The Sterilized Male Technique could slow Colorado’s beetle problem |

The Sterilized Male Technique could slow Colorado’s beetle problem

Karen A. Kurtak
Special to the Sky-Hi Daily News

Back in 2001, before the people of Grand County saw their beloved green lodgepole pine forests transform almost overnight into the familiar rust that is marked by the devastation caused by the mountain pine beetle (Dendroctonus ponderosae), a scientific article appeared predicting that small increases in the mountain temperatures would result in unprecedented increases in the populations of the pine beetle. In 2004 another scientific article came out with more evidence to support this. The predictions have already come true.

An Overlooked Solution

Is it possible that we’ve overlooked an effective, safe and known solution that could be used on the unprecedented epidemic of mountain pine beetle? While getting my undergraduate degree in environmental biology I learned about different biological techniques for controlling various insect outbreaks. The goal was to find something that worked with minimal disruption to the ecosystem. For this reason, chemical pesticides were only a last resort.

A procedure known as “The Sterile Male Technique” had varying degrees of success in controlling large insect outbreaks. In the 1950s The Sterile Male Technique was first used to eradicate outbreaks of screw worms, which were causing huge annual livestock losses in the southern U.S. Within one year, the pest was completely eliminated in the target zones.

The technique works by introducing factory-reared and sterilized males into the natural population. The sterilization is done by exposing a target pest to enough gamma radiation to make them sterile but not enough to reduce their general vigor.

When the males mate with the females, sterile eggs are produced thus reducing the population for the following reproduction cycle. This is considered to be one of the safest techniques because it introduces no new chemicals, pests or diseases to the ecosystem and the sterilized males have no ability to reproduce. This technique is known to have some drawbacks but after reviewing them, it appears that this is an optimal way to begin to quell the pine beetle epidemic.

One aspect that makes this technique optimal for the pine beetle is that it works better if the in the pest in question is limited to a defined area. Since the pine beetle only lives in pine forests, once the populations are reduced, we won’t have new ones coming in from an outside source. This technique can’t work as quickly in the mountain pine beetle as it did in the screw worms because the pine beetles only mate one time per year.

However, the majority of the pine beetles have their reproductive cycle in the same two- to three-week span. This means that implementation of The Sterile Male Technique at the right time could have a huge impact on their entire population. A concerted effort could begin the process of reducing pine beetle populations back to a more “normal state” and slowing the devastation to the forests. We could also begin using the technique to slow outbreaks of spruce and Epps beetles, which have already devastated spruce forests in Alaska and are working their way south.

Our northern friends in Alberta recently celebrated as their temperatures plummeted below -40 F, the temperature necessary to kill the pine beetle larvae inside the trees. We don’t have time to wait and hope that these chilling temperatures come to our rescue. The loss of these large forests faces us with several more pressing problems.


Water that was once taken up by the trees and cooled the air is now going to run off into our streams and rivers causing an increase in the erosion of their banks. The Rocky Mountains already have very little soil. Roots from our forests’ trees and grasses hold onto the soil and keep it from washing away, in turn allowing trees and grasses to grow, die and decompose, making more soil.

If there are no trees to hold onto the soil, most of it will quickly wash down the mountains. With no trees to block the winds what little soil remains will be blown off the mountain. Our balding mountains will have very little left to support the current ecosystem and we will see a large reduction in populations of many species from bugs and birds to elk and bear. This could have a major impact on hunting as well as the economic boost it gives the mountain towns.

Of even more concern, the beetle outbreaks are no longer occurring only in lodgepole pines, which are dependent on fire for their reproduction and even give off a chemical that attracts the pine beetle. Now we are beginning to see outbreaks in the higher-altitude white pines where, until recently, because of the cooler temperatures, the beetles have been rarely able to carry out their life cycles. Unlike lodgepole pines, white pines are not dependent on fire for their reproduction and therefore don’t benefit from beetle attacks. White Pines are crucial to survival of this current ecosystem. They are a keystone species, a species which many other species like squirrels, birds and bears, are dependent upon for survival.

According to an article that appeared in the journal Ecoforestry by Ingmar Lee, “White Pines also serve as snow fences where snow is captured and accumulated at altitude, creating a snowpack which more gradually releases water down the mountain side in the spring and summer.”

If this natural sequestering of water reserves disappears, many of the small, high-altitude streams could run dry earlier and earlier each year along with any plants that are sustained by them. Without white pines, the entire ecosystem will be permanently altered.


The imminent forest fires pose not only danger to wildlife, people, their homes and businesses but after-effects that will change the landscape forever. When the rains come to put out the fires, our waters will turn black. Concurrent rains will cause more and more erosion, muddying our once crystal-blue waters and threatening the survival of many of the aquatic resident species. Open mountainsides increase the risk for avalanches, threatening the loss of once protected homes.

Since the beetle jumped the Continental Divide this past year, our Front Range ponderosa forests are susceptible to attack as well. People will resort to the use of more and more pesticides like permethryn, which slows infestation of individually treated trees. Although it is safer than its predecessor, DDT, it still has a significant environmental impact because it affects most insects that live in the trees and can ultimately affect animals higher in the food chain.

We can reap some benefit from tragic loss. Two Canadian firms, Suncor and Lignol, are receiving $30 million from the Department of Energy to build an $88 million cellulosic ethanol plant in Commerce City. This plant will use the beetle killed trees to produce environmentally kinder fuels that reduce carbon emissions and add fewer toxins to the air we breathe. Using these dead trees will be a great help in cleaning up much of the dead forests and reducing the fire danger.

However, this doesn’t stop the ensuing chain of events that threatens to change the mountain landscape forever. Furthermore we will lose an abundant source of carbon sequestration if we don’t manage the loss of the forests by either replanting trees or allowing them to reproduce in a natural way. That is, by burning the pinecones to release the seed and re-scattering them AND burning the unusable slash and re-scattering this as well to create a nitrogen-rich soil for the germinated seeds to grow and thrive. This will also give the understory plants a boost to help stabilize the soil.

We share this loss with states to our north like Idaho, which last year witnessed nature’s wildfires, and our friends to the north in Canada, where in British Columbia the beetles have already chewed through 10 million hectares (25 million acres).

Can the Epps and spruce beetles, which have already wiped out spruce forests in Alaska, be far behind?

There are some tough questions to answer. The pine beetle epidemic, though unprecedented, could be considered part of the natural process. Nature is always changing. The animals that are here today are completely different than ones found here 10,000 years ago. Lodgepole pines are dependent on fire for reproduction. The pine beetles offer an effective way to create this. The pine beetle is an endemic species of pine forests. In fact, the trees themselves give off a chemical that attracts the pine beetle. If the epidemic is due to disruptions of the environment from human activity, then perhaps it is our responsibility to restore some semblance of balance.

Final Thoughts

Feeling certain that someone had already thought of this idea and determined that it wouldn’t work, I spent several hundred hours trying to find the explanation. I haven’t found one article, scientific paper or discussion that mentions using The Sterile Male Technique for reducing the pine beetle populations let alone explaining why it wouldn’t work. This said, I ask anyone who is reading this article to please start writing letters to your local, state and national representatives, the Forest Service, The Nature Conservancy, hunting clubs, etc . If they are willing, The Nature Conservancy is probably the best equipped organization to coordinate this project. They are known for working with the various local and government agencies to accomplish projects like this.

It’s already too late for Grand County but we can still help bring many of Colorado’s forests back into balance.

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