Unwanted or introducedcan have a huge impact on New Zealand’s environment, and native and . Chemicals such as pesticides or poisons can get rid of these species, but are often bad for the environment or affect other species. Alternatives such as trapping, culling or weeding can be time consuming and may only have a tiny impact on the pest population.
A successfulprogramme reduces or removes the need for other controls.
Getting rid of weeds
In New Zealand, biocontrol agents have been used to control the spread of weeds. For example, six different biocontrol agents currently control the spread of gorse – a prickly and invasive weed introduced from Scotland. The small red spider mite has been the most successful of these biocontrol agents as it can eat enough gorse to reduce the plants’ growth and spread.
Protecting pasture from pests
Biocontrol can also be used to control insect pests that destroy farmland. The clover root weevil is a pest that was accidentally introduced to New Zealand in the late 1990s and has degraded pasture, especially in the Waikato, where it thrived. The introduction of a tiny wasp from Ireland is now helping to control clover root weevil numbers. Find out more about in this article, Irish wasp to the rescue.
Ryegrass is an important food for grazing stock in New Zealand. A type of Amazing ryegrass., called an , is being used to protect ryegrass from attack by insect pests, like the Argentine stem weevil and black beetle. Find out more about in this article,
The possum problem
The possum is one of New Zealand’s worst pests. Possums have aeffect on the environment – eating native forests, spreading disease, and preying upon native birds. At present, possum numbers are controlled with a combination of poison (1080) and trapping. Scientists are currently researching effective and humane alternatives for controlling possum numbers.
One biocontrol strategy being investigated is the development of immunocontraceptives that use baits,, viruses, or parasitic worms. These immunocontraceptives prevent the possums from producing offspring by making them .
The Pest detective is an online guide to help identify the signs left by pest animals. Developed by the National Pest Control Agencies (NPCA) in partnership with the Ministry for Primary Industries, TbFree New Zealand, the Department of Conservation, and Local Government New Zealand, with substantial sponsorship.