MEDIA RELEASE
26 January 2016
Weevils to wage war on weed
Hundreds of Chilean weevils will be released over the coming weeks to control the widespread weed Darwin’s barberry.
Around 100 Darwin’s barberry seed weevils were released for the first time in New Zealand in March last year. Landcare
Research imported the weevils and conducted extensive tests to make sure they were safe before they were released in
Southland. The fast-spreading orange-flowered thorny shrub is a growing problem in parts of the country, threatening to
overrun native plants and farmland, particularly in Southland.
Environment Southland is due to release an additional 400 weevils shortly. Horizons Regional Council and the Greater
Wellington Regional Council are also deploying the weevil to help combat the weed. Around 1000 weevils would be released
across the three regions.
Hugh Gourlay, a member of the weed biocontrol group at Landcare Research, has been rearing the weevils at the Crown
research institute’s containment facility in Lincoln for the releases.
He said there was a limited window of opportunity in which the releases could be made.
“We need to release the new adults soon after they start emerging as potted plants do not produce sufficient new growth
to nourish them sufficiently.”
Although the adult weevils feed on the new growth, the main damage to the plant is caused by the larvae that feed on the
seeds.
Darwin’s barberry produces large numbers of viable seed that can be spread hundreds of metres by birds that consume the
fruit on the weed.
Gourlay said weevils were often confused with beetles but their “elongated nose, like an elephant’s trunk” actually set
them apart.
The Environmental Protection Authority approved the release of the weevils in 2012. Research into the weevils has been
funded by the National Biocontrol Collective.
ENDS