This year’s mild winter was a boon to the stink bug, an invading insect from Asia with a formidable appetite for berries, tree fruits and vegetables.
VANCOUVER, Wash. — On a hot June day, Joe Beaudoin ducked into the shade of his orchard to check for peaches with shallow dimples — the telltale signs left by the brown marmorated stink bug.
This invader from Asia has a formidable appetite for the berries, tree fruits and vegetables that Beaudoin grows on his 80-acre farm.
This spring, even before the trees sprouted all their leaves, the bug already had begun to pierce the tiny peaches to suck out juice.
“This is our third year finding them,” Beaudoin said. “But I have never seen the damage so early.”
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Beaudoin expects more crop losses in what is shaping up to be a big year for the stink bugs.
The same mild temperatures that sabotaged the region’s snowpack were a boon to these bugs, reducing their mortality during the coldest months and generating plenty of early spring bounty for forage.
And as climate change unfolds in an increasingly interconnected world, the warmer weather forecast for the decades ahead could make the Northwest a more welcoming region for some of the pests that arrive from elsewhere.
The stink bugs get their name from the scent they release, which some describe as akin to a musky cilantro. They are well-entrenched in the Portland-Vancouver area, and — to a lesser extent — in Seattle. In both cities, some urban homeowners have been beset by infestations as the bugs find indoor spaces to overwinter.
These insects have also spread south through the Willamette Valley, where Oregon State University researchers have purposefully mixed in the stink bugs with the grape crush to try to figure out how many insects it takes to mess with the taste of the region’s fabled Pinot Noir.
“We should be able to keep them out of the wine, but even if they get in, we’re looking at some processing steps so that you can get rid of the flavor,” said Elizabeth Tomasino, an Oregon State University researcher.
So far, in the orchard country of Central Washington, only a few stink bugs have been found in nearby residential areas, and there are still plenty of questions about how well they can adapt to such an arid area.
But these farmers are on alert.
Spurred by the government phaseout of some insecticides, they have under taken a major effort to develop alternative pest controls. If the population booms in their orchards, they would likely dramatically step up their spraying.
The weird warm weather has also boosted the populations of another recent Asian invader: a tiny fly called the spotted winged drosophila that lays its eggs in the fruit of cherries, berries and other crops. This year, Beaudoin says he had to spray his strawberries, marionberries and blackberries once a week to keep these fruit flies at bay.
The stink bugs attack a broader range of crops — including the apples that are Washington’s most valuable harvest.
The brown marmorated stink bugs grow to less than an inch long and are shaped like a shield.
They can be differentiated from native U.S. stink bugs, which have not been a big pest problem, by two white bands on their antennae.
These insects have a complicated life cycle, living for up to a year and evolving through five different stages before adulthood, when their wings enable them to cover many miles in search of food. In the Northwest, they typically produce one generation per year, but due to the warm weather this year, they may produce two.
Their destructive power was amply demonstrated in Pennlysvania, which was where the bug was first detected in the United States back in 1998. Over time, their numbers grew, and in 2010 the bug contributed to severe losses in apple orchards, scarring the fruit with so many blemishes that some acreage was not worth harvesting.
Homeowners also have had creepy experiences with the stink bugs, with some in eastern states reporting thousands infesting their residences.
Beaudoin’s farm location — within the Vancouver urban boundaries and close to residential subdivisions where stink bugs overwinter — makes his acreage particularly vulnerable to attacks. And during the past three years, his operations have evolved into a kind of field laboratory for the study of the insect’s Northwest behavior.
Beaudoin was surprised to find, at least in his orchards, the bugs appeared to show a decided preference for Russet and Granny Smith apples but left more than a dozen other varieties untouched. He lost several rows of one variety of peaches, but not others. And 90 percent of his French pumpkins were lost to the stink bugs, which penetrated from the ground,
Researchers are scrambling to figure out not only what are the most effective insecticides to use on the stink bugs, but also when best to apply them. So far, for Beaudoin, that’s still uncertain.
“This is all new. For timing, it’s just going to be a guess,” Beaudoin said.
Tastes like … bugs
As the bugs spread from the Portland area in search of food, the vineyards of Western Oregon represent close-by targets. So far, they have not shown up on grapes in sufficient quantities to pose a problem for winemaking, according to Tomasino, the OSU researcher. If they did, blowers used during sorting could hopefully keep them out of the crush.
But with so much at stake, OSU researchers decided to figure out how many stink bugs it would take to taint the wine, and what consumers thought of that product.
They made wine in 2012, 2013 and 2014, then served it up after a year of aging in blind taste tests with untainted vintage. (All the wine fell well within the Food and Drug Administration thresholds for insect levels in the crush, according to Tomasino.)
The researchers concluded that the recipe for a decidedly stink-bug flavored Pinot was three and a half insects per cluster of grapes, which is well above the levels found to date in the vineyards.
About 10 percent of those who blind tasted the stink- bug wine didn’t mind the flavor.
Others who sampled the wine either disliked or strongly disliked the stink- bug taint.
“It does two different things,” Tomasino said. “It masks a little bit of the fruitiness, and then in your mouth the main compound from stink bugs is cilantro, and of course that’s not something you would associate with a high quality wine.
Hopes for a treatment
The stink bug could potentially wreak the most damage in Washington east of the mountains, where many high-value crops are grown with irrigation.
Even amid this desert agriculture, invasive species can sometimes take hold. In the orchards of the Yakima basin, farmers have long battled the codling moth of west Asian origin.
To fend off the codling moth, farmers for years repeatedly sprayed apples with azinphos-methyl, an organophosphate pesticide derived from World War II-era nerve agents.
The chemical was phased out of the orchards in 2012 by the Environmental Protection Agency.
Today, most apple growers get much of their control by a gentle alternative. They hang small wire dispensers in the trees that flood the orchards with pheromones and disrupt the moth’s mating cycle. This approach also enables more beneficial insects to build up in the orchards and help keep other pests under control.
“It’s been a major success but it’s been a long, long road to figure out how to manipulate those moths to keep them from finding each other,” said Peter Landolt, a U.S. Department of Agriculture entomologist based in Wapato.
There’s no similar treatment for stink bugs.
Instead, with azinphos-methyl now off-limits, farms in areas with stink bugs have turned to other compounds — such as pyrethroids — that kill a wide range of insects. Then, with the beneficial insects knocked back, they sometimes have to turn to additional sprays to treat other pests that move in.
“We’re afraid of what will happen if they get here,” said Jim Doorink, an apple grower in the Yakima Basin. “The products we use against it are broad spectrum and indiscriminate.”
Researchers are hoping to come up with alternative treatments, such as introducing natural predators that can feed on the stink bugs, or finding some way to attract masses of the bugs to a lethal trap.
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At the Wapato research station, stink bugs dwell in a plexiglass cage. Chemist Lee Ream picks one up with tweezers and tickles its belly so the stressed-out bug emits a pungent aroma.
The scent has undergone detailed analysis, but researchers still have a long way to go to figure out the stink bugs.
Some, such as Landolt, are hopeful that the lack of water and climate extremes of the desert climate will limit the bugs’ populations.
Doorink, as he gazes out from his hilltop house on thousands of verdant irrigated acreage, is less optimistic.
“I think all the (dry climate) is going to do is affect how quickly they can get established here,” he said. “There are plenty of places out there for them.”