Journal of Agricultural Science and Food Research
Open Access

Abstract

Verbenone Plus Reduces Levels of Tree Mortality Attributed to Mountain Pine Beetle Infestations in Whitebark Pine, a Tree Species of Concern

Christopher J. Fettig, Beverly M. Bulaon, Christopher P Dabney, Christopher J Hayes and Stephen R McKelvey

In western North America, recent outbreaks of the mountain pine beetle, Dendroctonus ponderosae Hopkins, have been severe, long-lasting and well-documented. We review previous research that led to the identification of Verbenone Plus, a novel four-component semiochemical blend [acetophenone, (E)-2-hexen-1-ol + (Z)-2-hexen-1- ol, and (–)-verbenone] that has been demonstrated to inhibit the response of a closely-related bark beetle species, western pine beetle, D. brevicomis LeConte, to attractant-baited traps and trees. In this study, we evaluate the efficacy of Verbenone Plus for protecting stands of whitebark pine, Pinus albicaulis Engelm., a species of concern being considered for listing as a threatened and endangered species, from mortality attributed to D. ponderosae infestations in the central Sierra Nevada, California, USA. The experimental design was completely randomized with two treatments (untreated control, Verbenone Plus) and four replicates (0.4-ha square plots) per treatment. A total of 450 trees were killed by D. ponderosae, 377 were P. albicaulis and 73 were lodgepole pine, P. contorta Dougl. ex Laws. Significantly, fewer pines (P. albicaulis and P. contorta) and P. albicaulis (only) were killed by D. ponderosae on Verbenone Plus-treated plots compared to the untreated control. On average, there was ~78% reduction in tree mortality attributed to Verbenone Plus. We discuss the implications of these and other results to the development of Verbenone Plus as a semiochemical-based tool for tree protection.