Bee sensitivity to a century of agricultural land-use change

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.

The proposed project will provide results of interest not only to academics, but to a wide range of beneficiaries including: (i) policy makers (ii) agriculturists (iii) commercial parties relating to the chemical/pesticide industries (iv) conservationists and wildlife trusts (v) museums and (vi) the general public.

Bee pollination provides a service that has an economic value of >£300 million in the UK alone (>$150bn p.a. globally) thus identifying the factors causing bee declines is of fundamental importance. In relation to (i) policy makers, the project will provide data that can aid pesticide regulatory authorities by informing on how bees are coping in a pesticide exposure landscape. The data produced could also contribute to evidence considered by the EFSA on the risks of pesticide exposure to beneficial arthropods (primarily bees). The neonicotinoid pesticide under investigation in our proposed demographic pinch point experiment is currently under restrictions for use on flowering crops, therefore our findings may help to inform decisions on future applications. We believe that research in this field has the potential to change policy especially if we consider that previous work by Gill was used to debate and influence the EU moratorium, and has been presented at Parliament.

Land managers, farmers and beekeepers (ii) have a vested interest in the success of insect pollinators. Our proposed research could inform these parties regarding warning signs of future population crashes and future trends. It will also assist them to identify best agricultural practices and to develop mitigation strategies to benefit pollinators regarding pesticide application procedures. Moreover, by identifying specific detoxification genes this will be of broad use to (iii) ecotoxicologists and the chemical companies themselves (such as Syngenta).

Understanding the threats to insect pollinators, such as bees, is on the priority list of the International Platform of Biodiversity and Ecosystem Services (IPBES). Our findings can help to predict future trends of insect pollinators and other beneficial organisms that may inadvertently be affected by agricultural land use change and agricultural practices. It will also provide conservation groups (iv) with data on the regional population and community status of bees.

In relation to museums (v), our project would bring together curators and collections across the UK to address a grand challenge and reinforce a UK entomological collection network. The multiple museum collections involved will benefit from the genetic data, 3D reconstructions and morphological measurements that we will obtain, and intend to link (likely via QR codes), to each specimen. We envisage that these will be displayed for the visiting public (vi) in each of the respective museums. As has been evident over recent years, there is large appeal of bees to the general public, for instance the press interest surrounding the decline of bees and its impact on food security. We therefore hope that by understanding the past to predict the future this proposed research can assist with mitigating the threats to insect pollinators for conservation, future food security and general human welfare.