National patterns of functional diversity and redundancy in predatory ground beetles and bees associated with key UK arable crops

1. Invertebrates supporting natural pest control and pollination ecosystem services are crucial to world-wide crop production. Understanding national patterns in the spatial structure of natural pest control and pollination can be used to promote effective crop management and contribute to long-term food security. 2. We mapped the species richness and functional diversity of ground beetles and bees to provide surrogate measures of natural pest control and pollination for Great Britain. Func- tional diversity represents the value and range of morphological and behavioural traits that support ecosystem services. We modelled the rate at which functional diversity collapsed in response to species extinctions to provide an index of functional redundancy. 3. Deficits in functional diversity for both pest control and pollination were found in areas of high arable crop production. Ground beetle functional redundancy was positively corre- lated with the landscape cover of semi-natural habitats where extinctions were ordered by body size and dispersal ability. For bees, functional redundancy showed a weak positive cor- relation with semi-natural habitat cover where species extinctions were ordered by feeding specialization. 4. Synthesis and applications. Increasingly, evidence suggests that functionally diverse assem- blages of ground beetles and bees may be a key element to strategies that aim to support pol- lination and natural pest control in crops. If deficits in both functional diversity and redundancy in areas of high crop production are to be reversed, then targeted implementation of agri-environment schemes that establish semi-natural habitat may provide a policy mecha- nism for supporting these ecosystem services.