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 or 'biocontrol' involves bringing some of those natural enemies to New Zealand to help control the plant. Biocontrol organisms are usually insects but can also be animals, rusts or viruses.
Biocontrol agents provide assistance in the control of pest plants that are widespread. It is a very long term approach to pest control.
Before any new organism is brought into 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 by either regional council or Department of Conservation (DOC) staff (after approval from the Environmental Protection Authority (EPA)). Release sites are studied further to ascertain the success of the release and to guide future releases.
Greater Wellington contributes towards the biological control collective which includes the majority of regional councils, DOC and several district councils. Greater Wellington biosecurity officers currently release biocontrol agents in the Wellington region. When agent populations are high enough, they may distribute them on to new sites.
The following are some of the many agents available in the Wellington region (as of October 2012). For more information contact a Biosecurity Officer.
|Broom||Broom seed beetle Bruchidius villosus|
|Broom twig miner Leucoptera spartifoliella|
|Broom psyllid Arytainilla spartiophila|
|Broom shoot moth Agonopterix assimilella|
|Broom leaf beetle Gonioctena olivacea|
|Gorse||Gorse colonial hard shoot moth Pempelia genistella|
|Gorse pod moth Cydia succedana|
|Gorse seed weevil Exapion ulicis|
|Gorse soft shoot moth Agonopterix umbellana|
|Gorse spider mites Tetranychus lintearius|
|Gorse thrips Sericothrips staphylinus|
|Nodding thistle||Nodding thistle crown weevil Trichosirocalus horridus|
|Nodding thistle gall fly Urophora solstitialis|
|Nodding thistle receptacle weevil Rhinocyllus conicus|
|Old man's beard||Old man's beard leaf fungus Phoma clematidina|
|Old man's beard leaf miner Phytomyza vitalbae|
|Old man's beard sawfly Monophadnus spinolae|
|Ragwort||Ragwort cinnabar moth Tyria jacobaeae|
|Ragwort flea beetle Longitarsus jacobaeae|
|Blackberry||Blackberry rust Phragmidium violaceum|
|Boneseed||Boneseed leafroller Totrix s.l.sp chrysanthemoides|
|Buddleia||Buddleia leaf weevil Cleopus japonicus|
|Californian thistle||Californian thistle blight Phoma exigua var.exigua|
|Californian thistle rust Puccinia punctiformis|
|Hemlock||Hemlock moth Agonopterix alstromeriana|
|Mistflower||Mistflower fungus Entyloma ageratinae|
|Mistflower gall fly Procecidochares alani|
|Scotch thistle||Scotch thistle gall fly Urophora stylata|
|Smilax||Smilax rust Puccinia myrsiphylli|
|Thistles||Green thistle beetle Cassisa rubiginosa|
|Tradescantia||Tradescantia leaf beetle Neolema ogloblini|
Biocontrol agents are currently being researched for a wide range of common pest plants including banana passionfruit, wild ginger, Japanese honeysuckle and Darwin's barberry