Bee nesting resources: the missing element of sustainable crop pollination

Project motivation and aims (<300 words):
Background and challenge: Fruit crops depend, at least in part, on pollination services for yield, quality and commercial value. Several projects, including some with WFL, have demonstrated that flower-rich strips in orchards can boost food for pollinators. There is still some work to fine tune these systems, but the basic principles and applications are established. However, supporting more pollinators doesn't always translate in to actual uplifts in pollination services and production. A key element is missing. The main pollinators of fruits crops are bees (especially ground-nesting bees for apples), therefore to sustainably supply pollinators requires the provision of a place to live in addition to forage.
Opportunity: We have some basic knowledge on the nesting requirements of the bees that pollinate fruit crops, and WFL and Reading have a pilot study exploring a simple management intervention to increase the area of bare ground for wild bees to nest in. However, there are many ways to create nesting resources and these need to be explored for their effectiveness and feasibility to be incorporated into existing management practices. We have a network of sites and experts to support a PhD student to identify the most effective and feasible best practices.
Programme of research(<300words):
Overall approach: We will survey orchards and record habitat conditions to characterise the areas which ground nesting bees most favour. We will work with growers to test a variety of different approaches (e.g. scrapes, shallow ditches, small banks) to re-create these conditions using small scale field trials which are compatible with normal orchard management. A cost:benefit analysis will assess the cost of establishment, maintenance and potential uplift in pollination services and commercial grading of each intervention.
Specific methods:
1. Surveys of nesting aggregations to measure soil, aspect, slope, vegetation parameters from >30 aggregations. This will be combined with a literature review to identify the most favoured (and range of) conditions preferred for nesting (year 1).
2. Modelling bee populations. Data from existing aggregations (age since establishment and parasite loads) will be used to assess how the health of aggregations changes over time (years 2-3).
3. Local colonisation experiments. Colonisation rates of newly created habitats (based on characteristics identified in 1.) adjacent to established aggregations will be recorded (years 2-3).
4. Developing and testing interventions. In sites without nesting aggregations of the target bee species, we will develop interventions to enhance local populations. The type of intervention will be based on outputs 1-3. We will use a BACI design with pairs of sites with and without the intervention(s) to monitor the occupancy of our introduced nesting substrates, and the local abundance of our target species (pantraps and timed transect walks). A cost:benefit analysis will assess the costs of the intervention (this studentship) and benefits to pollination (data from ongoing BBSRC project) (years 3-4).
Expected Outcomes: (1) A proven tool to sustainably enhance pollination services and production. (2) Robust evidence to underpin a cheap to establish innovation which can be retrofitted to any commercial orchard. (3) A best practice guide for growers.