23 Feb 2018

Brown stink bug could cost NZ $3 billion

From Morning Report, 7:40 am on 23 February 2018

An invasion of the brown marmorated stink bug - the pest discovered recently in three Japanese car shipments - would devastate New Zealand's fruit, vegetable and wine industries, destroying more than $4 billion of export value and costing thousands of jobs, according to a new report from the New Zealand Institute of Economic Research (NZIER).

A female Brown Marmorated stink bug.

A female Brown Marmorated stink bug. Photo: Supplied

More than 100 of the stink bugs, which originate in Asia but have spread to the US and Europe, were found last week by Ministry of Primary Industries biosecurity staff in three car carriers that arrived at the dock in Auckland.

But this is just the latest disturbing infestation.

Border biosecurity patrols have discovered previously unheard of quantities of the imported beetles over the last two years.

Of course, stink bugs are nothing new in New Zealand. Most gardeners will have come across our native bright green, shield-shaped stink bugs, which suck sap from veges and give out a nasty smell when squashed.

These insects, often called shield bugs, are pretty harmless. Not so their mottled brown Asian cousins.

A soon-to-be released report commissioned by Horticulture New Zealand from NZIER suggests that if the brown marmorated stink bug becomes established in New Zealand, real GDP could fall by a minimum of $3.6 billion over the next 20 years, and horticultural exports could fall by $4.2 billion a year.

Chief executive of Horticulture New Zealand Mike Chapman is unequivocal - the insect must be kept out of New Zealand.

"If this stink bug arrives in New Zealand, it's going to devastate our horticulture, it's going to devastate our food production, it's going to devastate our rural communities, it's going to infest our homes across the country, and not just rural homes, urban homes.

"It's going to take out people's vegetable gardens, it's going to attack their flower gardens. This is one really nasty bug."

Some farmers have compared the potential impact of the stink bug to that of foot and mouth disease outbreaks in animals; Mr Chapman likens it to the impact of the bacteria PSA, which devastated kiwifruit growers and workers.

This infestation would be worse, he says, because it wouldn't be restricted to one industry, but would hit fruit and vegetable producers across the board.

"It just eats everything. It is a very hungry little bug. It has been sweeping across the United States; it's swept through Europe. We are talking about long term effects here. We are talking about billions of dollars. We are talking about rural communities."

NZ Winegrowers biosecurity and emergency response manager Dr Edwin Massey says it isn't clear why marmorated stink bug numbers have skyrocketed in countries like Japan, the US and Italy. But the more bugs multiply overseas, the more they hitchhike to New Zealand.

Between 2014 and 2016, MPI staff found stink bugs 55 times at the borders. Now it's far more.

"In terms of interceptions, we are well into the hundreds now, with that accounting for thousands of bugs. Most of those are dead, but this year there has also been an increase in the number of finds of a mixture of both dead and alive bugs, which is concerning."

In the US, some farmers have reported crop losses of up to 90 percent when stink bugs move in.

And homes in some areas have been inundated by the nasty-smelling insects.

So far, MPI efforts at the border have kept the marmorated stink bug out of this country. But it's a cunning critter.

Escaping the cold weather in the northern hemisphere, stink bugs can congregate in warehouses, where they get into goods being exported, says MPI manager Sharon Tohovaka.

"You don't normally see them. So in the vehicles for instance, we are finding them up behind mudguards, on the shelf where the battery sits, between the batteries of trucks. So they find very small crevices, where they can huddle up to get warm, but they huddle in large numbers.

"There could be, in somebody's house for instance, or in a field, hundreds of thousands."

They have turned up in a wide variety of imports, from heavy machinery to tiles, whey protein to barbie dolls - and from several destinations.

Dr Massey says MPI has been proactive in working with industry, and has already introduced measures to reduce stink bug numbers arriving in this country. Before Christmas, the ministry made it mandatory for all containers coming from Italy to be treated against stink bugs - a move which has had a significant effect in cutting bugs numbers.

Similar restrictions are in place for imports from the US, which are either heat treated, or fumigated with sulfuryl fluoride, before leaving the US. Now MPI is considering the same thing for Japanese car shipments.

"Treatment on that car-carrying pathway is the best option," Dr Massey says, "but I understand some of the limitations we have with treatment options in Japan at the moment."

The trouble is, if the bugs did get established in New Zealand, it would be near impossible to get rid of them, Ms Tohovaka says - as other countries have found.

"There are no natural predators for them in New Zealand, and insecticide sprays and things don't work, so there's nothing to kill them off."

Dr Massey says although MPI is doing a great job, everyone needs to keep a look out for brown stink bugs. Particularly if you live in the city.

A potentially disastrous outbreak in Chile was prevented when householders in the capital, Santiago, found the bugs in their homes and dobbed them in, he says.

"The most likely place you will find one is in an urban centre and that's because urban centres are the key source of the risk - trade and travel concentrate in urban centres. When we've looked overseas, they have almost always been detected in urban centres first."

Marmorated means veined - the bugs are shaped like a normal New Zealand green shield bug but with a streaked brown body.

And if you do spot one at home?

"If you find one, the best thing to do is catch it, snap it, report it, and call the MPI biosecurity hotline," Dr Massey says, referring to the need for people to take a photo of the bug, so experts can decide whether it is dangerous or not.

Although New Zealand does have its own native brown stink bug, Ms Tohovaka says MPI would much rather people called in with a false alarm sighting, than ignored a real pest.

Anyone who thinks they see one should call the hotline on 0800 80 99 66.