Each year brings new challenges to the field. Whether it be a crop pest or significant weather events, producers are always adapting inputs and timing to maximize efficiency and yield. This summer, producers will face yet another crop pest: stink bugs.
Aaron Cato, a post-doctoral fellow working with Alabama Extension entomologist Ron Smith, said producers will need to vigilantly watch for stink bugs and stink bug damage in summer crops. Alabama producers are not unfamiliar with stink bugs, but two relatively new species encroaching on summer crops may pose different-than-normal threats in the field.
Brown Marmorated Stink Bugs
People accidentally introduced the Brown Marmorated Stink Bug (BMSB) to the United States from Asia in the 1990s. First found in Pennsylvania, the pest has now spread to much of the country.
Adult BMSB are about three-quarters of an inch long with the shield-like shape characteristic of stink bugs. While these stink bugs are brown, their whitish antennae bands and patterned abdomen distinguish them from brown stink bugs.
Where there is one BMSB, there are likely more. These pests congregate in large numbers—a BMSB distinguishing feature. These congregations are especially evident in the fall and winter months when they invade houses, barns and other structures.
Cato suspects there are likely two generations per year in Alabama.
“It takes 40 to 60 days for BMSB to go from a fresh egg to an emerging adult, and it is likely Alabama will be closer to the 40-day mark,” Cato said. “Considering that we’ve started seeing emerging adults in early April combined with the record heat we’ve seen, I expect at least two distinct generations.”
Cato reminds growers that the BMSB is a pest of many crops.
“Like our native species, BMSB have a large host range and feed on the developing fruit of many different plant species,” Cato said. “Outside of just their ability to damage our field crops such as corn, cotton, and soybeans, BMSB are a much more serious pest of fruits and vegetables, especially when considering home gardens.”
Cato said bifenthrin works well to kill BMSB when it is available. It is an economical control option.
“It is not a difficult insect to kill and there are many control options,” he said. “Field edge treatments are likely going to be the most economical route because this pest doesn’t move very far from the edges when it gets into a field.”
Scouting should occur on field edges near wooded areas or tree lines, as well as near other crops where it could move from—such as corn. Treatment should occur when scouts find four BMSB per 25 sweeps in soybeans, and as soon as producers observe BMSB in cotton field edges. Cato suggests spraying as far from edges as BMSB are present.
Red Banded Stink Bugs
The Red Banded Stink Bug (RBSB) is a key pest in soybeans throughout South America, and has quickly become a soybean pest in the Southeast. Adults emerge in the spring looking for secondary hosts and move to soybeans when they begin podding—around R3.
RBSB generations overlap—meaning nymphs and adults are present concurrently—making control difficult. These pests are generally half of the size of other stink bugs, and are identifiable by the fixed spine arising from the abdomen and a red band along their back.
“The RBSB showed its ability to cause severe damage in Arkansas in 2017,” Cato said. “This is a very serious pest of soybeans. With the mild Alabama winter, producers should be on the lookout for this pest—particularly in southern Alabama. Producers in Louisiana, Mississippi, and Arkansas are already finding RBSB as of early July.”
While these stink bugs are soybean pests, they also feed on other legume crops including beans, peas, lentils and alfalfa.
Thresholds for RBSB in soybeans are four to six insects per 25 sweeps. RBSB do not act like normal stink bug species, and are more likely to run away and hide.
“These stink bugs will drop immediately from plants and run for cover when they hear disturbances, which is one reason thresholds are so low,” Cato said. “Additionally, their reproductive potential is much higher than our native stink bugs, and if populations aren’t controlled early it is difficult to get back on top of them.”
Cato said combination products generally provide the best control. Simple pyrethroids like lambda-cyhalothrin or bifenthrin alone don’t provide as much control. Acephate and bifenthrin or lambda-cyhalothrinand thiamethoxam combinations are going to be the standards for controlling this pest.