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Biocontrol Workshop | Waikato Biodiversity Forum

Earlier in April, a few members of our North Island team travelled to Hamilton to participate in a Biocontrol Workshop hosted by the Waikato Biodiversity Forum.

Biocontrol is quite a drastic contrast to biosecurity:

Biocontrol – The control of an invasive species by the introduction of a natural predator

Biosecurity – Measures aimed at preventing the introduction of foreign species

In short, where biosecurity is aiming to keep foreign species out of the country, biocontrol is deliberately introducing new species in an attempt to control populations of existing weeds and insects. This may cause concern, given New Zealand's history with possums and ferrets. However, the processes before any species of insect or fungi are incredibly robust, and there is a large amount of research dedicated to ascertaining any adverse effects of this introduction.

The day consisted of two main components. The first was the workshop, where our team learned about a plethora of different NZ weeds and their implications to our native fauna. Just to list a few examples:

- Tradescantia is a weed that smothers forest floors, outcompeting all other flora.

- Woolly Nightshade is a plant with large leaves that prevent sunlight from reaching smaller ones. It also produces fruit that is toxic for many animals.

- Moth plant is a sturdy vine with similar implications and is difficult to control with herbicides.

Two scientists from Landcare Research delivered the majority of the presentation. They described control methods for not only these weeds, but plenty more, by using organisms from their respective native countries. 

An excellent lunch was provided following the conclusion of the presentation, after which our team embarked on a field trip to Donny Park.


Currently, the Tradescantia weed is running rampart around the park, and the effects of this were nothing short of devastating. Very little native fauna could grow through the thick layer of this one species, with the only exception being a few trees. To control this, two biocontrol methods have been introduced here:

- Brazilian yellow leaf spot fungus

- Three species of Tradescantia beetle

Both control agents are highly specific to the Tradescantia weed, meaning that they will not affect any of our other species. The results were not only noticeable, but incredible. Though the weed was still prevalent, it was sick. Rather than green, many of the leaves were yellow with fungi. There were holes in most leaves or stems from the beetles. 

By using biocontrol as a method of control for these weeds, we do not need to use herbicides that may harm our other species. Not only this, but after the initial cost of rearing and establishment of the agents, the process of this control is free.

All in all, the team at SPS Biota would like to thank Waikato Biodiversity Forum for hosting the workshop, and Landcare Research for the insight into a field we previously had not heard about.

- Tanner Stott, SPS Biota