Spectral optimization of beacon lights for the protection of night‐swarming mayflies

Abstract

1. Negative ecological effects of artificial night-time illumination on wildlife are becoming more and more widely investigated. Flight-to-light behaviour of insects is a well-known phenomenon, which becomes really conspicuous when numerous individuals are simultaneously attracted to light. Mass mortality of night-swarming mayflies at lamp-lit urbanized areas, particularly at bridges, is a well-known phenomenon.2. White beacon lights are able to keep the mayfly swarms above the water surface. Firstly, it is beneficial for the offspring particularly in the case of protected species. Secondly, this method facilitates maintaining traffic safety on the bridge.3. Our primary aim was to find the optimal emission spectrum for the mayflyprotecting beacons. With equal-intensity quasi-monochromatic light sources, we measured the attraction of Ephoron virgo and Caenis macrura mayflies to light as a function of wavelength in the 432-744 nm spectral range.4. We established that phototaxis of these mayflies increases with decreasing wavelength. We also estimated the attractiveness of different light source types widely used in public lighting to E. virgo. According to our results, lamp types emitting light rich in short wavelengths (cool white/bluish to the human eye) are noticeably more attractive to E. virgo and to other night-swarming mayflies than lamp types with longer-wavelength-dominated emission spectra (warm white/yellowish to the human eye).5. Finally, we report on the construction of the very first, permanently installed, spectrally optimized mayfly-protecting beacon system on the bridge of Tahitótfalu (Northern Hungary), which was realized as a practical application of our results.

Towards Insect-Friendly Road Lighting—A Transdisciplinary Multi-Stakeholder Approach Involving Citizen Scientists

“…In "Tatort Streetlight" data, the orders Ephemeroptera and Trichoptera constitute a significant proportion of the insects collected. The differences in numbers of individuals caught at day and night-time indicate a high vulnerability of these insect groups to road lights close to freshwater bodies, which corroborates prior studies [39,65]. Another group that might be disproportionally affected by artificial light near freshwater ecosystems contains aquatic Heteroptera [66], which were also found significantly more often in the night-time samples.…”

Impacts of Artificial Light at Night on Nocturnal and Diurnal Insect Biology and Diversity

“…Several detailed plans have been drawn up to mitigate the impact of ALAN especially in protected areas (Jägerbrand and Bouroussis 2021). For example, in Hungary, researchers have successfully reduced attraction of many species of the Ephemeroptera to light by optimising the spectrum of beacon lights on a bridge such that the adults do not show a mass phototactic response (Mészáros et al, 2021). Since adult Ephemeroptera live only for a few hours, and spend their development stages in water, the judicious adoption of such mayfly-protecting lights near water bodies is a practical mitigation measure.…”

Spectral sensitivity transition in the compound eyes of a twilight-swarming mayfly and its visual ecological implications

“…In a recent study, when our primary aim was to optimize a phototaxis-based mayfly protecting system [12] (electronic supplementary material, movie S4), we revealed that the attraction of E. virgo and another twilight-swarming mayfly ( Caenis macrura Stephens, 1836) to light is the highest for UV and blue light and decreases with increasing wavelength [13]. Similar results were reported for other, non-identified twilight-swarming mayfly species [14].…”