Help needed for invasive stinkbug

Brown marmorated stinkbugs overwinter in protected areas, emerge in April in the mid-Atlantic area, and lay eggs from May through August.

Entomologists in the mid-Atlantic states are still honing their pesticide recommendations so fruit growers will be prepared to battle the brown marmorated stinkbug this season.

While they think growers will be able to handle the bug early in the season with existing labeled insecticides, they see a potential protection gap when fruit is nearly ripe and pressure is intense. At that time, they need an effective insecticide with a short preharvest interval (PHI). They think they have a candidate in dinotefuran.

The Virginia Department of Agriculture and Consumer Services plans to petition the U.S. Environmental Protection Agency in April for a Section 18 emergency use permit for use of dinotefuran (Venom, Scorpion) on pome and stone fruits, according to Dr. Chris Bergh, an entomologist with the Virginia Polytechnic Institute and State University. Bergh is part of a team of university and U.S. Department of Agriculture entomologists working to combat this aggressive new invasive stinkbug species. They hope to have EPA’s approval by late August, when fruit harvest and stinkbug populations are both peaking.

Emergency label

Dinotefuran has labels for application to grapes and some vegetables, for which the PHI is one day, Bergh said. The insecticide is used by tree fruit growers in Asia. The entomologists plan to ask EPA for a three-day PHI. The emergency label would apply in seven states hard-hit by the stinkbug last year—Delaware, Maryland, New Jersey, North Carolina, Pennsylvania, Virginia, and West Virginia.

Bergh is preparing the petition, while entomologists and Department of Agriculture representatives from the participating states are submitting data and letters in support.

Dinotefuran is a neonicotinoid insecticide marketed by Valent BioSciences as Venom and by Gowan as Scorpion. It was developed by Mitsui Chemicals and registered in Japan in 2002. In the United States, EPA has given it status as an organophosphate alternative and a reduced-risk insecticide.

U.S. entomologists don’t have a long history with brown marmorated stinkbug, which had been gradually increasing in numbers. It emerged last year as a serious problem, damaging almost half the peaches in Pennsylvania.

“We don’t have much field data to support recommendations for season-long management of brown marmorated stinkbug,” Bergh said. “Growers will have to do whatever it takes in 2011, and we hope to know much more by the end of this season, so we can refine our ­recommendations.”

He’s working with five growers in Virginia, testing various insecticide protocols and using attractant-baited traps to monitor stinkbug populations. Laboratory bioassays have determined that some insecticides work better than others. “Growers will have to mix and match them through the season while trying to avoid killing beneficial insects, protecting pollinators, and maintaining control of the other insect pests of tree fruits,” he said.

Bergh and other entomologists in the mid-Atlantic region will be working closely with chemical companies to evaluate the effectiveness of various products and seasonal programs targeting the stinkbug in 2011.

The list of labeled insecticides that show promise includes endosulfan, some pyrethroids, some neonicotinoids, and methomyl. Disadvantages of some of these are long preharvest intervals, long reentry intervals, short residual activity, and/or toxicity to beneficial insects. Those with long PHIs are only useful ­earlier in the season.
It is not yet known how quickly the stinkbug populations will build this yea

. In some areas where high populations clustered around buildings seeking overwintering protection, they could reach high numbers early in the season. “We may need to begin targeting brown marmorated stinkbug shortly after the crop is set,” Bergh said.

Having an effective insecticide for use during the late summer and fall peach and apple ripening period will help growers, many of whom experienced high losses last year. But suppressing them in the orchards will not likely have a large effect on the stinkbug population as a whole, Bergh said. Besides fruits and vegetables, the stinkbug is known to feed on field and sweet corn, soybeans, and some woodlot and ornamental trees. Some 300 host plants have been identified so far, so there is little potential to drive down the overall population with late-season ­insecticide applications in orchards.

On the benefit side, it is not just the fruit growers fighting this bug. They are in league with homeowners and other ­farmers for which this insect has become a nuisance if not an economic scourge.