Degradation of Odour signals by air pollution: chemical Mechanisms, plume dynamics and INsect-Orientation behaviour (DOMINO)

This project will investigate the mechanisms by which air pollution can disrupt vital airborne chemical signals that insects use for critical processes, such as mating or finding a flower, and will evaluate the ecological consequences of this phenomenon.

Air pollution is a global issue that regularly hits the front pages of newspapers. Despite tough legislation, pollution levels in many areas remain above the legal limits. For example, multiple locations in London breached annual limits for the traffic-produced gas nitrogen dioxide within the first week of January 2016. Exceeding these limits not only poses major risks for human health, but also leads to substantial EU imposed fines for the UK. In developing nations the problem can be even greater. For example, in December 2015 China issued its second ever "red alert" for air pollution in Beijing, resulting in restrictions on vehicle use and the closure of schools. Air pollution, however, is not limited to large industrialised cities. Rural areas are also regularly exposed to pollution transported from cities and major roadways and are increasingly impacted by ozone pollution due to both a rise in the global background and regular weather-induced episodic ozone peaks often referred to as ozone bubbles. One such episode was triggered during the August 2003 heat wave and is thought to have resulted in 2139 deaths in England and Wales.

Concerns over public health have driven current efforts to reduce air pollution, but there is strong evidence to suggest that the health of plants and insects are also at risk. The honey bee for example, finds food by following the unique blend of volatile organic compounds (VOC) emitted by flowers. However, we and others have recently demonstrated in laboratory experiments that common air pollutants, such as diesel exhaust and ozone, can disrupt these floral odours, but we do not yet understand what consequences this might have in the real-world. Nonetheless, it is clear that any disruption to these signals may have wide ranging and as yet unquantified impacts on the important ecosystem services they provide, such as pollination (estimated to be $361bn globally and £691m in the UK) and pest-regulation ($417bn globally).

This project will result in a step-change in our knowledge of this subject by radically advancing our conceptual understanding of how air pollution interacts with the VOCs that many insects rely on to communicate and interact with their environment.

Initially we will conduct studies to provide comprehensive evidence of how a range of key air pollutants (nitrogen dioxide, nitrate radicals and ozone) in isolation and in combination, react and interact with a series of selected VOCs, which function as either floral attractants or pheromones. We will then establish which products of these reactions a pair of model insects, the silver y moth and the buff-tailed bumblebee, are capable of detecting. Next, we will for the first time measure how degradation occurs spatially within odour plumes at time scales relevant to atmospheric mixing processes and insect navigation. Finally, we will use these data to: (i) quantify the effects of diesel exhaust (a major contributor to nitrogen dioxide pollution) and ozone pollution on the ability of male moths to locate females and pollinators to locate and pollinate flowers in field studies; and (ii) establish the effects of odour degradation in the plume on in-flight orientation behaviour of moths flying to the selected VOCs in a wind tunnel. This will provide us with a significantly advanced erudition of the mechanisms by which pollutants can degrade volatile odours used by insects and the effects that this has on insect behavioural ecology and the vital ecosystem service of pollination.

This multidisciplinary research project will be of interest to a wide range of researchers, practitioners, organisations and the general public. This is a very novel area of research, therefore precise quantification of possible impacts poses a challenge. However, we have identified four key stakeholder groups with the potential to directly benefit from the planned research:

1. NGOs: A number of non-governmental organisations may benefit from the outcomes of the project, particularly wildlife and conservation organisations. Insects are a critical part of all terrestrial and freshwater ecosystems and are required for healthy ecosystem functioning and the maintenance of biodiversity. This project will provide information on how air pollution may interfere with insect ecology. This will be used to provide actionable insights for wildlife and conservation organisations in planning and developing conservation strategies, which will impact upon the management of wildlife reserves.

2. Practitioners: The two main sub-divisions of practitioners who will benefit from the research are: (i) beekeeper groups, and (ii) producers and advisors. The value of insect pollination to UK agriculture is estimated at £691M p.a. (2011). Under current agricultural practices, honey bees play a vital role in global production of pollinated crops, e.g. in the United States pollination by honey bees is estimated to be worth $11.68bn, 3 times the value of wild pollination. Using, field studies, this project will provide the first ever estimate of the effects of odour signal degradation on the ability of insects to provide pollination services and therefore the potential scale of this problem for practitioners. The outcomes of the research will be used to design and provide advisories for beekeepers on how best to manage pollinators to reduce impacts of air pollution, with respect to siting of hives. It will benefit producers/advisors, by providing information on how to enhance pollination services by taking into account the potential impacts of air pollution.

3. Policy makers: The project will play a significant contribution in shaping policy, both nationally and internationally. There is currently great political interest and debate relating both to the wider environmental and health impacts of air pollution, and to declines in pollinator populations and wider biodiversity. The outcomes of this project will be used to inform both debates and influence future policy. At national level Defra's recent National Pollinator Strategy and associated Implementation Plan are critical policy implements, but currently the effects of air pollution interrupting odour communication are not featured because there is insufficient evidence and very limited understanding of field scale effects. This project will provide that lacking evidence and thus have a major influence on future policy, for example by contributing actionable outcomes from the project to influence package design for the Countryside Stewardship Scheme to greater benefit pollinator communities.

4. General public: The recent VW emissions scandal garnered much attention in the mainstream media and has brought air quality issues to the forefront of public awareness, meaning the subject of this research project will resonate strongly. Furthermore, there is already significant public interest in pollinator and biodiversity declines. In 2010 it was estimated that nearly 6k people died prematurely in London alone as a result of NOx pollution. The public will benefit from this research because it is very likely to provide increased political pressure to ensure that current air pollution legislation is rigorously enforced and tightened. Additionally, because those ecosystem services that pollinators and other insect groups provide sustain the production of high value nutritious foods the positive impacts of this project for practitioners in food production will also have direct benefits on UK consumers.