Biosecurity is the protection of the environment from biological threats. In Aotearoa New Zealand, action is taken to prevent unwanted organisms from damaging the economy, natural biodiversity, or public health
The Department of Conservation states, “Biosecurity is about keeping New Zealand free of unwanted organisms and for controlling, managing or eradicating them should they arrive in the country, to prevent or reduce any damage these may cause should they occur, and to protect and preserve the land, water, industry and people of New Zealand”.
Biosecurity threats include invasive animals, plants, insects, and diseases that can enter, spread and establish in Aotearoa New Zealand. These threats can arrive through travel, trade, natural movement, or illegal introduction. Once established, they can be difficult and costly to control.
Invasive animals
Invasive animals can damage ecosystems, reduce biodiversity, and impact farming and forestry. Some browse native plants and prevent forests from regenerating. Others prey on native wildlife that evolved without mammalian predators. Some can also spread diseases. Common examples in New Zealand include:
- Possums – damage native forests and spread bovine TB
- Stoats and ferrets – major predators of native birds and lizards
- Wild deer and goats – overgraze native vegetation
- Wallabies – spreading into new areas and altering habitats
Invasive plants
Invasive plants (weeds) can spread quickly and outcompete native vegetation. They can smother forests, change habitats, and reduce biodiversity. Many spread easily through seeds, wind, water, or human activity. Controlling invasive plants often requires ongoing effort, combining prevention, early action, and long-term management. Well-known examples include:
- Old man’s beard – smothers and collapses native trees
- Wilding pines – spread rapidly across hill country
- Moth plant – climbs and overtakes native vegetation
- Privet and woolly nightshade – dominate forest edges and disturbed areas
Insects
Invasive insects can have major impacts on New Zealand’s environment, food production, and economy. Some attack crops and forests, reducing yields and damaging industries. Others can spread quickly and are difficult to control once established. A small number can also affect human health and quality of life. Strong border control, surveillance, and public reporting help reduce the risk of new insect pests establishing. Examples include:
- Fall armyworm – now established and affecting maize and other crops
- Brown marmorated stink bug – a high-risk threat not yet established in New Zealand
- Red imported fire ant – a serious pest intercepted at the border, but not established
- Argentine ant – already established and disrupts native ecosystems and households
Diseases
Diseases affecting plants, animals, and people are a major biosecurity concern. New diseases can impact food production, trade, public health, and the environment. Because New Zealand is free from many global pests and diseases, new incursions can have serious consequences. Biosecurity systems focus on keeping diseases out, detecting them early, and responding quickly to limit their spread.
Recent or significant examples include:
- Myrtle rust – affects native species like pōhutukawa and mānuka
- Kauri dieback – threatens iconic kauri forests
- HPAI (avian influenza) – a global risk to wild birds and poultry
- Varroa mite – impacts bee health and crop pollination
Resources
For more information, visit:
Ministry for Primary Industries https://www.mpi.govt.nz/biosecurity
Department of Conservation https://www.doc.govt.nz/our-work/biosecurity/