The stink bug invasion

Ashlea Surles writes:

The brown marmorated stink bug has moved to America.  Scientists say the shield-shaped brown insect likely hitchhiked from Asia on a cargo load into Allentown, Pennsylvania in the late 1990s and prospered.    

Spreading to 38 states and already reaching epidemic levels, the stink bug has colonized America.  Within the next 10 years scientists expect they will invade the entire continental United States, sparing no state.  

They are named for the spicy arsenic-cilantro odor they emit when squished, but, while the name might be funny, the problem they are creating is decidedly less so.

The stink is the least of the worries.          

They are a threat because they eat just about every major crop grown in America.       

University of Maryland professor Michael Raupp said entomologists have never seen a pest as serious as this.  “This one feeds on fruit, it feeds on grapes, it feeds on corn, it feeds on soybeans, on tomatoes, on peppers, in agricultural fields, in people’s home gardens and then in the autumn, it’s coming into people’s homes.  This is what I call a perfect pest.”

From tobacco to cabbage to melons to cotton – they are indiscriminant eaters who haven’t eaten in months.

Hibernating in crevices and warm spaces since the fall – making their malodorous presence known in homes – the invasive insects are now coming out into the open to feast, and they will destroy millions of dollars worth of crops. 

Stink bugs ate through more than 50 million dollars worth of fruit crops alone last year, this season they will be worse.   

“We’re now seeing the price of food going up,” said Virginia Congressman Frank Wolf at a stink bug town hall event in his district.   “Nationwide, this could be a serious impact of the cost of food.    

If you’re a farmer, and you’re life is invested in your crop, and you’re wiped out …” Wolf trailed off.  “The last time we saw something like this hit the farmers was the drought.”

“We’ve seen ‘em along the edges of the field, and we’re just anticipating that they’re gonna be in the field come the spring,” said Tyler Wegmeyer, a strawberry farmer.  “We are worried about it.”

At this point, farmers are helpless – some reduced to walking the orchards and crop rows, picking off the stink bugs they see with their hands and throwing them in a bucket of detergent or oil.

“I’m worried I’m throwing away an entire crop,” said John McCann, who lost an entire harvest of Asian pears to stink bug damage last year.

Scientists are researching pheromone traps that could be placed amid crops to attract the bugs and also pesticides that are effective yet safe to consume, but the brown marmorated stink bug is remarkably resistant.  While some have been shown to paralyze the bark-colored bug for hours, few chemicals have been found to actually kill it.  There is no golden ticket product scientists are endorsing.

And not only will the stink bugs be eating this summer, they will also be reproducing.  Last year, in some parts of the mid-Atlantic region, they completed two generations (laid two batches of eggs), reproducing at double the pace. 

 In China, in the warm, southern part of the area they inhabit, they can complete six generations a year, Raupp said.  “If we look at the latitude of where they are China, and we superimpose that on North America … we’re concerned that when these stinkers move into the southern states – Georgia, the Carolinas – there could be multiple, as many as four or five generations a year.”

The stink bug plague is spreading like kudzu because there is nothing to mitigate the population – nothing in the environment kills it.  While there are a variety of stink bug species living in North America, these generally go unnoticed because natural predators keep their populations in check.  The brown marmorated migrated solo.

But United States Department of Agriculture scientist Kim Hoelmer has zeroed in on the insect that is the stink bug’s natural enemy in Asia and is now in the process of offering the single best hope for farmers across the country girding for a stink bug infestation.

“These wasps that we’re considering introducing we know will only attack stink bug eggs and will not themselves become a problem anywhere else,” Hoelmer says from his lab situated on a remote swatch of the University of Delaware campus. 

The insects Hoelmer keeps behind a series of pressurized quarantine doors actually look more like feckless gnats than their relatives, the paper wasps that descend on picnics and build basketball-sized nests in the summer.  These are smaller than ants, just big enough to drill through stink bug eggs masses and incapable of stinging humans or animals.

“These wasps are so closely tied in to the biology of their host that their fate depends on the fate of the stink bug.  If the stink bug were to cease to exist, these wasps would cease to exist,” Hoelmer described. 

But there are still risks to the predator introduction method.  Raupp calls it an “imperfect science,” citing parasitic flies released in the early 1900s to combat the gypsy moth population in New England, which them moved over to attack native silk moths.

But Raupp and Hoelmer both say that the risks are comparatively small and these wasps are farmers’ best chance.

USDA regulations have tightened since the gypsy moth experiment and the vetting process for releasing a new insect is vigorous: Hoelmer must demonstrate unequivocally that these wasps will eat only brown marmorated stink bug eggs and nothing else.

“The kind of research needed to make this determination will take about two years typically to conduct,” Hoelmer says, predicting the wasps could be released in 2013, a dent in the stink bug population maybe seen a year after that.

For the next two to three years, farmers can hope--and that’s about it. 

Ashlea Surles is a production assistant for NBC Nightly News in the Washington D.C. bureau