PARENT SESSION
Oral Session 6: Herbivory I: Dynamics, Communities, and Photosynthesis.
Presiding: C Ivey
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room B 114.

When studying the effects of light on herbivory, should one consider temperature?

Kluger, Emily ^*,1, Niesenbaum, Richard¹, ¹ Muhlenberg College, Allentown, PA

ABSTRACT- There has been much interest regarding the relationship between light environment and herbivory. One problem with the study of the effects of light level on leaf quality and defense, and consequently on rates of herbivory, is that light intensity and temperature should be directly related, but temperature is not typically considered. Presumably ambient and leaf surface temperature should influence feeding rates, digestive physiology, and development rates of insect herbivores. We investigated the light and thermal environment of the herbivore, Epimecis hortaria, while feeding on the plant, Lindera benzoin, and how it affected rates of consumption and efficiency of conversion. Ambient and leaf surface temperatures were significantly warmer at sunnier sites. Larvae feeding in warmer temperatures consumed more leaf material than their counterparts in cooler environments in the laboratory. Conversion efficiencies, or larval weight gain per unit area of leaf eaten, were higher in larvae feeding on leaves from sun habitats for all field and laboratory treatments, and were independent of ambient temperature. These results contradict patterns of herbivory in the field where herbivores tended to remove less leaf material from plants in warm, sunlit habitats. We consider this in relation to plant quality, plant defense, the role of inducible defenses, and the influence of predators and parasitoids in the field as opposed to the lab. Given that light influences feeding temperature, leaf defense, and leaf nutritional quality, future work on the effects of light must begin to tease these confounding factors apart.

Key words: plant-insect interactions, herbivory, temperature, light