Interactions Between Rumex spp., Herbivores and a Rust Fungus: Gastrophysa viridula Grazing Reduces Subsequent Infection by Uromyces rumicis

Abstract

The chrysomelid beetle Gastrophysa viridula and the rust fungus Uromyces rumicis both occur on leaves of Rumex crispus or Rumex obtusifolius. We investigated reciprocal interactions between herbivory and infection. In both Rumex species the amount of leaf eaten by Gastrophysa viridula was not affected by prior rust infection of the same leaf, whereas there was a significant reduction in infection when the same leaves had been previously grazed by Gastrophysa viridula. Herbivory induced an 80 % reduction in pustule density within and immediately around the feeding site within 1 day of feeding damage; it also induced resistance throughout the undamaged portion of the leaf, and a less effective, and slower, resistance in undamaged leaves (...)