Mountain pine beetle is a native bark insect that attacks pine forests in western North America. The life span of a mountain pine beetle is one year though it may vary depending on temperature. Female beetles attack first to lay eggs in the suitable host trees. The larvae live under the inner bark over the winter and complete the development in the following spring. Adult beetles disperse for new host trees over the summer and early fall (Natural Resources Canada 2014).
The Government of B.C. estimated a total of 18.3 million hectares of forest (4 times more than the size of Vancouver Island!) has been affected by mountain pine beetle infestation, with 723 million cubic meters of timber being killed since the early 1990s (The Province of British Columbia 2013; Natural Resources Canada 2014).
Climatic variables such as temperature and precipitation are a key driver of MPB epidemics in B.C. (Kurz et al. 2008). Increased temperature and reduced summer precipitation due to climate change allows mountain pine beetle to invade areas that were ‘climatically (un)suitable’ (Kurz et al. 2008). The warmer and drier summer also intensifies moisture stress that deteriorates the health of the pine forests, creating a cascading effect on the mountain pine beetle epidemics (Kipfmueller et al. 2002). Host trees suffering from moisture stress are not able to produce sufficient resin to resist beetle attack (Craighead 1925; Thomson and Shrimpton 1984; Safranyik 1989 as cited in Kipfmueller et al. 2002, p.5) and thus facilitate MPB expansion to epidemic level (Safranyik 1989, as cited in Kipfmueller et al. 2002, p.6).
The infestation is estimated to continue expanding northwards and eastwards in the near future based on current trends. Following are the determining factors for the expansion besides climate/weather (Natural Resources Canada 2014):
- Dispersal ability of adult beetles
- Susceptibility of boreal pine forest
- Effectiveness of forest pest control
Please visit the following websites for more information on mountain pine beetle:
- Mountain pine beetle by Ministry of Forests, Lands and Natural Resource Operations
- Mountain pine beetle by Natural Resources Canada