The effect of ALAN on the ecobiological attributes of fireflies (Coleoptera: Lampyridae: Luciolinae): A study from a tropical habitat in India

Artificial Light at Night (ALAN), particularly the blue lights with short wavelength (450 nm) sourced from LED contributing about 72% of the total ALAN has emerged as a thriving hazard, especially to the nocturnal biotic communities. Fireflies, possessing intrinsic property of bioluminescence are quite vulnerable to the negative impacts of ALAN which threatens the natural courses of their life cycle. The present field-based research highlights the effect of the exposure of differential ALAN intensities on the occurrence of fireflies (Coleoptera: Lampyridae: Luciolinae) for the first time from the Indian subcontinent. Declining effects on the abundance of larvae and adults of three terrestrial firefly species Abscondita chinensis, Abscondita perplexa, and Abscondita terminalis were observed at sites exposed under differential levels of ALAN intensities. Microhabitat occupancy of larvae altered significantly. Availability of larval prey snails increased. The ratio of biomass of the larvae and females represented a deteriorating trend. However, site-specific entomofaunal association did not vary significantly. Cluster analysis reflected the categorization of the study specimens under 3 different assemblages according to the lowest, medium, and highest ranges of ALAN exposure. Principal component analysis indicated that the abundance of adult insects was positively influenced by Sky Quality Meter (SQM) (PC1:0.98) and Naked- eye limiting magnitude (NELM) (PC1:0.97), whereas, the artificial brightness (AB) and total brightness (TB) (PC1: 0.92 for each) had shown negative impacts. The results suggest the scope of utilization of fireflies as a potential bioindicator for light pollution.