The Insect Microcosm of Western Juniper Berries

Abstract

On the Ground • Expansion of western juniper has been a major concern of ranchers and managers working on rangelands. • Insects and mites associated with juniper berries can impact juniper seed production, but little is known about arthropods inhabiting western juniper or their effects on seeds. • Our study of insects and other arthropods found inside juniper berries at two sites in northeastern California found 37 species of insects and one mite species, ranging from those that eat berries or seeds to parasitoid insects that develop from eggs laid inside other insects, ultimately killing their host, and hyperparasitoids that parasitize other parasitoids. • We identified several granivores that consume western juniper seeds and, when abundant, may reduce the production of viable seeds considerably.