Bridging the gap: Combining genomics & ecology to determine the effects of field applications of pesticides on the UK bumblebee, Bombus terrestris.

Pollinating insects are a vital component of biodiversity that provide economically and ecologically important services through wildflower and crop pollination. Populations of pollinating insects are declining, and there is an urgent need for research to understand the causes. A key hypothesis for the decline is pesticide use in agriculture. Pesticides are readily available to pollinators through their direct application onto crops, and also through their translocation through soil into plants. Recent research suggests exposure to pesticides has detrimental effects on behaviour, physiology, growth and productivity of non-target insects. Pesticides work by binding to specific receptors in the genome and disrupting molecular function. Thus, to understand the direct impact of pesticides on an insect, gene-level analyses are required. Relatively little is known about how pesticides impact on the molecular machinery of bees, which are key pollinators, and there have been no studies on the genome-wide effects of exposure on gene expression, regulation or protein production. Such knowledge is fundamental for understanding why the detrimental phenotypic effects occur, and ultimately towards the development of more bee-friendly pesticides. Recent advances in molecular technologies mean we can analyse the transcriptomes of wild bees at a cost and efficiency previously unattainable. This project capitalises on these advanced technologies to conduct a genome-wide analyses of how field-realistic pesticide exposure alters the molecular phenotype of the common UK bumblebee, Bombus terrestris.

The UK farming industry is worth £5.5 billion and is increasing annually. An increasing population means demand for food is higher, while land available for agricultural purposes decreases (over 70% of the UK is currently used for agricultural practises). Sustainable farming, which maximises crop outputs while improving the delivery of environmental outcomes, is of increasing importance and has been outlined a key priority in a number of government plans, both in the UK, the EU and globally. Pollinating insects provide economically and ecologically important services through wildflower and crop pollination and therefore there is an urgent need for research to understand the causes of pollinator decline and to reduce environmental pressures of farming practises.

Potential tensions exist between improving the environment and increasing food production. However, the grant provided by the Cabot Institute has funded site visits to a number of farms across the UK to establish field sites for this project and to facilitate new connections with members of the agricultural industry.

Six fieldwork sites have been set up for this project; 3 organic farms and 3 arable (conventional) farms in Devon, Hereford, Somerset and Surrey. The three major UK arable crops (oilseed rape, wheat and spring barley) are treated annually with >11000 tonnes of pesticides, including two or more insecticides, fungicides and a seed treatment. Oilseed rape in particular is an important food source for bees and other pollinators and is in turn, heavily dependent on bees for pollination. The three arable farms to be used as field sites for this project are all major producers of oilseed rape and pesticide applications are vital for its production. Participating agronomists have highlighted the difficulties experienced by farms following the recent neonicotinoid ban and have provided vital information to use in my grant applications on the amount and type of pesticides which are currently used in the UK. This will be a key component in making my grant field-realistic and identifying the synergistic effects of pesticide mixtures. The organic farms will be used as 'control' sites to compare the genomic profiles of pesticide-exposed bees to non-exposed bees. Both the arable and organic farms have also provided me with important information on local bee populations which will be integrated into the fieldwork.

This huge genomic database on the effect of realistic pesticide exposures on bees will provide a UK-wide data set on the effects of different land-use on the molecular phenotype of bees.

The grant from the Cabot Institute has provided field-work sites and pilot data for a NERC fellowship, as well a BBSRC standard research grant. For more information, please follow the link above to the Sumner lab group website.