: reproductive success, colony health and foraging in an anthropogenic environment

Ash Samuelson

Research output: ThesisDoctoral Thesis

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Bees are extremely important pollinators but are under threat from reduction in forage availability, parasites and disease and pesticide exposure. Urbanisation is a rapidly expanding driver of land-use change that is likely to interact with these threats, but it is unclear whether urban areas support or impair bee populations. While there is evidence that the abundance and diversity of bee species may be higher in urban areas, it is not known whether this is driven by effects of land-use on reproductive success or migration, and which mechanisms are behind these effects. This thesis employs a colony-level approach to investigating the effects of urbanisation on honeybees and bumblebees. I first developed a land
classification protocol to analyse land-use attributes at a resolution relevant to pollinator use of the landscape. Using this protocol, I investigated bumblebee colony success in city, village and agricultural sites by placing lab-reared colonies of Bombus terrestris into the field and monitoring their development. I found reduced reproductive output, colony size, longevity and queen survival in colonies in agricultural areas. These colonies were also less likely to contain pollen and nectar stores. Building on these findings in wild bees, I investigated the effect of urbanisation on honeybee pollen foraging and colony health by sampling 51 beehives located across a gradient of urbanisation in South-East England in the spring and autumn. Here I found increased pollen species richness, larger colony sizes and lower Nosema infection in colonies located in urban areas. These results in honeybees and bumblebees suggested forage availability may play an important role in mediating the relationship between
urbanisation and colony success. To investigate differences in forage availability between urban and rural areas I decoded waggle dances performed by honeybees in ten urban and ten rural sites across an entire foraging season. Urban bees showed consistently lower foraging trip distances, suggesting higher
forage availability. This was not compensated for by differences in nectar sugar content, with urban bees collecting nectar with a higher average sugar content than rural bees. Analysis of land-use preferences highlighted the role of residential areas containing gardens in the city and the reliance on
mass-flowering crops in the countryside. The results of this thesis suggest that bees are able to thrive in urban areas, and serve to highlight the poor suitability of agricultural land to provide habitat resources for bees and other pollinators.
Original languageEnglish
Awarding Institution
  • Royal Holloway, University of London
  • Leadbeater, Elli, Supervisor
  • Gill, Richard, Supervisor
  • Brown, Mark J F, Advisor
Thesis sponsors
Award date1 Oct 2019
Publication statusUnpublished - 2019


  • Bee
  • Urbanisation
  • Honeybee
  • Bumblebee
  • Land-use
  • entomology
  • ecology
  • social insects

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