Biocontrol
Biological control (or "biocontrol") involves using the natural enemies of a pest to help reduce the damage it causes. Biocontrol reduces the population density or impact of a specific pest, making it less abundant or less damaging than it would otherwise be. In Southland, biocontrol of weeds has been in use since 1984, with 28 different biocontrol agents released in the region (25 insects, two mites and one fungus).
How safe are biocontrol agents?
All potential biocontrol agents undergo rigorous testing before applications to the Environmental Risk Management Authority are made to bring them into New Zealand. Only those organisms which feed specifically on their targeted host plant are released. Much of the biocontrol research done in New Zealand is carried out by Landcare Research. Click here to read more about biocontrol in New Zealand.
Some advantages of biocontrol include:
- Biocontrol agents are specific to their host plant so other plants are not affected.
- Biocontrol agents actively seek out their host plant and will damage weeds in areas that may not be known about.
- Once populations become established, biocontrol agents are self-sufficient and require no human supervision.
- Biocontrol agents are not constrained by property boundaries.
- Over time, biocontrol can be more cost-effective than mechanical or chemical control methods.
- Biocontrol is compatible with organic agriculture and is viewed positively by overseas markets.
The Biological Control of Weeds Programme in Southland is administered by Environment Southland. There is a strong focus on biocontrol agents which specifically target broom, ragwort and thistles as these weeds are widespread and abundant throughout the region. The programme involves monitoring and distributing existing biocontrol agents in Southland, and coordinating the release of new agents when they become available. Biocontrol agents will eventually spread to wherever their host plants are present. By harvesting and releasing agents from established populations we can speed up this natural dispersal. Biocontrol agents are wholly reliant on their host plant and will not eliminate every last plant. However, biocontrol agents can reduce the impact of their host plants to a manageable level, freeing up resources to tackle other invasive weeds.
Biocontrol agents are available free to Southlanders through the Biological Control of Weeds Programme. Their availability is determined by the amount of agents ready for harvesting, and the suitability of potential release sites. Biocontrol may be compatible with using herbicides depending on the agent and when the herbicides are used.
To find out more about specific biocontrol agents in Southland follow the links below:
For more information or to discuss releasing agents on your property contact:
Biosecurity Officer (Pest Plants)
P: 0800 76 88 45 (inside Southland only)
F: +64 3 211-5252
E: service@es.govt.nz
Environment Southland is the brand name of Southland Regional Council.