Misconceptions about biological controls

June 24, 202188

By Ethan Proud
PREVIEW Columnist

For some, biological controls (biocontrols) seem like a silver bullet, capable of removing invasive species without using herbicides. To others, it seems counterintuitive to release a non-native species on an invasive species wreaking havoc on the ecosystem.

Biocontrols, unfortunately, do not eradicate a population, though there are some exceptions and populations can decrease by large margins when an insect herbivore is released into the environment. These biocontrol agents will suppress the population of invasive species and can help slow the spread, though they will not completely eradicate the noxious weed. 

Biocontrols must be released repeatedly to see success and a onetime release will not yield great results. Paired with chemical or mechanical control, an acceptable level of control can be achieved. Release biocontrols in areas that are difficult to reach with a backpack, ATV mounted sprayer or equipment for manual control. It’s easier to hike into a difficult area with a small container of insects than it is to carry a shovel and a bag — especially when the bag is completely full and it is time to hike out. Utilize mechanical and chemical control around the perimeter of the release site and you will have a one-two punch, biocontrols suppressing the heart of the infestation and chemical or mechanical control containing the spread.

When it comes to approving a new biocontrol agent, the insects must first be carefully studied through a round of choice and no-choice tests, where it is determined that A) the insect will feed on only the target species and B) the insect will starve to death before finding a new food source. These tests are conducted by the U.S. Department of Agriculture Animal and Plant Health Inspection Service Plant Protection and Quarantine Program, or USDA APHIS PPQ for short. The process of approval takes many years, meaning that new biocontrol agents are not only very exciting, but few and far between.

In short, biocontrol agents need to be paired with another control method to be truly effective and they are not an option for certain weeds. However, they are a great tool for integrated pest management and can reduce our dependency on herbicides.

For more information on biological control agents that can be released in Colorado and are available to landowners, visit the Colorado Department of Agriculture website and click Biocontrols underneath the Conservation Banner.

Archuleta County Weed and Pest is your local resource for managing noxious weed populations and controlling other pests.