Understanding the impact of agri-environment schemes on emerging infectious diseases in pollinators

Lead Research Organisation: UNIVERSITY OF EXETER
Department Name: Biosciences

Abstract

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Technical Summary

Emerging diseases and the multi-host pathogens that cause them threaten animal and human health and can put ecosystem services at risk. Insect pollinators, particularly wild and managed bees, provide a key ecosystem service and are crucial for maintaining food security. But bees are in decline, and multiple lines of evidence suggest that emerging diseases may play a key role in these declines. Inter-specific transmission in pollinators is facilitated by niche overlap; sharing floral resources can promote indirect disease transmission. However, the provision of floral resources through agri-environment schemes is the key component in current programs to enhance pollinator assemblages for ecosystem services in agricultural landscapes.
Based on this landscape-scale experiment, we will study the fundamental ecology of disease transmission in this community to determine who and what drives transmission and how we can optimize management to reduce the risk of disease emergence. We will combine studying disease transmission dynamics in the field with targeted experiments to dissect the drivers of disease transmission in agricultural landscapes. We will first assess the full viral community of pollinators across conventional and enriched agricultural landscapes. Then we will determine the spatio-temporal source-sink dynamics of 3 key pollinator viral pathogens by using cutting-edge phylogenetic modelling to reconstruct transmission dynamics under conventional and enriched agricultural schemes. We will use lab-experiments to determine how time-lags, and floral complexity affect within- and between-species transmission. Informed by fieldwork and lab experiments, we will experimentally determine how transmission is mediated by floral resources and pollinator density in semi-natural enclosures. With these results, we will provide fundamental insights into the evolutionary ecology of emerging diseases and, ultimately, improved agricultural management schemes for pollinators.

Planned Impact

This project will: (i) substantially enhance our understanding of the landscape of RNA viruses, both emerging and non-emerging, in wild and managed pollinators, (ii) determine the dynamics, directionality, and overall epidemiology of emerging diseases in wild and managed pollinators and test whether these are affected by agri-environment schemes, (iii) elucidate the mechanisms behind disease transmission and determine how they impact transmission at semi-field scales, and consequently (iv) provide suggestions for management of agri-environment schemes that are designed to benefit wild and commercial pollinator populations, in order to minimize the threat of emerging disease. In addition to the academic community (see 'academic beneficiaries'), we have identified 5 sectors that will benefit from this work. We aim for rapid and high impact of our results on policy for pollinator management, enhancing the UK's biodiversity and agri-economy.

1) national and international policy-makers, regulators & government
Emerging disease is a significant focus of attention for national and EU-level policy makers, e.g., the designation of notifiable diseases and requirement for health certificates prior to international bee transport. Policy makers and government will benefit from this work as it will fill a major hole in our understanding of whether and how viruses emerge across the commercial-wild pollinator divide, as well as the impact of agri-environmental schemes on this emergence. This is critical during the ongoing development and implementation in the UK of the reformed Common Agricultural Policy and the National Pollinator Strategies, as well as the development of new agri-environment schemes. Consequently, our outputs will enable the development of evidence-based policy to protect the ecosystem service of pollination.

2) land management and seed producers
Agri-environment schemes aim to improve ecosystem services and conservation. To achieve this for pollinators, seed producers that provide nectar and pollen seed mixtures and land managers need to understand how these schemes affect not only pollinator abundance and diversity, but also how they affect pollinator health. Our results will allow seed producers to optimize the seed mixtures they sell and will allow land managers to improve pollination services and pollinator conservation.

3) conservation agencies
Numerous conservation NGOs in the UK (e.g., Bumblebee Conservation Trust, Buglife, Bee Guardian Foundation, RSPB) and globally (IUCN) require a deeper understanding of the factors driving wild pollinator declines in order to devise both policy and on-the-ground management. Our research will provide the information necessary to enable such agencies to manage both floral interventions and commercial honeybees, to maximise the health of wild pollinator populations

4) commercial honeybee managers
Currently, over 40,000 honeybee colonies are managed commercially in the UK, for pollination services and honey production. Our research results will enable commercial producers to minimize both the impacts of emerging diseases spreading from managed honeybees into wild bees, and the likelihood of acquiring such diseases from the wild, which will therefore increase the value and efficiency of these important commercial pollinators.

5) publics
From specialist interest groups, such as Beekeeping Associations, through to schools and adult communities, there is a deep and abiding interest in bees and their health. Results from our work will be of broad interest to this range of public communities, enabling them to understand how science is trying to address the global problem of bee decline. Moreover, our results will have a direct and immediate role in conserving pollinators, as urban gardens are currently important refuges for these beneficial insects due to their forage availability. Our research results may directly benefit the design of bee-friendly gardening schemes

Publications

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Bailes EJ (2020) Host density drives viral, but not trypanosome, transmission in a key pollinator. in Proceedings. Biological sciences

 
Description We have demonstrated for the first time that viruses which are known to damage the health of managed honey bees and wild bumblebees can be vectored by hoverflies. This has implications for understanding how these viruses are spread from insect to insect, and thus how to manage and understand these diseases. More recently, we have shown that viral spread, but not trypanosome spread, in bumblebees is determined by host density. The higher the density of bumblebees, the more the virus will spread. This has implications for how we manage landscapes for bee health. We have summarised current knowledge from a One Health perspective in an invited review.
Exploitation Route We believe our results could contribute to the design of agri-environment interventions - particularly flower-rich planting - to minimise the risk of disease spread in flower-visiting insects. Once our project is complete we will, as per our PTI, bring this information to relevant stakeholders to help in the design of practice and policy
Sectors Agriculture

Food and Drink

 
Description Informing wildflower seed producer Emorsgate Seeds of plants utilised by pollinators in agricultural habitats, with a view to improving seed mixtures for environmental stewardship and general wild flower margins
First Year Of Impact 2018
Sector Agriculture, Food and Drink,Environment
Impact Types Economic

 
Description BBSRC Agritech Catalyst Seed Fund
Amount £10,609 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 12/2017 
End 02/2018
 
Description China Partnering Award
Amount £30,000 (GBP)
Funding ID BB/P025854/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 04/2017 
End 04/2021
 
Title Conservation measures or hotspots of disease transmission? Agri-environment schemes can reduce disease prevalence in pollinator communities 
Description Insects are under pressure from agricultural intensification. To protect pollinators, conservation measures such as the EU agri-environment schemes (AES) promote planting wildflowers along fields. However, this can potentially alter disease ecology by serving as transmission hubs or by diluting infections. We tested this by measuring plant-pollinator interactions and virus infections (DWV-A, DWV-B and ABPV) across pollinator communities in agricultural landscapes over a year. AES had a direct effect on DWV-B, reducing prevalence and load in honeybees, with a tentative general dilution effect on load in early summer. DWV-A prevalence was reduced both under AES and with increasing niche overlap between competent hosts, likely via a dilution effect. In contrast, AES had no impact on ABPV; its prevalence was driven by the proportion of bumblebees in the community. Epidemiological differences were also reflected in the virus phylogenies, with DWV-B showing recent rapid expansion, while DWV-A and ABPV showed slower growth rates and geographic population structure. Phylogenies indicate that all three viruses freely circulate across their host populations. Our study illustrates how complex interactions between environmental, ecological and evolutionary factors may influence wildlife disease dynamics. Supporting pollinator nutrition can mitigate the transmission of important bee diseases, providing an unexpected boost to pollinator conservation. 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
URL http://datadryad.org/stash/dataset/doi:10.5061/dryad.msbcc2g2q
 
Title Data table for Spring 2017 analyses 
Description Description of spring 2017 farm data including, site name, farm scheme, wildflower strips (WFS) category (yes or no), habitat type and number of insect visited flower species. 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
URL https://figshare.com/articles/dataset/Data_table_for_Spring_2017_analyses/19213428
 
Title Data table for analyses 
Description Description of summer 2016 transects including, site name, farm scheme, time point, category (wildflower strip (WFS) or non-WFS), habitat type, temperature (°C), cloud cover (%), wind speed (Beaufort scale), insect abundance (total pollinators, total bees as observed from plant-insect interaction data), flower species richness and density, insect-visited flower species richness, network metrics (number of taxa, bee species' niche overlap, bee species' generality indices), centred data and z-scoeres calculated for niche overlap and generality. 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
URL https://figshare.com/articles/dataset/Data_table_for_analyses/19213350
 
Title ESM data files from Host density drives viral, but not trypanosome, transmission in a key pollinator 
Description Data files 1 - 9 containing all data used for analyses in the article "Host density drives viral, but not trypanosome, transmission in a key pollinator" by Bailes et al., found at https://doi.org/10.1098/rspb.2019.1969 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
URL https://rs.figshare.com/articles/dataset/ESM_data_files_from_Host_density_drives_viral_but_not_trypa...
 
Title ESM data files from Host density drives viral, but not trypanosome, transmission in a key pollinator. 
Description Data files 1 - 9 containing all data used for analyses in the article "Host density drives viral, but not trypanosome, transmission in a key pollinator" by Bailes et al., found at https://doi.org/10.1098/rspb.2019.1969 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
URL https://rs.figshare.com/articles/dataset/ESM_data_files_from_Host_density_drives_viral_but_not_trypa...
 
Title ESM data files from Host density drives viral, but not trypanosome, transmission in a key pollinator. 
Description Data files 1 - 9 containing all data used for analyses in the article "Host density drives viral, but not trypanosome, transmission in a key pollinator" by Bailes et al., found at https://doi.org/10.1098/rspb.2019.1969 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
URL https://rs.figshare.com/articles/dataset/ESM_data_files_from_Host_density_drives_viral_but_not_trypa...
 
Title Flower Survey 
Description For each summer transect, we recorded the number of flower units per species in a 0.25m2 quadrat randomly thrown every ten meters. Flowering units were defined as in Carvell et al (2007); one flower 'unit' was counted as a single flower or, in the case of multiflowered stems, as an umbel, head, spike or capitulum. Flowering plants were identified to species in most cases, otherwise to the family or genus. 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
URL https://figshare.com/articles/dataset/Flower_Survey/19208310
 
Description Identifying agri-environment sites for pollinator pathogen study 
Organisation UK Centre for Ecology & Hydrology
Country United Kingdom 
Sector Public 
PI Contribution Study design to test whether agri-environment schemes affect disease transmission dynamics in pollinators
Collaborator Contribution Consulting on site selection and providing contacts, ongoing advice during field season
Impact Initial selection of prospective field sites
Start Year 2015
 
Description Msc project: Plant pollinator networks and disease transmission at the Eden Project 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Msc Thesis mirroring part of our research work for the agri-environment grant, transposing this research to the Eden Project. Engagement with visiting public during project, and data on plant-pollinator networks which is forming the basis for future work and outreach projects with Eden.
Year(s) Of Engagement Activity 2016
 
Description Talk at Pollinator Health conference, Kew Gardens, London 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited talk at an international 2-day conference, online, with apps around 200 researchers, students and practicioners from different continents present at the time of streaming. Talks were recorded and available freely on Kew Garden's website - it is therefore reasonable to assume that it has an even wider audience world-wide.
Year(s) Of Engagement Activity 2021
URL https://www.kew.org/science/engage/get-involved/conferences/pollinator-health