CORVALLIS, Ore. – Orchardists can minimize damage to their fruit and nut crops by monitoring populations of brown marmorated stink bugs, rotating pesticides and encouraging the pest’s natural enemies, according to a research summary just out from the U.S. Department of Agriculture.
“We’ve been studying this pest since 2012, when it became a known threat in Oregon,” said Vaughn Walton, Oregon State University Extension entomologist and expert in economically important pests at OSU’s College of Agricultural Sciences.
Oregon’s berry, grape and tree fruit growers are still adjusting to the impact of the spotted wing drosophila, which arrived in 2008 and is now widespread in the Willamette Valley and Columbia Gorge, Walton said.
“The brown marmorated stink bug is another exotic pest affecting Oregon’s specialty crops,” he said. “It affects all the same crops as spotted wing drosophila, and others as well, including hazelnuts, vegetables and ornamentals.”
Walton is a coauthor of the new publication, called Integrated Pest Management for Brown Marmorated Skink Bug in Orchard Crops. It was released this month by USDA’s Specialty Crops Research Initiative, which funded the multi-university research team that included Walton and fellow Extension researchers Nik Wiman, Clive Kaiser and Rick Hilton.
The brown marmorated stink bug, or Halyomorpha halys, was accidentally imported from Asia in the 1990s. In 2010 it severely damaged crops of sweet corn, peppers, tomatoes, apples and peaches in the mid-Atlantic states.
It was first spotted in Oregon in 2004, appeared in commercial crops for the first time in 2012, and has caused economic damage in Oregon hazelnuts, apples and peaches. Home gardeners have reported damage to backyard tree fruits, beans, tomatoes, cucumbers, raspberries, hops and many ornamental plants. Flocks of the bugs are also a nuisance around urban homes, especially in the fall.
This pest can produce up to two generations in a year. The eggs hatch and progress through five “nymph” stages before molting into a winged adult that can fly as far as 70 miles in a day. The bugs are voracious and undiscriminating eaters, munching on fruits, vegetables, ornamentals and landscape and forest plants.
The stink bug is a particular worry for orchardists because its feeding produces brown rotten spots in the flesh of fruits. The damage often renders the crop unmarketable. The insect’s tough mouthparts can even penetrate a hazelnut shell, leaving the nut with a shriveled meat or none at all.
The new publication compiles the team’s research and suggests integrated strategies for lowering populations of the pest and minimizing damage to orchard crops.
For example, the researchers found that traps baited with certain pheromones, which are natural chemicals secreted by the insects that trigger behaviors such as attraction or aggregation, are effective at capturing both adults and juvenile stink bugs all season long. The publication gives illustrated instructions for building and checking the traps.
“These traps are highly effective,” said Walton. “They can help growers target their pesticide applications to when and where they’re most needed.”
More-strategic spraying, he said, helps reduce the number of sprays while still preventing damage to crops.
A sampling of additional findings:
- This pest lives across the landscape and is not specific to a crop. Therefore, pressure is often highest along the edges of orchards, especially those bordering woodlands. Spraying around the perimeter of an orchard can be just as effective as spraying throughout.
- Peaches and nectarines need to be protected starting very early in the fruit’s development, when the growth of the fruit has split the flower - a stage known as shuck split - whereas apples and pears begin to need protection when the fruit is bigger, in May or June. For hazelnuts, it may be more beneficial to spray in the fall.
- The overwintering generation of the bug is more susceptible to pesticides than the summer generation. Depending on crop, region and pest pressure, it’s possible that targeted fall sprays will reduce populations the following spring.
- Pesticides that will kill this bug, which are listed in the publication, also harm natural predators such as predatory mites, parasitoid wasps and lady beetles, as well as bees and other pollinators. Growers should rotate their sprays among pesticide products with different modes of action, and apply them judiciously.
- Various species of parasitic wasps are potentially effective natural enemies. They have not yet made much of a dent in pest populations, but they should continue to spread, say the researchers, and may ultimately help provide control.
The OSU team asks growers to report damage to commercial crops from this pest using this email address: BMSB@oregonstate.edu.