Long-Term Comparison of Attraction of Flying Insects to Streetlights after the Transition from Traditional Light Sources to Light-Emitting Diodes in Urban and Peri-Urban Settings

Abstract

Among the different light sources used for street lighting, light-emitting diodes (LEDs) are likely to dominate the world market in the coming years. At the same time, the spectral composition of nocturnal illumination is changing. Europe and many other areas worldwide have implemented bans on energy-inefficient lamps, such as the still very common mercury vapor lamps. However, the impact of artificial light on insects is mostly tested with light-traps or flight-intercept traps that are used for short periods only. By comparing the numbers of insects attracted by street lamps before and after replacing mercury vapor light sources (MV) with light emitting diodes, we assessed the impact in more typical (urban and peri-urban) settings over several years. We found that LED attracted approximately half of the number of insects compared to MV lights. Furthermore, most insect groups are less drawn by LED than by MV, while Hymenoptera are less attracted by MV than by LED. Thus, the composition of the attracted communities differed between the light sources, which may impact ecosystem processes and functions. In green peri-urban settings more insects are attracted than in an urban setting, but the relative difference between the light sources is the same.

Low impact of two LED colors on nocturnal insect abundance and bat activity in a peri-urban environment

“…A negative coefficient indicates that fewer insects were observed at lights with 6500 K (cold white) compared to 2700 K (warm white) difference in attraction between cold-white and warm-white LEDs was found for insects (Table 2). This is in disagreement with studies that report clear attraction to cold-white rather than warm-white LEDs, particularly for Lepidoptera (Somer-Yeates et al 2017;van Geffen et al 2015;van Langevelde et al 2011, but see (Longcore et al 2015;Macgregor et al 2019)). Reasons may be manifold.…”

“…Specifically, Altermatt and Ebert (2016) showed evidence that the response to ALAN exposure may result in reduced flight-to-light behavior in light-exposed urban moth populations compared to moths in dark areas. In the long term, lowered mobility negatively impacts competitiveness due to reduced foraging, dispersal or pollination (Altermatt and Ebert 2016;Knop et al 2017), thus impacting ecosystem processes and functions (van Grunsven et al 2019). Given that our study area has been exposed to ALAN for at least 40-50 years, it may thus well be that today's insect community has already undergone this selective process towards less light sensitive insectseven if exposed "only" to HPS light sources for the majority of these 40-50 years.…”

“…Second, nocturnal insects are well adapted to low-light vision based on a range of physiological properties (Boyce 2019; Warrant 2017) such as highly sensitive photoreceptors (Honkanen et al 2017). As a consequence, the long-term exposure of nocturnal communities to ALAN can lead to changes compared to communities that are less exposed to light (Altermatt and Ebert 2016;van Grunsven et al 2019). Specifically, Altermatt and Ebert (2016) showed evidence that the response to ALAN exposure may result in reduced flight-to-light behavior in light-exposed urban moth populations compared to moths in dark areas.…”

Impact of artificial light intensity on nocturnal insect diversity in urban and rural areas of the Asir province, Saudi Arabia

“…intensive agricultural practices), which leads are prominent examples that may affect insect’s population in rural and urban areas [ 27 , 28 ]. As a consequence, long-term exposure of nocturnal insect communities to ALAN can lead to changes compared to communities that are less exposed to light [ 29 , 30 ]. Most of the studies on the effect of light intensities have focused on birds, larger vertebrate animals and only a few studies have devoted on insect population affection light intensities.…”

Grasping darkness: the dark ecological network as a social-ecological framework to limit the impacts of light pollution on biodiversity

“…Besides, although light from high-pressure sodium lamps or red LEDs, for example, attract fewer insects, it still has negative impacts on bat commuting (Stone et al 2009, Zeale et al 2018). However, it should be noted that spectrum-related effects remain highly diverse, either in bats (Voigt et al 2018), in insects (van Grunsven et al 2019), and more generally in flora and fauna (Schroer and Hölker 2017).…”