To most of us, they’re just a nuisance: smelly, persistent pests that creep and buzz their way into our homes and go crunch in the night.
But for farmers in Virginia and a growing number of states, the brown marmorated stink bug is a thing to fear.
An invasive species from East Asia that first arrived in Pennsylvania via shipping crate in the late 1990s, the bug that drives people to distraction each fall when it swarms indoors seeking shelter from the cold has proven to be a formidable agricultural pest. It loves to feed on the buds, seeds, and fruit of a vast number of crops, often destroying them or rendering them unmarketable in the process. And because stink bugs are so new to the scene, researchers—including a number of Virginia Tech entomologists—face challenges trying to control them.
The first brown marmorated was spotted in the Commonwealth in 2004, and has since spread to 44 Virginia counties. “They call it the interstate bug,” said Tech’s Ames Herbert, who is studying the stink bugs’ effect on soybeans in the Tidewater. “They love to travel, love to hang onto equipment and containers.”
And they love to eat. As generalists, they will happily feast on more than 300 types of plants, poking their sharp mouthparts into fruits, veggies, and even cotton bolls to suck out juices. Doug Pfeiffer, another Tech entomologist and Virginia Agricultural Extension agent who works in the Charlottesville area, said the apple orchards and vineyards of the Piedmont have been hit especially hard, in part because the bugs are attracted to farms in forested areas, where they can retreat to trees at night.
The problem for grape growers is two-fold, he said. “When the stink bugs are in the clusters when they’re harvested, they’re crushed along with the clusters, and there’s a bad odor and taste to the juice,” he said. “There were some wineries that were so bad in 2010, they just dumped all their juice, and the whole crop was ruined.”
And then, of course, there’s direct damage from the hungry insects: Where they bite, necrotic spots develop, and can lead to fungal infection.
There are a few pesticides that seem to work on the invaders, but many farmers are finding that stink bugs will come back after a spraying, making it even more expensive to fend them off. “Organic growers have a tougher chore ahead of them,” said Pfeiffer. “There aren’t too many organic pesticide alternatives, especially with the long residual control that you need.” The method many have to resort to? Hand removal.
But it’s not all doom and gloom. Scientists up and down the East Coast are putting their heads together to share knowledge of the still-new pest and find fixes. Current research is focused on understanding the stink bugs’ life cycle, behavior, and spread. Meanwhile, said Pfeiffer and Herbert’s graduate student colleague John Aigner, U.S. entomologists are turning to translators to help them access existing studies, which are almost exclusively in Chinese and Japanese.
A Delaware lab is currently evaluating a very specific kind of biological weapon that could be unleashed within a year: A Chinese wasp that lays its eggs inside stink bug eggs, killing the hosts before they can hatch. But introducing another new species to wipe out an existing invasive is a tactic with a long history of failure.
They may not have to resort to such drastic measures. Aigner said Maryland researchers discovered similar parasitic wasps native to the U.S. are learning to attack brown marmorated eggs, so there’s hope the system may right itself on its own.
“It is amazing how you can sit back and watch nature do what nature does,” he said.