What is in this article?:
• Since the north to south movement of brown marmorated stink bugs began, researchers have tracked their relatively slow migration.
• In 2009, when kudzu bugs were first found in north Georgia and began a rapid south to north movement, the tracking game took on a new intensity.
CLEMSON ENTOMOLOGIST Jeremy Greene hosted a regional workshop-field day on kudzu bugs in early September in South Carolina.
With the warm winter across the Upper Southeast there were some concerns that BMSB may occur earlier than in previous years, but that didn’t happen. If anything movement of these insects was later this year and we don’t understand BSMB well enough to know why they were slower to start occurring in soybean fields this year.
The Virginia Tech Entomologist says once the new stink bugs began to show up, they spread across the state much faster than in previous years. “Once they started happening, they started popping up everywhere,” Herbert says.
Virginia only grows soybeans in 70-75 counties and BMSB have now been documented in more than 40 of these counties. “We are already seeing ‘stay green syndrome’ damage on the edge of soybean fields, indicating damage from BMSB was there and the grower didn’t pick it up,” Herbert notes.
The majority of damage we see this year is along the edges of soybean fields, but again they threw us a curveball by moving farther into some fields. A big change this year was that we never found BMSB alone — they had always occurred in mixed populations with native stink bugs.
In cage studies conducted in cotton fields, researchers have found BMSB not only like cotton, but that they are physically able to cause more damage than their native cousins, brown and green stink bugs.
“We are concerned because we have now documented BMSB in at least two counties in Virginia in which both cotton and soybeans are grown. One BMSB was in cotton, though both were in cotton producing counties, and we are concerned that BMSB will become a problem in cotton in coming years,” Herbert says.
Cotton and brown marmorated stink bugs would be a bad combination for growers. Herbert says BMSB appear to prefer older, larger bolls. In some cases they did damage last year to bolls that in the past we have considered safe from native species. If this year’s data shows the same trend toward BMSB damage to older, bigger bolls, then we will have to be really more concerned about cotton, Herbert says.
The BMSB species has a longer and stronger feeding beak. In corn, for example, these insects can easily penetrate the husk and do great damage to corn kernels.
“That’s probably what’s happening with cotton. They just simply are better equipped than native species to penetrate older cotton. In soybeans, the damage is not different, but penetrating a soybean pod is easy for native species,” Herbert says.
In North Carolina, North Carolina State University Entomologist Jack Bacheler found a few BMSB in some soybean fields in areas bordering Virginia.