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Snapdrageon Slayers 

by Clint Burgess


The Washington Department of Fish and Wildlife is adding a new weed exterminator to its land management efforts. But this one doesn't have four-wheel drive and a big yellow spray tank on the back -- it's a tiny weevil.


The mecinus weevil is going to be released to eat its way through the weed toadflax, which has intruded into some parts of the state. The agency has high expectations for the new weevil on the block.


Fish and Wildlife has been using different types of weevils for weed management in other parts of the state, but this will be the first time weevils of the mecinus variety have been widely distributed.


Madonna Luers, spokesperson for Fish and Wildlife, is optimistic about the use of these weevils for weed control. She says the ability to control weed populations with bio-agents has been available for years. In fact, the seedhead weevil is already being used to combat weeds in wildlife areas in Chelan and Okanogan counties. The mecinus weevil was approved for use by the government about three years ago, but it is just now coming into the toadflax-control picture.


That plant is an invasive noxious weed that was imported to the U.S. from Europe about 200 years ago for its aesthetic beauty. Also known as the spurred snapdragon, toadflax grows to be two feet tall and blooms in a variety of colors -- most often yellow -- from March through June. It migrated from the East Coast with the settlers to the West, and commonly showed up along travel routes like highways and railways. Unfortunately, the plant spreads (not surprisingly) like a weed and has been a nuisance to effective land management for quite some time. The plant also retains a waxy composition that makes it resistant to herbicides.


Similarly, the mecinus weevils have been imported to the U.S. to combat toadflax. They were introduced in British Columbia as far back as 1991 and have been successful in reducing the infestation there. Since their introduction in Canada, the weevils have been observed migrating south into Stevens County, but the number of weevils in that area isn't great enough to have a significant effect on the toadflax.


The advantage of the weevils as bio-control agents is that they are plant-specific and don't live long. Weevil larvae tunnel into the stems of the toadflax and cause the plant to wilt in the process. This goes on for about a month. After emerging, adults live about six weeks. Even though they have voracious appetites, the weevils don't stray from a strict toadflax diet, so they are not a threat to native plants. Once the specific weed is gone and their food source has been eliminated, they die. So ends the saga of the weevil.


Fish and Wildlife is looking forward to working with private landowners on this project.


"The future of land management is working cooperatively with private landowners to ensure and enhance fish and wildlife access," says Luers. She says it's not only their job to manage government-owned land, but to protect and perpetuate the wildlife on that land so that recreational opportunity is maximized. It is in the best interest of the land and its inhabitants that projects like this are carried out with the bottom line in mind, she says, so landowners have to make sure that lands are not overrun by weeds or pests.


So who is paying the bill and what makes anyone so sure this is the right fix for the problem? The federal government is funding the weevils just as it funds many other cooperative agreement programs. These programs allow agencies such as Fish and Wildlife to offer private landowners solutions to land management problems. A small box with 100 weevils will set a buyer back $50. The weevils can be purchased from Washington State University's Department of Entomology in Pullman.


WSU's Dr. Gary Piper is a big reason why the weevil program is becoming reality. Piper has been with the university since 1978 and has studied many different insects, including the mecinus weevils. He says any insect that may be used as a bio-agent must be scrutinized very closely to make sure the release won't have any unintended side effects. It takes around five years for an insect to be approved for use.


"We've had excellent success in other areas of the state controlling St. John's Wart with a beetle that eats the leaves of that plant," Piper says. He is very optimistic that the weevils will be able to reduce the spread of toadflax.


It will take about five years for the weevils to build up a sufficient population to affect the weed. But this process can be accelerated if more weevils are put into the areas where the weed has taken over.


Successful bio-control does not mean toadflax will be gone from the Washington landscape.


"Bio-control does not attempt to decimate a plant species," says Piper, "but to use bio-control agents to keep plant levels at a manageable level."
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