Document: ALI-3-48-32

A positive link between resistance to herbivores and flowering phenology in Arabidopsis thaliana.

ALBRIGHT, H.R.* and A.K.BRODY

University of Vermont, Burlington VT 05404, USA ¹

Abstract:
A long standing tenet of life history theory predicts that if plants have limited energy budgets, then fast-growing, early-flowering plants should invest more energy into reproduction and less in defense against herbivores, while slow-growing, late-flowering plants will have more resources to engage in defense. In a series of experiments, we tested these predictions by comparing the survival and population growth of herbivores on Arabidopsis thaliana ecotypes known to differ in their growth rate and flowering phenology. We used a generalist herbivore, Tetranychus urticae, the two-spotted spider mite as our bioassay. Early trials with A. thaliana showed a significant difference among several ecotypes with differing life history strategies: early-flowering ecotypes supported more mites than later-flowering ecotypes (F_1,98 = 5.99; P < 0.02). These results supported the prediction of trade-offs between investment in early reproduction versus defense. However, because of differential growth among ecotypes, plants were at different stages of flowering phenology when infected. In a second set of experiments, we controlled the timing of infection with respect to phenology. Our results demonstrated that herbivore performance was enhanced when plants were infected after they began flowering (F_3,56 = 16.05; P < 0.0001). Thus, the timing of infection with respect to flowering phenology may be equally if not more important than plant life history strategy in governing the patterns of resistance to herbivory in A. thaliana.

Keywords: plant-herbivore interactions, life history theory, flowering phenology

This abstract is being presented at: 3:30 PM in session:
PLANT-ANIMAL INTERACTIONS