Optimising Nature's pharmacies: plant chemicals and pollinator health at the landscape scale

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Bumble bees are not just the beloved buzz of summer meadows, they are essential to the fertilisation of wild flowers, and without them and other flower-visiting insects many of our flowering plant species would disappear. Bumble bees are one of the most important pollinating groups for wild flowers but many bumble bee species are in decline around the world. One reason for their decline is the impact of parasites on their health. Our recent work has shown that flowers not only supply visiting bumble bees with nectar for sugar and pollen for protein, but that they also provide substances that can help to combat parasite infections, and thus improve bumble bee health. If we can understand where and when these substances are produced and under what circumstances they can improve bumble bee health, we will be able to manage the landscape to maximise their benefit. In essence, we can turn natural landscapes into pharmacies for bees.Recently, we found that ling heather, which dominates heathland and moorland in the UK, and is one of the top 4 producers of nectar for bees, produces a natural substance called callunene in the nectar, which prevents the infection of individual bumble bees with a gut parasite that can have dramatic impacts on bee health. However, lowland heathland is a highly threatened habitat, with more than 80% lost over the last 200 years, and the UK holding 20% of the global remains. In this study we will test whether the positive impact of callunene on individual bumble bees scales up to similar impacts on the health of bumble bee colonies. We will do this under controlled laboratory experiments, through controlled exposure in the field, and then in actual lowland heath, to unravel how positive impacts emerge. We will also quantify callunene production across lowland heaths to understand what factors drive its production. This will allow us to calculate the additional health value of lowland heaths to bumble bees, and understand how we can manage heaths to maximise their value to bee health.Overall, we will assess the value of Nature's pharmacy to bee health, and provide information and guidance to managers of lowland heath to aid them in maximising the health of the bees on which heather relies.