Reclaiming the night sky for moths: what drives the flight-to-light response and how can this be mitigated?

How ALAN impacts local insect populations is a topic of growing interest within the field of environmental biology. Recent findings have shown that over the last 50 years, 33% of moth species have declined in total abundance in Britain. This tragic loss of biodiversity is poorly understood, but artificial light at night (ALAN) has been shown to disrupt moth reproduction, larval development, and pupal diapause. Recent research has also begun to demonstrate that these factors have potential to translate into population level impacts. Moths provide an array of ecological functions, such as pollination, supporting higher trophic levels as prey, and serving as indicators of a healthy ecosystem. Consequently, their population decline may have wider reaching ecological consequences, and hence there is a need to propose a solution to reduce ALAN's impact on biodiversity.
To date, experimental comparisons of different moth responses have largely been conducted on a single or small group of species. Furthermore, these experiments tend not to focus on the significance of different wavelengths, but instead conduct experiments with colours of light, 'blue', 'red' for example, across the visible and UV spectrum (350-700 nm). Our experimental design will be more mechanistic and examine responses across moth taxonomy using a set of candidate species to understand their flight-to-light behaviour in response to light intensity, wavelength structure and diffuse versus directed light. We will test the long-standing hypothesis that phototaxis increases with decreasing wavelength and increasing intensity. We will build a simple electroretinography set-up to assess visual capabilities of moth eyes by determining the magnitude and speed of the photoreceptor responses on the surface of the eye, thereby implicating different wavelengths as important or not. The purpose of this will be to demonstrate the principles of spectral tuning to minimise impacts on moths. Through this, we hope to provide and demonstrate a solution to reduce ALAN's impact on insect biodiversity.