AUBURN, Ala.—Alabama row crop producers have faced different challenges this year than they did last year. Now, in addition to late rainfall and increased native pest pressures, Alabama Cooperative Extension System entomologists are warning producers about red-banded stinkbugs.
Red banded stinkbugs (RBSBs) are native to South America and have been reported as the principal stink bug pest of soybeans in Brazil since 1970. RBSBs were first found in the U.S. in Florida in the early ‘90s. Louisiana producers have dealt with this pest in soybeans since 2004. The stinkbugs were first found in Alabama in Baldwin County in July 2010. Last year, Extension entomologists found RBSBs in soybeans on July 12 at research fields near Prattville. This year, red-banded stinkbugs made their first appearance in soybeans in Henry County the second week of July.
These tropical pests are sensitive to cold temperatures, and generally do not survive cold winters. Alabama Extension entomologist Dr. Ron Smith said he is especially concerned about the pressures from RBSBs because of back-to-back mild winters in Alabama.
RBSBs require at least 30 days at 80 degrees F to develop from egg to adult, and the females only begin laying eggs 20 days after they have emerged as adults. RBSBs always lay eggs in 2 rows with a total of 10 to 15 eggs per mass. No other stink bug lays eggs in two rows. Adults live up to 40 days in the laboratory.
Where Are They
“RBSBs have been found from Marianna, Florida to Marianna, Arkansas—as well as Headland, Alabama and Southwest Georgia,” Smith said. “These bugs remain active during the winter, so they are able to continue breeding. This causes issues for producers during the summer months.”
Dr. Tim Reed, an Alabama Extension entomologist specializing in soybean pests, said that as of mid-July of this year he had not found any RBSB’s in his soybean test plots in Prattville or Brewton. However, he noted that the soybeans in these plots had not set pods. Extension regional agronomist Brandon Dillard reported finding RBSBs in podded soybeans at Headland earlier this month. RBSBs do not cause damage to soybeans until beans begin forming in the pods.
“Growers have had problems controlling RBSBs in other states due in part to their ability to re-infest fields quickly, and their tendency to stay lower on the plants than brown, green and Southern green stinkbugs,” Reed said.
Deadly Stinkbug Soybean Complex
Smith said the stinkbug “complex” is one of the most deadly threats to soybeans. The complex is a combination of brown, green and Southern green stinkbugs. Now, in addition to the stinkbug complex to which producers are accustomed, the RBSB presents another dimension to consider. The presence of another invasive stinkbug, the brown marmorated stinkbug, has also been confirmed in 24 Alabama counties.
Producers in Louisiana have experienced up to 15 percent yield losses from RBSB-damage. These pests may cause significant damage in late planted soybeans—or soybeans planted behind wheat. Smith said these stinkbugs will cause damage all the way up to the R7 growth stage, where the pods are turning from green to brown.
Red-Banded Stinkbug Control
Alabama producers will need to scout crops diligently as the summer growing season progresses. Thresholds for RBSBs from bloom to pod-fill are one per 3 row feet using a ground cloth or 2 per 15 sweeps using a sweep net. The greatest number found to date in ground cloth samples was 0.5 adults and 3 immatures per 6 row feet in late R6 stage soybeans in Brewton on August 31, 2016.
“It is more difficult to control RBSBs than native stinkbugs,” Smith said. “Red-banded stinkbugs rebuild numbers easily and are able to move from field to field quickly.”
While Smith and Reed have only had an opportunity to conduct one insecticide screening trial that included in the RBSBs , Reed said their counterparts in Arkansas have reported higher rates of acephate (0.97pounds of active ingredient per acre) are generally effective.
“Mid-south entomologists also report that using a combination of insecticides with two modes of action is better than using a single chemistry both with respect to the level of control and resistance management,” Reed said.
Reported examples of effective insecticide combinations for red-banded stinkbugs are acephate + bifenthrin and lambda-cyhalothrin + thiamethoxam.
Photos in gallery by Dr. Ron Smith, Alabama Extension
Soybean pod damage image by Dr. Angus Catchot, Mississippi State Extension Entomologist