Search
US Forest Service Research & Development
Contact Information
  • US Forest Service Research & Development
  • 1400 Independence Ave., SW
  • Washington, D.C. 20250-0003
  • 800-832-1355
You are here: Home / Research Topics / Research Highlights / Individual Highlight

Research Highlights

Individual Highlight

Use of insects tested to control invasive riparian weed

Members of the Southern Idaho Biocontrol Program help with a study to determine if releasing large numbers of flea beetles is an effective way to control leafy spurge, an invasive weed. Robert Progar, Forest ServiceSnapshot : Leafy spurge is an invasive weed that has appeared along streams throughout much of the country. Resource managers need way to control leafy spurge without use herbicide that might damage other components of the riparian ecosystem. This study found that releasing 50 beetles per flowering stem reduced the biomass, crown, and stem density by 80 percent and seedling density by 60 percent, compared to untreated plots. The Salmon Challis National Forest, ranching communities in Idaho, and others are now using this technique to control leafy spurge along streams.

Principal Investigators(s) :
Robert Progar 
Research Station : Pacific Northwest Research Station (PNW)
Year : 2011
Highlight ID : 344

Summary

Riparian ecosystems are particularly sensitive areas that can be threatened by invasive species and by the herbicide or pesticide options commonly used in uplands to control the invaders. Leafy spurge is one such invasive weed that has appeared along streams throughout much of the country. Forest Service scientists and collaborators set out to determine if the weed could be controlled by releasing a large number of flea beetles (Aphthona spp.), an easily collected natural enemy of leafy spurge, in infested riparian areas. They focused their efforts by releasing large, or inundative, numbers of biological control insects on weed populations found in small isolated patches along three streams in southwestern, central, and eastern Idaho.

They found that releasing 10 beetles per flowering stem had inconclusive, potentially small negative effects on leafy spurge biomass, crown, stem, and seedling density. But releasing 50 beetles per flowering stem reduced the biomass, crown, and stem density by 80 percent and seedling density by 60 percent, compared to untreated plots.

These findings enabled the Jordan Valley Cooperative Weed Management Area to receive a $25,000 grant to employ inundative beetle releases on leafy spurge in areas along tributaries of the Owyhee River in Idaho. The Salmon Challis National Forest is using this protocol to reduce leafy spurge populations on islands in the Salmon River. Forest Health Protection personnel in Ogden, Utah, used inundative releases to effectively control leafy spurge in regional riparian areas. Inundative releases of biocontrol insects also were used in the Hold the Line Program to deter the spread of leafy spurge into the Yellowstone and Teton ecosystems.

Forest Service Partners

External Partners

 
  • USDA Agricultural Research Service, Forest Health Protection, Rocky Mountain Research Station
  • USDI Bureau Land Management
  • Idaho State Department of Agriculture

Research Topics

Priority Areas

  • Invasive Species
  •