Dr. Carin Bondar – “The Complexity of the Mountain Pine Beetle”

By Guest

This is a guest post written by Dr. Carin Bondar.  You can check out Dr. Bondar’s website here.  She blogs about science research and posts a weekly column about fun biology jobs.  Her “Nerd Corner” column includes some really great interviews of scientists that you should definitely check out.

I’m so happy to be a guest blogger on Miss Baker’s Biology Class Blog!

LOVING the emphasis on invertebrates on this blog.  Quite often the human-world forgets that over 95% of the organisms on this planet are spineless!  I recently read a paper in my favorite journal, Behavioral Ecology and Sociobiology, which emphasizes the complexity and sophistication of invertebrates.

The Complexity of the Mountain Pine Beetle

One of the most profound biological disasters affecting British Columbia, Canada (the province where I live) is the infestation of our forests with the mountain pine beetle (Dendroctonus ponderosae).  Over 14 million hectares of forest is infested with the pine beetle, causing massive destruction of our forests (trees infected with beetles are eventually killed).  A combination of warm winters and prevention of natural wildfires has made our mature lodgepole pine forests an easy target.  Most people think about the wrath of the pine beetle at the large scale of its devastation, however, very few think about the beetles as individuals.

What a mistake!

It turns out that the colonization of a new tree is a very complicated process at the level of the individual.  When organisms live in groups and forage in groups (as the beetles do), there are individuals that rist being the first one to attack a new prey item or to colonize a new site.  These ‘pioneer’ individuals often face some kind of adversity for being the first to investigate a new site.  For the pine beetles the first individual to attack a new tree often suffers a greater risk of mortality (from the trees’ defenses) and a decreased reproductive rate.  In a set of detailed experiments, investigators found that beetles with an intermediate body condition were the most likely candidates to pioneer a new site.  Those in great condition opted out, as did those in poor condition.  This provides support for the ‘desperation’ hypothesis, where individuals base their foraging decisions on their current needs.  The new pioneers still had the physical ability to move to a new site (unlike individuals in poor condition) BUT they weren’t in good enough shape to simply sit back and wait for someone else to do it (a luxury enjoyed by the individuals in great condition).  In addition, beetles were more likely to pioneer to new sites based on the time of year (and hence the liklihood of being followed to a new site by members of their group) and the overall size of the tree.

So, far from being ‘just another pest’, the mountain pine beetle displays a complex sophistication when it comes to decision making.  Time for the Homo sapiens to display a little humility!

Reference: Bark Beetle Who Goes First

  • Alec

    Great post Dr. Bondar. In addition to your post, pioneer organisms are vital to society. To be more specific, pioneer organisms are the first organisms to reoccupy an area after that area has been “disrupted”. Pioneer organisms modify their environment which untimately creates less favorable conditions for thenselves, but create an environment in which more advanced organisms can life.

    The mountain pine beetle does just that. Mountain pine beetle outbreaks are largely limited to trees under stress from injury, poor site conditions, fire damage, root disease, or old age. As the beetle population increases in an area, the beetles then attack the largest trees in an outbreak area.

    The mountain pine beetles by breaking into the bark of the tree until it reaches the phloem layer of the tree, which is where the beetles get their food and lay eggs.

    the information from this comment was found on:


  • Charlot

    I never knew that intermediate beetles would be the pioneers. I would have predicted that the bigger and stronger beetles would go, but it makes sense that they wouldn’t want to take the risk because they are already well-fed and strong.

    I found some information on the mountain pine beetle that is quite interesting. The beetles dig through the bark of pine trees and reach the phloem layer. When they reach this layer, they feed on it and lay their eggs there, causing the tree not to get water and nutrients. That’s why the tree will eventually die. Also, the pioneers are most likely to be females, and they let off pheromones so that other beetles will be attracted and will come to the tree. There have been more outbreaks because the warmer weather is causing the beetles to live longer and attack more trees.


  • Sean

    Great post. Being as sophisticated you mentioned, this made me question more about the bark beetle, so I researched the bark beatle to learn more about it. I learned they are only 5 millileters long, so they are small, but many together can destroy entire forests like Dr.Carin Bondar mentioned. You can tell there are alot of these beetles too, 14 million hectares of forest infected by them, that is 54,054.302 miles square for us americans to understand, a small bit larger than North Carolina, so this is a very important topic. I also discovered some of these bark beatles known as “ambriosa beatles” can weaken trees by using fungi. They are so sophisticated they are like allies with fungus, they carry fungal spores and use to help break down the trees chemical defense system. To learn more, check out these websites: http://www.absoluteastronomy.com/topics/Bark_beetle
    States smaller than the amount of forest infested by the bark beetles (less than 54,054.302 miles square) go to:http://www.enchantedlearning.com/usa/states/area.shtml

  • Michael L.

    I love the post Dr. Carin Bondar, I found it interesting how things as small as beetles can take down an entire forest. I decided to research beetles more and try to find their predators and animals that prey on them. I thought since they are destroying these forests, why can’t the forest just add more of the animals that prey on the beetle such as: Birds, Bats, Reptiles, and other insects. Then I later thought about the fact that Sean said about how big they are and how many there are. Then I found out about the Fungus Beetle, this beetle is about 1 and 1/16 of an inch long. They also can eat trees apart to the part in which they die. They only live though in places where fungi are found. They are very good to hide in trees because of their color, and they are not preyed upon as often.


  • Anna

    This was a very interesting post that Dr. Carin Bondar wrote. I researched the Mountain Pine Beetle and learned that there are many signs and symptoms we can look for when the beetle has attacked a tree. Some symptoms that we may see are Popcorn-shaped masses of resin. These are called pitch tubes, on the trunk this is usually where beetle tunneling begins. The color of pitch tubes may be brown, pink or white. Also, evidence of woodpeckers feeding on trunk, is usually another sign. Patches of bark are removed and bark flakes lie on the ground or snow below the tree. Another sign may be that if the foliage starts turning yellowish to reddish throughout the entire tree crown. If there is a presence of live Mountain Pine Beetle eggs, larvae, pupae. These can usually be found under the bark, then this is the most certain indicator of infestation. Once a Mountain Pine Beetle has infests a tree, nothing practical can be done to save that tree. If there is an epidemic or outbreak conditions, enough beetles can emerge from an infested tree to kill at least two, and possibly more, trees the following year. I found a great link on the Mountain Pine Beetle this site talks about some interesting facts as well as the signs and symptoms of an attack by a beetle. It also talks about its history and its life cycle. It shows you what an infested tree looks like, and what they do to try to control an outbreak. There are some great photos as well.


  • Alex

    Thanks Dr. Bondar for posting such a fascinating and informative post! It is, as she mentioned, shocking that over 95% of species are invertabrets. Here’s a really intresting article I found on the Mountain Pine Beetle’s destruction of Colorado’s forests. The 5 millimeter, North American native beetles cut through 1.5 million acres (which is about 70% of Colorado’s forest)! And due to evolution, the modern day Mountain Pine Beetle is a far less picky eater than it’s ancestors. Experts are worried, because this Mountain Pine Beetle fiasco is similar to that of Colorado in 1970. But worse than that, the beetles have destroyed a total of 12 million acres in the past 12 years alone.
    Here’s a link to where I got my information:
    Here is a picture:

  • Marielle

    The Mountain pine beetle is commonly found in western forests in North America. During outbreaks mountain pine beetles large amounts of trees during outbreaks. Older, damaged or trees in poor growing conditions are most likely to be taken. They are also called the Black Hills beetle. Their outbreaks can kill millions of trees. Mountain pine beetles develop in pines. The Douglas-fir beetles and spruce beetles frequently kill trees. During attacks MPBs leave popcorn shaped resins on the trunk when the beetles begin tunneling.


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