How to conserve beneficials while fighting stinkbug
Penn State University entomologist Dr. David Biddinger provided some rules of thumb growers can apply so as not to destroy all natural enemies and the integrity of integrated pest management programs as they go about controlling the brown marmorated stinkbug.
Insecticide selection—Choose the product least harmful to natural enemies, but also keep in mind preharvest intervals and rate limitations on the label.
Insecticide timing—Only apply a highly effective insecticide for stinkbugs when they are in your orchard. This requires vigilant monitoring of the blocks and surrounding habitat (woods, corn, or soybean fields). The stinkbug is most active at night.
Dosage—The toxicity of any chemical compound is directly related to its dose. Always apply the lowest effective dose possible to conserve beneficials.
Application techniques—Frequent low-dose applications by the alternate-row-middle technique has worked for some pests in Pennsylvania orchards in the past. With continual invasions of the orchards from surrounding habitat, frequent applications by these contact materials may give better continual residual control than complete sprays with longer intervals. The alternate-row-middle technique works better to conserve mobile predators like lady beetles than for less mobile predatory mites.
Selective placement/border sprays—Since the stinkbug is likely to move into orchards from the surrounding landscape or from overwintering sites in buildings, restricting applications of broad-spectrum insecticides to border rows will likely conserve many natural enemies.
Hope for biological control—Native stinkbugs do some fruit damage, but have been controlled for many years by a number of natural enemies. One, which attacks eggs, may adapt to attack brown marmorated stinkbug. Other predators may adapt as well. The U.S. Department of Agriculture is evaluating the possibility of introducing egg parasitoids of the brown marmorated stinkbug from Asia.
Biological control does not have to give 99 percent control of a pest like a biopesticide such as Bacillus thuringiensis (Bt) does, Biddinger said. A number of natural enemies, each giving a relatively small level of control of multiple stages of the stinkbug, can greatly decrease the overall population levels that develop outside of the orchards.
Given the broad host range and the mobility of the stinkbugs, the best hope is to achieve control everywhere in the environment, not just in the orchards, he added.