Vertebrate Herbivores as Predators of Insect Herbivores: An Asymmetrical Interaction Mediated by Size Differences

Abstract

We have analysed the effect of wild goat (Capra pyrenaica) on the reproductive success of a chalcid gall maker (Systasis encyrtoides), both species being herbivores of Hormathophylla spinosa, a stunted mediterranean high-mountain shrub. The gall's position on H. spinosa is very specific, reflected in the fact that the gall maker attaches principally to the basal floral buds of the inflorescence, and in the lower sector of the plant. We labelled inflorescences with and without galls in order to quantify goat herbivory and gall predation