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Pest plants

Biocontrol

Most pest plants have arrived in New Zealand without their natural enemies that may have kept them in check in their own countries.

Biological control (Biocontrol) involves bringing some of those natural enemies to New Zealand to help control the pest plant. Biocontrol organisms are usually insects but can also be rusts or viruses.

Before any new organism is brought to New Zealand, strict testing procedures are followed, often over a period of years, to ensure that the new organism poses no risk to valued species. The biocontrol agent has to be proven to attack only the pest plant and no other plant species.

Landcare Research undertakes the research and trialling of such biocontrol organisms which are then released (after approval from ERMA) by either Regional Council or DoC staff. Release sites are studied further to ascertain the success of the release and to guide future releases.

To date biocontrol agents in New Zealand control the following pest plant species:

  • Alligator weed
  • buddleia
  • blackberry
  • boneseed
  • broom
  • californian thistle           
  • nodding thistle
  • scotch thistle
  • gorse
  • hawkweed
  • heather
  • hemlock
  • mistflower
  • old man's beard
  • ragwort
  • st johns wort

    • The Auckland Regional Council contributes approximately $130,000 a year to biocontrol research.

    Biocontrol agents are currently being researched for tradescantia, moth plant, woolly nightshade, banana passionfruit, wild ginger, Japanese honeysuckle, Darwin's barberry, nassella tussock and lantana.

    Continue to Pest plant control techniques