Urbanisation is associated with reduced Nosema sp. infection, higher colony strength and higher richness of foraged pollen in honeybees

Ash E. Samuelson,Richard J. Gill,Ellouise Leadbeater

doi:10.1007/s13592-020-00758-1

Ash E. Samuelson, Richard J. Gill + Show 1 more

Open Access

https://doi.org/10.1007/s13592-020-00758-1

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Abstract

Bees are vital pollinators, but are faced with numerous threats that include loss of floral resources and emerging parasites amongst others. Urbanisation is a rapidly expanding driver of land-use change that may interact with these two major threats to bees. Here we investigated effects of urbanisation on food store quality and colony health in honeybees (Apis mellifera) by sampling 51 hives in four different land-use categories: urban, suburban, rural open and rural wooded during two seasons (spring and autumn). We found positive effects of urban land use on colony strength and richness of stored pollen morphotypes, alongside lower late-season Nosema sp. infection in urban and suburban colonies. Our results reveal that honeybees exhibit lower colony performance in strength in rural areas, adding to the growing evidence that modern agricultural landscapes can constitute poor habitat for insect pollinators.

Highlights

Honeybees (Apis mellifera L.) pollinate a significant proportion of the world’s crops and wild plants (Grünewald 2010)
Land category had a significant effect on colony strength, with the best model retaining only land category as a predictor (Figure 2a; ΔAICc to best model = 3.05, Table S1a)
Based on the pairwise interactions between land categories, we found model estimates of colony strength to be highest in suburban colonies followed by urban, rural wooded and lastly rural open (Table I(a))

Summary

Introduction

Honeybees (Apis mellifera L.) pollinate a significant proportion of the world’s crops and wild plants (Grünewald 2010). While numbers of managed hives in the UK (Alton and Ratnieks 2013) and some parts of Europe (Potts et al 2010; Breeze et al 2014) have declined in recent decades, urban areas may be an exception due largely to an increase in popularity of urban beekeeping (Alton and Ratnieks 2013; Lorenz and Stark 2015). Urban areas are expanding, with a three-fold increase in global urban land cover estimated between 2000 and 2030 (Seto et al 2012) and a predicted increase in global human urban population from 55

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