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Red-banded stink bugs hit soybeans

Red-banded stink bugs are becoming increasingly numerous in many Mississippi soybean fields, and because populations can quickly mushroom they can be difficult to control, says Angus Catchot, Mississippi Extension associate professor of entomology and plant pathology.

“There has been a lot of discussion about this pest over the past five years or so,” he said at the annual meeting of the Mississippi Agricultural Consultants Association. “It has been a problem in Louisiana and seems to be getting worse and moving farther north.

“This insect is an extremely good flyer, and we’ve found it all the way to the top of Mississippi, and as far north as the Missouri Bootheel and Jackson, Tenn., in August and September.”

In an attempt to get an idea of where this pest has been occurring in Mississippi, where treatments were being made, and how bad the problem was, Catchot conducted an informal survey of farmers, dealers, and Extension representatives, and developed a map showing distributions over the state.

“In central and western Mississippi Delta counties there were reports of populations that, in many cases, greatly exceeded threshold levels (six stink bugs per 25 sweeps). In 21 counties, there were reported levels exceeding threshold, and eight counties were at threshold.

“I had known we had this pest, I just didn’t know to what extent, and I found this somewhat alarming.”

The red-banded stink bug is different from the more common southern green and brown stink bugs, Catchot notes, in that they lay eggs in rows of two, for the most part on pods and stems.

“The eggs are dark gray or black in color and barrel-shaped — a unique appearance compared to other stink bugs. The red stripe is not always characteristic; it can sometimes be beige or white.”

In the adult stage, it can sometimes be confused with the red-shouldered stink bug, which also occurs in Mississippi. “But you can very easily key in on which it is: just flip it over and the red banded stink bug will have a pretty pronounced spine between the hind legs. After you’ve examined a few of them, you can easily tell the difference by body appearance and shoulders.”

Preliminary data from cage work in Arkansas indicate significantly more seed discoloration, shriveling, and seed weight loss from the red-banded stink bug, Catchot says. “This seems to bear out previous work in Louisiana showing damage from this pest about two times more than with the southern green and brown stink bugs. My counterpart at Louisiana State University, Roger Leonard, calls them ‘intensive pod-feeders.’


“We’d heard a lot of stories about how hard this pest is to control, but in efficacy tests last year on late-planted beans, we got very good control with just about everything we applied, and we were feeling pretty good. Three days after application, everything was still looking good. Roger told me, ‘Just wait.’

“Seven to 11 days later, every treatment had exceeded threshold again. The problem is that even though you can initially get good control, they can quickly re-infest a field. There were some beans around us that hadn’t been treated, and as they matured, we got additional numbers moving into the treated areas.

“Even though we got good control initially, by six to 10 days after treatment there was not enough residual with any treatment to hold back migrating adults into the field.”

Studies by Leonard and his associates in 2005-2008, using all classes of chemistry, showed the pest is more difficult to control than the southern greens and browns, Catchot says.

“Based on work from USDA-ARS at Stoneville, Miss., we do know that the larger instars cause more damage and that fourth and fifth instars are harder to control. From some of the cage work, I would think that immatures of red-banded are equally or more damaging than the same stages of the greens and browns.”

The insect’s tolerance to pesticides seems to be increasing and populations rebound very quickly after an application, Catchot says.

“From Roger Leonard’s work, they have seen about a two-fold increase in tolerance, at least in their lab bioassays from 2006 to the present. While most products provide decent initial knockdown, they don’t give extended control. Our studies indicate that the best control is obtained with mixture.”

For 2010, we are recommending intensified scouting for this pest, particularly in south Delta counties.

“Just remember, if you treat for it you may initially get good control for two or three days, but a week later you may be seeing what you think is product failure. It may look like you got zero control, when in fact you got 80 percent to 90 percent control, but you’ve now got another population coming on. It may be a difficult situation to distinguish.

“South of Highway 82, particularly as you start moving southwest down the Mississippi River, you may have to budget for another application or two, especially for late-planted beans. That’s what producers are doing down around Alexandria, La.”

There have been “a lot of questions,” Catchot says, about overwintering of the red-banded stink bug and whether the really cold temperatures this winter will suppress them.

“Currently, we don’t think they are overwintering in northern Mississippi, and that most of their movement is during the course of the season, but right now, we just don’t know.

“Last year, we didn’t really have much of a stink bug problem until late in the season. We do know that the southern greens are very sensitive to cold temperatures and we think the winter of 2008 beat them back substantially — but then they came on strong late in 2009.

“We have a graduate student who’ll be looking at this as part of his work this year. Another objective is to identify alternate hosts. Right now, we know they prefer hemp sesbania, which supports some high numbers late in the year, crimson clover, and black medic, but we just don’t have a good idea of what the host range is.”

Another insect consultants and growers should be aware of, Catchot says, is the bean plataspid — which has been identified in Georgia — that has the potential to move into this area. “If you find one, please let us know as quickly as possible.”

Native to India and China, it is commonly called lablab bug and globular stink bug. While it primarily is a pest of kudzu, it will also eat legume crops, including soybeans.

“The National Cotton Council has also asked that we help to make everyone aware of a pest called the cottonseed bug (Oxycarenus hyalinipennis), which is now in the Bahamas and is considered a potential threat to the U.S.”

Adults and nymphs suck oil from mature seeds and fluid from leaves of young stems to obtain moisture, and if present in sufficient numbers, the cotton fiber becomes stained during processing by the maceration of their bodies.

“If this insect gets into the U.S., it could take off very quickly, with as many as five generations per year predicted,” Catchot says. “We hope you’ll familiarize yourself with it and let us know if you should spot one.”


TAGS: Soybean
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