Samurai wasp warrior

10 Feb 2017

by Richard Palmer

Orch Feb 2017 V5 LRSAM

While the brown marmorated stink bug hasn’t made it to our shores, forces are rallying just in case the worst happens.

The voracious marmorated stink bug (Halyomorpha halys) is taking the world by storm in a very bad way. It is a seriously nasty pest of fruit trees, vegetable crops and ornamental plants. It is also a pest for maize, corn and wheat. In 1996 it left its home territory of Asia by hitching a ride on a container of household goods travelling from Beijing to Pennsylvania.

The brown marmorated stink bug (BMSB) is now a significant agricultural pest in the United States, causing economic losses in the mid-Atlantic states.

And from there, it has begun spreading throughout the world. Right now the stink bug is cutting a swathe through kiwifruit in Italy – early indications are suggesting it could have a much greater impact on kiwifruit than we had realised. It has only been in that country for about two years.

And it’s not just a problem for horticulture and farming, it’s a lifestyle problem for urban dwellers. In winter it clings to houses for warmth and will happily destroy an urban garden. It’s also a very tough dude; it smells when squashed and is difficult to kill.

Experience in the United States tells us that management requires chemical controls at four times the usual number to control the bug.

So it’s in everyone’s interests to work hard to ensure it doesn’t get here. There’s a lot going on at the border, and just as importantly, a lot being done to make sure we have a Plan B if it does establish here.

New Zealand’s approach to the stink bug is world leading. We are making damn sure we are doing everything in our power to prevent it from entering at the border; but more than that, we are building an arsenal – otherwise known as an integrated pest management plan – to hit it head-on should it manage to set up home here.

The endgame for us is that attempted eradication of the brown marmorated stink bug will include a mix of chemical and biocontrol agents. The Ministry for Primary Industries (MPI) has identified three existing chemicals that can kill the bug, and is having these chemicals assessed and approved for use in urban environments.

Meanwhile, the Samurai wasp (Trissolcus japonicus) is also part of our plan. It originates from China, Japan and South Korea, where the brown marmorated stink bug is also native.

NZGrower Feb17 V4 WASP1

In fact the Samurai  wasp is one of several natural enemies of the brown marmorated stink bug and possibly the most effective. The female wasp lays her eggs inside the eggs of the brown marmorated stink bug, and the wasp larvae develop inside the stink bug egg. The wasp destroys between 63% and 85% of brown marmorated stink bug eggs.

The United States has been studying the Samurai wasp as a brown marmorated stink bug biocontrol agent since 2007. New Zealand industry, scientists and MPI have set up a steering group to develop an application to import the Samurai wasp into this country should the stink bug establish here.

A cost/benefit analysis and risk assessment report is being funded by MPI and industry and we are consulting with Māori and other key stakeholders.

Better Border Biosecurity (B3) is conducting research to determine if the Samurai wasp will have any impact on stink bugs native and naturalised to New Zealand.

We hope to have an application to the Environmental Protection Authority (EPA) by May this year and a decision from EPA before the next risk season for BMSB arrivals. But, ultimately, it would be much better to not have to import the Samurai wasp.

The most important thing now is constant vigilance. Watch out for signs of the brown marmorated stink bug. Imported machinery and stacks of stored goods (like timber) are particularly important to check because the bug likes to hide in the nooks and crannies offered by these items and materials.

If you see something, say something. Catch it. Snap it. Report it.


Richard Palmer is HortNZ’s biosecurity and trade policy manager.

This article first appeared in the February 2017 issues of NZGrower and The Orchardist. For more information or to subscribe, click here.