The brown marmorated stink bug (Halyomorpha halys) is an invasive species in the United States that can damage fruit and vegetable crops and cause nuisance infestations to residences. It is a shield-shaped “true bug” of the order Hemiptera, and the common name refers to its brown, variegated appearance (marmorated means variegated). Halyomorpha halys eats many different foods, helping it expand its range and making it difficult to control.
As a residential nuisance, meanwhile, it enters homes in the autumn in search of overwintering sites. The stink bugs often become dormant within hidden areas of houses such as attics, but sometimes they later become active in winter in response to heat and enter living areas. There has been a lot of research on monitoring and managing populations of H. halys, but there has been less research on the species as a nuisance pest and how the nuisance can be controlled.
To help fill this need, Christopher Bergh, Ph.D., and doctoral student Nicole Quinn at Virginia Tech conducted behavioral research on brown marmorated stink bugs in nuisance situations. Their findings are reported in a study published in August in the journal Environmental Entomology.
In preliminary research, investigators have observed that H. halys seems to prefer certain building colors and certain building materials more than others. So far, methods of discouraging stink bug infestations include sealing entry points to buildings and applying insecticides. One recently evaluated strategy is to put up black netting impregnated with pyrethroid insecticides such as deltamethrin and alpha-cypermethrin. (The netting is sometimes referred to as long-lasting insecticide netting.)
Bergh and Quinn’s research tested whether brown marmorated stink bugs use visual cues to choose where to land when approaching a building. They also tested the effect of insecticide-treated black netting on stink bugs to explore this strategy.
In one experiment, they sampled the presence of brown marmorated stink bugs on a single-story building in Virginia surrounded by woods, fields, and fruit orchards. They observed the presence of the stink bugs on all sides of the building in September and October over five different years. The highest numbers were seen between September 15 and October 15; 88 percent of stink bugs were counted in that period. They observed significantly more bugs on the north- and east-facing walls than on south- and west-facing walls. They also found significantly more stink bugs in doorways than on walls in all directions. The highest density of bugs were in north- and east-facing doorways.
In separate experiments, they presented H. halys with portable pine-framed panels to test how they responded to particular visual stimuli on the walls of a building. The panels measured 1 square meter and were mounted on the east side of a garage on top of a small hill.
In one panel experiment, they presented H. halys with open panels with no netting and panels that had polyethylene netting containing no insecticide (non-treated panels). They found that significantly more bugs landed on non-treated panels than on open panels.
As to the study’s most important discovery, Bergh says, “One of the most important findings was that there was a consistent effect of wall compass direction on the abundance of dispersing adult brown marmorated stink bugs.”In a second panel experiment, they presented Halyomorpha halys with non-treated panels and with panels with netting treated with insecticide (treated panels). They found no significant difference in the number of brown marmorated stink bugs that landed on the treated panels versus the non-treated panels. They found that stink bugs that landed on the insecticide-treated netting and stayed long enough became intoxicated, but they did not die. Bergh and Quinn suggested that, in the future, using a higher dose of insecticide might be more effective as a control tactic.
Bergh says the most important next steps in this research will be the following: “One, to determine the duration of exposure to insecticide-treated netting needed to kill adult brown marmorated stink bugs and, two, to see whether we can achieve this exposure duration by modifying the panels and/or by adding additional sources for exposure to the home’s exterior walls.”
“If we cannot cause the necessary duration of exposure,” Bergh says, “it will be important to understand the fate of adult stink bugs that are exposed to the netting, since even a short duration exposure caused many to become moribund and intoxicated. For instance, if the intoxicated individuals fall to the ground, are they subject to predation when they are unable to walk or fly?” If so, this would provide some indirect control via predation even though the insecticide did not directly cause mortality.
The use of insecticide-treated netting is an intriguing avenue for more research but, Bergh says, “its use as a brown marmorated stink bug exclusion tactic for homeowners is still very experimental.”
Residential infestations of brown marmorated stink bugs are not a terrible problem: They do not cause structural damage to homes, and they do not spread disease. But the infestations can be a serious nuisance. And H. halys does cause extensive crop damage to foods such as apples, peaches, tomatoes, beans, and corn. Also, as an invasive species, it may cause disruptions to the ecology of ecological communities that we have not even discovered yet. As such, breakthroughs about its microhabitat selection, and its precise dose vulnerability to particular insecticides, can help inform its management and control.