PARENT SESSION
Oral Session # 53: Herbivory IV: Communities, Populations, and Genetics.
Presiding: JA Rudgers
Wednesday, August 6. 1:30 PM to 5:00 PM, SITCC Meeting Room 103.

Inbred plants in the field: Can plant defense theory accurately predict plant-insect interactions involving inbred plants?

Hull-Sanders, Helen¹, Eubanks, Micky¹, ¹ Auburn University, Auburn, AL

ABSTRACT- Inbreeding (self-pollination) frequently occurs in many plant populations. Inbreeding typically results in broad, detrimental changes in plant morphology and physiology. These phenotypic changes may be analogous to other environmental stresses. Two plant defense theories may predict plant-insect interactions involving inbred plants. The Plant Stress Hypothesis predicts that stressed plants will be more susceptible to generalist herbivores. The Plant Vigor Hypothesis predicts that specialist herbivores prefer and perform better when feeding on the most vigorous plants (low stress plants). We studied the interactions between insect herbivores and their inbred and outbred host plants in the field in an attempt to determine if plant defense theory could accurately predict the effect of inbreeding on plant-insect interactions. Our work with the morning glory, Ipomoea hederacea var. integriscula (Convolvulaceae), and its generalist and specialist herbivores suggests that plant defense theory may accurately predict the outcome of interactions between inbred plants and their specialist herbivores, but may have differing effects with the suite of generalist herbivores that attack in the field. While inbreeding depression in I. hederacea has been documented in the greenhouse, the effects of inbreeding are less clear under field conditions and vary according to season. Specialist herbivores may be sensitive to small physiological changes in inbred plants in the field, but the suite of generalist herbivores may attack plants indiscriminately and may not be sensitive to I. hederacea defense characteristics.

Key words: Ipomoea hederacea, specialist herbivores, plant defense, generalist herbivores