A cold shoulder

Freezing winter temperatures should help knock down redbanded stink bug populations.

By Vicky Boyd

February 2018 soybean south cover
Cover photo by Bruce Schultz, LSU AgCenter

Sub-freezing winter temperatures throughout much of the South and Mid-South likely knocked down redbanded stink bug populations, prompting cheers from growers and consultants who have battled the pest for the past two years.

Nevertheless, Dr. Jeff Davis, an associate professor of entomology with the Louisiana State University AgCenter in Baton Rouge, recommends growers and consultants continue to scout this summer in case some redbanded stink bugs escaped the cold snap. Other stink bugs native to the region, such as the green stink bug, can withstand colder temperatures and could still be troublesome.

Davis was part of a group that just published research results showing 10 hours at 23 degrees can kill 90 percent of a redbanded stink bug population.

“We had more than enough hours to do that,” he says, adding the 23 degrees is air temperature. In the fall, the pest seeks protected areas, such as leaf litter and buildings, in which to overwinter.

As a result, some small populations may survive the hard freeze. Areas south of Interstate 10, such as Beaumont, Texas, only dipped a few degrees below freezing briefly and may not see the same population reductions.

The Mid-South experienced hard freezes in 2010 and 2014 similar to this winter, with redbanded stink bug populations significantly reduced the following season.

A legume-only diet

redbanded stink bug
An adult redbanded stink bug — photo by Vicky Boyd

Redbanded stink bugs do not go into diapause, a sort of hibernation, during the winter. They continue to feed and reproduce, but at a much slower rate, Davis says. Warm winters, such as the past two, have allowed one to two generations to reproduce, so you start the spring with much higher numbers.

Redbanded stink bugs only feed on legumes, consuming clovers during the winter and moving into soybeans once the crop has emerged. The recent freezes also killed most of its food sources, meaning many will starve.

The pest, which is native to Central America, typically migrates north through Texas and Louisiana with the rising temperatures of spring and summer, says Gus Lorenz, University of Arkansas Extension entomologist.

“We frankly haven’t had much acreage for red banded stink bugs in the last four to five years,” he says. “So these two mild winters we’ve had in a row have had a huge impact. They were extremely problematic for growers — especially in the southern part of the state — who typically made from one to four additional pesticide applications to get them under control, costing an additional $12-$60 an acre.”

A cold reception

The cold temperatures should help growers deal with other pests, too, says Nick Bateman, University of Arkansas assistant entomology professor.

“A lot of the insect pests we deal with are weather-sensitive,” he says. “Fall armyworms, rice water weevil and other pests that traditionally migrate — this will help push them back out of the state, rather than overwintering here. It’ll take them a longer time to migrate back into the state.”

Although the cold also can affect beneficial insects, Lorenz says they are more likely native to a given area and are better adapted to the local environment.

Beating back the redbanded stink bug may be welcome news, but he and Davis say growers should still be ready to do the work necessary to put themselves in the best position for success in 2018.

“As we go into the 2018 season, the things that growers can do to take full advantage of this weather are the same things we would normally tell them to do to avoid pests, including planting early and using early-maturing varieties,” Lorenz says. “If you plant early, you avoid a lot of these pests.”

The University of Arkansas Division of Agriculture contributed to this article.

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