An integrated model for predicting bumblebee population success and pollination services in agro-ecosystems

It is now widely recognized that both wild and managed pollinators provide a vital ecosystem service, essential for the maintenance of biodiversity in natural and semi-natural ecosystems, and necessary for crop production in ~75% of the world's crop species. Recent estimates suggest that crop pollination in the UK is worth £440 million. The main crop pollinators in the UK and throughout the temperate northern hemisphere are honeybees and bumblebees; honeybee populations are threatened by health issues, while many bumblebee species have undergone range declines, probably primarily due to habitat loss. There is thus an urgent need to develop farm management strategies which sustain both healthy populations of pollinators and crop yields. For bumblebees, we lack a detailed understanding of the relationships between the growth and survival of bumblebee nests, the spatial and temporal distribution of the floral resources on which they depend, and the spatial distribution of pollination services they provide. We cannot predict how many bumblebee nests a landscape can support, or how many crop plants they can pollinate. We do not know how many flowers are needed to support a single healthy nest, or how important predators and parasites are in removing bees and whole nests. This project proposes to use a systems approach to answer these questions, combining simulation models with a range of field and genetic studies to provide a new insight into factors governing bumblebee populations in agroecosystems. We will quantify the spatial and temporal distribution of pollen (protein) and nectar (sugar) provided by flowers in 10 representative landscapes (5 in England, 5 in Scotland) using GIS-based maps. In lab studies we will quantify the resources (protein and sugar) needed for healthy growth of a nest. Using novel camera systems developed by the applicants we will monitor wild bumblebee nests to establish rates of predation of nests and of individual bees. These data will feed in to models which will be developed to simulate the growth of realistic numbers of bumblebee nests seeded into our ten landscapes, with models also simulating the foraging of individual workers (agents) from each nest, estimating which food patches they are likely to exploit. Colonies will interact in the landscape through exploitation of resources, and be subject to realistic rates of predation and parasitism. The model will be validated by measuring actual colony growth rates of experimental nests placed into these landscapes, and by measuring the number of nests of different bumblebee species exploiting particular patches of forage within these landscapes (quantified using genetic techniques to identify sisters). Once validated, the models will then be used to predict the spatial distribution of crop pollination services for field beans, and these predictions tested by field measurements of bee visitation rates. The models will also be used to simulate the consequences of adding floral resources to the landscape in terms of pollen and nectar strips, enabling us to quantify how many extra bee nests, and how much extra crop pollination, can be supported. The project will build on and contrast with honeybee models currently being developed in a BBSRC-funded project at Rothamsted. Overall this project will, for the first time, provide us with mechanistic links and quantitative, validated predictions linking bumblebee populations, wildflowers, bee predators and crop pollination.

We propose to use a systems approach to enable us to understand the mechanistic links between bumblebee populations, the distribution of floral resources in the landscape, bee predators and parasites, and delivery of crop pollination. We will develop, parameterise and validate simulation models in which individual bees (agents) from multiple nests operate within replicated synthetic landscapes based upon 10 real agro-environments, 5 in central England and 5 in Scotland. Bees from nests will interact through resource depletion, and both individual bees and nests will be subject to realistic levels of predation and parasitism. Sub-models based on forager behaviour will predict where foragers from particular nests are likely to feed. Predictions will be validated by measuring growth of real colonies in these landscapes, and by using genetic techniques to quantify the number of colonies of different bumblebee species which are visiting patches of forage in these landscapes. Validated models will be used to predict the spatial distribution of pollination services within these landscapes, which will be tested for field beans. The models will also be used to simulate the effectiveness of adding areas of pollen and nectar flower strips to the landscape in boosting bee populations and pollination services. The models will provide a powerful tool for designing sustainable management practices for pollinators and pollination services in agroecosystems.

The impact of this project will be a substantially enhanced understanding of the dynamics of an important group of pollinators (bumblebees) in farmland and their subsequent service to crops. This can be used to predict how crop management and environmental changes are likely to alter provision of this ecosystem service, and provide opportunities to mitigate negative effects to ultimately enable us to farm in sustainable systems. It is therefore of high relevance to many stakeholders.

As well as scientific publications, the project will deliver models that can be used as tools to inform policy makers, farmers, land managers and conservationists about the potential usefulness of management initiatives and for ensuring the survival of bumblebee populations. Furthermore, pollination is crucial for farmers, and the results will help ensure bees can be deployed practically and sustainably to provide good yields for appropriate crops. This will become increasingly important as summers become warmer and drier and new crop species are planted e.g. sunflower.

Who will benefit and how?

Policy makers (e.g. Defra)
The project will provide outputs to policy makers and regulators in regional, national, EU and other agencies. These will serve as the basis for the development of sound policies with respect to pollination and agri-environment schemes, as well as practical advice and recommendations to practitioners in the land-based industries.

Farmers and the associated agri-food industry
We translate our scientific outputs into practical advice for farmers and the agri-food chain (including providers of agricultural chemicals, seeds and software) via workshops, seminars, reports and farm walks in association with organisations that link directly to the farmers. The findings of this study will also be used by Syngenta to focus and optimise the beneficial effects of their "Operation Pollinator" encouraging farmers to sow nectar and pollen mixtures. The model of foraging bumblebees can be used alongside our honeybee model to improve the agrochemical industry's understanding of how different bees are likely to be exposed to its products (see letter of support).

The NGO community: wildlife, conservation and environmental organisations and advisors.
Conservation organisations and stakeholders, such as Natural England, British Trust for Ornithology, the RSPB, The Game and Wildlife Conservation Trust, Butterfly Conservation and the British Beekeepers Association already collaborate with us and utilise the results we publish to enhance public awareness and advise land managers. In particular, Prof Goulson is the founder of the Bumblebee Conservation Trust (BBCT), which has 8,000 members and the data from this project will be fed into the first national Bumblebee monitoring scheme, "BEEWALKS" which was launched by the BBCT in 2010, and more generally will be used to inform the conservation strategies of the Trust.

The public
The public at large are fascinated by bees and pollination, and rely on them for production of food to ensure a healthy and balanced diet. The applicants have an excellent track record in reaching a wide audience with high profile and exciting science, via talks, specific events (workshops, Open Days, Chelsea Flower show exhibits etc) and all forms of media (web, press, radio, television). We will continue to use all these types of communication to maximise impact. In particular, Goulson's direct involvement in the BBCT provides an ideal opportunity to publicise the results and get the public involved. Thanks to recent funding successes, BBCT is launching a new nationwide project, "Bees for Everyone". Each year from 2012-14 this will deliver: 75 talks to local interest groups; 30 guided walk and bee identification days; 10 farmer liaison days; 3 bumblebee conservation symposia (England, Wales & Scotland). These events provide an ideal medium for disseminating the results of the proposed research.