Bee sensitivity to a century of agricultural land-use change.

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The world's natural resources have been placed under significant pressure over the past century, due to the exponential growth rate of the global human population. This has resulted in a significant increase in agricultural land-use and subsequent loss of 'natural habitats', a pattern associated with high losses in biodiversity. Declines of insect pollinators, such as bumblebees, are of particular concern as their role in maintaining floral health and diversity is vital, and as agricultural crop pollinators they possess large economic benefits. Understanding threats to these populations is therefore of high priority.Here we take the approach that to understand future threats and solutions we must understand the past, and that to accurately predict future patterns and risks to species, we must gain a better understanding of what is causing those changes. Unfortunately, archival data on insect pollinator abundance rarely goes back more than a couple of decades, and most have been collected in a haphazard way. To fill this knowledge gap we will take a novel approach in which, using a combination of DNA sequencing, morphological and phenological (life-history data looking at seasonal activity) measures, along with experimental test of pesticide resistance, we will test whether populations experiencing different agricultural land use change intensity show signatures of population declines and adaptation to these new agricultural environments (i.e. support for a causal relationship).Here, we will study a large collection of historical bumblebee specimens from six leading natural history museums across the UK. The morphological and genomic data represented in these specimens holds the key to determining how variation in population size, body shape and genetic diversity have changed over the last century.Recent advances in the recovery and analysis of ancient DNA, and developments in the resolution of CT scanning, will enable us to gain unprecedented and novel insights. By working with historical samples from locations that have undergone different amounts of agricultural land use change (for example differences between the east and west of UK) we can specifically test whether temporal changes occur, rather than relying on end point data.It is widely considered that bumblebees are threatened by two of the major factors associated with agricultural intensification: the loss of flowers leading to reduced nutritional resource, and increased exposure to pesticides. However, to our knowledge the interactive effects of these have not been experimentally tested. This project will also conduct a controlled laboratory experiment to understand how changes to nutritional availability and pesticide exposure impact on colony growth and the production of new queens and males.