Using nature to fight the war on weeds
Our biosecurity team undertakes biological control using living organisms to manage pests. Manaaki Whenua Landcare Research leads in this eco-friendly method, releasing agents like fungi and beetles to control invasive weeds.
Biological control is the use of one living organism to control another, with the organism that undertakes the control called the ‘biological control agent’ or ‘biocontrol agent’. In weed control this is often an insect or a fungus. Biological control has a long history dating back to 200 A.D when ants and their nests were used to control insect pests on citrus trees in China.
Manaaki Whenua follows an extensive process to identify and introduce agents that are effective and safe. All potential agents are highly regulated by the Ministry for Primary Industries and the Environmental Protection Agency.
Controlling weeds
Recent biological control releases include tradescantia yellow leaf fungus in Christchurch and Kaikōura to help control tradescantia, an invasive creeping weed also known as wandering willie.
Buddleia beetle was also released near the Hae Hae Te Moana River in Woodbury, South Canterbury and near the Rakaia Gorge in Central Canterbury to control buddleia, an invasive garden escapee which easily invades and dominates riverbed habitats, altering river flow, and allowing silt to build up causing flooding issues.
Some weeds cannot be effectively controlled by conventional methods in our region, such as herbicides, while others grow in areas that are difficult or dangerous to access for hand control.
They may also be too widespread making them a non-cost-effective solution.
Biological control is an important and useful tool for us. It is a sustainable and environmentally friendly approach to weed control, reducing our reliance on chemicals and impacts on non-target species.
They are particularly beneficial to use in sensitive or rare native habitats where chemical control is not an option.
The success of biological control is not immediately obvious. It can take decades with the goal of helping keep the population under control.
Morgan Shields, biosecurity advisor investigating the tradescantia yellow leaf fungus used to help control tradescantia
Find out more about weed biocontrol
You can learn more about what makes a good agent, and what agents are released across the country by visiting: