Canadian Forest Service Publications

The biology and epidemiology of the mountain pine beetle in lodgepole pine forests. 2006. Safranyik, L.; Carroll, A.L. Pages 3-66 (Chapter 1) in L. Safranyik and W.R. Wilson, editors. The mountain pine beetle: a synthesis of biology, management, and impacts on lodgepole pine. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, British Columbia. 304 p.

Year: 2006

Available from: Pacific Forestry Centre

Catalog ID: 26039

Language: English

CFS Availability: PDF (download)

Abstract

The biology, habits and epidemiology of the mountain pine beetle, Dendroctonus ponderosae Hopk. (Coleoptera: Scolytidae), are reviewed with particular reference to lodgepole pine, Pinus contorta Dougl. ex Loud. var. latifolia Engelm., the main host in Canada. Critical aspects of mountain pine beetle life history (i.e., those that have large impacts on establishment and survival) include (i) efficient host selection and dispersal, (ii) a highly evolved mutualistic relationship with blue stain fungi that aids the beetle in overcoming host resistance, (iii) a semiochemical communication system that mediates mass attack and regulates attack density, (iv) stage-specific development thresholds that ensure synchrony of development within and among growing seasons, and (v) development rates specific to sub-populations that ensure univoltinism over a large part of the geographical range. Mountain pine beetle populations exist in one of four phases: endemic, incipient epidemic, epidemic (i.e., outbreak) and post-epidemic (i.e., declining). Each of these phases is defined in terms of population size relative to the abundance of available host. Endemic populations principally exist in weakened, often small-diameter trees, and interactions with other bole-infesting bark beetle species are an important determinant of mountain pine beetle establishment and survival. Incipient-epidemic populations develop when the larger-diameter host trees can be successfully colonized either because of a local decline in host resistance or increases in population size due to immigration or favourable breeding conditions, or a combination of these factors. Epidemics exist at the landscape level, and develop mainly as a consequence of large, highly contiguous areas of susceptible host and favourable weather conditions. Epidemics decline either due to adverse weather conditions, or depletion at the landscape level of the host component in which increasing populations can be maintained (i.e., large-diameter trees). Due to the nature of the interaction between the mountain pine beetle and its host trees, effective management requires detailed yearly surveys and prompt, thorough action against emerging incipient-epidemic infestations. However, given that the mountain pine beetle has evolved as a natural disturbance agent of pine forests, long-term mitigation of large-scale epidemics can only be achieved through management strategies that reduce the susceptibility of lodgepole pine over the landscape.

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