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

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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.