Tuesday, August 7, 2007

PS 29-60: Trading places: The plasticity of leaf quality and herbivory on Lindera benzoin with light

Richard A. Niesenbaum and Norris Z. Muth. Muhlenberg College

Leaf chemistry and physiology vary with light environment and are often thought to directly affect patterns of herbivory; however, little is known about the plasticity of response in plant quality and/or herbivores as light environment changes. We examined a variety of herbivory related leaf characteristics in Lindera benzoin, and the abundance and impact of its lepidopterous herbivore Epimecis hortaria on plants in sun and shade populations and on reciprocally transplanted plants.  Although herbivore abundance per plant did not vary with light environment, the leaf area eaten and the number of leaves damaged by E. hortaria larvae were significantly greater in shade populations of L. benzoin.  Leaves from plants in high light environments differed from those in the shade habitats in a number of important leaf characteristics known to influence herbivory.  Transplant experiments showed that numerous characteristics related to plant growth, defense, and leaf quality were plastic.  Herbivore response (growth and efficiency of conversion) was largely affected by final environment, independent of plant origin; however, the impact of herbivores on the plant was mostly determined by from where the plants originated rather than the environment to which they were transplanted.  This suggests that larvae are more affected by their immediate environment while their impact on plants is more strongly influenced by the legacy of the plant’s native environment.