Meeting Abstract
Understanding the role of climatic limits for invasive species is important for determining future range dynamics. The spread of the gypsy moth (Lymantria dispar) across wide climatic gradients in North America provides an ideal system for studying the role of thermal limits in invasion. Previous work has shown that spread rate variability at the southern invasion front is correlated with supraoptimal temperatures. Here, gypsy moth individuals were exposed to daily temperature ramping cycles of optimal (22-28°C) or supraoptimal temperature treatments (30-36°C, 32-38°C, or 34-40°C) at specific developmental stages (1st through 4th instar, pupa) for either 2 or 7 days. We measured survival and long term effects on development time and pupal mass. Survival generally decreased as temperature increased. The 34-40°C treatment had the largest effect on larval survival, with 7 days of exposure being lethal for all stages except 2nd instar and pupae. All other treatments had more than 75% survival after 7 days for all stages. Long term effects of 2 day exposure to heat were more pronounced for females than males and exposure at later larval stages resulted in larger decreases in pupal mass. These negative effects of high temperature exposure support spread patterns seen at the southern invasion front and provide important data on the susceptibility of gypsy moth to high temperatures at different developmental stages. As global temperatures rise, understanding how temperature influences the spread of invasive populations will be critical for management decisions.
