Mountain pine beetle

From Wikipedia, the free encyclopedia

Adult mountain pine beetle
Dendroctonus ponderosae

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

Binomial name

Dendroctonus ponderosae
Hopkins, 1902

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

Wikispecies has information related to:

Mountain pine beetle

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 most large trees in the outbreak area.

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

[edit] Tree infestations

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 get out of hand and that's when there starts to be a problem. There are too many beetles and they start killing off big areas of trees.

[edit] 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.

[edit] Current outbreak

The current outbreak of mountain pine beetles is ten times larger than previous outbreaks.^[3] The recently mild winters have Alberta 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]

[edit] 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.^[3]