Adult: small, dull, cylindrical bark beetle with elbowed, club-like antennae. Adults are 3.7 to 7.5 mm long; immature adults are light creamy tan in colour, changing to black as they mature.
Larvae: white grub-like larvae with red-brown heads, about 5 mm long in the fourth (final) instar.
Pupae: white at first, changing to light brown, about 5 mm long.
(Parks Canada, 2009, NRCan, 2012).
Photo: USDA Forest Service - Region 2 - Rocky Mountain Region Archive, USDA Forest Service, Bugwood.org
Mature moutain pine beetle adults
The majority of the MPB life cycle occurs underneath the bark. Adult beetles bore into the tree where they will mate. The female will then burrow vertically up the tree underneath the bark, laying eggs along the way. The eggs hatch into larvae which burrow linearly away from the main gallery. The larvae spend the winter under bark, and continue to feed into the spring. During the summer, the larvae pupate, and transform into adult beetles. By mid-July, the fully formed adults begin to emerge from the bark, and fly to a new host tree. Adult beetles continue to emerge from an infested tree throughout the summer and into early fall.
Photo: William M. Ciesla, Forest Health Management International, Bugwood.org
Mountain pine beetle galleries formed underneath the bark of a ponderosa pine
A key stage in the life cycle occurs when the beetle transmits a blue stain fungus to the tree. Attacking adult beetles carry fungal spores within a specialized sac (mycangium) on the maxillary cardine (mouthparts). The fungus gains access to the tree, affecting water transport, and eventually overcoming the tree’s defence system (NRCan, 2012).
The main host is lodgepole pine (Pinus contorta), though MPB can attack almost any species of pine. Impact on jack pine (Pinus banksiana) is of particular concern as MPB begins to spread into the jack pine dominated Canadian Shield.
Photo: Chris Schneph, University of Idaho, Bugwood.org
Lodgepole pine is the main host tree for MPB
in Western Canada. The recent MPB outbreak
has devastated populations of this tree.
Photo: Joseph O'Brien, USDA Forest Service, Bugwood.org
Jack pine, which stretches across the Canadian Shield into Eastern Canada, is a potential host tree for MPB
Signs and Symptoms
Signs and symptoms of a MPB infestation include:
Drying tree foliage as the conduction of water up the tree is interrupted by the beetle infestation
A gradual change in the colour of the foliage
Needles fall off of the tree and tree appears grey with no needles
Depending on environmental conditions and the severity of the attack, it can take up to 4 years for the tree to lose its needles. This foliage colour can be seen during aerial surveys, and is useful for detection and distribution mapping (NRCan, 2012).
|Photo: Dr. Dezene Huber, University of Northern British Columbia
The advancing front of Mountain Pine Beetle spread at various stages of pine infection and mortality.
When beetles bore through the bark and dig galleries, they produce a type of sawdust called “frass”. Frass can be seen in the bark and on the ground surrounding the trunk of the tree. When a healthy tree is under attack, it will produce a thick resin to deter beetle infestation. Known as pitch tubes, this hardened resin can be found on the bark of affected trees. Mountain pine beetles also introduce a blue-stain fungi (Grosmannia clavigerain) to the sapwood of the pine, which helps to kill the tree. The fungi give a blue-grey appearance to the wood (Parks Canada, 2009).
Photo: USDA Forest Service - Region 2 - Rocky Mountain Region , USDA Forest Service, Bugwood.org
Pitch tubes, hardened resin, found on the bark of a ponderosa pine in response to the MPB.
Mountain pine beetle is considered a native species to Western Canada. Recently, MPB has expanded beyond its traditional range, extending further north in British Columbia and further north east in Alberta. It is now considered an invasive pest, as it has spread beyond its native range.
Photo: Canadian Forest Service, Taylor Scarr, OMNRF
|Distribution of mountain pine beetle in Canada (Canadian Forest Service, 2011), showing population spread north towards Northwest Territories, and east towards Saskatchewan.
Mountain pine beetle is an insect, native to western North America, where its main host is lodgepole pine. The beetles invade the trunk and overwhelm the tree’s ability to produce resin to drown or pitch out the beetles. Once inside the trunk, the beetles and their larvae kill the tree by feeding on the phloem, which cuts off the transport of nutrients in the tree. MPB adults carry blue-stain (Grosmannia clavigerain) fungal spores on their bodies, which are introduced into host trees at the time of attack. Once introduced into tree, the blue stain fungi spread rapidly, discolouring the wood. The beetle and the fungi work together to kill the tree, by cutting off water transport.
As a result of its negative impacts on pine species and the forest industry, MPB has become one of the most devastating invasive forest pests in Canada, resulting in huge ecological, economic, and social costs. Currently, there are no populations in Ontario, however reports have predicted that climate change may allow the beetles to spread north and east into other provinces and territories. In fact, the beetle has already spread far outside of its native range and has reached within 50 kilometers of the Saskatchewan border. Northern Ontario is particularly at risk to the impacts of MPB because of the high concentration of jack pine across the boreal forest. If MPB becomes established in Ontario and other eastern provinces, it will affect forest management plans, wood supply planning, fire frequency and severity, wildlife habitat, biodiversity, watershed management, recreation, and property values.
Photo: Taylor Scarr, OMNRF
|Dead stand of lodgepole pine following mountain pine beetle infestation. Widespread mortality of pine has devastating impacts on the forestry industry by significantly reducing long term timber resources.
The mountain pine beetle has already had significant economic impact on the forest industry in Western Canada and on Canada’s economy. The cost of fighting the insect in western Canada has been staggering. Since 2001, the BC government has spent more than $917 million fighting the beetle. The Government of Canada has committed $340 million since 2002 and has made a commitment for an additional $800 million. The BC situation has also resulted in excess supply of low quality and low priced pine timber salvaged from affected forests. The depressed lumber prices resulted in increased softwood lumber tariffs imposed by the US (which increases export costs), and made it difficult for eastern mills (i.e. Ontario and Quebec) to compete with the BC lumber.
Should the beetle spread to Ontario and eastern provinces, its impacts on jack pine, red pine, and white pine could destroy the wood supply for industries that rely on pine forests. As seen in Western Canada, the economic costs of infestation can be extremely high.
Mountain pine beetle has ravaged immense areas of western Canada, having affected approximately 16 million hectares of forest throughout the region, dramatically changing the landscape and ecology. If the beetle reaches Ontario, it has the potential to result in extensive tree mortality to the jack pine, red pine, and white pine dominated boreal forest. This would in turn alter our forest ecosystems and biodiversity, increase fire hazards, and reduce habitat for native wildlife.
If mountain pine beetle reaches Ontario, it could have significant impacts on forestry jobs, which many communities in northern regions rely on. In Northern Ontario, the $11.9 billion forestry industry, which supports more than 55,000 jobs, faces the risks of invasive pests such as the mountain pine beetle. A decrease in pine supply due to MPB could lead to mill closures and would have negative impacts on forest-based communities.
Photo: David Stephens, Bugwood.org
A decrease in pine supply due to MPB could have negative consequences on forest-based communities
Detection for mountain pine beetle is accomplished using landscape scale surveys. Usually aerial surveys are performed from fixed wing or rotary aircraft, where technicians use a combination of sketch mapping, GPS coordinates, and aerial photography to record the areas where MPB has attacked the trees. Aerial surveys are usually followed by localized ground surveys, which provide a more detailed account of the level of infestation (Wulder et al., 2004).
Photo: William M. Ciesla, Forest Health Management International, Bugwood.org
Aerial view of tree mortality caused by the MPB
Respond & Control
In Alberta, the management of the beetle has been aggressive. The province’s approach includes aerial surveys to detect recently attacked trees as quickly as possible. Mechanical and silvicultural control is used to cut down and burn infested trees, in attempts to slow the spread of the beetle eastward.
Saskatchewan is also providing monetary support to Alberta towards the costs of survey and control efforts, in hopes to delay or prevent the entrance of the beetle into eastern provinces.
Saskatchewan also has put barriers in place to restrict the movement of pine material out of BC, and informs other eastern provinces of approved log shipments from the west to the east. This measure aims to prevent the artificial spread of the beetle through the movement of infested products.
The Mountain Pine Beetle Program was established in 2007 by the federal government to fight the country’s MPB infestation. The program ran until 2010 and had three main objectives:
to control the spread of the mountain pine beetle infestation, particularly slowing the eastward progression
to assess the impacts and develop options for recovering , where reasonable, the use of beetle-kill timber and to complete natural resource surveys within the beetle zone
to mitigate post-beetle impacts on community health and safety and on forest resource sustainability
Detection and Monitoring of the Mountain Pine Beetle
Wulder et al./Natural Resources Canada
Silviculture to Reduce Landscape and Stand Susceptibility to the Mountain Pine Beetle (Whitehead et al., 2003)
The Mountain Pine Beetle: A Synthesis of Biology, Management, and Impacts on Lodgepole Pine (edited by Safranyik and Wilson, Canadian Forest Service, 2006)