Biocontrol our best defence

14 May 2018

CSH Trissolcus japonicus standing 1 2

Winter, the risk season for the brown marmorated stink bug (BMSB), is finishing in the Northern hemisphere countries where it lives. In winter, this bug hibernates in dark and protected places such as houses, cars, machinery, and suit cases. Just go onto YouTube and you can see some horrific videos of what this nasty bug does. 

As well as infesting homes and cars, in summer the BMSB gets out and about to eat every bit of fruit and suitable vegetables it can find; commercial crop loses have been reported to go as high as 90%. In New Zealand, research done by NZIER estimated that the economic impacts could be as much $2 billion a year if the bug gets established here. When you squash it, it stinks, hence the name. So this is one bug we do not want in New Zealand.

Our first line of defence is to keep it out of New Zealand. That has not worked in Europe and the US, where the stink bug is invading in massive numbers. Earlier this year, more stringent measures were put on the importation of cars and machinery into New Zealand. Fumigation was required for containers, and ships carrying used cars were turned around if they had not been adequately treated for BMSB. This was well done by the Government. 

In horticulture, we are preparing for the arrival of this bug. Some say it is likely to arrive. 

Spraying is not particularly effective in getting rid of these bugs as in summer, they live at the top of trees. For spray to be effective, it has to be a contact spray and that means there has to be lots of spraying. 

There is a better solution that, in combination with spraying, will hopefully lead to the eradication of any BMSB population that establishes in New Zealand. That solution is a biological control agent called the Samurai wasp. It is tiny - about the size of a pin head – and it doesn’t sting. The wasp actively seeks out BMSB eggs which it then lays its own eggs into, killing the BMSB. Samurai wasps can be more than 70% effective in controlling BMSB, but it is not in New Zealand. 

To get the Samurai wasp into New Zealand, the Environmental Protection Authority (EPA) needs to agree to it being introduced. The EPA’s considerations will include the Samurai wasp’s effect on native bugs. Research suggests that it will not be a lot. But that’s a decision for the agency to make.

More information is available here and submissions close 24 May. To be successful with the EPA we encourage you to have your say. 

- Mike Chapman, CEO