Blue Bird Mine Release Site - an example of a biological control release site where the insects are starting to kill spotted knapweed!!
Above left photo taken in 2000. Notice the sickly knapweed plants!! Picture by: Ron Gibson, USDA Forest Service.
Above right photo taken in 2005. Note the lack of knapweed plants!!! Picture by: Todd Breitenfeldt, Whitehall Project.
by: Catherine Dale, 2/01. Updated 2002 & 2005 by T. Breitenfeldt
Pictures of damaged and dying spotted knapweed plants at the site
Pictures of the site
Pictures from 2005 and comparison
A large area along an old road bed shows sever damage to the knapweed with most of the plants killed. A half a mile area on either side shows damage caused by the agents!! Three species of biocontrol agents were found damaging roots and flower heads. This is an example where multiple releases have been made over several years.
Ron Gibson 01/29/01
History: The first releases were ten to twelve years ago. One of the insects that were released at this time was Agapeta zoegana. Shortly afterward, about five years ago, Cyphocleonus achates were released, and about two years ago Larinus minutus were released at this site just North of the Boulder River. Mr. Gibson says that recently there has been an effect!
Goals: This Blue bird mine site is a site that can be used to propagate bioagents to assist in killing knapweed in areas that can't be chemically killed. It is also a very good site to grow agents that can be used in other site.
Todd Breitenfeldt 01/08/01
Goals: This site is a good spot to start! This will be a great spot to create an example of a field release sight. "This is the best knapweed release site in Jefferson County." It would also be a great education and collecting site.
Mr. Breitenfeldt has GPS mapped almost all release sites in the county and hopes to revisit the promising ones and use them to redistribute more insect in the future. This is a GREAT resource for weed control!!
Feelings: "Great! This is a site where bioagents are really working. Our insect rearing project is starting to pay off...." "The plants have a 50-70 year head start on us. We have to be patient and just keep plugging away at it to help the biocontrol agents catch up..."
Todd Breitenfeldt 08/24/05:
We now collect Cyphocleonus weevils at this site but have never found high numbers compaired to some sites in warmer areas. The damage continues to spread and Agapeta and Larinus continue to spread up and down the valley. Cyphocleonus spread is slower because they do not fly.
A brief description of the insects at this site:
This insect, known as a seed head weevil, has been a part of biological control in the United States for ten years now. Up until this point Larinus minutus was native to Europe. Now this insect is found in Idaho, Arizona, Wyoming, California, Minnesota, South Dakota, Wyoming, Montana, Colorado, Washington, Nebraska, Utah, and Oregon. It is established in Washington, Montana, Wyoming, and Oregon to control the spread of spotted knapweed.
The life cycle of this weevil begins as the female weevil begins to feed on the flowers of knapweed, she must for the development of the ovaries. The egg laying cannot begin until the knapweed has started to bloom. It takes three days for the larvae to hatch at witch time the larvae begin to feed on the flowers themselves. They then consume the seeds and develop to the full larvae stage. The larva pupate and emerge from the seed head and are now new adults. This development takes four weeks until the new adults begin to feed on plant foliage, go into the ground litter, and hibernate for the winter. This enables the process to start over again when the weevil emerges in late spring.
Larinus Minutus is brown-grey in appearance. It has a large round snout and it is about 4-5 mm in length. These weevils are strong fliers which is good for dispersing knapweed. In the spring when the adults first emerge they are light gray with yellow fuzz. You will often see them in knapweed infested areas for control reasons.
This is a root boring weevil. It was first released in the United States in 1987 from Eastern Europe and Asia. It has been released in Arizona, California, Colorado, Idaho, Minnesota, Montana, Nebraska, Nevada, Oregon, South Dakota, Utah, Washington, and Wyoming. Cyphocleonus
achates has been established in Colorado, Montana, and Wyoming, some individuals have been recovered in Oregon.
This weevil's life cycle begins as an adult emerges in late July through September. The adults feed on knapweed's more tender leaves. The eggs are then on the root just below the soil and will hatch in ten to twelve days. The larvae then feed on the root of the spotted knapweed where multiple larvae may be. The female weevil lays an average of sixty-five eggs in a lifetime. Cyphocleonus achates produce a generation each year.
C. achates are large, brown-grey mottled weevil. They are about 20 mm in length and they blend well with the ground and mature seed heads of knapweed. It normally sits very still and if it is disturbed it will drop to the ground like it is dead. Since they blend so well with knapweed it is
Agapeta zoegana is a root boring moth of the order Lepidoptera. It was released in the USA in 1948 from Europe. This weevil has now been released in Arizona, California, Colorado, Idaho, Minnesota, Montana, Nebraska, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington, Wisconsin, and Wyoming and the moth is also established in these areas.
The life cycle of A. zoegana begins as an adult moth emerges and mating begins in that twenty-four hours. They emerge in late July through September and the female lays her eggs the day after the emergence. Eggs are found in the stem crevices and the leaves of spotted knapweed. The larvae hatch in seven to ten days and mine the root of the weed. They are capable of killing small rosettes, then they move to another weed. The larvae pupate, midsummer, in the root.
The adults live from 11- 14 days. In this time period a female may lay twenty-one to seventy-eight eggs. They are strong fliers and invade their habitat of knapweed very vigorously.
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