Information

Agent

Urophora affinis (Frauenfeld)

Class: Insecta
Order: Diptera
Family: Tephritidae

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.
- 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.

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 & France; Ex. Russia & France via Canada
Year: 1973
Region: North America
Country: United States of America
Subregion of Country: AZ, CA, CO, ID, MD, MT, OR, WA, WY
Subregion specific:

Release History: CA 1976-1981, ID 1974, WA 1974-1975 1979-1980, MD 1983, OR 1973 1975, MT 1973-1977, CO late 1980s, WY 1984; Additional introductions from Canada made in CA ID MT OR WA 1981; Redistributed within WA and OR 1981-1985, to AZ year unknown

Release Notes: Initial releases made from material collected in Austria and France. Subsequent introductions were made via Canada, which had originally been collected from Centaurea spp. in France and Russia. Released first on Centaurea diffusa and C. stoebe subsp. micranthos in 1973. Spread naturally and intentionally redistributed to C. virgata subsp. virgata by 1988.

Source Information References:
- Barbosa, P., S.M. Braxton, and A.E. Segarra-Carmona. 1994. A history of biological control in Maryland. Biological Control 4: 185-243.
- 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.
- Harris, P. 1980. Establishment of Urophora affinis Frfld. and U. quadrifasciata (Meig.) (Diptera: Tephritidae) in Canada for the biological control of diffuse and spotted knapweed. Zeitschrift für Angewandte Entomologie 89: 504-514.
- Piper, G.L. 1985. Biological control of weeds in Washington: status report. 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. 817-826.
- 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.
- 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. 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.
- Woods, D. and V. Popescu. 2009. Diffuse knapweed biological control in California: 1976-2008. In D.M. Woods, Ed. Biological Control Program 2008 Annual Summary. California Department of Food and Agriculture, Plant Health and Pest Prevention Services, Sacramento, California. pp. 43-46.

Original Host Species

Unknown

Establishment

Established: Yes
Established in Subregion of Country: AL, CA, CO, ID, MN, MT, NE, NV, OR, SD, UT, WA, WI, WY
Established in Subregion specific:

Establishment References:
- 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.
- 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.
- Woods, D. and V. Popescu. 2009. Diffuse knapweed biological control in California: 1976-2008. In D.M. Woods, Ed. Biological Control Program 2008 Annual Summary. California Department of Food and Agriculture, Plant Health and Pest Prevention Services, Sacramento, California. pp. 43-46.

Abundance

High

Abundance 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.
- 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.
- Andreas, J.E., J. Milan, C. Randall, and J. Price. 2020. Biological Control. In E. Peachey, Ed. Pacific Northwest Weed Management Handbook. Oregon State University, Corvallis, Oregon. pp. A1-A7.

Agent Impact

Impact: Slight
Geographic Scale of impact: Widespread throughout range
Impact Notes: Well established throughout most Centaurea diffusa and C. stoebe subsp. micranthos-infested areas of USA, particularly the Northwest. More abundant than Urophora quadrifasciata but together contribute to seed reduction of more than 50% at some sites. Seed reduction may retard the rate at which weed spreads, but has not appreciably lowered stand density because sufficient seeds remain. Not considered as effective as Larinus spp. on this weed, and frequently inferior competitor to Larinus spp. and Metzneria. Being displaced by other seed feeders in CA. Overwintering predation limits many populations.

Impact 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 M. Mayer. 2005. Field cage assessment of interference among insects attacking seed heads of spotted and diffuse knapweed. Biocontrol Science and Technology 15(5): 427-442.
- 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.
- Woods, D. and V. Popescu. 2009. Diffuse knapweed biological control in California: 1976-2008. In D.M. Woods, Ed. Biological Control Program 2008 Annual Summary. California Department of Food and Agriculture, Plant Health and Pest Prevention Services, Sacramento, California. pp. 43-46.
- Andreas, J.E., J. Milan, C. Randall, and J. Price. 2020. Biological Control. In E. Peachey, Ed. Pacific Northwest Weed Management Handbook. Oregon State University, Corvallis, Oregon. pp. A1-A7.

Limiting Factors

Interspecific competition; Predation

Limiting Factors References:
- Smith, L. and M. Mayer. 2005. Field cage assessment of interference among insects attacking seed heads of spotted and diffuse knapweed. Biocontrol Science and Technology 15(5): 427-442.
- 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.

Other Attack

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

Research Organizations

University of Wyoming, Laramie (State (13))
California Department of Food and Agriculture, Sacramento (State (14))
University of Idaho (State (6))
Montana State University (State (7))
Washington State University (State (9))
Bozeman, Montana (USDA (10))
Davis, California (USDA (14))
Albany, California (USDA (7))

Notes