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Program in Focus: PPQ Montana Helps Tribes Fight Rangeland Weeds With Biocontrols

Native Americans play a crucial role in preserving the centuries-old traditions of cattle farming in Montana—and fight a constant battle against invasive weeds that crowd out the grazing grasses their livestock need.  But through decades-long partnerships with APHIS’ Plant Protection and Quarantine (PPQ) program, the area’s Tribes have found that tiny foreign insects—a “biocontrol” arsenal—can help them win that struggle.

Invasive noxious weeds such as Russian knapweed, leafy spurge, Dalmatian toadflax weed, and spotted knapweed have been an unwelcome presence in Montana and adjacent reservations for generations.  Although herbicides, grazing, and mechanical controls such as plowing have a role in weed management, biological controls such as non-native insects are increasingly popular among some Tribes.

Carefully screened by PPQ and its research partners, such “biocontrol agents” harm only target plant species.  For Montana and adjacent Tribal lands, these biocontrol agents comprise a small coterie of insects from Europe and Eurasia that use the area’s invasive weeds as a nursery where they can lay eggs.  After the larvae hatch, they nibble on the weed’s roots, stems, or flowers—whichever the particular species prefers.  This stresses the weeds and stunts their growth and development.  

Although the concept seems simple, getting the system to work is an effort that requires ongoing coordination between the office of PPQ’s State Plant Health Director for Montana, Gary Adams, a multitude of weed specialists, and participating Tribes: the Confederated Salish and Kootenai Tribes, the Blackfeet Nation, the Fort Belkap Indian Community, the Chippewa-Cree Tribe, the Crow Nation, and the Northern Cheyenne.  For its part, PPQ works with natural resource specialists from each Tribe and the Bureau of Indian Affairs to gather insects established in Montana (or in other States, if necessary).  Cooperatively, they release those insects in areas with significant weed infestations.  The hope is that these insect populations can become established on their own and serve as a reservoir of sorts for the Tribes to use in the future.

PPQ helps monitor these catch-and-release sites, called “insectaries,” when they are established, and then for their effectiveness and potential to provide insects in the future.  PPQ also provides funding to the Indian Nations Conservation Alliance (INCA) to support these efforts in Montana and to provide “field day” workshops.  Open to Tribal and non-Tribal producers, as well as to natural resource specialists, these workshops teach participants how to identify target weeds, handle the equipment and insects used in biocontrol operations, and pursue alternative methods for controlling weeds.  

For their part, the Tribes survey weed-infested land to determine where to place insectaries for housing and breeding their biocontrol insects.  The Tribes maintain the insectaries, are responsible for ensuring they remain free from pesticides and safe from animals, and ultimately become self-sustaining biocontrol practitioners.
Although it can take several years for results to show, surveys attest that the tiny migrants are doing their job.  A case in point is the Fort Belknap Indian Community, which includes the Gros Ventre and Assiniboine Tribes.  Starting in the early 1990s, the Fort Belknap Indian Community has been collaborating with PPQ Montana staff on identifying sites for insectaries and releasing insects that attack leafy spurge.  By 2006, the weed’s presence had dramatically diminished on the reservation (see examples of before and after pictures below).  Even though leafy spurge resurfaced after a 2011 flood severely damaged the community’s insectaries, PPQ, INCA, and the Tribes have continued their efforts with renewed vigor and hope to have the weed under control again within a few years.

In the meantime, Adams and his team plan to keep strengthening their current Tribal partnerships and reaching out to form new ones.  “New personnel working for some Tribes are just becoming aware that there’s a biocontrol option out there,” says Adams. “Although it may be a slow process, it can be a long-term, cost-effective solution” to keeping Native herds and economies thriving.  In the end, says Adams, the best indicator of PPQ’s success “is how we work together with the Tribes” toward a goal all can agree on: protecting Indian Country agriculture and “keeping the stewards of the land on the land.”  

For more information on PPQ Montana’s efforts, including field day training, interested Tribal members may contact Gary Adams at Gary.D.Adams@aphis.usda.gov.


Leafy spurge infestations, 1998 (left) and in 2006 (right), after use of biocontrols; photos by Richard W. Hansen, APHIS

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