Response of Bark and Woodboring Beetles to Host Volatiles and Wounding on Western Juniper

Abstract

Abstract In central Oregon, management of western juniper (Juniperus occidentalis var. occidentalis Hook.) has included use of prescribed fire and mechanical removal. After these treatments, several species of bark and woodboring beetles have been observed on treated trees and also occasionally on trees outside management areas, suggesting that these insects might contribute to juniper mortality. In this 2-year (2002–2003) study, we identified bark and woodboring beetles that attack western juniper along with associated beetle predators and examined whether these insects can be manipulated for use in juniper management. Using funnel traps and sticky traps on trees wounded by pruning or treated with host volatiles (juniper berry oil, cade oil, and ethanol) that may attract insects, we captured beetles in the families Buprestidae, Cerambycidae, and Scolytidae (20 species in 17 genera) and known predators in the families Cleridae and Trogositidae (8 species in 7 genera). Cedar bark beetles (Phloeosinus spp.) were the most prevalent insects captured on trees treated with host volatiles and/or wounded. Treatments that included ethanol plus wounding were most attractive to these beetles. However, there was no obvious insect-caused damage or mortality of treated trees in either year of this study.