Week in Review

Stink Bugs: Be Afraid, Be Very Afraid

Dr Catherine Duthie loves insects. This internationally-respected biosecurity expert, who works for the Ministry for Primary Industries, has 20 bugs tattooed on her arm, including an ant, a wasp, a weta, a crane fly and weevils.

But bigger than all of them is her tattoo of a brown marmorated stink bug (BMSB).

Which fits in well with the BMSB being New Zealand’s number one most feared pest. 

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The stink bug hasn’t become established in New Zealand yet - or at least biosecurity officials don’t think it has. But a 2017 report from NZIER found that under a worst case scenario, our GDP losses from a full-blown stink bug invasion could reach $3.6 billion by 2038. It says living standards could fall by up to $2.8 billion over 20 years, as employment and real wages decrease. 

Horticultural export values could fall by up to $3 billion over 10 years and $4.2 billion over 20 years. The wine industry alone could lose $600 million worth of exports. 

Be afraid, be very afraid.

The damage is already done overseas. At the height of the US stink bug crisis in 2010, some farmers in Maryland and Pennsylvania lost 90 percent of their peaches and nectarines, 50 percent of their apples and pears.

And now the stink bug has spread to 32 other countries, from Canada and Croatia, to Greece and Germany. In Italy, it’s decimating kiwifruit, apples, pears, grapes, soya beans, maize - and more.

In Georgia it arrived via Italian construction materials imported for the 2014 winter Olympics in the neighbouring Russian city of Sochi, and by 2017 had destroyed 90 percent of the country’s precious hazelnut crop. 

Only massive spraying programmes have caused any improvement in Georgia, but that’s at the expense of the country’s hard-won organic status.

Dr Catherine Duthie is a leading expert on stink bugs. Photo: Supplied

Insanely versatile

The problem is that stink bugs eat practically anything, love to hitchhike to new places, and are virtually impossible to get rid of once they move away from their natural predators. 

Duthie first started doing research on stink bugs back in 2010, when she was a brand new graduate. 

“We were MAF back in those days. My manager said ‘There’s this bug causing us a few troubles in America. Can you have a look at it and tell us if it’s something we should be worried about?’”

So Duthie looked and realised this was definitely something New Zealand should be worried about, though at first it was tough to get the message across. 

“We’ve got so many things that are of concern - fruit flies, foot and mouth disease, all sorts of other insects and viruses and fungi that threaten our border on a daily basis. So it’s really hard when someone comes along with something new and says ‘Pay attention to this’. It’s ‘How do I prioritise this against all the other things I need to be concerned about?’”. 

The turning point came with a visit by a US insect specialist expert, Dr Tracy Lesky who “scared the pants off everybody”, Duthie says.

“She showed some of the damage that was being done to fruits and vegetables in the US, some of the losses that the growers were seeing and - the biggest thing of all - pictures of these bugs inside people’s houses.

“That’s what gets just about everybody. In the wintertime they have a habit of aggregating en masse in people’s houses. Sometimes there can be tens of thousands of bugs; the inside of people’s houses and the outside of people’s houses just crawling with stink bugs.”

There’s a bittersweet stink bug joke: What’s the best way to get rid of stink bugs from your home? Burn it down. 

And, as the name suggests, they really do stink, especially when they are threatened - like if you try to sweep them up, or squash them.

“If you can imagine dirty teenage boy socks which have been hanging around in the bottom of the school bag for a week or two, it smells a bit like that,” Duthie says. “I’ve smelled single bugs, I’ve not smelled tens of thousands. Even one can be smelly enough.” 

Destruction in the orchard

While they are annoying in your home, they are devastating in your field or your orchard.

Stink bugs have mouth parts that act like a tiny syringe, poking into the plant tissue and sucking out the contents. That doesn’t destroy the fruit, but it makes it look ugly and taste bad. 

An apple damaged by the brown marmorated stink bug Photo: Supplied.

When stink bugs get into a vineyard and get harvested along with the grapes, it can taint wine, particularly red wine. Smelly teenage sock vintage isn’t great.

Duthie says stink bugs will eat just about anything. 

“Way back, when I was looking into the effects of the brown marmorated stink bug, I started recording all the different species it had been found feeding on. I diligently went through the literature and every time I found something different I’d add it to my list. I stopped when I got to 300 species and I thought ‘That’s probably enough.’” 

For example: apples, kiwifruit, peaches, pears, cherries, corn, grapes, lima beans, soy beans, green beans, peas, peppers, tomatoes, sweet corn, satsumas, oranges, sorghum, cotton, apricots, blueberries, broccoli, cauliflower, sweet potatoes, turnips.

You get the message.

“It will feed on the fruit, it will feed on the flowers, also on the young leaves. It feeds on the sap of stems and feeds through the bark of trees.”

It likes the pods on legumes like peas and beans, so if it got into New Zealand, it has the potential to cause damage to natives like kowhai, Duthie says. 

Where does it come from?

The story starts, harmlessly enough, in East Asia - China, Korea, and Taiwan, where the brown marmorated stink bug has lived for hundreds of years. And down there it’s just any old ordinary bug doing its thing. Eating and getting eaten.

“They just exist. They just do what bugs do. They feed, they reproduce, they enjoy their lives,” Duthie says.

And stink bugs didn’t set off deliberately to do their big OE - head off to the US and then Europe and beyond. What they do like is finding some warm, dry, dark place to snuggle up together during cold weather. It might be someone’s home, but they are just as likely to choose a factory, or a warehouse. And then if something from that factory or warehouse gets shipped to New Zealand, the bugs come with it. 

In another scenario they might choose a used car or a piece of agricultural machinery, or some construction materials destined for export. And they will tuck themselves into a dry, warm, dark cavity where no one can see or disturb them, release a ‘come hither’ smell to get their mates to join them (the official name is an aggregation pheromone) and, unbeknownst to anyone - hitchhike to, say, New Zealand

Of course, when the stink bugs arrive and it’s spring or summer in New Zealand, that triggers them to wake up, realise they are a bit peckish and - if no one catches them first - they’ll head out to get something to eat - and another bug to mate with. And bang, you’ve got a possible plague on your hands.

Robo bug

And stink bugs are super hard to kill. They move about perched up on six skinny legs like the terrible robot killer dog in the “metalhead” episode of Black Mirror. And they eat from the inside of fruit using their syringe-like nose parts. This means they can often survive general spraying programmes, says Dr Ed Massey, biosecurity and emergency response manager for New Zealand Winegrowers and chair of the Brown Marmorated Stink Bug Council.

“Stinkbugs are very robust. Residual insecticides, where you spray them on and have the insect walk over, are much less effective than where you actually spray the insecticide directly onto the bug. 

“In the past I’ve seen stink bugs knocked down by residual spray, then getting up after a few hours and wandering off.” 

That means massive amounts of spraying - which is just what fruit and vegetable producers in New Zealand are trying to get away from. 

Dr Ed Massey (left, with cap) and other BMSB Council reps on a surveillance operation in Chile  Photo: Supplied

They are coming

Over the past five years, a lot of these bugs have been hitchhiking towards New Zealand. In everything from boxes of shoes to Barbie dolls; from medical equipment to people’s suitcases. 

But they especially like vehicles and machinery. So people like David Vinsen, chief executive of imported motor vehicle industry association VIA, are taking the risk very seriously.

His members, who include used car importers, shipping companies, dealers, and biosecurity companies licensed to check and treat used cars, collectively lost millions of dollars in early 2018 when several car-carrying ships were turned away from New Zealand after live stink bugs were found on board. 

It took seven weeks before trade was back up and running normally.

“Nobody knew how we could deal with this, and we had no cash flow and we had huge costs stacking up against us. It was a real crisis,” Vinsen says.

Chemical treatments for the cars were an option, but some of most effective ones are banned in Japan where most of the cars come from. Others aren’t allowed in New Zealand. 

So the industry and got together with biosecurity officials and decided to set up heat treatment facilities on the wharf in Japanese ports, Vinsen says. 

Every vehicle that comes out of Japan during stink bug season is heat treated,” Vinsen says. “They drive the cars in, the temperature goes up to 60 odd degrees and is held there for 20 minutes and then it’s cooled down and the cars are driven out.”

There are also traps on the ships, and fogging systems that can blast individual decks, or even the whole ship, if any bugs are found. 

Vinsen says the new precautions have added around $250 to the cost of each used car in New Zealand.

There’s a dog for that

But what if that’s not enough, or if bugs arrive a different way, there are further inspections on the wharves in New Zealand, including specific BMSB dogs.

BMSB dog trainer Alan Willox, with Georgie pinpointing a stink bug with her nose. Photo: Nikki Mandow

James Reed is on the biosecurity front line for MPI at northern ports, including Auckland. 

He says the number of live bugs arriving in New Zealand is increasing every year.

“I think last season, the figure for total bugs, live or dead, was over 3000; sometimes you might have 600 dead ones in one container. But live bugs, that happens more often than you think.” 

He says as the threat has increased, so has the response from MPI.

Last stink bug season, any vehicles, machinery or parts on the car ships that weren’t in a sealed container, had to be treated offshore first. 

From September 1 this year, cars, machinery and parts have to be treated, even if they are inside a container. And the number of risk countries has been expanded to 33. 

Meanwhile, as the crisis continues in Italy, almost anything imported from that country has to have been treated, Reed says. 

“It’s easy to say, but it’s a very difficult thing to manage, because there are thousands of containers on these ships. But the message to industry and to importers is really clear: make sure you know the rules before you purchase something to import and make sure those rules have been met before you load.” 

Everyone hopes brown marmorated stink bugs won’t get established in New Zealand. But many in the know think it probably will.

Cath Duthie is surprised we’ve held out this long. 

“When I first started working on this issue more than eight years ago, I thought we would have an incursion of stink bug within five years and I’m really happy I’m wrong.”

Is it inevitable it will arrive in the end?

“It’s very possible we will have an incursion we have to respond to sometime in the next couple of years,” Duthie says. “However I am more confident now we will be able to respond appropriately and have a really good shot at eradication. Because we now have the technology to detect these bugs at low levels and we have really good plans in place so we would know what to do if we found a small population.”

NZ Plant and Food Research scientist Max Suckling in Italy with one of the new live traps his team is working on. Photo: Supplied

 Find out more, including about the cool research that scientists like Professor Max Suckling are doing on stink bug eradication by listening to the podcast.

Find other Newsroom.co.nz stories on stink bugs:

Preparing for the war on stink bugs and The foul-smelling bugs threatening New Zealand wine.

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