NOT E Efficacy of Fipronil for Protecting Individual Pines from Mortality Attributed to Attack by Western Pine Beetle and Mountain Pine Beetle (Coleoptera: Curculionidae, Scolytinae)'

Bark beetles (Coleoptera: C~rculionidae, Scolytinae) are commonly recognized as important tree mortality agents in coniferous forests of the western U.S. Most species feed on the phloem and cambium, or xylem tissue of woody plants; and a few are recognized as the most destructive of all forest insect pests. The last decade has seen elevated levels of bark beetle caused tree mortality in spruce, Picea spp., forests of south-central Alaska and the Rocky Mountains; lodgepole pine, Pinus contorta Dougl. ex Loud., forests of the Rocky Mountains; pinyon-juniper, Pinus-Juniperusspp., woodlands of the Southwest; and ponderosa pine, P. ponderosa Dougl. ex Laws., forests of Arizona, California, Colorado and South Dakota (Cain and Hayes 2009, U.S. Dept. of Agric. For. Servo Gen. Tech. Rep. PNW-GTR-784). Today, about 8% of forests in the U.S. are classified at high risk (defined as >25% of stand density will die in the next 15 years) to insect and disease outbreaks (Krist et al. 2007, U.S. Dept. of Agric. For. Servo FHTET Report 2007 06). Mountain pine beetle, Dendroctonus ponderosae Hopkins, is ranked most damaging of all mortality agents considered and colonizes several pine species, most notably P. contorta, P. ponderosa, sugar pine, P. lambertiana Dougl., whitebark pine, P. albicaulis Engelm., limber pine, P. flexilis James, and western white pine, P. monticola Dougl. ex D. Don. (Furniss and Carolin 1977, U.S. Dept. of Agric. For. Servo Misc. Publ. 1339). The western pine beetle, D. brevicomis LeConte, is also a major cause of P. ponderosa mortality in much of the western U.S., specifically in California (Furniss and Carolin 1977). Together, these 2 bark beetle species are