Information

Agent

Euhrychiopsis lecontei (Dietz)

Class: Insecta
Order: Coleoptera
Family: Curculionidae

Agent Name References:
- Creed, R.P. and S.P. Sheldon. 1995. Weevils and watermilfoil: did a North American herbivore cause the decline of an exotic plant? Ecological Applications 5: 1113-1121.
- Sheldon, S.P. and R.P.J. Creed. 1995. Use of a native insect as a biological control for an introduced weed. Ecological Applications 5: 1122-1132.

Weed

Myriophyllum spicatum L.

Family: Haloragaceae
Common Name: Eurasian watermilfoil

Origin: Europe, northern Africa, Asia

Weed Name References:
- Johnson, R.L. and B. Blossey. 2002. Eurasian Watermilfoil. In R. Van Driesche, S. Lyon, B. Blossey, M. Hoddle, and R. Reardon, Eds. Biological Control of Invasive Plants in the Eastern United States. FHTET-2002-04. USDA Forest Service, Forest Health Technology Enterprise Team, Morgantown, West Virginia. pp. 79-90.

Weed Common Name References:
- Johnson, R.L. and B. Blossey. 2002. Eurasian Watermilfoil. In R. Van Driesche, S. Lyon, B. Blossey, M. Hoddle, and R. Reardon, Eds. Biological Control of Invasive Plants in the Eastern United States. FHTET-2002-04. USDA Forest Service, Forest Health Technology Enterprise Team, Morgantown, West Virginia. pp. 79-90.

Weed Origin References:
- Johnson, R.L. and B. Blossey. 2002. Eurasian Watermilfoil. In R. Van Driesche, S. Lyon, B. Blossey, M. Hoddle, and R. Reardon, Eds. Biological Control of Invasive Plants in the Eastern United States. FHTET-2002-04. USDA Forest Service, Forest Health Technology Enterprise Team, Morgantown, West Virginia. pp. 79-90.

Release and Source Information

List: 2 - Native Organisms Intentionally Redistributed

Source: Ex. USA
Year: pre 1994
Region: North America
Country: United States of America
Subregion of Country: MA, MI, NY, OR, VT, WI
Subregion specific:

Release History: Laboratory-reared adults and larvae released in lakes in MA VT WI pre 1994; Redistributed OH to OR 2010; Available commercially for a time so additional states received releases but data and details lacking

Release Notes: Previously available as Milfoil Solution®, which entailed placing egg- and larvae-infested plant material into new locations. No longer commercially available. Releases into lakes and ponds often intended to only supplement existing populations as this species is naturally already widespread in North America.

Source Information References:
- Coombs, E.M. 2013. (personal communication) Oregon Department of Agriculture, Noxious Weed Control Program, 635 Capitol St NE Salem, OR 97301 USA.
- Creed, R.P.J. 1997. (personal communication) Appalachian State University, Department of Biology, Boone, North Carolina 28608, United States of America.
- Creed, R.P.J. and S.P. Sheldon. 1994. The effect of two herbivorous insect larvae on Eurasian watermilfoil. Journal of Aquatic Plant Management 32: 21-26.
- Creed, R.P. and S.P. Sheldon. 1995. Weevils and watermilfoil: did a North American herbivore cause the decline of an exotic plant? Ecological Applications 5: 1113-1121.
- Johnson, R.L. and B. Blossey. 2002. Eurasian Watermilfoil. In R. Van Driesche, S. Lyon, B. Blossey, M. Hoddle, and R. Reardon, Eds. Biological Control of Invasive Plants in the Eastern United States. FHTET-2002-04. USDA Forest Service, Forest Health Technology Enterprise Team, Morgantown, West Virginia. pp. 79-90.
- Menninger, H. 2011. A review of the science and management of Eurasian watermilfoil: recommendations for future action in New York state. New York Invasive Species Research Institute, Cornell University, Ithaca, New York. 46 pp.
- Sheldon, S.P. and R.P.J. Creed. 1995. Use of a native insect as a biological control for an introduced weed. Ecological Applications 5: 1122-1132.

Original Host Species

Unknown

Establishment

Established: Yes
Established in Subregion of Country: MA, MI, NY, VT, WI
Established in Subregion specific:

Establishment References:
- Creed, R.P.J. 1997. (personal communication) Appalachian State University, Department of Biology, Boone, North Carolina 28608, United States of America.
- Creed, R.P. and S.P. Sheldon. 1995. Weevils and watermilfoil: did a North American herbivore cause the decline of an exotic plant? Ecological Applications 5: 1113-1121.
- Menninger, H. 2011. A review of the science and management of Eurasian watermilfoil: recommendations for future action in New York state. New York Invasive Species Research Institute, Cornell University, Ithaca, New York. 46 pp.
- Sheldon, S.P. and R.P.J. Creed. 1995. Use of a native insect as a biological control for an introduced weed. Ecological Applications 5: 1122-1132.

Abundance

Variable

Abundance References:
- Creed, R.P.J. 1997. (personal communication) Appalachian State University, Department of Biology, Boone, North Carolina 28608, United States of America.
- Johnson, R.L. and B. Blossey. 2002. Eurasian Watermilfoil. In R. Van Driesche, S. Lyon, B. Blossey, M. Hoddle, and R. Reardon, Eds. Biological Control of Invasive Plants in the Eastern United States. FHTET-2002-04. USDA Forest Service, Forest Health Technology Enterprise Team, Morgantown, West Virginia. pp. 79-90.
- Menninger, H. 2011. A review of the science and management of Eurasian watermilfoil: recommendations for future action in New York state. New York Invasive Species Research Institute, Cornell University, Ithaca, New York. 46 pp.
- Sheldon, S.P. and R.P.J. Creed. 1995. Use of a native insect as a biological control for an introduced weed. Ecological Applications 5: 1122-1132.
- Havel, J.E., S.E. Knight, and K.A. Maxson. 2017. A field test on the effectiveness of milfoil weevil for controlling Eurasian watermilfoil in Wisconsin lakes. Hydrobiologia 800: 81–97.

Agent Impact

Impact: Variable
Geographic Scale of impact: Variable
Impact Notes: Associated with weed declines in some lakes in CT, MA, MI, MN, NY, OH, VT and WI, but not in others. High weevil densities can suppress weed populations, however most infestations can potentially recover when weevils move to shorelines for overwintering. Impact could be due to combination of this species and Acentria ephemerella, as damage caused by the two often difficult to differentiate. Fish predation and lack of suitable over‐wintering habitat likely factors limiting weevil populations. Augmentation with larvae and/or eggs ineffective for increasing adult weevil counts or decreasing weed density. Augmentation with adults increases weevil densities the year following release. Establishment in OR suspected but not confirmed.

Impact References:
- Buckingham, G.R. 2004. Eurasian watermilfoil, Myriophyllum spicatum. In E.M. Coombs, J.K. Clark, G.L. Piper, and A.F. Cofrancesco Jr., Eds. Biological Control of Invasive Plants in the United States. Oregon State University Press, Corvallis, Oregon. pp. 169-173.
- 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.
- Creed Jr., R.P. 1998. A biogeographic perspective on Eurasian watermilfoil declines: additional evidence for the role of herbivorous weevils in promoting declines? Journal of Aquatic Plant Management 36: 16-22.
- Creed, R.P.J. and S.P. Sheldon. 1994. The effect of two herbivorous insect larvae on Eurasian watermilfoil. Journal of Aquatic Plant Management 32: 21-26.
- Creed, R.P. and S.P. Sheldon. 1995. Weevils and watermilfoil: did a North American herbivore cause the decline of an exotic plant? Ecological Applications 5: 1113-1121.
- Johnson, R.L. and B. Blossey. 2002. Eurasian Watermilfoil. In R. Van Driesche, S. Lyon, B. Blossey, M. Hoddle, and R. Reardon, Eds. Biological Control of Invasive Plants in the Eastern United States. FHTET-2002-04. USDA Forest Service, Forest Health Technology Enterprise Team, Morgantown, West Virginia. pp. 79-90.
- Menninger, H. 2011. A review of the science and management of Eurasian watermilfoil: recommendations for future action in New York state. New York Invasive Species Research Institute, Cornell University, Ithaca, New York. 46 pp.
- Sheldon, S.P. and R.P.J. Creed. 1995. Use of a native insect as a biological control for an introduced weed. Ecological Applications 5: 1122-1132.
- Havel, J.E., S.E. Knight, and K.A. Maxson. 2017. A field test on the effectiveness of milfoil weevil for controlling Eurasian watermilfoil in Wisconsin lakes. Hydrobiologia 800: 81–97.

Limiting Factors

Predation; Habitat

Limiting Factors References:
- Menninger, H. 2011. A review of the science and management of Eurasian watermilfoil: recommendations for future action in New York state. New York Invasive Species Research Institute, Cornell University, Ithaca, New York. 46 pp.

Other Attack

Were other species attacked?: Yes
Other Species Attacked Notes: Native host is Myriophyllum sibiricum Kom. Feeds on other native Myriophyllum spp. when densities are high, but due to lowered fecundity, weevil impact is considered to be significantly less on all native Myriophyllum spp. than on Eurasian watermilfoil.

Non-Target References:
- Sheldon, S.P. and R.P. Creed Jr. 2003. The effect of a native biological control agent for Eurasian watermilfoil on six North American watermilfoils. Aquatic Botany 76: 259-265.

Research Organizations

Middlebury College, University of Minnesota, Vermont (State (29))
Vermont Department of Environment and Conservation (State (30))
Wisconsin Department of Natural Resources, Madison (State (31))

Notes

Several states require that the mass-reared individuals used for augmentative releases be offspring of locally collected weevils.