APHIS-PPQ completes a second season of the statewide biological control monitoring program in cooperation with Montana Dept. of Ag. and the BLM. Over the past two years, this project has been helping counties, state and federal agencies, and Indian Reservations with monitoring past biological control releases and assessing the potential for collectibility when they find established populations.  Download your copy of  the report for the work completed in 2010.
2010 Statewide Biological Control Monitoring Report
Thursday, October 21st, 2010Influence of Seed Head-Attacking Biological Control Agents on Spotted Knapweed
Wednesday, March 24th, 2010Complete Title: Influence of Seed Head-attacking Biological Control Agents on Spotted Knapweed Reproductive Potential in Western Montana over a 30-year Period
Authors: Jim M. Story, Lincoln Smith, Janelle G. Corn & Linda J. White
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Summary: Studies were conducted on the impact of seed head insects on spotted knapweed reproductive potential in western Montana over a 30-year period. Results indicated that seed head insects are reducing seed production by about 94% in many areas of western Montana. The reduction of knapweed seed production has resulted in a 98% reduction in the knapweed seed bank which, in turn, has contributed to the decline of knapweed in these areas. Of the seed head insects, the fly, Urophora affinis, and the weevils, Larinus obtusus and L. minutus, are having the greatest impact on knapweed seed production. The current decline of spotted knapweed in many areas is likely due to the impact of the seed head insects on the knapweed seed bank and the effects of the root weevil, Cyphocleonus achates, on mature plants.
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Decline of Spotted Knapweed Density in Montana with Large Populations of the Root Weevil
Monday, March 15th, 2010Full Article Name: Decline of spotted knapweed density at two sites in western Montana with large populations of the introduced root weevil, Cyphocleonus achates (Fahraeus)
Authors: J.M. Story, N.W. Callan, J.G. Corn, L.J. White
Summary: Spotted knapweed plant density was monitored over a 11-year period (1993-2004) at two sites in western Montana where the root weevil, Cyphocleonus achates was released. Spotted knapweed density declined significantly over time at both sites (99% and 77%, respectively), after C. achates numbers increased dramatically at both sites. The current decline of spotted knapweed in many areas is likely due to the effects of C. achates on mature knapweed plants and the impact of the seed head insects on the knapweed seed bank.
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