title: Characterizing the pollinator communities &amp; pollination sustainability of four economically important crops in Great Britain
Creators: name: Hutchinson, Louise A.
Publisher: name: University of Reading
Year: 2023

description: Bees provide a critical ecosystem service for agricultural production by contributing to 
the pollination of the majority of leading global crops. A growing body of research indicates 
that species rich pollinator communities benefit the yields and stability of insect-pollinated 
crops. Additionally, species rich communities may promote more resilient crop pollination 
services, which is particularly imperative due to increasing rates of anthropogenic induced 
environmental changes. However, this ecosystem service is being compromised due to 
declines in bee species, driven by a loss of floral and nesting resources due to agricultural land 
expansion and intensification. Whilst agri-environment schemes have been implemented 
across Europe to halt biodiversity losses, recent evidence suggests that they predominantly 
benefit common bumblebee species, and are of limited value to solitary species, which also 
provide important crop pollination services. Currently there is limited information on which 
species provide crop pollination services to guide management and monitoring, and preserve 
pollination services. Identifying crop pollinating bee species, monitoring their populations in 
agricultural landscapes and understanding how crop pollinator communities vary across time 
and space have recently been identified as key research objectives for national and 
international policy and monitoring programmes. 
Focusing on Great Britain, which has comprehensive data on its bee fauna, and 
considering four of its most economically important crops – apples, field bean, oilseed rape 
and strawberries – this thesis aimed to address key knowledge gaps in our understanding of 
bee crop pollinator communities. The first objective of this thesis was to produce national 
lists of bee pollinators for each of the four focal crops. Building upon this information the 
second objective was to evaluate the capacity of different survey methods to sample bee species in each of these crops. The final objective was to investigate how pollinator 
community composition, and pollinator species richness, may affect the stability of crop 
pollinator occurrence. 
The results of chapter 2 indicate that whilst a smallsuite of common species may make 
a disproportionate contribution to flower visitation to our focal crops, at least a quarter of 
bee species in Great Britain, including some rare and specialist ones, could act as potential 
pollinators of these crops. These findings indicate that current agri-environment schemes, 
which have been predominantly developed around the needs of bumblebees, may not be as 
effective at supporting pollination service in crops such as apples and oilseed, which are also 
visted by a diverse range of solitary bees. 
Chapter 3 revealed that different survey methods sample distinct components of crop 
pollinator communities, and that the efficacy of different survey methods to sample bee crop 
pollinators may be contingent upon the guild and crop being targeted. Transect walks were 
superior at measuring both abundance and richness of bumblebees in all crops, and may be 
sufficient to sample bee pollinators in crops such as field bean, which are almost exclusively 
visited by bumblebees. Pan traps, notably yellow ones, detected the greatest abundance and 
species richness of solitary bees in apple, oilseed and strawberry crop sites, and may be an 
essential complementary sampling technique in crops for which solitary bees are key
pollinators. These findings can be used to inform national pollinator monitoring schemes 
which aim to sample crop pollinators in agricultural areas. 
Finally, the results of chapter 4 indicate that bee crop pollinator communities 
composed of a small number of closely related species, such as field bean, are likely to exhibit 
more synchronized inter-annual occupancy dynamics, and show a greater variance in mean occupancy, compared to crop pollinator communities comprised of a more diverse set of bee 
species, such as oilseed. Additional analyses also indicate that more species rich pollinator 
communities may result in greater stability of crop pollinator occurrence over time, which 
could have positive benefits for the resilience of crop pollination services under future 
environmental changes.
The outcomes of this thesis show that agri-environment schemes need to be adapted 
to cater for the resource requirements of a wider diversity of bee species than at present, and
strategies to achieve this are discussed within the context of the wider literature. The 
implications of differences in the capacity of different survey methods to sample and monitor
crop pollinating bee species are also discussed. Additionally, a consideration of how 
management in agricultural landscapes can promote stable bee populations in and around 
cropped areasis also provided. Together these recommendations provide an overview of how 
species-rich and stable bee crop pollinator populations could be protected and promoted in 
agricultural landscapes in order to safeguard production of insect pollinated crops.