Part-night exposure to artificial light at night has more detrimental effects on aphid colonies than fully lit nights

Experimental study on the impact of continuous and dynamic artificial light at night on moths originating from different skyglow conditions

Biodiversity is negatively affected by light pollution, caused by artificial light at night (ALAN). Light-emitting diodes facilitate new lighting technologies to mediate the negative effects of ALAN, such as dynamic ALAN where light intensity can be adjusted to traffic density. Organisms living in highly light-polluted areas may show adaptations to mitigate the negative effects of ALAN. In a split-brood rearing experiment, larvae of two moth species (Ochropleura plecta and Agrotis exclamationis) originating from low-medium and high-medium skyglow populations were grown under either continuous ALAN, dynamic ALAN or control-dark conditions. We tested for ALAN effects on larval mortality, feeding behaviour, development and body mass, and whether effects depended on skyglow levels in the population of origin. Contrary to previous studies, we found either no or positive effects of ALAN on larval development, with similar or stronger effects of dynamic ALAN compared to continuous ALAN. For A. exclamationis, we showed evidence for faster development, increased growth rate and higher body mass under ALAN. This could reduce larval exposure to parasites and increase fecundity. We found no evidence for evolutionary responses in low-medium or high-medium skyglow larvae. Our results show that ALAN does not affect larval development the same way in all species.

Current evidence in support of insect-friendly lighting practices

Anthropogenic light pollution is an emerging threat to natural ecosystems with myriad effects on insects in particular. Insect conservationists are increasingly interested in mitigating this driver of insect declines via sustainable lighting practices. Current recommendations often follow the five principles for responsible outdoor lighting developed by DarkSky International, a nonprofit organization founded by astronomers. While these principles unquestionably increase star visibility, their ecological costs and benefits remain relatively unexplored. Herein, we review recent research into the effects of each principle on insect fitness broadly defined. Most studies test the efficacy of spectral tuning, followed by dimming, although both mitigation methods seem generally ineffective in practice. In contrast, both shielding and motion detectors show promise as mitigation methods but remain remarkably understudied. Nonetheless, a preponderance of evidence now demonstrates that removing unnecessary light sources from natural habitats can reverse their varied impacts on diverse insect taxa and greatly benefit insect conservation.

Plant invasions under artificial light at night

Artificial light at night (ALAN) is a global change driver but how it interacts with plant invasions is unclear. Determining this requires understanding direct effects of ALAN on physiology, phenology, growth, and fitness of both invasive and native plant species and its indirect effects mediated through mutualistic and/or antagonistic interactions.

Light pollution in complex ecological systems

Light pollution has emerged as a burgeoning area of scientific interest, receiving increasing attention in recent years. The resulting body of literature has revealed a diverse array of species-specific and context-dependent responses to artificial light at night (ALAN). Because predicting and generalizing community-level effects is difficult, our current comprehension of the ecological impacts of light pollution on complex ecological systems remains notably limited. It is critical to better understand ALAN's effects at higher levels of ecological organization in order to comprehend and mitigate the repercussions of ALAN on ecosystem functioning and stability amidst ongoing global change. This theme issue seeks to explore the effects of light pollution on complex ecological systems, by bridging various realms and scaling up from individual processes and functions to communities and networks. Through this integrated approach, this collection aims to shed light on the intricate interplay between light pollution, ecological dynamics and humans in a world increasingly impacted by anthropogenic lighting. This article is part of the theme issue 'Light pollution in complex ecological systems'.