NIESENBAUM, RICHARD A.* and EMILY KLUGER. Biology Department, Muhlenberg College, Allentown, PA, 18104-5586. - Variation in rates of herbivory in Lindera benzoin: the role of light, chemistry, and other factors.
The aim of this study has been to assess how rates of herbivory vary
in populations of Lindera benzoin, and to better understand how
light environment, plant growth rates, leaf toughness, and plant
chemistry influence these rates. Over the entire season, plants from
shade locations experienced greater levels of herbivory than plants in
sun locations while the abundance of herbivores did not differ across
habitats. Leaves originating from high light environments were
significantly tougher and had a stronger fragrance (and perhaps more
aromatic compounds) than leaves from low light environments. Gas
chromatography spectra and solid phase micro-extraction revealed that
plants in high light environments had a greater concentration of lower
molecular weight compounds while shade plants had a greater relative
abundance of heavier compounds. Laboratory feeding trials with the
primary herbivore, the geometrid larvae of Melanolophia
canadaria, showed that larvae raised on leaves from sun or shade
habitats exhibited no differences in feeding rates or larval
development. The relationships between leaf age, light environment,
leaf defense and nutritional quality, and fine scale variation in
rates of herbivory are considered.
Key words: chemical defense, herbivory, light, Lindera benzoin, Melanolophia canadaria