Insect declines and agroecosystems: does light pollution matter?

Abstract

Drastic declines in insect populations, 'Ecological Armageddon', have recently gained increased attention in the scientific community, and are commonly considered to be the consequence of large-scale factors such as land-use changes, use of pesticides, climate change and habitat fragmentation. Artificial light at night (ALAN), a pervasive global change that strongly impacts insects, remains, however, infrequently recognised as a potential contributor to the observed declines. Here, we provide a summary of recent evidence of impacts of ALAN on insects and discuss how these impacts can drive declines in insect populations in light-polluted areas. ALAN can increase overall environmental pressure on insect populations, and this is particularly important in agroecosystems where insect communities provide important ecosystem services (such as natural pest control, pollination, conservation of soil structure and fertility and nutrient cycling), and are already under considerable environmental pressure. We discuss how changes in insect populations driven by ALAN and ALAN itself may hinder these services to influence crop production and biodiversity in agricultural landscapes. Understanding the contribution of ALAN and other factors to the decline of insects is an important step towards mitigation and the recovery of the insect fauna in our landscapes. In future studies, the role of increased nocturnal illumination also needs to be examined as a possible causal factor of insect declines in the ongoing 'Ecological Armageddon', along with the more commonly examined factors. Given the large scale of agricultural land use and the potential of ALAN to indirectly and directly impact crop production and biodiversity, a better understanding of effects of ALAN in agroecosystems is urgently needed. (Hallmann et al., 2017), popularly named 'Ecological Armageddon'. The authors used Malaise traps to collect data from 63 sites located within protected areas that are embedded in an agricultural landscape in two regions in Germany and found that biomass of flying insects decreased more than 75% over 27 years. This trend could not be explained by the changes in habitat, climate or land use (Hallmann et al., 2017), suggesting that another large-scale factor must therefore be involved. We suggest

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

“…We will only outline the main traits and processes relevant to this article. For more extensive treatment, several review articles and book chapters have been published that can be referred to (Desouhant, Gomes, Mondy, & Amat, 2019;Gaston, Davies, Nedelec, & Holt, 2017;Grubisic, Grunsven, Kyba, Manfrin, & Hölker, 2018;Longcore & Rich, 2004;Owens & Lewis, 2018;Perry, Buchanan, Fisher, Salmon, & Wise, 2008;Rich & Longcore, 2006;Stevens & Zhu, 2015). At the physiological level, ALAN is a major source of circadian disruption that F I G U R E 1 Mean latitudinal distribution of artificial light at night (ALAN) and cloud cover fraction as measured from satellite images (a and c, respectively) and their standard deviations (b, d).…”

Narrow oviposition preference of an insect herbivore risks survival under conditions of severe drought

“…However, although average warming might benefit some temperate species (Caillon et al, 2014;Derhé et al, 2010;Roy & Thomas, 2003), increased extreme weather events can quickly push these warm microclimates beyond tolerable limits and consequently underlie some of the recently reported declines in insect abundances worldwide (e.g. Grubisic, van Grunsven, Kyba, Manfrin, & Hölker, 2018;Hallmann et al, 2017;Leather, 2018;Seibold et al, 2019).…”

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

“…Illumination of nocturnal landscapes has increased rapidly during the last few decades [1,2] and is considered an important ecological threat [3][4][5]. One of the best known impacts of artificial light at night (ALAN) is the attraction of insects by light sources and this has been recognized as a potential threat for a long time [6].…”