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.

Induced floral resistance in a native California annual, Nemophila menziesii.

McCall, Andrew^*,1, Waugaman, Robin¹, ¹ University of California-Davis, Davis, CA

ABSTRACT- Induced responses to foliar herbivory have been relatively well-studied, but such responses in floral tissues have received considerably less attention. If there is a cost to resistance traits or if resistance traits in floral tissue negatively affect pollinator service, then plastic resistance responses in flowers may be effective strategies for plant populations. Thus far, there has been little evidence that induced floral responses to either prior leaf or floral herbivory occur in natural populations. Here we demonstrate induced floral resistance in a population of Nemophila menziesii (Hydrophyllaceae) in California over two years. In the first experiment, flowers damaged with larvae of Platyprepia virginalis (Lepidoptera: Arctiidae) produced subsequent flowers that were less palatable to P. virginalis than control plants without damage. In a second experiment, plants with artificially-damaged flowers produced both second and third flowers that received roughly 10 times less natural floral herbivory than flowers on control plants. There were, however, no significant differences in total seed set, seeds per fruit, or average weight of seeds between treatments. Induced resistance in flowers seems to occur in N. menziesii, although more experiments are needed to demonstrate if this trait is adaptive in the face of natural floral herbivory.

Key words: floral herbivory, induced resistance, pollination biology, Nemophila menziesii