Dendroctonus ponderosae

Dendroctonus ponderosae
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Dendroctonus_ponderosae".

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Mountain pine beetle

Adult mountain pine beetle
Dendroctonus ponderosae

Scientific classification

Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Family:	Scolytidae
Subfamily:	Scolytinae
Genus:	Dendroctonus
Species:	D. ponderosae

Binomial name

Dendroctonus ponderosae
Hopkins, 1902

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 shell and measures about 5 millimetres.

Mountain pine beetles inhabit pines, particularly the Ponderosa Pine, Lodgepole Pine, Scots Pine and Limber Pine. The bristlecone pines and pinyon pines are less commonly attacked. During early stages of an outbreak, attacks are limited largely to trees under stress from injury, poor site conditions, fire damage, overcrowding, root disease or old age. As beetle populations increase, the beetles attack the largest trees in the outbreak area.

1 Tree infestations
2 Life cycle
3 Current outbreak
4 Effect on carbon cycle
5 References
6 External links

Tree infestations

Killed trees appear as red patches in Kootenay National Park

The beetles kill the trees by boring through the bark into the phloem layer on which they feed and in which eggs are laid. Pioneer female beetles initiate attacks, and produce pheromones which attract other beetles and results in mass attack. The trees respond to attack by increasing their resin output in order to discourage or kill the beetles, but the beetles carry blue stain fungi which, if established, will block the tree resin response. Over time (usually within 2 weeks of attack), the trees are overwhelmed as the phloem layer is damaged enough to cut off the flow of water and nutrients. In the end, the trees starve to death, and the damage can be easily seen even from the air in the form of reddened needles. Entire groves of trees after an outbreak will appear reddish for this reason. Usually older trees die faster. After particularly long and hot summers mountain pine beetle population can increase dramatically which can lead to the deforestation of large areas. the transfered from asia

Life cycle

Approximately two weeks following oviposition, pine beetles hatch as white larvae. They dig into tree bark where they spend the winter, then grow up to 7mm long in the spring. The pupal stage ends in the late spring or early summer, and from mid-July to mid-August, the beetles leave their tunnels and fly to new trees. Female beetles release pheromones to attract males and encourage mass attacks.^[1] The lifespan of a single pine beetle is about one year.^[2]

Temperatures down to −30 °C to −40 °C (−22 °F to −40 °F) for at least several days, or at least twelve hours of −40 or lower, kills most mountain pine beetles.

Current outbreak

A lodgepole pine tree infested by the mountain pine beetle, with visible "pitch outs".

The current outbreak of mountain pine beetles is ten times larger than previous outbreaks.^[3] Huge parts of central BC along with parts of the forests of Alberta have been hit badly. The recently mild winters have British Columbia, Canada forestry officials worried because the beetles will have a devastating impact on an ecosystem which may be ill-equipped naturally to deal with it. Fortunately, a cold snap in early 2008 is hoped to have dropped the pine beetle population to more manageable levels. ^[4] However, preliminary results from the summer of 2008 indicate that the cold winter was less successful at killing pine beetle than predicted.

As of 2008, there was also a large outbreak in Colorado. The largest problem in the eradication of the beetle is that homes in the area are so close to the infected trees that a controlled burn is impossible. Furthermore, since the trees that are being hit are older and the Ponderosa Pines affected are stimulated to spread seeds by heat of around 130 degrees from either fire or solar radiation much forest will die before it is renewed.

Effect on carbon cycle

Researchers from the Canadian Forest Service have studied the relationship between the carbon cycle and forest fires, logging and tree deaths. They concluded that by 2020 the pine beetle outbreak will have released 270 megatonnes of carbon dioxide into the atmosphere from Canadian forests. There is yet to be an accepted study of the carbon cycle effect over a future period of time for North American forests.^[3]