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.
The influence of specificity in induced plant responses on herbivores at different spatial scales.
Viswanathan, Danush*,1, Thaler, Jennifer*,1, 1 University of Toronto, Toronto, Ontario, Canada
ABSTRACT- Recent studies have found that specificity in plant responses to separate early season attackers can differentially affect herbivore occurrence in the field. In this study we additionally examine whether spatial structure in a host plant population can influence host use by foraging herbivores. We created an experimental field landscape of 60 Solanum dulcamara patches containing 12 plants each. One of three different early-season herbivory treatments was then assigned to each patch: Psylliodes affinis, Plagiometriona clavata, or mechanical damage. Using this system, in a smaller scale field study lacking patch structure we had previously found that P. affinis but not P. clavata feeding reduced P. clavata oviposition relative to mechanically damaged plants, correlating with the induction of several putative plant defensive compounds by only P. affinis herbivory. In the current study, following removal of treatment herbivores after the initial damaging phase, four individually marked adult P. clavata were introduced into each patch and their movement between patches was assessed at regular intervals. We also determined rates of P. clavata oviposition in each patch type. In contrast to results at a smaller spatial scale, both P. clavata and P. affinis herbivory had an initial tendency to reduce P. clavata oviposition relative to mechanical damage, but final egg number was equal across all treatments. Marked P. clavata adults generally remained in the patch to which they had been introduced, suggesting that the distance between patches may have resulted in forced oviposition despite poor host quality.
Key words: responses, Solanum dulcamara, induction, specificity