PARENT SESSION
Symposium #21: Effects of inbreeding and loss of genetic diversity on interactions with natural enemies.
Organized by: CT Ivey, DE Carr, and MD Eubanks
Wednesday, August 7. 1:00 PM to 4:30 PM. Crystal Ballroom, TCC.
Is inbreeding just another stress? Using plant defense theory to predict the effect of inbreeding on plant-insect interactions.
Hull-Sanders, Helen*,1, Eubanks, Micky1, 1 Auburn University, Auburn, AL
ABSTRACT- Inbreeding and loss of genetic diversity typically produce broad, detrimental changes in plant morphology and physiology. These detrimental phenotypic changes almost certainly affect interactions between inbred plants and other organisms. We studied the interactions between insect herbivores and their host plants in an attempt to determine if plant defense theory could accurately predict the effect of inbreeding on plant-insect interactions. The Plant Stress Hypothesis predicts that stressed plants will be more susceptible to generalist herbivores and that generalist herbivores will have higher fitness when consuming these plants. The Plant Vigor Hypothesis predicts that specialist herbivores prefer and perform better when feeding on the most vigorous plants (low stress plants). Our work with the mixed mating morning glory, Ipomoea hederaceae (Convolvulaceae), with generalist and specialist insect herbivores suggests that plant defense theories may accurately predict the outcome of interactions between inbred plants and their herbivores. Inbreeding exacerbated the effects of the generalist herbivore Spodoptera exigua (Lepidoptera: Noctuidae). Conversely, outbred plants were more heavily damaged by specialist tortoise beetles Deloyala guttata and Charidotella bicolor (Coleoptera: Chrysomelidae) than inbred plants. Additionally, specialist herbivores developed slower and were smaller when reared on inbred plants and adult beetles preferred outbred plants. Thus essential tenets of the Plant Stress/Plant Vigor hypotheses accurately predicted the effects of inbreeding on the outcome of interactions between I. hederaceae and its generalist and specialist herbivores. It appears that as far as the ecology of plant-insect interactions is concerned, inbreeding may be just another stress.
KEY WORDS: Ipomoea hederaceae, Plant Defense Theory, generalist herbivores, specialist herbivores