Mountain pine beetle

The mountain pine beetle (Dendroctonus ponderosae) is a species of bark beetle native to the forests of western North America from Mexico to central British Columbia. It has a hard black exoskeleton, and measures approximately , about the size of a grain of rice. In western North America, a recent outbreak of the mountain pine beetle and its microbial associates has affected wide areas of lodgepole pine forest, including more than of forest in British Columbia. The outbreak in the Rocky Mountain National Park in Colorado began in 1996 and has caused the destruction of millions of acres/hectares of ponderosa and lodgepole pine trees. At the peak of the outbreak in 2009, over were affected. The outbreak then declined due to better environmental conditions and the fact that many vulnerable trees had been already destroyed. Mountain pine beetles inhabit ponderosa, whitebark, lodgepole, Scots, jack, limber, Rocky Mountain bristlecone, and Great Basin bristlecone pine trees. Normally, these insects play an important role in the life of a forest, attacking old or weakened trees, and speeding development of a younger forest. However, unusually hot, dry summers and mild winters in 2004–2007 throughout the United States and Canada, along with forests filled with mature lodgepole pine, led to an unprecedented epidemic. The outbreak may have been the largest forest insect blight seen in North America since European colonization. Monocultural replanting, and a century of forest fire suppression have contributed to the size and severity of the outbreak, and the outbreak itself may, with similar infestations, have significant effects on the capability of northern forests to remove greenhouse gases (such as CO2) from the atmosphere. Because of its impact on forestry, the transcriptome and the genome of the beetle have been sequenced. It was the second beetle genome to be sequenced. Mountain pine beetles affect pine trees by laying eggs under the bark. The beetles introduce blue stain fungus into the sapwood that prevents the tree from repelling and killing the attacking beetles with tree pitch flow.