Exploring Mayflies and Bats: Assessing the Risk to Chemicals (EMBARC)

Food security is critical to the effective functioning of human society and plant protection products (PPPs) such as herbicides, insecticides and fungicides, play a vital role supporting this endeavour by maintaining crop yields through the reduction of pests. However, there is always a risk that by releasing chemicals inherently designed to be toxic to some target pest or disease, that unacceptable effects on the wider environment may also result. As such, environmental risk assessment (ERA) plays an essential role in the regulation of PPPs in the UK and European Union as well as globally.
Current ERA methods require a comparison of predicted exposure following the use of a product to a known effect concentration of that product. Exposure has been predicted using mechanistic fate models for two decades, whilst determining effects endpoints (e.g. LD50, the concentration of a product that results in mortality of 50% of organisms) has consistently required animal testing under simplistic exposure regimes. The problem with this approach is that exposure is dynamic and simple assumptions of constant exposure in the laboratory tests are therefore not realistic. Furthermore, the effects of a product are identified on an individual organism (e.g. the effect on the number of eggs an organism lays), however, we are often more interested in what the effects on a whole population are and protecting a certain level of ecosystem functioning that maintains all the services humans enjoy from their environment (e.g. food security in agriculture, wildlife ecotourism). As such, this project looks to explore the link between individuals and populations using ecological models to address issues with the current risk assessment methodology and unnecessary / excessive animal testing.
Two groups of species will be studied: bats and mayflies. Our current understanding of the risk to bats is lacking, as it is not known whether they are active when agricultural products are being applied, nor how they may come into contact with chemical residue after application (e.g. though foraging and drinking). Field surveys will be performed to assess the presence / absence of bats in agricultural landscapes throughout the growing season and to observe the links between chemical exposure (direct spraying and residues) and food items within these landscapes. Ecological models will then be used to explore how exposure on individual bats leads to changes in bat populations.
Mayflies meanwhile are indicators of good water health as they are sensitive to changes in the environment and also to exposure to many chemicals. However, they are difficult to culture in the laboratory and provide variable results in experimental tests on chemical effects. In this project we will establish a laboratory culture of mayflies by exploring environmental cues that induce synchronised swarming. Once established, experimental studies will be performed to investigate how changes in the environment result in changes in growth, reproduction and survival. The results will be used to parameterise an ecological model that can then explore the effects of chemicals on populations of mayflies.
The species selected for this project are of significant interest with regards to environmental health and knowledge of population-level responses to chemical exposure will allow appropriate mitigation of risk to be considered in the registering of plant protection in the future, all whilst further reducing animal testing.