Current evidence in support of insect-friendly lighting practices
Avalon C. S. Owens, Michael J. O. Pocock, Brett Seymoure
Abstract
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. • We do not know if ‘sustainable’ lighting practices actually reduce harm to insects. • The benefits of spectral tuning and dimming are ambiguous and frequently negligible. • While motion detectors show promise, timers may be less effective or even harmful. • Relative to its potential, shielding has attracted strikingly little scientific attention. • The least disputed mitigation method remains complete removal of unnecessary lights.