WEDNESDAY, SEPTEMBER 21, 2016

David and Goliath battle for weed control

A battle of David and Goliath proportions between tiny insects and giant weeds could provide a solution to a growing weed problem threatening New Zealand’s wetlands and waterways.

The Environmental Protection Authority (EPA) is calling for submissions on an application to release two insects as biological control agents for the weed giant reed.

Northland Regional Council has applied to introduce the arundo wasp and the arundo scale insect to work together to control the weed giant reed (Arundo donax).

The giant reed is a leafy, woody bamboo-like grass that grows up to 5 metres high and has plumes of feathery flowers in summer. It forms in dense clumps and grows well near river and stream margins and can threaten wetlands, block waterways and cause flooding. It can also be a habitat for rats and possums. The reed is mainly a problem in the north of the North Island, but isolated infestations can be found as far south as Queenstown.

“Natural enemies of a plant – or biological control agents – can be used to reduce weed populations, such as the giant reed. We’re calling for submissions on introducing a wasp and scale insect as biocontrol agents, so the EPA can consider all views about potential risks and benefits of introducing them,” said Dr Fiona Thomson-Carter, General Manager Hazardous Substances and New Organisms.

“The wasps lay their eggs into the stems of the giant reed, which causes a growth or gall that stunts, and sometimes kills the stem. The scale insects suck nutrients from the stem, reducing the growth rate of the giant reed,” Dr Thomson-Carter said.

The reed is thought to be native to Eurasia and, although once valued as an ornamental plant, it’s now an environmental weed in a number of countries. The wasp and scale biocontrol agents have been released successfully in the USA and Mexico, where they’re beginning to reduce the vigour of the giant reed.

The application, from Northland Regional Council on behalf of the National Biocontrol Collective, was made under the Hazardous Substances and New Organisms (HSNO) Act 1996.

Submissions are invited on the application, with the submission period opening on 21 September and closing at 5pm on 3 November 2016. A public hearing may be held before a decision is made.
View application details and information
Read more about the submission and hearing process
What we do: The EPA decides on applications for the release of new organisms under the HSNO Act. We assess the benefits, risks and costs of releasing new organisms to safeguard people and the environment.

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