Effects of street lighting technologies on the success and quality of pollination in a nocturnally pollinated plant

Abstract

Artificial light at night (ALAN) is an increasingly important driver of global change. Lighting directly affects plants, but few studies have investigated indirect effects mediated by interacting organisms. Nocturnal Lepidoptera are globally important pollinators, and pollen transport by moths is disrupted by lighting. Many street lighting systems are being replaced with novel, energy-efficient lighting, with unknown ecological consequences. Using the wildflower Silene latifolia, we compared pollination success and quality at experimentally lit and unlit plots, testing two major changes to street lighting technology: in lamp type, from high-pressure sodium lamps to light-emitting diodes, and in lighting regime, from fullnight (FN) to part-night (PN) lighting. We predicted that lighting would reduce pollination. S. latifolia was pollinated both diurnally and nocturnally. Contrary to our predictions, flowers under FN lighting had higher pollination success than flowers under either PN lighting or unlit controls, which did not significantly differ from each other. Lamp type, lighting regime, and distance from the light all significantly affected aspects of pollination quality. These results confirm that street lighting could affect plant reproduction through indirect effects mediated by nocturnal insects, and further highlight the possibility for novel lighting technologies to mitigate the effects of ALAN on ecosystems.

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.…”

“…Although new developments in LED technology provide long-lived and energy efficient lighting infrastructure (Djuretic and Kostic 2018), they have been the focus of many critical assessments claiming that LED might be particularly detrimental because their spectral composition peaks in the blue range to which many nocturnal insects appear sensitive ((Donners et al 2018;Eccard et al 2018;Grubisic et al 2018;Longcore et al 2015;Pawson and Bader 2014, but see Macgregor et al (2019)). Replacing the older street lights with energy saving LEDs can also lead to brighter illumination.…”

Urbanization‐driven homogenization is more pronounced and happens at wider spatial scales in nocturnal and mobile flying insects

“…Although such evolutionary reduced attraction to light sources may hence directly increase survival and reproduction, the authors anticipated that it comes with reduced mobility, negatively affecting foraging and thus indirectly their role in pollination too. ALAN's direct effects on moths are indeed expected to trigger cascading impacts on ecosystem functioning, for instance with disrupted nocturnal pollination networks—as moths are globally important pollinators –causing negative consequences for plant reproductive success (Borges, ; Knop et al, ; Macgregor, Evans, Fox, & Pocock, ; Macgregor, Pocock, Fox, & Evans, ).…”

Assessing the effects of artificial light at night on biodiversity across latitude – Current knowledge gaps

“…The uncoupling between thermal and photic cues caused by ALAN may affect the timing of seasonal processes like dormancy (Aubé et al, 2013;ffrench-Constant et al, 2016;Hut et al, 2013;Solano-Lamphar & Kocifaj, 2018). However, the actual consequences for plant populations largely remain to be investigated (Knop et al, 2017;Macgregor, Pocock, Fox, & Evans, 2019).…”