Impacts of duration and intensity of artificial light at night on life history, mating, food consumption, and chemical surface profiles of a leaf beetle species

• Artificial light at night (ALAN) can influence various traits of organisms • We tested the impacts of distinct ALAN durations and intensities on a leaf beetle • ALAN of long duration and high intensity prolonged larval development • Chemical surface profiles of adults, important for communication, were modulated • Part-night lighting and dimming may mitigate effects of ALAN Artificial light at night (ALAN) is a global change factor of rapidly growing importance. It has been linked to various changes in species physiology, behaviour, communication, and life history. While most studies compared absence vs. presence of ALAN, there is a demand for studies testing several light scenarios (ALAN durations, intensities) in parallel to decipher potential dose-response relationships. In this study, we assessed the impact of different durations (part-night, continuous) and intensities (low = 5 lux, high = 50 lux) of ALAN on life history, mating, and food consumption, as well as on adult chemical surface profiles of the leaf beetle Phaedon cochleariae . Insects were individually housed in separate compartments, being illuminated with digital LEDs. Only individuals exposed to continuous ALAN of high intensity showed a prolonged development until adulthood, indicating a response threshold. More time spent in the sensitive larval stage may enhance the mortality risk. We found no effect of ALAN on other life history, mating, and consumption traits, including survival, body mass, mating latency, egg number, hatching rate, and food consumption indices. However, ALAN modulated the chemical surface profiles of adult females and males, analysed by gas chromatography coupled with a flame ionisation detector. Altered chemical profiles may impair the intraspecific communication. Our results suggest that part-night lighting and dimming strategies, ideally combined with provisioning dark refuges, may reduce harmful ALAN effects.