Lack of local adaptation of feeding and calling behaviours by Yponomeuta cagnagellus moths in response to artificial light at night

Abstract

Artificial light at night (ALAN) is one of the suggested drivers of the global decline in insects, including moths. ALAN strongly affects moth physiology and behaviour, but it remains unknown whether ALAN is a selective pressure that drives adaptation and evolution in moths. We assess whether feeding and calling behaviours of Yponomeuta cagnagellus moths are locally adapted to ALAN. Collected from locations that were either illuminated or dark at night-time for several decades, moths were exposed to different light intensities in a laboratory experiment. Male moths, but not female moths, fed less frequently in bright light than in dark or dim conditions. Female calling was less frequent in dimly or brightly lit conditions than in the dark treatment. Individuals from illuminated source populations showed increased feeding behaviour by males and marginally decreased calling behaviour by females. Our study suggests that ALAN affects the phenotypical calling behaviour by females and feeding behaviour by male moths of Y. cagnagellus but has not resulted in adaptation. Long-term ALAN conditions also affected feeding and marginally affected calling frequency. Reduced calling in lit conditions, perhaps driven by a reduced need for such behaviour because of an increase in visual cues or through the proximity of individuals in lit conditions, may result in long-term adaptation. Studies into more moth species are required to determine the extent to which a lack of adaptation to ALAN may contribute to current global declines in moth populations.