19 December 2007
The Environmental Risk Management Authority (ERMA New Zealand) has
received an application to import a Brazilian beetle to control the weed
Tradescantia fluminensis, commonly known as wandering willie.
General Manager, New Organisms, Libby Harrison, says the application,
which is now open for public consultation, has been made by the Auckland
Regional Council on behalf of a consortium of regional councils and the
Department of Conservation.
“Tradescantia is a real and growing conservation threat in many parts of
the country and a well-known weed in home gardens. Dense mats of it can
smother low-growing native plants and it is a threat to forest
regrowth,” Dr Harrison says.
Herbicide or physical removal can be used to kill tradescantia, but
neither approach is feasible over the huge number of sites in the
country where this weed is a problem. The use of biological control is a
viable option because the beetles seek out the weed and maintain
themselves from year to year.
The proposed control agent is Lema obscura, a leaf-eating beetle that
comes from the cool, upland regions of south east Brazil – the home
range of tradescantia. The larvae of the beetle feed on the plant’s
leaves and, in large enough numbers, can cause severe damage to the
clogging mats.
Landcare Research has carried out laboratory testing to assess the
safety of the beetle for release in the New Zealand environment. Risk to
native plants is judged to be negligible, as tradescantia is not related
to any New Zealand plants.
The application is open for public submissions to ERMA New Zealand until
25 February 2008. If submitters have difficulties meeting this date,
they should contact ERMA New Zealand.
For further information contact:
David Venables, Communications Manager, ERMA New Zealand.
¨ Telephone +64 4 918 4835 ¨ Mobile 021 224 3304
¨ Facsimile +64 4 914 0433
¨ Email: david.venables@ermanz.govt.nz