Friday, August 18, 2017
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Biocontrol

The District has been working to release insects for biological control of yellow starthistle, spotted knapweed, and most recently field bindweed. The District has a long-standing cooperative program with the Nez Perce Bio-Control Center and University of Idaho to release agents and provide public outreach.

 

Special Weapons in the Battle for Weed Control

Since 2002, the District has cooperated with local landowners and agencies to collect and release insects to battle yellow starthistle, spotted knapweed, and diffuse knapweed.

Eustenopus villosus (seed head weevil)All over the state of Idaho noxious weeds are invading private and public lands, destroying native habitat, and choking out desirable vegetation. In an effort to battle this growing threat, weed control workshops are held and bio-control efforts are implemented.

Workshops explain the process of biological weed control. Presentations focus on the biology of the target weed, the weed’s natural predators, and how to collect and monitor insect agents.

After workshops, participants collect Eustenopus villosus (seed head weevil), photo at left, and Larinus curtus (flower weevil) to take and release on their private lands.

Workshops are held in the summer (usually June) of each year.

The District and local agencies such as the Nez Perce Tribe Bio-Control Center and the Idaho Department of Fish and Game coordinate an insect control day in June of each year. During this date, insects are collected. The collected insects are placed in release containers with 300 insects each. The District provides these insects free of charge to local landowners for release on their properties. To get on the distribution list, landowners should call the District office. Insects are usually collected and released in the last week of June or first week of July.

The District has developed a bio-control release plan which focuses on the distribution of insects in prioritized drainages. To implement this project, the District received funds from the Idaho Department of Agriculture and the Clearwater Basin Weed Management Area to collect and release insects.

Why Do We Need BioControl?

As weeds were introduced to America, by accident or as ornamental plants, their natural enemies were not brought across the ocean. With no natural predators, these weeds grow large and plentiful, choking out native plant species.

Getting Agents Here...

After years of insect collection, in-depth research, and litigation, insects have slowly been introduced in the United States to manage weed populations. This process takes anywhere from 4-7 years.

Locally efforts are underway to make these insect available to landowners. Insects for yellow starthistle, spotted/diffuse knapweed, canada thistle, rush skeleton, and dalmation toadflax are presently being raised in Lapwai, Idaho by staff at the Nez Perce Tribe Biocontrol Center and by staff at the University of Idaho in Moscow, Idaho.

 

Yellow Starthistle Biocontrol
Yellow starthistle is prevalent within Nez Perce County’s rangelands, roadsides, pastures, recreation lands, and cropland.

Yellow Star Thistle Map

Figure 1. Yellow Starthistle Distribution in Nez Perce County. Yellow shaded areas show distribution areas. Click on image to view a larger version.


CONTROL

Since 2002, the District has assisted landowners in releasing bio-control agents to control yellow star thistle. Early releases were randomly placed throughout the county. In 2005, a coordinated approach was developed which identify target release areas within the Big Canyon and Lapwai watersheds. The goal of this effort was to ensure that there was a sufficient population of the insects to provide a sustainable control level. Beginning at the lowest elevation in the watershed, the insects were released approximately every mile along drainage corridors.

There are three insects approved for release in the State of Idaho. Of these the District focuses on the release of the hairy weevil, Eustenopus villosus, which attacks the seed heads resulting in 90 to 100% reduction of seed production. The insects emerge in late May and persist until August of each year. The weevil lays its eggs in the seed head. As the insects hatch they feed on the developing seeds. Releases consist of 300 insects per site. District staff collects the insects the last week of June each year and relocates them to areas of heavy yellow star thistle infestations. Releases follow the United States Department of Agriculture’s Biology and Biological Control of Yellow Starthistle protocol.

Yellow Starthistle Insect Distribution Survey

In cooperation with the Nez Perce Tribe’s BioControl Center, District staff assisted with a county wide survey to determine the extent of the bio-control agent distribution. The survey was conducted the summer of 2012 and included 129 sites across Nez Perce County (122 sites) and Clearwater County (7 sites). Paul Brusven, Biocontrol Center Director, summarized the results and presented the findings to the Nez Perce Soil and Water Conservation District Board at their January 2013 meeting. A pdf of the power point presentation is available for download.

Yellow Starthistle Biological Control Agent Survey - 2012 (7.8 MB)

Two insects were surveyed; the hairy weevil, Eustenopus villosus, (EUVI) and the flower weevil, Larinus curtus, (LACU).

The survey concluded the following:

  • EUVI and LACU are established across Nez Perce County and beyond where yellow starthistle exists
  • EUVI numbers were highest at 0-20% bloom on average
  • EUVI appears to be displacing the LUCU weevil based on the adult numbers collected
  • Insectaries are established for future collections and redistribution efforts based on agent numbers
  • There is a need for additional new agents to be approved for use. Ideally a root feeding agent to reverse the impact yellow starthistle is having on the landscape.

The following map illustrates the locations of insect releases (yellow dots) and the location of the insects found during the survey (purple dots). Click on image to view a larger version.

Yellow Star Biocontrol Map


Partners and Funding

The District works closely with the Nez Perce Bio-Control Center to coordinate release site locations and obtain staff training. In addition, release site locations are transmitted to the Nez Perce Bio-Control Center as part of a regional database.

This project was funded through the Bonneville Power Administration’s Fish and Wildlife program and the Idaho State Department of Agriculture’s Noxious Weed Program. The Bonneville Power Administration provides funding to the District for steelhead habitat restoration. The bio-control releases are a component of the Lapwai Creek restoration plan’s objective of reducing noxious weeds within the watershed. The Idaho State Department of Agriculture’s Noxious Weed program funds are prioritized through the Clearwater Basin Cooperative Weed Management Area.

2014 Activities

71,500 insects were released at five sites within the county. The 2014 releases are estimated to impact 25 acres of yellow star thistle. Figure 5 illustrates the 2014 release locations.

Bio-Control Summary of Activities - 2014

Figure 5. 2014 Yellow Starthistle Releases. Click on image to view larger version.

2014 Yellow Starthistle Target Map

2013 Activities

700 insects were released at seven sites within the county. The 2013 releases are estimated to impact 35 acres of yellow star thistle. Figure 3 illustrates the 2013 release locations.

Bio-Control Summary of Activities - 2013

Figure 4. 2013 Yellow Starthistle Releases. Click on image to view larger version.

Yellow Star Thistle Target Map

2012 Activities

1,050 insects were released at seven sites within the county. The 2012 releases are estimated to impact 35 acres of yellow star thistle. Figure 2 illustrates the 2012 release locations. Yellow Starthistle Bio-Control Summary of Activities - 2012

Click on image to view a larger version.

Yellow Star Biocontrol Releases Map

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Spotted Knapweed Biocontrol

Spotted Knapweed is prevalent within Nez Perce County’s rangelands, roadsides, pastures, recreation lands, and cropland.

CONTROL

Since 2004, the District has assisted landowners in releasing bio-control agents to control spotted knapweed. The goal of this effort was to ensure that there was a sufficient population of the insects to provide a sustainable control level.

There are five insects approved for release in the State of Idaho. Of these the District focuses on the release of the knapweed flower weevil, Larinus minutus, and the knapweed root weevil, Cyphocleonus achates, which winters as larvae in the root. The flower weevil females produce between 28 and 130 eggs which are laid in clusters in open flowers. The root weevil winter in the root, where the larvae mine and gall the vascular tissue. Releases follow the United States Department of Agriculture’s Biology and Biological Control of Knapweed protocol.

Partners and Funding

The District works closely with the Nez Perce Bio-Control Center to coordinate release site locations and obtain staff training. In addition, release site locations are transmitted to the Nez Perce Bio-Control Center as part of a regional database.

This project was funded through the Bonneville Power Administration’s Fish and Wildlife program and the Idaho State Department of Agriculture’s Noxious Weed Program. The Bonneville Power Administration provides funding to the District for steelhead habitat restoration. The bio-control releases are a component of the Lapwai Creek restoration plan’s objective of reducing noxious weeds within the watershed. The Idaho State Department of Agriculture’s Noxious Weed program funds are prioritized through the Clearwater Basin Cooperative Weed Management Area.

2014 Activities

4,800 insects were released at eight sites within the county. The 2014 releases are estimated to impact 40 acres of spotted knapweed. Figure 6 illustrates the 2014 release locations.

Bio-Control Summary of Activities - 2014

Figure 6. 2014 Spotted Knapweed Releases. Click on image to view larger version.

2014 Spotted Knapweed Target Map

2013 Activities

1,200 insects were released at six sites within the county. The 2013 releases are estimated to impact 30 acres of spotted knapweed. Figure 4 illustrates the 2013 release locations.

Bio-Control Summary of Activities - 2013

Figure 4. 2013 Spotted Knapweed Releases. Click on image to view larger version.

Spotted Knapweed Map

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Field Bindweed Biocontrol

Field Bindweed is prevalent within Nez Perce County’s rangelands, roadsides, pastures, recreation lands, and cropland.

CONTROL

Since 2013, the District has assisted landowners in releasing bio-control agents to control field bindweed. The goal of this effort was to ensure that there was a sufficient population of the insects to provide a sustainable control level.

There is one insect approved for release in the State of Idaho. The District focuses on the release of the Field Bindweed Gall Mite, Aceria malherbae. The adults feed on upper leaf surfaces – causing them to distort and curl tightly inward.

Gall MiteDamaged Field Bindweed
Figure 1. Field bindweed gall mite (Aceria malherbae). The microscopic biocontrol agent for field bindweed. Photographer USDA Agriculture Research Service Archive, USDA Agricultural Research Service, Bugwood.org
Figure 2. Damage to young field bindweed plant, caused by gall mite. Photogapher Bob Nowierski, Montanta State University, Bugwood.org.

Partners and Funding

The District works closely with the Nez Perce Bio-Control Center to coordinate release site locations and obtain staff training. In addition, release site locations are transmitted to the Nez Perce Bio-Control Center as part of a regional database.

This project was funded through the Bonneville Power Administration’s Fish and Wildlife program and the Idaho State Department of Agriculture’s Noxious Weed Program. The Bonneville Power Administration provides funding to the District for steelhead habitat restoration. The bio-control releases are a component of the Lapwai Creek restoration plan’s objective of reducing noxious weeds within the watershed. The Idaho State Department of Agriculture’s Noxious Weed program funds are prioritized through the Clearwater Basin Cooperative Weed Management Area.

2013 Activities

2,400 insects were released at two sites within the county. The 2013 releases are estimated to impact 10 acres of field bindweed. Figure 3 illustrates the 2013 release locations.

Bio-Control Summary of Activities - 2013

Figure 3. 2013 Field Bindweed Bio-Control Releases. Click on image to view larger version.

Field Bindweed Map

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Contact Us

Nez Perce
Soil and Water
Conservation District

Office Location:
27880 Chambers Road
Culdesac, ID 83524
(Map of Office Location)

Phone: (208) 843-2931
Fax: (208) 843-2234

E-mail NPSWCD

Mailing Address:
P.O. Box 131
Culdesac, ID 83524

Office Hours:
10:00 a.m. - 2:00 p.m.
Monday-Thursday
or by appointment


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