PARENT SESSION
Oral Session # 21: Herbivory I: Susceptability and Resistance.
Presiding: D Lincoln
Tuesday, August 5. 8:00 AM to 11:30 AM, SITCC Meeting Room 200.

Where is spicebush the spiciest? – Variation in leaf quality, chemistry, and herbivory in Lindera benzoin.

Niesenbaum, Richard^*,1, Kluger, Emily¹, ¹ Muhlenberg College, Allentown, PA

ABSTRACT- The aim of this study has been to assess how rates of herbivory vary with light environment in populations of Lindera benzoin (spicebush). Specifically we have focused on how plant growth rates, leaf toughness, plant chemistry and nutrition, and insect biology and ecology vary with light environment and 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. Shorter term feeding trials with the lepidopteron herbivore Epimecis hortaria also showed that leaves in the shade are consumed at a greater rate, and that younger leaves are preferentially eaten. Also, herbivores experienced greater rates of weight gain when feeding on leaves in the sun. 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. Plants in the shade had significantly more nitrogen per unit weight of leaf than plants in the sun. The relationships between leaf age, light environment, leaf defense, and fine scale variation in rates of herbivory are considered.

Key words: insect herbivory, Lindera benzoin, defensive chemistry, leaf nitrogen