Light Attraction in Carabid Beetles: Comparison Among Animals From the Inner City and a Dark Sky Reserve

Vera Kaunath,Jana A Eccard

doi:10.3389/fevo.2022.751288

Abstract

Artificial light at night (ALAN) is altering the behaviour of nocturnal animals in a manifold of ways. Nocturnal invertebrates are particularly affected, due to their fatal attraction to ALAN. This selective pressure has the potential to reduce the strength of the flight-to-light response in insects, as shown recently in a moth species. Here we investigated light attraction of ground beetles (Coleoptera:Carabidae). We compared among animals (three genera) from a highly light polluted (HLP) grassland in the centre of Berlin and animals collected at a low-polluted area in a Dark Sky Reserve (DSR), captured using odour bait. In an arena setting tested at night time, HLP beetles (n= 75 across all genera) showed a reduced attraction towards ALAN. Tested during daytime, HLP beetles were less active in an open field test (measured as latency to start moving), compared to DSR (n= 143). However, we did not observe a reduced attraction towards ALAN within the species most common at both sides,Calathus fuscipes(HLP = 37, DSR = 118 individuals) indicating that not all species may be equally affected by ALAN. Reduced attraction to ALAN in urban beetles may either be a result of phenotypic selection in each generation removing HLP individuals that are attracted to light, or an indication for ongoing evolutionary differentiation among city and rural populations in their light response. Reduced attraction to light sources may directly enhance survival and reproductive success of urban individuals. However, decrease in mobility may negatively influence dispersal, reproduction and foraging success, highlighting the selective pressure that light pollution may have on fitness, by shaping and modifying the behaviour of insects.

Highlights

Light pollution is defined as the alteration of natural light levels at night by anthropogenic artificial light sources (Cinzano et al, 2001; Falchi et al, 2016)
In this study we investigate the attraction to light sources, and the importance of long-time exposure of carabid beetle populations by comparing animals from two populations – either originating from a grassland habitat exposed to intense light pollution for many decades, or from location exposed to low light pollution levels
The latter area was awarded as an “Sternenpark” [Dark Sky Reserve (DSR)] by the International Dark Sky Association (IDA) in 2014

Summary

Introduction

Light pollution is defined as the alteration of natural light levels at night by anthropogenic artificial light sources (Cinzano et al, 2001; Falchi et al, 2016). It is no longer confined to urban areas, with the effects visible in remote and rural areas, sometimes many kilometres away from the light source, i.e., sky glow (Grubisic et al, 2018). Nocturnal invertebrates, including both flying and ground dwelling insects, are especially affected from light pollution due to their attraction towards. Polarised light, reflected from incoming light by aquatic surfaces, is used by aquatic insects, such as mayflies, to detect suitable oviposition locations (Longcore and Rich, 2004; Szaz et al, 2015)

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Conclusion