The impact of light pollution on the visual ecology of Aquatica ficta (Coleoptera: Lampyridae)

The majority of fireflies in Taiwan communicate with conspecifics via the exchange of bioluminescent signals. The characteristic courtship signals of different species have been well described, yet we know little about the ways in which environmental conditions can affect signaling behavior. The impact of anthropogenic light pollution is of particular interest, as it must contribute some noise to the signal transmission milieu. Herein we explore the ways in which a local species, Aquatica ficta, reacts to environmental light. We expose larval Aq. ficta to low levels of artificial night lighting over two weeks, then analyze their RNA transcriptome expression. We also expose adult Aq. ficta to LED pucks of varying wavelength and intensity, while observing the intensity and frequency of flash signals produced by specimens under these conditions. The transcriptomes of larval specimens exposed to artificial night lighting indicated a significant stress response. Adult Aq. ficta exposed to wavelengths at or below 533nm produced flash signals of greater intensity with diminished frequency; no significant behavioral changes were observed during exposures to wavelengths at or above 597nm. Whether the plasticity of firefly signaling behavior is sufficient to ensure successful transmission of courtship signals remains to be seen. If Aq. ficta are unable to compete with growing levels of anthropogenic light pollution, their reproductive rates will be greatly reduced. Therefore, the action spectra produced by this study should be used to inform decisions about the types of street lamps to be placed near firefly habitats; such consideration will minimize the impact of anthropogenic light pollution on the rich biodiversity and thriving ecological tourism industry of Taiwan.