Climate-related geographic variation in performance traits across the invasion front of a widespread nonnative insect

Aim: Invasive species are an ideal system for testing geographic differences in performance traits and measuring evolutionary responses as a species spreads across divergent climates and habitats. The European gypsy moth, Lymantria dispar dispar L. (Lepidoptera: Erebidae), is a generalist forest defoliator introduced to Medford, Massachusetts, USA in 1869. Currently, the invasion front extends from Minnesota to North Carolina and the ability of gypsy moth populations to adapt to local climate may contribute to its continuing spread. We evaluate the performance of gypsy moth from populations along the climatic gradient of the invasion front to test for a relationship between climate and ecologically important performance traits.

Methods: Gypsy moth from 14 populations across the US invasion front and the interior of the invasive range were reared from hatch to adult emergence in six constant temperature treatments. The responses of survival, pupal mass, and larval development time wer...