Brown Marmorated Stink Bug Found in Iowa and Illinois

In February, Iowa State University Extension Plant and Insect Diagnostic Clinic (ISU-PIDC) and the Iowa Department of Agriculture and Land Stewardship confirmed that a single dead specimen of the brown marmorated stink bug (BMSB) had been collected in Cedar Rapids and submitted for identification. It was the first confirmation of this pest in Iowa. Because the BMSB travels readily in shipping containers and with people, it was not known whether the find indicated an established population or an isolated individual.

In Illinois, the presence of the brown marmorated stink bug has been confirmed in two counties. A single BMSB was confirmed in the fall of 2010 in Cook County. In January 2011, the presence of an infestation of BMSB in a house in Kane County was confirmed.

Kelly Estes, state survey coordinator for the Illinois Cooperative Agriculture Pest Survey, says, “Previously, we had two interceptions in the state in 2009 – one in a mailing and one in a warehouse. While our current reports focus on urban settings, we are concerned with the potential of this insect to be found in agricultural areas.”

Originally from Asia, the BMSB was first found in Pennsylvania in 1998. Since then, it has been making its way across the United States.

“Marmorated” describes the BMSB’s marble-like coloration on the body. Adults are approximately one-inch long and have dark and light brown wings with light bands on their antennae. They have small, round, copper-colored or metallic blue depressions on the head. BMSB nymphs have a yellowish to off-white abdomen, and just before adulthood, their abdomens have reddish spots. Their eyes are deep red.

BMSB feeds on sap of host plants including field crops (particularly legumes, including soybeans), as well as many fruits (including apples, grapes and peaches), vegetables, shade trees and other woody ornamentals. The bug feeds by puncturing plant tissues (leaves, fruits, stems) and sucking on the plant juices with its beak, similar to aphids or leafhoppers.

In addition to the damage they do to crops, gardens and landscapes, BSMB adults annoyingly migrate into houses and other buildings in the fall to overwinter. In fact, homeowners are generally the first to notice the BSMB’s presence as it invades their homes. Homeowners on the East Coast describe the stink bugs as worse than box elder bugs and lady beetles combined.

“Entomologists are actively working on developing research objectives to describe the brown marmorated stink bug’s economic importance to agriculture,” says Iowa State University Entomologist Erin Hodgson.

“While the brown marmorated stink bug needs monitoring because it has potential to cause significant damage to soybeans, this pest may not become an ag issue for several years,” Hodgson says. “Initially, it will be a nuisance pest around homes and gardens.”

In spite of recent attention to the BSMB, farmers should also be aware of several other stink bugs that can be found in Midwestern soybeans.

Green and Brown Stink Bugs

Currently, Iowa and Illinois farmers may more commonly see two species that are pests to soybeans, the green stink bug and the brown stink bug.

The potentially more damaging of the two is the green stink bug. Adults are ¾-inch long and are bright green in color.

“Green stinkbugs migrate north each year, and typically, there’s just one generation per year in northern states,” Hodgson says. “The nymphs and adults can feed on fruiting trees and corn, but prefer to feed on soybeans in August.”

Brown stink bugs are also easily found in soybeans. Adults are ½-inch long and grayish-brown in color. Both nymphs and adults can be found feeding on soybeans in August.

These stink bugs prefer to feed on soybean seeds, resulting in shriveled seed of reduced quality.

Soybean farmers should examine developing pods for feeding punctures, as the holes can also allow disease to enter the pod.

“Because of their ability to damage tender plant tissues, especially developing seeds, these stinkbugs are capable of causing economic losses to soybean producers,” says University of Illinois Extension Entomologist Mike Gray.

While green and brown stink bugs are a concern, Gray notes that treatment thresholds have been well established. Growers should consider a treatment when adult bugs or large nymphs reach one per foot of row during pod fill.

Spined Soldier Bugs

Not all stink bugs found in soybean fields are pests. Some are beneficial. The third common stink bug species growers see is the spinedsoldier bug, which pierces the body and sucks the internal fluids out of a variety of soybean pests, including caterpillars. The spined soldier bug can regularly be found in soybeans after blooming and can be identified by very sharp pointed “shoulders” and dark wing tips.

Monitoring

Though stink bugs are considered a major pest of soybeans in the southern parts of the country, they have not yet become a significant cause for concern among Midwestern farmers. However, David Wright, director of contract research at Iowa Soybean Association, warns, “As we experience climate changes, particularly due to milder winters, we can expect new challenges posed not just by stink bugs, but by other pests, as well.”

Because stink bugs are on the move, Gray says a survey will be conducted in Illinois this summer to research the presence of all the aforementioned species, as well as the red-banded and red-shouldered stink bugs, which have been observed in several southeastern states causing significant management

challenges.

Soybean growers should be vigilant in scouting fields for suspicious-looking insects and should work with university extension in managing threats posed by green or brown stink bugs.

Iowans who observe insects similar to the BMSB are encouraged to submit a sample or send a digital photo to the Laura Jesse at the Iowa State University Extension Plant and Insect Diagnostic Clinic, www.ent.iastate.edu/pidc/ In Illinois, any BSMB spotting should be reported to Kelly Estes, state survey coordinator for the Illinois Cooperative Agricultural Pest Survey Program, at www.inhs.uiuc.edu/research/CAPS/con

tacts.html.