Dr. Patricia Glynn Tillman, an entomologist with the U.S. Department of Agriculture in Tifton, Georgia, has found a green alternative for controlling various stink bugs that attack crops, which may also help monarch butterflies.
Many farmers currently control stink bugs with broad-spectrum insecticides, which can also harm beneficial insects — ones that pollinate crops or feed on pest insects. Dr. Tillman’s work involves setting up barriers to keep pest insects away from crops, while simultaneously growing certain plants near the crops that are known to attract beneficial insects.
Dr. Tillman collected stink bugs from corn, peanut, and cotton fields for six years and then studied a number of strategies designed to control them. In one study, she and her colleagues placed nectar-producing buckwheat plants, sorghum Sudan grass (an annual grass that grows to about eight feet), and two different-sized plastic sheets (one about six-feet high, the other about two-feet high) between peanut and cotton fields. The grass and plastic sheets were introduced to see if they would prevent stink bugs from migrating from low-growing peanut plants into cotton.
She found that the plastic and the grass were effective, as long as the barriers were at least as high as the cotton (4.5 feet). She also found that the buckwheat attracted Trichopoda pennipes, a small fly that is a parasitoid of stink bugs that can be used for biological control (using one organism to control another). Results were published recently in the Journal of Pest Science.
The researchers also placed potted milkweed plants along the edges of cotton fields in peanut/cotton production areas and sampled the cotton for stink bugs and T. pennipes. They found significantly higher numbers of T. pennipes parasitizing and controlling stink bugs near the nectar-producing milkweed. They also found that the milkweed attracted monarch butterflies, an eye-catching migratory species that has prompted concern among conservationists because of the loss of milkweed habitats. Results were published recently in Environmental Entomology.
While these strategies will not eradicate stink bugs entirely, the studies show that they can potentially help to control them.
“These measures have the potential to provide some control of stink bug populations, but they will work best if used as one part of an overall management plan,” Dr. Tillman said.
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