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Nature

Stink Bugs Now Invading 33 U.S. States, USDA Studies Natural Solution

Brown_marmorated_stink_bug

When first brought to national attention via the New York Times in September of 2010 (‘Move Over, Bedbugs: Stink Bugs Have Landed’), the bugs insects — brown marmorated stink bugs — had already begun decimating fruit orchards and even soybean crops as early as 2009.

Native to China, Japan, Korea and Taiwan, the  stink bug (Halyomorpha halys) has actually been in the U.S. since 1998 where it was first discovered in Allentown, Pennsylvania. With no natural predators in that region, the “bug” quickly managed to get a foothold amongst the plentiful food supply of the farmlands of Pennsylvania, then spread to Maryland and New Jersey.

At the time of that reporting, evidence of these non-native stink bugs already had been documented in 15 states, with collected specimen samples in 14 others.

What brings the bugs back into newsworthiness is that the number of states invaded has more than doubled over the last year; the innocuous-looking insect (that gives off a skunk-like odor when touche or crushed) has now officially spread to 33 U.S. States, leaving large swathes of cropland riddled with its tell-tale bore-hole signature.

Brown marmorated stink bug eggs hatched
Brown marmorated stink bug eggs hatched.

Currently, the USDA is still researching the bugs, but with a budget of only 800, 000.00 per year, some entomologists associated with the effort feel that this is not enough — arguing for a quadrupling of the budget to bring on more researchers.

But a potential solution is out there: in its native lands, a species of tiny, parasitic wasp (Trissolcus halyomorphae) lays its eggs inside the stink bugs’ eggs, whereupon the wasp larvae eat the eggs, inside out, and thereby control the stink bug population.

A native stink bug — the green stink bug (Acrosternum hilare)— is kept in check by its natural, native predators, and is not a major pest problem.

While many ecologists bristle at the idea of introducing (yet another) non-native species  into the larger ecosystem, others feel it may be the only solution that doesn’t result in further poisoning of soils and crops. Further, using more pesticides can ruin years of “integrated pest management” practice in which some species — like wasps that prey on larvae or eggs –are allowed to thrive while other pests (without predators) are targeted with chemicals.

Brown marmorated stink bugs, adults
Brown marmorated stink bugs (adults)

The USDA is looking at this “natural” strategy, but cautions that the tiny wasp predators  need to be adequately studied first — meaning a quarantine process that could take 2 or more years before this biological pest-control solution is implemented, if ever. Also, there are now documented accounts of native parasitic wasps preying on stink bug eggs, and a few species of spider and preying mantis attacking adult bugs have been observed.

So, the solution may not require introduction of a non-native species — giving relief to farmers and ecologists alike.

The Asian stink bug is known as a good traveler; it easily hitchhikes on many types of cargo (not only food cargo) as it seeks out warmer climes in which to thrive.

Many climate scientists have predicted that warming global temperatures will permit the spread of  large populations of insects (e.g., the red pine beetle’s invasion of  Western U.S.) into regions that were previously off-limits due to colder temperatures. Whether this is the case with the spread of the stink bug — or just good adaptation and timing — may not be fully known.

Photos: (Brown marmorated stink bug, Halyomorpha halys) David R. Lance, USDA APHIS PPQ ; Image Number 1460048 at Invasive.org, a source for images of invasive and exotic species operated by The Bugwood Network at the University of Georgia and the USDA APHIS Plant Protection and Quarantine program




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