IAP2-22-477

Mitigating the impact of LED streetlighting on insects

Many moths have been undergoing dramatic declines in Great Britain over the past couple of decades1. This is important because adult moths are important pollinators2 and they are a crucial part of the food chain for other vertebrate and invertebrate predators. Some of the drivers of moth declines, including habitat loss, agricultural intensification and climate change, are large-scale drivers which need to be addressed at national and international scales. However, artificial lighting at night is another potential driver of moth declines3: previous PhDs in our labs have demonstrated the negative impacts of streetlighting on adult moths4 and on their larvae5, and our preliminary work (unpublished) suggests impacts on the development of nocturnal butterfly larvae.

LED lighting (which emit more light in the blue spectrum than the traditional sodium streetlights) has been shown to be particularly problematic5. This is concerning because of the large-scale, widespread shift towards LEDs for public lighting over the past decade6. However, LEDs are beneficial because they are more energy efficient and reliable than alternative light sources and, crucially, can be individually and remotely controlled. This provides options to fine-tune the lighting regime (e.g. reducing the brightness of the lights, part-night lighting or part-night dimming, dimming linked to movement sensors, or changing the colour temperature from bluer to yellower lighting) to reduce impacts on nocturnal nature and on humans. Furthermore, lighting has been proposed to indirectly affect moth populations via parasitism, although this remains untested3. Parasitoids are primarily diurnal, so artificial lighting potentially releases them from their day-time niche.

Field work will primarily be conducted on the Isle of Wight. The whole island is a UNESCO Biosphere reserve (recently awarded in 2019, with the aim of bringing the community together in pursuit of a culturally and ecologically sustainable future) and the island’s council is applying for the south-west of the island to be an International Dark Skies Park. The Isle of Wight was one of the early adopters of LED street lighting, with the switch to LEDs complete in 2015. The LED streetlights can be individually controlled remotely in terms of brightness and timing by our end-user collaborator (Ringway Island Roads Ltd). Our other end-user collaborator (ARC Consulting) has a strong track record in public engagement, so can support assessment on the public acceptability of potential changes (considering the trade-off between biodiversity benefits and public safety).

This project will have the following objectives:
OBJ. 1: To test the real-world impact of changing the regimes of LED streetlighting (brightness, timing and/or colour hue) on moths (adults and larvae, and their parasitoids);
OBJ. 2: To experimentally test the impact of changing regimes of LED lighting on growth rates of lepidopteran larvae (nocturnal-feeding moth and butterfly larvae);
OBJ. 3: To predictively model the impact of changing lighting regimes on regional moth populations, including constraints such as public acceptability, best practice of lighting professionals and costs.

Impact summary: This work is combines fundamental ecological research with solutions-focussed impact, specifically exploring how impacts of LED lighting on biodiversity can be mitigated, thus aligning strongly with NERC and UKRI’s strategies. Recent research by the team5 received international press coverage and was cited as evidence in statements from local councils about the importance of reducing the impacts of light pollution. The current research will address the gap in evidence about societally-acceptable ways of mitigating the impacts of artificial lighting. At the regional level, within our Isle of Wight case study region, we have already established good links with the Isle of Wight council through Island Roads (the contractors responsible for delivering streetlighting on the island). Our findings will therefore directly link to the delivery of future lighting on the Isle of Wight and more widely, through their contacts with the Institute of Lighting Professionals. ARC Consultancy (end-user collaborators) were instrumental in the Biosphere Reserve designation and so will facilitate wider impact amongst the public in the Isle of Wight, including the application for a Dark Skies Park on the island.

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Image Captions

The impact of streetlighting can be locally severe. What can be done to mitigate these effects on biodiversity? (Photo credit: Douglas Boyes)

Methodology

This project will examine the effects of LED streetlighting regimes (brightness, timing and colour temperature) on moth larvae and adults using a real-world experiment on the Isle of Wight and using laboratory experiments of larval development based at labs at UKCEH in Wallingford (where the student will be primarily based). The field experiments on the Isle of Wight will be designed in collaboration with lighting practitioners at Ringway Island Roads Ltd and ecologists on the Isle of White at ARC Biodiversity & Climate Ltd, and with the project supervisors (e.g. using power analysis to determine sample sizes). Sampling of adult and larval lepidoptera will be conducted according to existing well-established methods. One or more stays on the Isle of Wight (depending on the specific design of the sampling) will be required. The student will undertake DNA analysis of field-sampled lepidopteran larvae to test for difference in the rate of parasitoids under different lighting regimes. Finally, island-scale modelling will be conducted to test the impact of changing lighting conditions on overall and well as local lepidopteran populations.

Project Timeline

Year 1

In year 1, the student will undertake 6 months research skills training and conducting a literature review prior to designing lab-based studies on growth rates of lepidopteran caterpillars under different lighting regimes. Nocturnal moth and butterfly larvae will be sampled from unlit sites in Oxfordshire and reared in experimental chambers under different lighting regimes to test the impact of mitigating the effects of LED streetlighting. The lighting regimes will be selected in collaboration with our end use partners to represent current and potential future options for lighting.
In year 1, the student will also work with the end use partners to construct a feasible, but statistically rigorous experimental design for altering lighting regimes at currently lit sites on the Isle of Wight to be implemented during the flight season of the moths.

Year 2

In year 2, the experimental sites on the Isle of Wight will be sampled for larvae and adult moths during a 6 month placement on the island. Public engagement on the Isle of Wight will help to inform constraints on changes in biodiversity-friendly lighting regimes Samples will be retained for genetic analysis for parasitoids by the student at the University of Newcastle, initially diagnostic PCR to assess rates of parasitism, followed by metabarcoding for molecular species identification.

Year 3

In year 3, the student will construct a spatial model (a ‘digital twin’ of the environment) to predict the impact of changing lighting regimes on moth populations on the Isle of Wight using the experimental and field data collected during this PhD, and spatial distribution data from the National Macro-moth Recording Scheme held by Butterfly Conservation. These models will include economic and social benefits and constraints of changes in lighting.

Year 3.5

The student is expected to lead on writing papers throughout the PhD, the final 6 month period of this PhD is reserved for completing the write up of the project.

Training
& Skills

The structure and implementation of this project ensures that the student is provided with training in the range of skills needed to develop as a well-rounded scientist capable of working in a multidisciplinary setting. The student will have full access to the training opportunities provided by UK Centre for Ecology & Hydrology, including a dedicated member of staff providing student support, a structure of learning and development opportunities on a 1:1, group and community basis and access to UKCEH internal training courses and personal development opportunities along with some access to externally provided training courses as required. The student is expected to write scientific papers during their research and mentoring will be provided by the academic supervisors.

The project will specifically provide training skills in field sampling and taxonomy (including the application of DNA-sequencing). Bespoke training will be provided by members of the team in ecological sampling, experimental design and analysis (Pocock, George, Fox, Evans), DNA analysis (Evans & Newcastle Network Ecology Group), ecological modelling (Pocock & Evans) and stakeholder engagement (Pocock and ARC Biodiversity & Climate). They will also have access to expertise in public lighting via Ringway Island Roads Ltd.

The project will be 42 months duration to allow the student time to receive training in a variety of ecological methods and to process large datasets.

References & further reading

1. Fox, R. et al. The State of Britain’s Larger Moths 2021. (2021).
2. Macgregor, C. J., Pocock, M. J. O., Fox, R. & Evans, D. M. Pollination by nocturnal Lepidoptera, and the effects of light pollution: A review. Ecol. Entomol. 40, (2015).
3. Boyes, D. H., Evans, D. M., Fox, R., Parsons, M. S. & Pocock, M. J. O. Is light pollution driving moth population declines? A review of causal mechanisms across the life cycle. Insect Conserv. Divers. 14, 167–187 (2021).
4. Macgregor, C. J., Evans, D. M., Fox, R. & Pocock, M. J. O. The dark side of street lighting: impacts on moths and evidence for the disruption of nocturnal pollen transport. Glob. Change Biol. 23, (2017).
5. Boyes, D. H., Evans, D. M., Fox, R., Parsons, M. S. & Pocock, M. J. O. Street lighting has detrimental impacts on local insect populations. Sci. Adv. 7, eabi8322 (2021).
6. Sánchez de Miguel, A., Bennie, J., Rosenfeld, E., Dzurjak, S. & Gaston, K. J. Environmental risks from artificial nighttime lighting widespread and increasing across Europe. Sci. Adv. 8, eabl6891 (2022).

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