Genetic erosion and projected habitat loss in the protected Alpine moth Actias isabellae galliaegloria (Lepidoptera: Saturniidae)

Montane and specialist insects are particularly vulnerable to habitat loss and climate change. The Spanish Moon Moth ( Actias isabellae ), a rare and protected species, hosts an isolated Alpine population (subspecies galliaegloria ) whose conservation status remains unclear. We combined Restriction-site Associated DNA sequencing (RADseq) and Ecological Niche Modelling (ENM) to assess its genetic diversity, population structure, and environmental vulnerability. Genomic analyses revealed extremely low genetic diversity and inbreeding in the Alpine subspecies, consistent with a historical bottleneck, reducing adaptive potential. Species distribution models predict a major contraction of suitable habitat by 2050 due to rising temperatures and declines in its primary host, Scots pine ( Pinus sylvestris ). These findings highlight the compounded risks posed by genetic impoverishment and habitat loss, emphasizing the urgent need for targeted conservation measures. Our study demonstrates the value of integrating genomic and ecological approaches to evaluate extinction risk and guide management strategies for montane specialist insects under rapid environmental change.