Adaptive capacity of Asian populations of Lymantria dispar to non preferred plants during northward expansion

The spongy moth ( Lymantria dispar ) is considered to be one of the most widespread folivorous insects in the Holarctic, with the capacity to form regular large-scale outbreaks. In the context of global climate change, the geographical distribution of the species is undergoing a shift, which necessitates adaptation to novel host plants, including conifers. The present study analyzed the adaptability of two populations, inhabit the flat region, Novosibirsk population and inhabit the mountain landscape Altai population, to feed on coniferous hosts (pine Pinus sylvestris and larch Larix sibirica ). Silver birch Betula pendula were used as the currently preferred host plant. The survival rate of the Novosibirsk population exhibited a decline on pine, while remaining constant on larch. In contrast, the Altai population demonstrated no alteration in survival, neither on larch nor on pine. The findings revealed that both populations exhibited a reduced egg-laying tendency on pine compared to birch and larch, with no discernible differences observed between larch and birch. Furthermore, hatching success was found to be independent of the host plant. Alkaline protease activity increased on larch and pine compared to birch but decreased on pine relative to larch, showing no population-specific dependence. Esterase activity exhibited variation exclusively in males, while malondialdehyde accumulation increased for both populations on larch. The findings demonstrate that the spongy moth exhibits sufficient physiological adaptability to utilize coniferous hosts, thus highlighting its potential to expand into new ecological niches under changing environmental conditions.