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California and Oregon tree fruit

The top of a pyramid-style trap in Corvallis, Oregon, uses an aggregation pheromone to lure brown marmorated stinkbug inside. The trap is not very effective early in the spring, but does work late in the season. (TJ Mullinax/Good Fruit Grower)

California and Oregon tree fruit

An experimental pyramid-style stinkbug trap. (TJ Mullinax/Good Fruit Grower)

Woe be to the grower who finds brown marmorated ­stinkbug in his or her crops.

To date, there are no good sampling techniques to alert growers of pest presence and the few effective chemicals are broad-spectrum insecticides that disrupt integrated pest management programs, killing good bugs along with the stinkbugs.
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Researchers across the ­country are feverishly working on a national ­project to develop ­management strategies for the brown marmorated stinkbug.
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Current traps for brown ­marmorated stinkbug have a lot of problems, said Dr. Nik Wiman, ­postdoctoral research ­entomologist at Oregon State ­University. Wiman, who spoke during winter tree fruit talks in ­Washington, has been working at OSU since 2011 on the national ­project, conducting ­statewide surveys and ­evaluating host-plant ­preferences, among other things.

The traps attract the stinkbug with aggregation pheromones and are ­effective in catching stinkbugs late in the season. But research has shown that brown ­marmorated stinkbugs are not responsive to the aggregation ­pheromone early in the season, which is when ­growers need to know if the pest is in the field.

It’s important that brown marmorated stinkbug be detected early because larvae and nymphs are more easily controlled than adults that migrate in and out of the orchard.

Adult brown marmorated stinkbugs overwinter in structures and move out in the spring to lay eggs. Eggs are laid in masses of 28 and deposited on the ­underside of leaves. In northern ­locations, the pest has one generation, but OSU’s research found that two ­generations were possible in Oregon.

Bad news

“That’s really bad news,” Wiman said. “Stinkbug populations have the potential to grow faster than we originally thought in the Pacific Northwest.”

Another problem with trapping is placement.

“We know little about where is the best place to put the traps,” he said. “We’ve had traps out that don’t catch anything, yet we find stinkbug in the field.”

Dr. Peter Shearer, OSU ­entomologist, is leading the West Coast component of the brown marmorated stinkbug research. One of Shearer’s priorities is to improve trapping and monitoring ­techniques.

In addition to developing a better trap, Shearer and the team of scientists are exploring other areas:

—Developing condos that could attract and kill the stinkbug in urban and rural settings

—Using lighted traps at night to attract stinkbugs

—Finding effective, new chemicals

—Determining the most active time of feeding

—Determining when the pest moves in and out of crops

—Learning if there is an optimal time to make insecticide applications

“For now, we’re not recommending that growers use pheromone traps on brown marmorated stinkbug because we don’t know what it means if you catch some or not,” Shearer told Good Fruit Grower. “We need to be able to relate the number of bugs in the trap to damage in the field so growers know what to do with the trap information.”

However, he’s optimistic an effective trap soon will be available to growers. •