Dancing bees evaluate central urban forage resources as superior to agricultural land

Ash E. Samuelson,Roger Schürch,Ellouise Leadbeater

doi:10.1111/1365-2664.14011

Ash E. Samuelson, Roger Schürch + Show 1 more

Open Access

https://doi.org/10.1111/1365-2664.14011

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Abstract

Abstract Recent evidence suggests that flower‐rich areas within cities could play an important role in pollinator conservation, but direct comparison of floral resources within agricultural and urban areas has proved challenging to perform over large scales. Here we use the waggle dances of honeybees Apis mellifera L. to perform large‐scale landscape surveys at heavily urban or agricultural sites for a key pollinator of wild and crop plants. We analysed 2,827 dances that were performed by 20 colonies in SE England. We show that hive median foraging trip distance is consistently lower at urban sites across the entire season. The sucrose content of collected nectar did not significantly differ between urban and agricultural land, ruling out the possibility that longer foraging distances in agricultural sites were driven by distant but nectar‐rich resources. Within cities, bees preferentially targeted residential areas on foraging trips, while trips to mass‐flowering crops overwhelmingly dominated at agricultural sites. For both land‐use types, distances flown increased in the summer, but there was high variation in temporal patterns between individual sites. Policy implications. From the self‐reported perspective of a generalist pollinator, forage was easier to find in heavily urbanized areas than in the modern agricultural landscapes that we studied. A focus on continuous spatial and temporal provision within agricultural environments is key to redressing this imbalance.

Highlights

The most pressing threat facing bee populations world-wide is habitat loss and fragmentation, mediated by agricultural intensification over the last century (Baude et al, 2016; Newbold et al, 2015; Potts et al, 2016)
We capitalize upon the unique waggle dances of honeybees to compare the floral resources available to this key pollinator in urban and agricultural environments at the landscape scale
Honeybees are generalists that collect a broad range of resources across a foraging range than can span several kilometres (Beekman & Ratnieks, 2000; Steffan-Dewenter & Kuhn, 2003), and unlike any other pollinator, communicate locations of profitable resources to their nestmates through waggle dances that can be decoded by human observers

Summary

| INTRODUCTION

The most pressing threat facing bee populations world-wide is habitat loss and fragmentation, mediated by agricultural intensification over the last century (Baude et al, 2016; Newbold et al, 2015; Potts et al, 2016). Honeybees are generalists that collect a broad range of resources across a foraging range than can span several kilometres (Beekman & Ratnieks, 2000; Steffan-Dewenter & Kuhn, 2003), and unlike any other pollinator, communicate locations of profitable resources to their nestmates through waggle dances that can be decoded by human observers These dances provide filtered real-time information on the resources that colonies have found through a large-scale search effort that has no access limitations (a key hurdle in surveying urban areas; Couvillon, Schürch, & Ratnieks, 2014a, 2014b; Visscher & Seeley, 1982; Waddington et al, 1994). By mapping dance distributions onto land-use maps, we investigated the importance of specific land-use types for floral resource provision within the urban and agricultural sites across the season

| MATERIALS AND METHODS

Findings

| DISCUSSION