Petzold, Jennifer , Gould, Fred .
Physical Response of Physalis Leaves to Eggs of a Specialist Herbivore Decreases Egg Viability.
The moth Heliothis subflexa is a specialist herbivore whose larvae feed only on fruits of plants in the genus Physalis. In response to eggs laid by H. subflexa, plants in the genus Physalis sometimes form 1) necrotic tissue, 2) a tumor-like growth (neoplasm), or 3) both necrosis and neoplasmic growth under the eggs of these insect herbivores. The goal of this study was to 1) determine if the probability of a response to an egg was affected by the location of the egg on the plant, plant age, or plant species and 2) determine if these reactions by the plant to the presence of H. subflexa eggs affected egg viability, and if so, whether this effect differed with plant age or species. Reactions to eggs were characterized for Physalis angulata and Physalis pubescens. Egg location on the leaf did not significantly affect the likelihood of a reaction, nor did the location of an egg in the plant canopy. However, plant age and species significantly affected the probability of a reaction to eggs: leaves of younger plants were more likely to elicit a response compared to older plants, and overall, plants of the species P. angulata were more likely to elicit a response compared to P. pubescens plants. The presence of a response under an egg significantly decreased the probability that an egg would hatch (from 68% to 53%). This decrease in egg viability was similar for both plant species and both age classes of plants. The physical response of P. pubescens and P. angulata leaves incurred a fitness cost of 11.8% and 13.4%, respectively, for H. subflexa. Thus, the formation of necrotic tissue and/or neoplasms on Physalis plant tissue in contact with eggs of H. subflexa appears to be an effective defense against this herbivore.
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1 - North Carolina State University, Plant Biology, 840 Method Rd, Unit 1, Raleigh, NC, 27695, USA
2 - North Carolina State University, Entomology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM