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Published: 2011-05-04 00:00:00

A South American beetle with exclusive tastes has been released for the first time in the Waikato region as a biological control agent for the pest plant Tradescantia fluminensis (commonly known as wandering jew or wandering willy).

With the help of the Te Pahu Landcare Group, Waikato Regional Council has recently released 305 tradescantia leaf beetles at the Karamu Reserve just south of Te Pahu, southwest of Hamilton.

It is hoped the beetle – a native of Argentina and Brazil which generally feeds only on Tradescantia fluminensis – will be effective in tackling the weed.

Tradescantia fluminensis – a very widespread and troublesome garden weed in New Zealand - has become common in frost-free parts of the North Island and parts of the South Island. Research suggests it could be a long-term threat to the survival of native forests and can cause an itchy reaction in dogs.

The beetle’s release at Te Pahu follows rigorous testing (and approval by ERMA for it to be introduced) which showed the beetle would not attack plants except Tradescantia fluminensis, did not contain unwanted parasites and would not cause any unwanted effects on New Zealand flora and fauna, said council biosecurity operations manager Peter Russell.

“In co-operation with the Te Pahu Landcare Group, we will be monitoring this initial use of the beetle in the Waikato closely to see if the beetle may be useful more widely in our region. One potential benefit if the beetle works as hoped is that it could reduce the cost of herbicide use in our region.”