Blue spruce (Picea pungens) and Engelmann spruce (Picea engelmannii) experience varying levels of spruce beetle (Dendroctonus rufipennis (Kirby)) colonization, yet the underlying differences and mechanisms resulting in lower colonization for blue spruce are not known. Both spruce species have important roles in subalpine ecosystems where examining changes in mortality, distribution,...
This work combines both applied and basic research regarding previously undescribed relationships between two ecologically and economically important insect groups in coniferous forests, bark beetles (Coleoptera: Curculionidae, Scolytinae) and wild bee (Hymenoptera: Apiformes) communities in Western North America. Across the continent, native bark beetle outbreaks are key drivers of structural...
The hemlock woolly adelgid (Hemiptera: Adelgidae: Adelges tsugae; HWA) is an invasive and damaging pest on hemlock in eastern North America. HWA is native to the Pacific Northwest, where it does not damage hemlock. In support of classical biological control of HWA in eastern North America, abundances of native predators...
The Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins) can kill large numbers of Douglas-fir trees (Pseudotsuga menziesii (Mirbel) Franco) across a landscape during periods of population outbreaks. High-value individual trees and small stands can be protected from Douglas-fir beetle infestation during outbreaks by applying the anti-aggregation pheromone, MCH (3-methylcyclohex-2-en-1-one). MCH treatments are...
Live western larch, Larix occidentalis Nutt., a tree species resistant to the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, produces the monoterpene 3-carene in higher concentrations compared to Douglas-fir, the preferred host of D. pseudotsugae (Reed et al. 1986). The inhibitory effects on attraction to aggregation pheromones and toxicity of 3-carene to...
Infestations of the western pine shoot borer (Eucosma sonomana Kearfott) in young stands of ponderosa pine (Pinusponderosa Lawson), were surveyed on the Deschutes National Forest. Elevation, slope, aspect, tree height, tree diameter, number of shoots in the terminal whorl, stand density, stand age and plant association for each stand were...
Invasive plants threaten ecosystems and economies worldwide. Classical biological control, introduction of specialist herbivores on invasive plants, is one of the tools employed to reduce the impact of invasive plants. Gorse, Ulex europaeus L. (Fabaceae), an invasive leguminous shrub, is the target of a biological control program in Oregon. The...
The spruce weevil (Pissodes strobi) is a serious pest of Sitka spruce in Oregon. Weevils cause damage by killing the leader of a tree, resulting in defects such as crooks and forks that can render the tree unmerchantable. In this study, spruce stands 16-25 years old were surveyed for weevil...
Three studies on Douglas-fir beetle (DFB), Dendroctonuspseudotsuae, were conducted to investigate its basic and applied biology. Studies included investigations into the spatial relationship of DFB infestations over multiple years and multiple landscapes, relationships between DFB brood adult lipid levels and position of development along the length of tree boles, and...
Hemlock woolly adelgid, Adelges tsugae Annand, is a serious threat to eastern hemlock, Tsuga canadensis Carriere, in the eastern United States. Infestations of A. tsugae are spreading rapidly and tree mortality caused by the insect is increasing yearly. As part of an integrated management approach, a classical biological control program...
