Every season, growers wage war against a seemingly endless number of enemies that threaten to wipe out their crops. From powdery mildew and botrytis to spider mites and thrips, crop protection is a full-time job. Every so often, however, a super-villain emerges. This invader is undeterred by preventative efforts, catching even the most prepared operations off-guard. For many fruit growers, the brown marmorated stink bug (BMSB) is the latest adversary. With more than 170 host plants, the bug’s impact can be distressing.
According to StopBMSB.org, a website run by a team of researchers that strives to deliver free, science-based research to the public, Halyomorpha halys first became a catastrophic problem in 2010 when Mid-Atlantic farms growing everything from sweet corn and peppers to apples and peaches reported significant losses. That was around the time USDA’s Agricultural Research Service (ARS) team stepped in to help.
“The initial challenge was to ensure growers had tools to keep going during a time when there was high damage,” said Brent Short, Research Entomologist at USDA-ARS.
From the Beginning
“We had to start at the beginning, and at first, we only had a lab study,” continued Dr. Tracy Leskey, Entomology Research Leader/Director at USDA-ARS, adding that the goal was to find a way to effectively manage the pest in tree fruit orchards, where much of the damage occurred. “We more or less created a Band-Aid in 2010, 2011, and 2012 so growers would have fruit to harvest.”
This isn’t a new problem. According to StopBMSB.org, long before American growers battled BMSB, the pest caused problems throughout Asia. Because it had more natural predators in the East, the pest wasn’t nearly as destructive in China, Japan, and Korea. The pest immigrated to North America in the late 1990s, but it took more than a decade to cause widespread problems.
Since then, growers have mostly been forced to use harsh chemicals to deal with BMSB invasions. As much of the industry moves toward organic inputs and Integrated Pest Management (IPM) programs, however, the goal is to find a more natural option. Seven years later, USDA-ARS continues to test and develop effective ways to manage BMSB, and there’s some promising research to suggest help is on the way.
An Uphill Battle
Keeping the bugs at bay isn’t easy. BMSB populations can be particularly hard to manage, Short explains, because the pests can travel vast distances in a short amount of time. They often feed at night and are less likely than native stink bugs to respond to certain pesticides. By the time a grower identifies the infestation and the problem area, the BMSB population may have already moved on, sometimes to a different section of the same farm.
With all this in mind, the USDA-ARS team knew any solutions needed to have residual effects to prevent the bugs from entering one crop to feed then leaving to attack another. Two promising options have emerged from the researchers’ efforts: attract-and-kill and monitoring traps.
Both control methods were developed when the researchers identified the BMSB’s aggregation pheromone, a chemical the bugs release to draw others to a specific location. Without this pheromone, Leskey says, there wasn’t a way to locate and attract the pest. The researchers then combined high doses of the pheromone with a stimulant and deployed it around the border of an apple orchard. The goal was to steer the bugs to these hot spots where they would encounter a lethal dose of active pesticide residue.
By enabling growers to lure the pest to specific areas, they could optimize their pesticide applications, saving time and money. While the attract-and-kill method has reduced BMSB populations in some plots, there’s more work to be done.
“The problem is with the price,” she says. “At this point, the experimental cost is so high that even large growers would find the pheromone too expensive. It’s not something that’s ready to be adopted, but it works in terms of proof of concept.”
Leskey says researchers are working on ways to make the process less cost-prohibitive, including reducing the number of kill sites and minimizing the dosage. Another option is to use monitoring traps. This tool is more practical for growers of all sizes because it helps maximize their BMSB eradication efforts. These baited traps, Leskey says, indicate whether BMSB populations pass the attack-and-kill sites. If the activity levels become too high, it triggers growers to spray the pesticides.
“This method allows the grower to treat the problem when there is one,” Short explains. “Like any other insect application, you want to spray optimally and maximize efficiency.”
The USDA-ARS team is also searching for ways to eliminate pesticide usage altogether. One promising alternative is netting. Short says the netting works well against the pests and has a years-long residual. The idea would be to draw BMSB populations to the netting where they forage on it and die.
While researchers continue to explore IPM-based BMSB treatments, Leskey encourages growers to check out the guidance and best practices documents available at StopBMSB.org. All the information on the website is current and will be updated with new developments as they become available. Attract-and-kill and monitoring traps remain in their infancy, but these tools take growers one step closer to winning the turf war against a truly formidable opponent.