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Brown marmorated stink bug threatens Virginia crops

Brown marmorated stink bug threatens Virginia crops

• The brown marmorated stink bug is posing a real threat to crops from Maryland southward deep into the heart of Virginia. • Next up could be a rich smorgasbord of grain and fiber crops in the Southeast.  

Coming this summer to a crop or home near you — one of Asia’s least likeable exports, the brown marmorated stink bug.

These stink bugs get the biggest headlines from irate homeowners who have battled the critters tooth and nail the past couple of years throughout the Mid-Atlantic states. Now, the aptly named insects are posing a real threat to crops from Maryland southward deep into the heart of Virginia. Next up could be a rich smorgasbord of grain and fiber crops in the Southeast.

From a strictly non-technical perspective the brown marmorated stink bug eats virtually anything, from the hard-to-get-to meat encased in an acorn to the soft flesh of a wine grape.

Already, it has caused debilitating damage to fruit operations in northern Virginia’s Shenandoah Valley and appears poised to make a run at field crops.

Peach growers are already dealing with the stinky insects in Virginia, and keeping easy to penetrate young peaches out of harms way will be real challenge. Even peaches sprayed numerous times to control brown marmarated sting bugs bear the scars of feeding, making the fruit unmarketable in many cases.

One Virginia peach grower reported spraying his orchards 18 times with an array of different insecticides, from Baythroid to Orthene, with good results each time. However, the stink bug populations just kept coming.

What’s next for these prolific insects is a big question for Virginia agriculture right now and maybe for other southern states in the near future.

Ames Herbert, a Virginia Tech Entomologist and leader of the state’s Integrated Pest Management program says he is stepping up tests to monitor brown marmorated stink bugs in cotton and soybeans this year.

“We saw some damage in field crops last year, but numbers weren’t high enough to cause widespread damage. We recently received reports of high populations of these insects in the Virginia Beach area, which, if accurate, will increase our concern for row crops.

“In the past couple of years, brown marmalated stink bugs were found in crops primarily in areas that border fruit production and confined to the northern part of the state. If the reports from Virginia Beach and Hampton Roads are accurate, that places them in large numbers in the Coastal Plain for the first time, which is a concern,” says the veteran Virginia Tech entomologist

Cotton crop in the way

Of particular concern is the state’s biggest ever cotton crop. Okra, a close cousin of cotton has shown to be highly susceptible to the marmorated stink bug. With an expected 50 percent increase in cotton acreage expected in Virginia this year, another potentially destructive pest is exactly what farmers don’t need.

As of June of this year, the winged native of Asia has become an aggravating pest for homeowners in 33 states and the District of Columbia. While row crop farmers may get their turn at bat with marmorated stink bugs, fruit growers in the Mid-Atlantic States are already battling the pest.

With peaches, apples, and even berries, the major issue is the visible damage a stink bug does. On apples, for example, the bug will insert its tongue into the fruit and suck, leaving a "corky dry area" that's visible to shoppers, says Tracy Leskey,an Agriculture Department entomologist who's co-leading a national working group researching the stink bug. "It looks bad," she says, though it won't affect the flavor.                            

The Virginia wine industry is particularly concerned about the relatively new pest. These stink bugs burrow into the fruit and vines and can easily be dumped into a wine vat and become part of the winemaking process.

How many stink bugs it takes to create off-flavor is unknown, but a major concern for Virginia wine grape growers.

"Some vineyards and some growers have been wiped out in the last year," says Virginia Rep. Frank Wolf, who is taking the lead in Congress on the issue. "They are devastating our vineyards, he says."

In grapes, the bugs stick to the clumps of fruit during the picking season and can end up in wine presses. As few as10 stink bugs crushed into one ton of grapes can ruin the wine.

For workers, charged with harvesting wine grapes, the little brown bug has become a major source of irritation. Finding a couple of these stinky bugs on a hand-sized clump is typical. Winery workers have to pull the half-inch-long bugs off by hand, which often produces a sickening odor that has been described as smelling like a decaying animal.

Other crops, including corn, tomatoes and soybeans have been damaged to varying degrees by the new pest.

Brown marmorated stink bugs have proven to be excellent hitch-hikers, easily making their way across the country. Their propensity for over-wintering in homes could prove to be a blessing or a curse for the little critters.

The stink bug home invasions have quickly raised the general public to action, a fate not usually found for predominantly agricultural insect pests. This kind of publicity could lead to quick and decisive action against these stink bugs — a good riddance according to row crop farmers.

The pests were first documented in the U.S. in the late 1990s and didn’t become much of a problem until the last couple of years. Because of its late arrival entomologists haven’t quite got a clear shot at them — at least not yet, but economically feasible, environmentally safe management strategies are coming along fast and furious.

Being a home-body may have its public drawbacks for brown marmarated stink bugs, but it could provide a plentiful and bountiful site for over-wintering. Though these bugs have yet to find many plants they don’t like to eat, over-wintering in a forest or fallow field is a bit tougher than making do in an attic or other home site.                                        

Prolific creatures

Controlling these critters is easy enough and insecticides to do the job are plentiful enough. The problem is the prolific nature of these stink bugs keeps new populations coming throughout the warmer months of the year. So, killing a huge population is too often rewarded by having to do it over and over again.

 Researchers at Virginia Tech may have serendipitously stumbled upon a natural solution to the problem. Amanda Koppel, a former graduate student, working at Virginia Tech’s Tidewater Research Station in Suffolk, Va., happened upon marmorted brown insects while doing research on parasitic wasps used to kill brown and green stink bugs that commonly attack Virginia field crops.

Back in November of 2009, she warned, “On the horizon Southeastern growers might well have another species of stink bugs to worry about. The brown marmorated stink bug, Koppel says, is now an infrequent pest around houses, but has the potential to become a pest of crops.”

Now, Koppel’s major professor and long-time Virginia IPM Director Ames Herbert says the new pest is, “expanding its range at an amazingly rapid rate.  It is attacking a large number of fruit, vegetable, ornamental and row crops, and is also found on a wide variety of trees, bushes and weeds.  In Virginia, it has spread into many new counties now as far south as Virginia Beach.”

The cutting edge biological work done by Koppel at Virginia Tech may take on a new level of importance, if conventional control methods for the new insect prove to be ineffective.

One possibility for control of brown marmorated stink bugs under study across the country is a tiny wasp, the size of a comma in this story. Koppel, during a trip to China as a graduate student, was among the first to consider the stink bug's natural predator in Asia as a possible way to manage the insect in the United States.

The non-stinging wasp lays its eggs in the eggs of the stink bugs. The wasp larvae then feed on stink bug eggs. Entomologists are treading softly on this approach, not wanting to create a bigger problem with the wasps than they already have with stink bugs.

For homeowners and fruit growers in the Mid-Atlantic states, treading lightly may not be the right approach. Instead they may echo the sentiments from the Jerry Clower story about the coon hunter who found a lynx, not a raccoon, in the tree — the call-to-action being ‘just shoot up here among us, cause one of us has got to get some relief’.

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