Low levels of light pollution may block male glow-worm’s (Lampyris noctiluca L.) ability to locate females

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Description/Abstract

Light pollution has been proposed as a factor in the reported decline of Lampyris noctiluca as it has the potential to interfere with reproductive signalling. To test this effect on the ability of males to find females, imitation females were set out under light polluted and control conditions at varying light intensities with the numbers of males attracted to each being recorded. Very low levels of light pollution were found to significantly interfere with phototaxis: no males were attracted at either 0.3 or 0.18 lux, with a custom model predicting 0.065 lux as a critical value below which the light no longer has an effect. These illumination levels are much lower than that of 1.5 lux which is recommended by local city councils in Britain to light footpaths and well below any previous published levels of light shown to affect this species. A survey of female L. noctiluca was also conducted with their number and distribution being recorded; a trend towards female clumping was observed but was not statistically significant.