Gypsy moth (Lymantria dispar dispar L.) is an invasive forest pest introduced from Europe to Massachusetts, USA in the late 1860s. Long-running monitoring programs have resulted in fine-scale documentation of its spatial spread at a resolution unmatched among invasive species. Since its introduction, gypsy moth has spread more than 900,000km and is currently found from Minnesota to North Carolina. Across this extensive geographic range, gypsy moth populations have established and persisted in a wide variety of climates. Our prior work has demonstrated that small changes in temperature can impact gypsy moth physiology, resulting in measureable fitness consequences that can be population specific. Here we explore a series of physiological metrics that can be linked to fitness and compare the performance of populations from across the northern and southern portions of the invasion front relative to the climate of their source locations. To date, we have compared thermal performance metrics for mass, development rate, and survival, as well as evaluating the response to cold temperature through chill-coma recovery time.
Results/Conclusions
We found evidence for climate-based differences in gypsy moth performance among populations for survival and mass, with individuals from warmer climates tending to have lower survival, but greater pupal mass. Chill-coma recovery time was positively related to the climate of source location, with populations from colder regions displaying shorter recovery times than those from warmer regions. However, patterns in larval development rate were not as clearly associated with source population. This unprecedented investigation comparing the two extremes of the gypsy moth North American invasion front provides a large-scale examination of the performance capabilities of wild gypsy moth populations and documents the relationship between climate and a currently invading forest pest. Our measures of population variation in ecologically important traits increase our understanding of thermal performance and the potential for local adaptation across the invasion front. The outcomes from this study contribute to quantifying future spread potential and fine-tuning risk assessment and management efforts.