Information

Agent

Agapeta zoegana (Linnaeus)

Class: Insecta
Order: Lepidoptera
Family: Tortricidae

Agent Name References:
- Piper, G.L. and S.S. Rosenthal. 1995. Diffuse knapweed. In J.R. Nechols, L.A. Andres, J.W. Beardsley, R.D. Goeden, and C.G. Jackson, Eds. Biological Control in the Western United States: Accomplishments and Benefits of Regional Research Project W-84, 1964-1989. Publication 3361. University of California, Division of Agriculture and Natural Resources, Oakland, California. pp. 237-241.
- Smith, L. and J.M. Story. 2003. Plant size preference of Agapeta zoegana L. (Lepidoptera: Tortricidae), a root-feeding biological control agent of spotted knapweed. Biological Control 26: 270-278.

Weed

Centaurea diffusa Lam.

Family: Asteraceae
Common Name: diffuse knapweed

Origin: Eurasia

Weed Name References:
- Seastedt, T.R., D.G. Knochel, M. Garmoe, and S.A. Shosky. 2007. Interactions and effects of multiple biological control insects on diffuse and spotted knapweed in the Front Range of Colorado. Biological Control 42: 345-354.
- Story, J.M., G.L. Piper, and E.M. Coombs. 2004. Knapweeds. In E.M. Coombs, J.K. Clark, G.L. Piper, and A.F. Cofrancesco, Eds. Biological Control of Invasive Plants in the United States. Oregon State University Press, Corvallis, Oregon. pp. 196-232.

Weed Common Name References:
- Seastedt, T.R., D.G. Knochel, M. Garmoe, and S.A. Shosky. 2007. Interactions and effects of multiple biological control insects on diffuse and spotted knapweed in the Front Range of Colorado. Biological Control 42: 345-354.
- Story, J.M., G.L. Piper, and E.M. Coombs. 2004. Knapweeds. In E.M. Coombs, J.K. Clark, G.L. Piper, and A.F. Cofrancesco, Eds. Biological Control of Invasive Plants in the United States. Oregon State University Press, Corvallis, Oregon. pp. 196-232.

Weed Origin References:
- Seastedt, T.R., D.G. Knochel, M. Garmoe, and S.A. Shosky. 2007. Interactions and effects of multiple biological control insects on diffuse and spotted knapweed in the Front Range of Colorado. Biological Control 42: 345-354.
- Story, J.M., G.L. Piper, and E.M. Coombs. 2004. Knapweeds. In E.M. Coombs, J.K. Clark, G.L. Piper, and A.F. Cofrancesco, Eds. Biological Control of Invasive Plants in the United States. Oregon State University Press, Corvallis, Oregon. pp. 196-232.

Release and Source Information

List: 1 - Exotic Organisms Intentionally Introduced

Source: Ex. Austria & Hungary
Year: 1984
Region: North America
Country: United States of America
Subregion of Country: AZ, MT, NV, OR
Subregion specific:

Release History: MT 1984; Redistributed AZ NV years unknown, and from Centaurea stoebe subsp. micranthos to C. diffusa in OR 1995

Release Notes: Released on Centaurea diffusa and C. stoebe subsp. micranthos in 1984 and C. virgata subsp. squarrosa in 1994.

Source Information References:
- Coombs, E.M. 1997. Biological control of weeds in Oregon. Annual Report. Project summaries 1996. Oregon Department of Agriculture, Noxious Weed Control Program, Salem, Oregon, USA. 33 pp.
- Coombs, E.M. 2013. (personal communication) Oregon Department of Agriculture, Noxious Weed Control Program, 635 Capitol St NE Salem, OR 97301 USA.
- Piper, G.L. and S.S. Rosenthal. 1995. Diffuse knapweed. In J.R. Nechols, L.A. Andres, J.W. Beardsley, R.D. Goeden, and C.G. Jackson, Eds. Biological Control in the Western United States: Accomplishments and Benefits of Regional Research Project W-84, 1964-1989. Publication 3361. University of California, Division of Agriculture and Natural Resources, Oakland, California. pp. 237-241.
- ROBO Database. 2012. Release of beneficial organisms in the United States and Territories. USDA ARS. www.ars-grin.gov/nigrp/robo.html. 10 September 2012.
- Story, J.M. 1985. Status of biological weed control in Montana. In E.S. Delfosse, Ed. Proceedings of the VI International Symposium on Biological Control of Weeds. 19-25 August 1984, Vancouver, Canada; Agriculture Canada. pp. 837-842.
- Story, J.M., G.L. Piper, and E.M. Coombs. 2004. Knapweeds. In E.M. Coombs, J.K. Clark, G.L. Piper, and A.F. Cofrancesco, Eds. Biological Control of Invasive Plants in the United States. Oregon State University Press, Corvallis, Oregon. pp. 196-232.

Original Host Species

Recorded as collected from Centaurea maculosa Lam. which is more recently referred to as the tetraploid cytotype of Centaurea stoebe L. sens. lat. but whose appropriate nomenclature remains to be resolved.

Original Host Species References:
- ROBO Database. 2012. Release of beneficial organisms in the United States and Territories. USDA ARS. www.ars-grin.gov/nigrp/robo.html. 10 September 2012.

Establishment

Established: Yes
Established in Subregion of Country: CO, MT, OR, UT, WA, WY
Established in Subregion specific:

Establishment References:
- Coombs, E.M. 2012. Biological control of weeds in Oregon. Annual Report 2012. Oregon Department of Agriculture, Noxious Weed Control Program, Salem, Oregon, USA. 35 pp.
- Coombs, E.M. 2013. (personal communication) Oregon Department of Agriculture, Noxious Weed Control Program, 635 Capitol St NE Salem, OR 97301 USA.
- Dewey, S.A., S.F. Enloe, F.D. Menalled, S.D. Miller, R.E. Whitesides, and L. Johnson, Eds. 2007. Weed Management Handbook 2006-2007. Montana, Utah, Wyoming: Cooperative Extension. 288 pp.
- Story, J.M., G.L. Piper, and E.M. Coombs. 2004. Knapweeds. In E.M. Coombs, J.K. Clark, G.L. Piper, and A.F. Cofrancesco, Eds. Biological Control of Invasive Plants in the United States. Oregon State University Press, Corvallis, Oregon. pp. 196-232.
- Randall, C.B., J.E., Andreas, and J. Milan. 2023. Knapweed Biocontrol Agents: History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2023-34-KNAPWEEDS-A.

Abundance

Limited

Abundance References:
- Coombs, E.M. 2012. Biological control of weeds in Oregon. Annual Report 2012. Oregon Department of Agriculture, Noxious Weed Control Program, Salem, Oregon, USA. 35 pp.
- Coombs, E.M. 2013. (personal communication) Oregon Department of Agriculture, Noxious Weed Control Program, 635 Capitol St NE Salem, OR 97301 USA.
- Dewey, S.A., S.F. Enloe, F.D. Menalled, S.D. Miller, R.E. Whitesides, and L. Johnson, Eds. 2007. Weed Management Handbook 2006-2007. Montana, Utah, Wyoming: Cooperative Extension. 288 pp.
- Story, J.M., G.L. Piper, and E.M. Coombs. 2004. Knapweeds. In E.M. Coombs, J.K. Clark, G.L. Piper, and A.F. Cofrancesco, Eds. Biological Control of Invasive Plants in the United States. Oregon State University Press, Corvallis, Oregon. pp. 196-232.

Agent Impact

Impact: Slight
Geographic Scale of impact: Localized
Impact Notes: Principal host Centaurea stoebe subsp. micranthos on which it is believed to only impact large plants but has not demonstrated any obvious effect on plant density. Reportedly damages C. diffusa to an even lesser extent.

Impact References:
- Coombs, E.M. 2012. Biological control of weeds in Oregon. Annual Report 2012. Oregon Department of Agriculture, Noxious Weed Control Program, Salem, Oregon, USA. 35 pp.
- Dewey, S.A., S.F. Enloe, F.D. Menalled, S.D. Miller, R.E. Whitesides, and L. Johnson, Eds. 2007. Weed Management Handbook 2006-2007. Montana, Utah, Wyoming: Cooperative Extension. 288 pp.
- Story, J.M., G.L. Piper, and E.M. Coombs. 2004. Knapweeds. In E.M. Coombs, J.K. Clark, G.L. Piper, and A.F. Cofrancesco, Eds. Biological Control of Invasive Plants in the United States. Oregon State University Press, Corvallis, Oregon. pp. 196-232.
- Randall, C.B., J.E., Andreas, and J. Milan. 2023. Knapweed Biocontrol Agents: History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2023-34-KNAPWEEDS-A.

Limiting Factors

None

Other Attack

Were other species attacked?: No
Other Species Attacked Notes:

Research Organizations

Oregon State Department of Agriculture, Salem (State (15))
University of Idaho (State (6))
Montana State University (State (7))
Washington State University (State (9))
Bozeman, Montana (USDA (10))
Davis, California (USDA (14))

Notes