|Biological agent type
Plant species attacked
diffuse knapweed (Centaurea diffusa)
spotted knapweed (Centaurea stoebe)
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Images by Eric Coombs, Oregon Department of Agriculture.
If images are downloaded and used from the ODA web site please be sure to credit the photographer.
Site of attack
Central vascular tissue of the root.
Mode of attack
The larvae mine the roots of diffuse and spotted knapweeds.
Collection and release information
Not collectable at this time. Consult with ODA for availability for your area.
History in Oregon
The root-boring moth Pterolonche inspersa was introduced in 1986. After numerous attempts of releasing this insect, it was recovered near Mosier in Wasco County in 1997. The infestation rate was less than 20% and dropped to less than 5% in 1998. When plant populations crashed no agents were recovered from 1999 to 2003. Eggs were observed on a few plants in late 2004 and nearly 50% of the rosettes in 2005 following a plant increase due to a late rainy season. Unfortunately, a parasitic wasp attacked most of the eggs found on the rosettes. The larvae can coexist below the galls caused by Sphenoptera jugoslavica.
Release status in Oregon
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