Dec 3, 2012BMSB numbers on the rise late in the season
Brown Marmorated Stink Bug (BMSB) numbers in mid-Atlantic states are surging, which is worrying growers and researchers, said Tracy Leskey, a research entomologist at USDA’s Appalachian Fruit Research Station in West Virginia. Leskey has been on the front lines in the fight against BMSB.
“Based on data we have been collecting in Maryland and West Virginia orchards, we observed a 10-fold decline in late-season populations from 2010 to 2011,” Leskey said. “Thus, in 2012, very few bugs were present in the early season.”
Over the course of the season, however, Leskey and other researchers watched BMSB populations rebound. They were at least six times larger in late 2012 compared to late 2011. If these larger populations survive the winter, there might be more bugs to deal with in spring 2013, Leskey said.
This late-season surge is a cause for concern.
“We did see problems in a number of locations, including the Hudson Valley in New York,” she said.
This was the first year that New York growers experienced economic injury from BMSB, said Peter J. Jentsch, an Extension entomologist at Cornell University’s Hudson Valley Laboratory.
“We found severe injury in Orange and Ulster counties this season in four orchard blocks,” Jentsch said. “Three varieties, Red Delicious, Golden Delicious and Pink Lady, were especially hardest hit. There also was damage on organic pepper this season, where a variety of hot pepper was abandoned due to feeding injury.”
The majority of the damage has been on the outer edges of fields and orchards. The level of feeding injury ranged from 38 percent to 97 percent, while an entire block of Pink Lady apples was assessed to have fruit damage at 21.2 percent, he said.
It wasn’t just BMSB causing issues this past season, Jentsch said. The green stink bug moved into orchards very early in the season, and was found in very high levels by early August. It also injured crops, he said.
BMSB, which has two generations in the Hudson Valley, was observed to move into orchards at the onset of the second generation around mid-August. Fruit damage, first detected in Red Delicious apples in early August, was predominately attributed to green stink bugs. Yet feeding damage continued through mid-October, with BMSB found almost exclusively to be feeding on the fruit, Jentsch said.
Stink bugs are very elusive, and not easily seen in the field, Jentsch said. To determine the composition and density of the stink bug populations, researchers are using a combination of newly developed lures from USDA (USDA No. 10 in combination with the geometric isomer of methyl 2,4,6-decatrienoate), along with high-intensity light trapping, he said.
“Using these trapping methods, we found both species along the field edge and within the center of orchard blocks,” he said. “After insecticide applications were made, only BMSB were observed continuing to feed on fruit. Apparently, green stink bug had succumbed to the control measures, while BMSB had not.”
There is some good news, according to Leskey. The spread seems to have slowed for now. It is still in 38 states and Washington, D.C., as well as in Hamilton, Ontario, Canada, she said.
Researchers have found a good way to kill the adults, too, she said.
“We have a good handle on materials that are effective at killing adults, particularly when they have contact with finished, wet spray material, but we are also learning that residual activity is very short,” Leskey said. “This highlights the need for sensitive monitoring tools to detect presence, abundance and seasonal activity. We are making good progress there with the identification of the pheromone, as well as light-based stimuli that can be incorporated into trapping tools.”