In recent years, the mountain pine beetle, Dendroctonus ponderosae Hopkins, has impacted >8.9 million hectares of forests in the western United States. Durin

This project was sponsored by the USDA Forest Service, Research and Development. Most authors are members of the Western Bark Beetle Research Group, a consortiu

During its life cycle, the tree-killing mountain pine beetle Dendroctonus ponderosae Hopkins interacts with phoretic organisms such as mites, nematodes, fungi,

The western pine beetle (WPB), Dendroctonus brevicomis LeConte, is a major mortality agent of pines in North America. A total of 706 adults of WPB from 81 geographical sites were analyzed with traditional and geometric morphometric methods to evaluate the variation of discrete and quantitative morphological characters with particular attention to the antenna, spermatheca, and seminal rod. Principal coordinates and canonical variate analyses supported three geographical groups in WPB: (1) West, from British Columbia to southern California along the Pacific coast, Idaho, and Montana; (2) East-SMOC, including Nevada, Utah, Colorado, Arizona, New Mexico, Texas, Chihuahua, and Durango; and (3) SMOR, including Coahuila, Nuevo Leon, and Tamaulipas. The pubescence length on the elytral declivity was a robust character for separating West specimens from the other groups. Additionally, the genitalia shape both female and male in dorsal view was a reliable character for discriminating among groups. Based on these results, which agree with genetic and chemical ecology evidence, we herein reinstate Dendroctonus barberi Hopkins (East-SMOC group) and remove it from synonymy with D. brevicomis (West group). Differences in the spermatheca and seminal rod shape of SMOR specimens suggest that these populations might be a different species from D. barberi and D. brevicomis.

The mountain pine beetle (MPB) (Dendroctonus ponderosae) is one of the most prevalent disturbance agents in western conifer forests. It utilizes various species of pines (Pinus spp.) as host trees. Eruptive populations can cause extensive tree mortality. Since the late 1990s, extensive outbreaks have occurred from the southern Rockies to British Columbia. In Colorado, lodgepole pine (P. contorta) forests have been the most affected. Since 1996, about 3.4 million acres of lodgepole and ponderosa pine (P. ponderosa) forests have exhibited MPB-caused tree mortality. A large portion of the larger diameter trees have been killed with significant reductions in basal areas and tree densities. Tree mortality has impacted many forest ecosystem services including fiber production, hydrology, nutrient cycling, wildlife habitat, property values, and recreation. In this article, we examine and summarize some of what we have learned about MPB impacts from observations and research over the past two decades in Colorado.