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Pine Beetle Strategy In Banff National Park Can Do More Harm Than Good, Research Shows

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One strategy to control the spread of mountain pine beetles in Banff National Park sometimes does the opposite, a study by a University of British Columbia researcher shows.

While pheromone baiting followed by tree removal — purposefully attracting the pests to a tree, which is then cut down in winter when the larvae are trapped inside — can be successful where there is a dense population of beetles, the strategy can increase the number of beetles in some areas of the Canadian Rockies, according to mathematical modeling led by Rebecca Tyson, an associate professor of mathematics at UBC’s Okanagan campus.

“What our study found is that where the beetle population is low, the pheromone is actually attracting more beetles and thus helping the beetle population increase,” said Ms. Tyson, whose research was recently published in ScienceDirect.

In these areas, the beetles have a hard time finding each other, she said. Additional pheromone, placed by humans, can help attract enough beetles to attack the baited tree.

“With pheromone baiting, this means that humans have put strong signals in the forest that help the beetles find each other. They can then collect in sufficient numbers to attack a tree,” she said. “In these situations, baiting is making things worse for the trees.”

Ms. Tyson described the mountain pine beetle as an endemic pest capable of killing entire stands of mature pine. While the beetle has a short lifespan, climate change and warmer winters have helped the population increase during an epidemic that began in the late 1990s.

The two-year simulation compared four strategies: no management (monitoring only), pheromone baiting, tree removal, and pheromone baiting combined with tree removal. Other management methods are prescribed burning and clearcutting, which Ms. Tyson said cause severe changes to the landscape and have not been proven to stop the spread of the beetle.

The study found that removal of beetle-attacked trees in the absence of baiting is the most successful strategy if managers are able to locate areas with significant pine beetle activity.

According to Ms. Tyson, an adult beetle emerges from a tree each summer and looks for a new one where it will nest. Once selected, the beetle emits a pheromone to attract other beetles to the same tree. Other beetles then arrive, release more pheromone, and the tree is attacked as adult beetles drill into the bark and make tunnels where they lay eggs. By the following summer, the larvae have hatched and turned into adults, and that tree is dead, with the needles turning red. The cycle continues as the beetles move to a neighboring tree.

Under normal population control circumstances, when a tree is baited with pheromone, it is cut down in winter when the larvae are trapped inside, Ms. Tyson said. Crews also search for other trees near the baited one, and all trees identified to contain beetles are removed.

“If all goes well,” said Ms. Tyson, “the beetle population is so severely reduced that it dies out.”

However, her models indicate that pheromone baiting is not working as expected.

“From the field work done in Banff, we know that baiting didn't stop the beetle epidemic,” she said. “Baiting may have slowed it down, but it did not stop it.”

Tyson was aided in her research by then-Ph.D. candidate Shaun Strohm and University of Calgary professor Mary Reid.

Comments

Interesting, when we had pine beetles come through Summit Count, people used pheromones to protect their trees.  The theory was that the scent acted as a "no vacancy" sign on the tree.  Must be different types of pheromones.  

BTW if GW is the cause of the outbreaks why do the infestations occur at the same time at widely varied elevations?  Take the Sugar Pines in Yosemite for example. Trees near the vally floor at 4,000 ft are being attacked at the same time as trees on Tioga Pass road at 8,000 ft. There probably is a 15+ degree difference in mean temperature between those locations.  Saw the same phenomen here in Summit County.  Also saw areas at 11,000 decimated while those nearby at 8,000 went untouched.   Not to mention our attack ended five years ago and Yosemite is only happening now even though our average high is 54 degrees and Yosemite's is 69 degrees.  If temperature and GW are the major cause why are cold areas being infested simultaneously or even years before warmer areas?

Went to a presentation where someone was arguing GW was leading to double life cycles in a single season.  Asked him this obvious question and he was totally stumped. 


1. There are attracting pheromones and repelling pheromones. They are indeed very different.

http://www.pc.gc.ca/eng/docs/v-g/dpp-mpb/sec2/dpp-mpb2b.aspx

2. There are more than 16 papers that clarify and quantify the link between warming and MPB outbreaks. Your question is answered in those papers. Here is one of the earliest:

http://www.cfs.nrcan.gc.ca/pubwarehouse/pdfs/25051.pdf


Interesting, from the introduction:

 However, for North America, despite the development of several models predicting climate change impacts (e.g., Logan and Powell 2001), there is little empirical evidence that global warming has affected insect populations


Stubborn, like a dog worrying an old bone.


Rick, just another example of the AGW predictions being wrong.  How long are you going to hold on to this failing theory.


I'm sure you think you're right. My only question is how many years down the road before you realize what an apology you owe your grandchildren. For now, I'm sure you think you're right.

 

If I'm wrong, we lose nothing. If you're wrong, we lose everything.


Someday, we humans will learn it's really true -- It's not nice to fool Mother Nature.


EC, I believe you misinterpreted that language in the introduction of the paper. My take is that the authors were making the statement that in the past there had been no connection between climate change and its effect on pine beetles, and that their studies now make the connection.

Midway through the paper they write:

It is important to note that the increase in the occurrence of mountain pine beetles in these formerly
climatically unsuitable areas can only be explained by changes in climate.

...and...

Given the rapid colonization by mountain pine beetles of formerly climatically unsuitable areas
during the past three decades, our results strongly suggest continued range expansion by the beetle with further global warming.

In the conclusion, the authors note:

Expansion by the beetle into new habitats as global warming continues will provide it a small, continual supply of mature pine, thereby maintaining populations at above-normal levels for some decades into the future.

...and...

Indeed, with a conservative increase in average global temperature of 2.5 °C associated with a doubling of atmospheric CO2 , as suggested by the Intergovernmental Panel on Climate Change as a plausible global warming scenario (Houghton et al. 1990), Logan and Powell (2001) predict a latitudinal shift of more than 7° N in the distribution of thermally benign habitats for mountain pine beetles. Perhaps as evidence of this shift, in recent years small but persistent mountain pine beetle populations have been detected along the northeastern slopes of the Rockies in Alberta – areas in which the beetle has not been previously recorded (Alberta Sustainable Resource Development 2003).  


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