Samurai wasp vs stink bug: Government eyes bio-control for insect invasion

The brown marmorated stink bug has the potential to cause huge damage to NZ horticulture.

The brown marmorated stink bug has the potential to cause huge damage to NZ horticulture.

An exotic insect that could devastate fruit and vegetable crops, ravage backyard gardens and devalue homes is arriving at New Zealand's borders in greater numbers than ever before.

Horticulture New Zealand biosecurity manager Richard Palmer said it was only a matter of time before the brown marmorated stink bug breached customs and spread across the country.

And when it does, the consequences could be disastrous for New Zealand's agriculture and horticulture industries and homeowners, he said.

The Ministry for Primary Industries (MPI) is working to gain approval to import a foreign wasp to control the stink bug should it become established.

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The Samurai wasp (Trissolcus japonicus) is a natural enemy of the stink bug and said to be one of the most effective biological controls.

The Samurai Wasp (Trissolcus japonicus) could be introduced in New Zealand as a biological control for the stink bug.

The Samurai Wasp (Trissolcus japonicus) could be introduced in New Zealand as a biological control for the stink bug.

The female wasp lays her eggs inside the stink bug's eggs. Studies have shown the parasitic wasp destroys between 63 and 85 per cent of stink bug eggs.

New Zealand authorities are conducting research to determine if the Samurai wasp will have any impact on native flora and fauna.

Palmer said there was only one native pentatomidae (stink or shield bug) in New Zealand, found in sub-alpine areas of Central Otago.

Introducing a foreign insect to control another was risky, Palmer said.

"There are examples in history where bio-controls have gone horribly wrong, there's no doubt about that."

A Samurai wasp emerges from stink bug eggs.
Christopher Hedstrom

A Samurai wasp emerges from stink bug eggs.

An application to import the wasp, being made to the Environmental Protection Agency in May, would seek to address any concerns.

However, Palmer said the only certainty was that the stink bug would arrive in New Zealand and have a significant effect on commercial plant production.

The numbers of stink bugs arriving at the border were much greater than previous years, he said.

It was "coming on everything" including luggage, vehicles, medical equipment, protein powder, roof tiles, furniture — even Barbie dolls.

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"It's kind of a hitch-hiker on lots of stuff."

The stink bug eats apples, kiwifruit, corn, tomatoes, cherries, wheat, maize and more.

"The value of maize alone in New Zealand is nearly $700 million to the grazing industry."

Native to China, Japan and Korea, the stink bug has made its way to parts of the United States and Europe, causing severe crop losses.

MPI diagnostic and surveillance services director, Dr Veronica Herrera, said it was estimated the stink bug would cause hundreds of millions of dollars of losses and the loss of overseas markets if it became established.

Herrera said bio-controls, like the Samurai wasp, were already used extensively in the horticulture industry and reduced the need for insecticides.

Palmer said the stink bug was also a major nuisance for homeowners.

"It will eat things in your garden, your tomatoes and peaches and heritage apples and the like, as well as getting into your house and making the place stink."

He said they had become such a problem in the US that spotting a stink bug at an open home could be an instant deal breaker.

Pipfruit New Zealand board member Evan Heyward, who grows apples and kiwifruit in the Motueka area, said the stink bug was a "serious threat".

"The first preference is to stop it coming in here. We just need to throw everything at that because that's the easiest way forward."

If you find a stink bug, take a photo of it and report it to the Exotic Pest and Disease Hotline on 0800 80 99 66.

 - Stuff


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