The mountain pine beetle (MPB)(Dendroctonus ponderosae) is a member of the bark beetle family and is a naturally occurring insect that is currently infesting pine forests in the southern Rocky Mountains and in areas west of the Continental Divide. Under normal, endemic population levels, the mountain pine beetle is a part of the natural ecological cycle that removes aged and weak trees, aids in nutrient cycling and can create habitat for some species. During an infestation, such as is presently occurring in Alberta, there is a much higher beetle population than normal. MPB infestations have been previously recorded in Alberta in the 1940’s and from 1977-1985. Past infestations have not compared to the current infestation in magnitude or area.
What does the MPB attack?
The MPB attacks old trees (over 80 years) and large trees (over 20 cm diameter). Trees smaller and younger may also be attacked when the population is high. The MPB will attack every species of pine; Lodgepole, jack, whitebark and limber pine as well as ornamental and shelterbelt species such as ponderosa and Scotts pine may be attacked.
When and How does the MPB attack a tree?
In July to mid-August, the beetles begin looking for trees to attack. If a beetle is able to get under the bark of a tree, it produces pheremones that attract other beetles to that tree. The female beetles bore holes in the wood and lay eggs. When the eggs hatch, the larvae immediately being feeding in the soft tissue between the bark and the wood. Larvae develop through the fall and overwinter. In the spring, they begin feeding again and then pupate. The lifecycle is generally one year, however, at higher elevations or farther north, this can change to 1.5 two year lifecycle.
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What does an infested tree look like?
The first sign that mountain pine beetle has attacked a tree is the appearance of pitch tubes (globs of sap) on the bole of the tree. Sawdust at the base of the tree and in the bark crevices can also be a sign of attack. Beetles introduce a blue stain fungus that spreads in the sapwood (the living portion) of the tree. It is through the combined effects of the beetle and larvae feeding and the blue stain that kills the tree by stopping water and nutrient transportation within the tree. Attacked trees generally die within one year. A group of infested trees looks different from the sky than it does up close. When the pine trees die, they turn a reddish-brown colour, and when observed from the sky it becomes clear the extent of damage that an MPB infestation can cause. |
How large is the MPB infestation?
Past infestations in BC and Alberta have ended with a cold weather event (-28 for 3 or more days) causing the beetles to die out. The current outbreak in Alberta can be attributed to milder winters and an abundance of mature pine forests due to many years of wildfire suppression. Current estimates are 800,000 to 1.5 million pine trees infested in the province (the largest recorded infestation in the past was 100,000 trees). British Columbia and Alberta are currently experiencing the largest recorded mountain pine beetle outbreak in North American history. It is estimated that 80 percent of the merchantable pine in BC’s central and southern interior may be dead by 2013.
Does the MPB have any natural predators?
Birds such as woodpeckers eat mountain pine beetle. In addition, while the birds feed, they remove bark and expose the remaining beetles and larvae to weather conditions that also can kill them. Insect parasites and predators such as the checkered beetle feed on MPB larvae. However, during outbreaks, natural predators have little effect on mountain pine beetle populations.
What are the environmental effects of a MPB infestation?
The effects of a large mountain pine beetle outbreak are just starting to be realized. Environmental effects such as changes in water table, steam flow, earlier run-off patterns, erosion, water quality, fisheries, forest fires, significant reduction in carbon sequestering, wildlife habitat and species at risk such as caribou and whitebark pine are now being researched in British Columbia.
How does MPB effect the Alberta economy?
The forest industry contributes $12 billion dollars a year to the Alberta economy, creates 48,000 jobs and plays a major role in the well being of about 50 Alberta communities, all of which could be jeopardized by a mountain pine beetle outbreak. While the forest industry will feel the major economic effects, other areas will feel spin-off effects such as declines in tourism and recreation.
What is the Government of Alberta doing about the MPB infestation?
The Government of Alberta has developed a Mountain Pine Beetle Action Plan that addresses the effects of the mountain pine beetle on the social, environmental and economic values of Alberta’s forests. The plan outlines three strategies: the beetle strategy, the pine strategy and the salvage strategy.
The beetle strategy involves cutting and burning single infested trees or harvesting stands with infested trees to help control the beetle population. The pine strategy involves harvesting susceptible pine stands to prevent the spread of the infestation by reducing the food source for the beetle. As part of the pine strategy, government has asked forest companies to focus their harvesting plans on highly susceptible stands in their Forest Management Agreement areas. The beetle and pine strategies are both currently being implemented. The salvage strategy will be implemented if the pine and beetle strategies are not effective. The salvage strategy is used to recover the fibre from dead or dying trees while there is still economic value, and before they become a forest fire hazard.
What can you do?
All Albertans can play a role in dealing with this potentially devastating issue. Learn to recognize the signs of mountain pine beetle. If you suspect a tree has been attacked call the Alberta Beetle Hotline at 310-BUGS (2847).
Erica Lee
Provincial Mountain Pine Beetle Prevention Specialist