Is light pollution driving moth population declines? A review of causal mechanisms across the life cycle

Abstract

The night‐time environment is increasingly being lit, often by broad‐spectrum lighting, and there is growing evidence that artificial light at night (ALAN) has consequences for ecosystems, potentially contributing to declines in insect populations. Moths are species‐rich, sensitive to ALAN, and have undergone declines in Europe, making them the ideal group for investigating the impacts of light pollution on nocturnal insects more broadly. Here, we take a life cycle approach to review the impacts of ALAN on moths, drawing on a range of disciplines including ecology, physiology, and applied entomology. We find evidence of diverse impacts across most life stages and key behaviours. Many studies have examined flight‐to‐light behaviour in adults and our meta‐analysis found that mercury vapour, metal halide, and compact fluorescent bulbs induce this more than LED and sodium lamps. However, we found that ALAN can also disrupt reproduction, larval development, and pupal diapause, with likely negative impacts on individual fitness, and that moths can be indirectly affected via hostplants and predators. These findings indicate that ALAN could also affect day‐flying insects through impacts on earlier life stages. Overall, we found strong evidence for effects of artificial light on moth behaviour and physiology, but little rigorous, direct evidence that this scales up to impacts on populations. Crucially, there is a need to determine the potential contribution of ALAN to insect declines, relative to other drivers of change. In the meantime, we recommend precautionary strategies to mitigate possible negative effects of ALAN on insect populations.

Insect decline in the Anthropocene: Death by a thousand cuts

“…(34,(42)(43)(44). Similarly, there is mounting evidence that light pollution is driving local declines in suburban and urban locations (45,46). Although not an emphasis of the 11 articles, urbanization is increasingly recognized as an important stressor (47,48).…”

Dealing with host and food searching in a diurnal parasitoid: consequences of light at night at intra‐ and trans‐generational levels

“…Until recently, light pollution had received less attention as a component of global change than other phenomena such as global warming, but a growing number of studies have now revealed the numerous and negative biological consequences of this light at night on many organisms (Hölker et al ., 2010; Gaston et al ., 2014; Bennie et al ., 2016). Insects seem particularly affected by artificial light at night, which has consequences at individual, population and ecosystem levels (Desouhant et al ., 2019; Boyes et al ., 2021). Artificial light at night has also been identified as a factor that could drive the decline of insect populations (van Langevelde et al ., 2018), raising questions about their conservation.…”

From forest to fragment: compositional differences inside coastal forest moth assemblages and their environmental correlates

“…Additionally, light pollution can be enhanced when more urban areas are surrounding the sampling site. Artificial light at night has major effects on nocturnal insect communities, disrupts the development of insects at different life stages (Boyes et al 2020 ), affects their fitness directly by reducing optical efficiency and orientation, and desynchronizes their internal clock (Owens and Lewis 2018 ). So, there are multiple possible reasons that might explain the observed patterns in β-diversity.…”