Reducing the blue spectrum of artificial light at night minimises insect attraction in a tropical lowland forest

Abstract

1. New infrastructure development in previously natural environments is introducing light pollution to habitats at an unprecedented rate, which has the potential to be devastating for native insect assemblages.2. We evaluated insect attraction to three lamp types emitting different spectra of light (white, yellow-filtered and amber-filtered 3000 K LED lamps) and an unlit control in a lowland forest site in the northern Peruvian Amazon previously naïve to artificial illumination.3. Lamp type was the only variable included in the most parsimonious models explaining morphospecies richness and abundance for all insects combined and for eight different insect orders. White lamps (3200 K) attracted far more insects, both morphospecies and individuals, including groups containing important vectors of pathogens, bacteria or parasites, than either yellow (2700 K) or amber (2200 K) lamps.4. Amber lamps attracted the fewest morphospecies and individuals overall but were the most attractive for a limited group of insects, including elaterid beetles (click beetles) and mycetophilid flies (fungus flies).5. While period of night was not a significant predictor of morphospecies richness or abundance, different assemblages of insects were collected during two different sampling periods (18:00-20:00 and 03:00-05:00).6. We strongly recommend that new infrastructure development projects introducing ALAN to light-naïve tropical forests use filtered amber LED lamps with no blue and minimal green light content in outdoor lighted areas. Similarly, operators should develop outdoor lighting plans that include overall reduction of nocturnal lighting and impact mitigation measures. These recommendations should also be used to retrofit existing infrastructure including roads and human settlements.Abstract en español. 1. El desarrollo de nuevas infraestructuras en entornos previamente naturales está introduciendo contaminación lumínica en esos hábitats a una taza sin precedentes, la cual tiene el potencial de ser particularmente devastadora para las comunidades de insectos nativos.2. Evaluamos la atracción de insectos a tres tipos de lámparas que emiten diferentes espectros de luz (lámparas LED blancas de 3000K sin filtro, con un filtro amarillo y con un filtro ámbar para limitar o eliminar los espectros azules de luz emitidos) y un control sin luz en un sitio de bosque bajo en el norte de la Amazonía peruana, previamente sin iluminación artificial.

Street lighting has detrimental impacts on local insect populations

“…This is worrying, given the current shifts in outdoor lighting technologies toward white LEDs ( 21 , 34 ). Yet, LEDs can be modified more easily than sodium lamps by adjusting their intensity (dimming) and spectral output (custom colors and filters) ( 38 , 63 , 64 ), offering the opportunity to minimize the negative impacts on insect populations, and linked ecosystem processes, at marginal costs.…”

11 Pressing Research Questions on How Light Pollution Affects Biodiversity

“…Although lighting professionals (e.g., design and industry) increasingly acknowledge ALAN as a threat to biodiversity, there are diverging views regarding potential obstacles to light pollution mitigation (Schulte-Römer et al, 2019;Pérez Vega et al, 2021). Current technological advancements in outdoor lighting, particularly LEDs, in principle allow developing lighting mitigation strategies that balance conflicting interests between humans and biodiversity, but this potential remains largely untapped (Longcore, 2018;Bolliger et al, 2020;Deichmann et al, 2021;Jägerbrand and Bouroussis, 2021). Furthermore, LEDs are an energy efficient technology that promises net savings in energy consumption.…”

Potential Reasons for Insect Decline

“…It distracts or disorientates either the courtship partners or simply reduces the efficacy of communication by flooding the background with illumination thereby decreasing the signal to noise ratio. Deichmann et al [48] suggested that switching to lights of longer wavelength in order to minimize the adverse effects on majority of insects in turn attract bioluminescent insects thereby posing threat to their survival. Langevelde et al [49] studied the effect of artificial light on feeding behavior of moths.…”