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Home > Plants, Pests & Pest Control > Pest Management > Biological Control

Biological Control

Spotted Knapweed Before and After
The leafy spurge infestation (left) was greatly reduced by biological control (right).

Emerald ash borer, Oobius agrili and Tetrastichus planipennisi
Adult Emerald Ash Borer (EAB) beetle and two parasitoid wasp species that feed on EAB eggs and larvae

Leafy spurge beetle release
Releasing Aphthona beetles to control leafy spurge.

Spotted knapweed seedhead weevils on a spotted knapweed flower
Spotted knapweed seedhead weevils

Non-native pests can be very destructive when introduced to new areas because those new areas lack the predatory insects and diseases that limit the pest populations in their native environments. Biological control, the use of natural enemies to control non-native pests, can be a cost-effective and powerful pest management tool.

Classical biological control reunites natural enemies, such as insects and pathogens, with the target pest to minimize pest damage. The goal of biological control is to reduce the target pest population and its corresponding impact to an acceptable level. Before any insect or pathogen is considered a viable candidate for biological control, scientists study it carefully to make sure it will not harm people or the environment.

Advantages of biological control

  • Cost-effective: Bioagents can control vast expanses of target pests. Through state and county programs in Minnesota, bioagents are a shared resource available at no cost to land managers. They are collected at sites with high bioagent populations and distributed to new sites.
  • Long-term, sustainable management: Established bioagent populations are self-sustaining and provide ongoing pest management.
  • Selective: The bioagents are very specific to the target pest and beneficial to the environment by reducing the pest population so that the desirable flora and fauna can flourish.


  • All bioagents approved for release will not harm humans and can be handled easily.
  • A process of testing and assessment minimizes the risk that a newly imported bioagent will have a negative impact on other species.

State of Minnesota biological control programs

Biological control programs in Minnesota are cooperative. Multiple agencies, associations, institutions, and private landowners work together to accomplish goals. Lead agencies help to coordinate efforts, disseminate information, provide expertise, and collect data.

Minnesota Department of Agriculture (MDA) biological control program

Insect biological control

Weed biological control

 For information on MDA's program, contact Monika Chandler, 651-201-6537 or Monika.Chandler@state.mn.us

Minnesota Department of Natural Resources (DNR) biological control program

Weed biological control

  • Purple loosestrife, Lythrum salicaria, L. virgatum, hybrids and cultivars
  • Garlic mustard, Alliaria petiolata (biocontrol is in development)

For information on DNR's program, contract Laura Van Riper, 651-259-5090 or Laura.Vanriper@state.mn.us

Spotted knapweed seedhead weevils on a spotted knapweed flower
Galerucella beetles feed on purple loosestrife