COLUMNS


Understanding New Insect Pests

By Sally Colby




A sleeve containing brown marmorated stinkbugs is placed in an apple orchard to help researchers determine its behavior patterns.
Photos by Sally Colby.

Growers are well aware of insect pests - which ones are in a particular region, which ones are in their orchard, when they're likely to hit, and what to do about them. But what about emerging insect pests? Who does the behind-the-scenes work that results in science-based information that growers can use?

In the case of the brown marmorated stinkbug (BMSB), teams of researchers from several universities have been conducting research and sharing information since the invasive species was first identified in the U.S. in 1998. The universities are also keeping graduate students busy with a variety of projects that will help nail down details about the life habits and potential control of one of the most damaging new pests to challenge growers.

"Invasive species like the brown marmorated stinkbug are causing a lot of problems for growers," said Deonna Soergel, who is currently pursuing a master's degree in entomology at Penn State University. "Stinkbugs can cause catfacing in peaches and corking problems in apples."

Soergel didn't originally plan to study the BMSB in depth. As an undergraduate biology major, she wasn't really interested in entomology, but a course in aquatic entomology sparked her interest. After a trip to England, where she took a course that integrated agriculture and environment, Soergel discovered that she was interested in entomology and decided to return to her family's orchard, Soergel Orchards, near Pittsburgh, Pa., where her multigeneration family grows a variety of tree fruits and vegetables.

"I was helping my dad with bug counts in the orchard, and he told me that Dr. Greg Krawczyk was coming to visit," said Soergel. "Dr. Krawczyk told us that the brown marmorated stinkbug was going to be a problem, but we didn't have any problems with it. But while he was there, we found the first BMSB in our orchard."

That was the fall of 2010, when the BMSB was starting to make its presence known throughout the Northeast. At the time, Krawczyk was looking for a graduate student, and Soergel was eager to work on a project that would help her family as well as other farmers.

Soergel says that designing a project to fulfill the requirements for graduate work depends on the professor, and Krawczyk was open to her suggestions. Soergel became interested in the biology and behavior of the BMSB, which is key to understanding any insect pest.

"The BMSB was a new pest that we knew almost nothing about," she said. "The literature hadn't been translated, and the bug would act differently here than in Asia. Until now, we've known very little about their biology and behavior."

Since little was known about the behavior of the BMSB, Soergel designed her project around discovering its habits. "I spent a lot of time with the sleeve project," she said. "The sleeve is a little home for the stinkbugs. I place the stinkbugs in these sleeves and place them in different fruit trees - apples, several varieties of peaches, and cherries. I used adults or nymphs, and went out several times a day to record their activity. I'd be out first thing in the morning, at noon, in the evening, at night, midnight and 2 in the morning."



Sunflowers produce a high level of volatiles and may be useful as a trap crop for the brown marmorated stinkbug.

Soergel says her goal of determining what stinkbugs were up to at different times in a 24-hour period meant sleep-deprived nights. "My observations were to see if we were seeing increased movement," she said. "What were they doing, and when were they doing it? Were they resting, feeding or mating? If we know they're in the orchard at night, we'd spray at night."

One trend Soergel observed was increased activity in the evening. She's exploring this further through a laboratory-based circadian rhythm project.

Although Soergel hasn't completed her research, she collected plenty of data over the summer and will spend the next several months working through it.



Deonna Soergel, a graduate student in entomology at Penn State University, explains her research efforts to a group of growers during a field day held as part of the International Fruit Tree Association study tour at the Fruit Research and Extension Center in Biglerville, Pa.

Soergel noted that Krawczyk has several stinkbug projects in the works and is conducting research in numerous areas, including trapping and efficacy of lures. "I'm taking some of the work he's doing and seeing if the stinkbugs show up in the traps at certain times of the day, or [if] their behavior [is] temperature-related," she explained. "It looks like they might be moving out of the crops and into the woods at night, but I haven't figured that out yet. Ideally, there will eventually be a commercial lure to help farmers monitor stinkbugs."

Because stinkbug behavior may lead them to settle in certain crops, Soergel is working on a trap crop experiment using peppers and sunflowers. "Are they going to feed in the sunflowers and stay there, or go into the peppers? Some literature published in Asia mentioned that the BMSB likes sunflowers," she said. "Sunflowers produce a lot of volatiles and have been used to attract other stinkbugs. Stinkbugs like tomatoes, peppers and other vegetables. Peppers are a small-scale cash crop we'd be trying to protect, just like we're trying to learn how to protect orchards."



Sticky traps with a light to attract stinkbugs may be effective in monitoring stinkbug populations.

Soergel hopes she can help producers develop more control strategies to deal with the BMSB. However, she is quick to point out that her work is just one small part of a very large research effort. "If we know when they're causing the most damage, when they're moving around the most, and when they're just being a nuisance, it gives us an opportunity to develop management strategies for growers that will have the most impact," she said. "There's a lot going on. What I'm doing is a very small component, but I hope my work will be helpful."

The author is a frequent contributor and freelance writer who farms and raises Great Pyrenees in south-central Pennsylvania. Comment or question? Visit http://www.farmingforumsite.com and join in the discussions.