Stink bugs in Minnesota soybean
Photo: Ione L. BugGuide.net
Photo: Russ Ottens, University of Georgia, Bugwood.org
Photo: Daren Mueller, Iowa State University, Bugwood.org
Photo: Phil Sloderbeck, Kansas State University, Bugwood.org
Figure 1. Stink bug species commonly found in Minnesota soybean. Plant feeding species: (A) one-spotted, (B) brown, and (C) green stink bugs; Predatory specie: (D) spined soldier bug
Several species of stink bugs (Pentatomidae) can be found in soybean.
- Shield–shaped bodies with a triangular structure (scutellum) on their backs
- 5–segmented antennae
- Piercing–sucking mouth parts (proboscis)
- Proboscis narrower than the thickness of the antennae for herbivores, and thicker than antennae for predators
Eggs are barrel–shaped and often laid under leaves.
- Smaller size and more rounded shape than adults
- No wings or small undeveloped wings
- Five nymphal stages (instars)
Most species undergo 1 to 2 generations per year.
Most feed on various crop and wild plants.
Most overwinter as adults under leaf litter and loose bark, but some are household invaders.
Photo: Dr. Suhas Vyavhare, Texas A&M Agrilife Research and Extension Center
Figure 2. Injury to soybean caused by stink bug feeding.
Prefer to feed on pods and developing seeds.
Penetrate plant tissues with proboscis, inject digestive enzymes, and remove nutrients.
Feeding causes abortion, deformation, and discoloration of seed, which can affect yield and quality (Figure 2).
Feeding can also cause delayed plant maturity ("stay–green syndrome").
Scouting and management
Stink bugs have infrequently reached economically significant levels in Minnesota, but invasive species and reported increases in abundance of native species could result in increased infestations.
- Start scouting as pods begin to develop and continue through seed development.
- Scouting can be performed with a sweep net.
- Stink bugs typically colonize field edges first, so counting should include edge and interior areas.
- Decisions are based on the combined count of nymphs (> 1/4 inch long) and adults of all plant–feeding species.
- Reasonable thresholds for use in Minnesota are as follows:
- Soybean grown for grain: 10 bugs / 25 sweeps
- Soybean grown for seed: 5 bugs / 25 sweeps
Labeled rates for insecticides should be used for treating stink bugs and follow directions on the product label.
Fields should be scouted after treatment to check for re–colonization.
Be on the lookout
Photo: S. Valley, Oregon Department of Agriculture, Bugwood.org
Figure 3. Brown marmorated stink bug. Note the bands on the antennae, alternating dark–light pattern on abdomen and wing veins outlined in black.
The brown marmorated stink bug has recently invaded Minnesota. This species looks similar to some of the native species, but can be distinguished by the light–colored bands on the antennae and the alternating dark–light pattern on the edge of the abdomen (Figure 3). In addition, under close inspection, the veins of the membranous parts of the wings are outlined in black.