Effect of spectral composition of artificial light on the attraction of moths Frank van Langevelde a , Jody A. Ettema a,b , Maurice Donners c , Michiel F. WallisDeVries b,d , Dick Groenendijk b,⇑ a Resource Ecology Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands b Dutch Butterfly Conservation, P.O. Box 506, 6700 AM Wageningen, The Netherlands c Philips Lighting, Mathildelaan 1, 5611 BD Eindhoven, The Netherlands d Laboratory of Entomology, Department of Plant Sciences, Wageningen University, P.O. Box 8031, 6700 EH Wageningen, The Netherlands article info Article history: Received 17 February 2011 Received in revised form 31 May 2011 Accepted 4 June 2011 Available online 29 June 2011 Keywords: Light pollution Cascading effects Body-size dependent effect Ecology of the night Lepidoptera abstract During the last decades, artificial night lighting has increased globally, which largely affected many plant and animal species. So far, current research highlights the importance of artificial light with smaller wavelengths in attracting moths, yet the effect of the spectral composition of artificial light on species richness and abundance of moths has not been studied systematically. Therefore, we tested the hypoth- eses that (1) higher species richness and higher abundances of moths are attracted to artificial light with smaller wavelengths than to light with larger wavelengths, and (2) this attraction is correlated with mor- phological characteristics of moths, especially their eye size. We indeed found higher species richness and abundances of moths in traps with lamps that emit light with smaller wavelengths. These lamps attracted moths with on average larger body mass, larger wing dimensions and larger eyes. Cascading effects on biodiversity and ecosystem functioning, e.g. pollination, can be expected when larger moth species are attracted to these lights. Predatory species with a diet of mainly larger moth species and plant species pollinated by larger moth species might then decline. Moreover, our results indicate a size-bias in trapping moths, resulting in an overrepresentation of larger moth species in lamps with small wave- lengths. Our study indicates the potential use of lamps with larger wavelengths to effectively reduce the negative effect of light pollution on moth population dynamics and communities where moths play an important role. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction During the last decades, artificial night lighting has increased globally (Cinzano et al., 2001; Garstang, 2004). The use of street lighting, security lighting and other urban light sources negatively affected many animal and plant species (Rich and Longcore, 2006), and it is considered to be one of the major threats to moth popu- lations (Frank, 2006; Conrad et al., 2006; Groenendijk and Ellis, 2011). Only recently, the effects of artificial night lighting on indi- viduals (e.g. flight-to-light behavior, Frank, 1988), population dynamics (e.g. reduced reproduction, De Molenaar et al., 2000) and communities of nocturnal species (e.g. increased predation, Gotthard, 2000) are getting more attention (Longcore and Rich, 2004; Rich and Longcore, 2006; Settele, 2009). Artificial night lighting attracts many moths, especially light with high ultraviolet (UV) emission (Frank, 1988, 2006; Nowinszky, 2003). A common, but still not fully convincing and complete explanation for their flight-to-light behavior is that moths mistake a strong light source for the moon and fly to it (Hsiao, 1973). This artificial lighting might have several effects on foraging and reproduction activities of moths and their inter- specific interactions (Frank, 2006). For example, moths flying around streetlights at night may experience increased predation by bats and other nocturnal and diurnal predators which have learnt to take advantage of these artificial feeding stations (Rydell, 1992, 2006; but see Kuijper et al., 2008). As different types of artificial lights are being used, knowledge about the effects of different types of lights on moths is important for their conservation. These light sources might largely differ in intensity and spectral composition, which determine their attrac- tion to insects (Mikkola, 1972; Eguchi et al., 1982; Kelber et al., 2002). For example, it has been shown that high pressure sodium lights attract moths, because of the presence of ultraviolet wave- lengths, while low pressure sodium lights of the same intensity, but not producing ultraviolet light, attract less (Rydell, 1992; Eisenbeis and Hassel, 2000; Eisenbeis, 2006). Moreover, artificial light with high ultraviolet emission could affect visual images per- ceived by moths, for example by accentuating ultraviolet markers which serve as ‘‘nectar guides’’ (Barth, 1985). It has been suggested for the protection of moths that these low pressure sodium vapor lamps should be used, while mercury vapor lamps and other lamp 0006-3207/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.biocon.2011.06.004 ⇑ Corresponding author. Tel.: +31 0317 467346. E-mail address: dick.groenendijk@vlinderstichting.nl (D. Groenendijk). Biological Conservation 144 (2011) 2274–2281 Contents lists available at ScienceDirect Biological Conservation journal homepage: www.elsevier.com/locate/biocon