When someone says stink bug, we generally think of the brown shield-shaped bugs that work their way into our homes, are stinky bugs, and can be difficult to control. But that bug – the brown marmorated stink bug is native to Asia and was introduced into the United States in the mid-1990s, possibly stowing away in a shipping container. Comparatively however, the marmorated stink bug, that is a major pest of homeowners, is new to the country compared to three native other species that have been attacking crops for decades in Georgia and other parts of the Southeast.


The three native species are

• the southern green stink bug (Nezara viridula) can develop in peanut and move to cotton crops.
• the brown stink bug (Euschistus servus) will damage corn, and also can develop in peanut and move into cotton.
• the green stink bug (Chinavia hilaris) will damage cotton after moving into it from non-crop sources at field edges.

 

Stink Bugs Damage Crops

This movement is of particular problem in areas such as Georgia where, each spring, many farmers plant corn first, then peanuts, and then cotton, often near each other or side-by-side. Additionally, all three of these stink bugs are immune to the Bacillus thuringiensis toxin that controls other insects in corn and cotton, so growers often spray “broad-spectrum” insecticides which also kills beneficial insects.

Agricultural Research Service entomologist Patricia Glynn Tillman, who is in the Crop Protection and Management Research Unit in Tifton, Georgia, has found ways to help growers reduce losses and adopt greener alternatives through the use of nectar-producing plants to attract beneficial insects and the placement of barriers between crops to discourage migrations.

For her study, Tillman and her colleagues collected stink bugs with hand-held nets and drop cloths from the Georgia corn, peanut and cotton crops for six years. Their purpose was the study of the stink bug migration patterns.

They found that:

• brown stink bugs and southern green stink bugs are present in all three crops and often migrate from one crop to the next.
• green stink bugs are rare in corn and peanut, but common in cotton.
• stink bugs are likely to migrate into cotton from adjacent woodlands and into corn from both woodlands and nonwooded areas.
• the taller the crop plant, the less penetration occurred.

They also evaluated stink bug colonization in three cropping systems common in the Southeast: corn/cotton, corn/peanut/cotton, and peanut/cotton. Results showed that:

• for southern green stink bugs and brown stink bugs, the risk of colonizing cotton was highest in corn/peanut/cotton cropping systems.
• for green stink bugs, the risk was highest in peanut/cotton systems.
• Green stink bugs are more attracted to cotton than to corn, but corn is more likely than cotton or peanuts to harbor southern green stink bugs and brown stink bugs.

 

Reducing Stink Bug Damage

To attempt to find solutions to the stink bug migration, Tillman placed and studied a variety of barriers including:

• Nectar-producing buckwheat plants, sorghum Sudan grass (an annual grass that grows to about 8 feet), and plastic sheets of two different heights (about 6 feet high and about 2 feet high) between peanut and cotton fields
  The results: The plastic and the grass were effective, as long as the barriers were at least as high as the cotton (4.5 feet). The buckwheat attracted the parasitoid Trichopoda pennipes, which cut back on stink bugs in nearby cotton.
• Potted milkweed plants about 4 feet from each other along the edges of cotton fields in peanut/cotton production areas.
  The results: There were significantly more T. pennipes parasitizing stink bugs in cotton near nectar-producing milkweed than in control plots. Additionally, the milkweed attracted Monarch butterflies, an eye-catching migratory species that has prompted concern among conservationists because of the loss of milkweed habitat.

Although the strategies will not eradicate stink bugs, they will help if used as one part of an overall management plan.

This research is part of Crop Protection and Quarantine, an ARS national program (#304) described at www.nps.ars.usda.gov.