Brown Marmorated Stink Bug in North Carolina
The brown marmorated stink bug (BMSB, Halyomorpha halys) is an invasive pest that was accidentally introduced from Asia into Pennsylvania in the 1990s. Its first detection in North Carolina was in Forsyth County in 2009, and it has since spread rapidly throughout the piedmont and mountain regions of the state. The coastal plain has had fewer occurrences during this period, although the insect has appeared in isolated locations. As of January 2020, it had been confirmed in 75 of NC’s 100 counties.
Our research focuses primarily on controlling BMSB in agriculture. For information on dealing with BMSB around the house, visit our FAQ page.
Although BMSB can be a destructive pest to a wide variety of crops, it usually establishes itself first in urban landscapes, roadside vegetation, and structures that provide attractive overwintering sites. This has been the case in North Carolina, with most early reports coming from property owners in urban areas between Raleigh and Asheville (the I-40 corridor) who have experienced BMSB “invasions” in late summer. Sightings in home gardens and on commercial farms increased from extremely isolated reports in 2010 to widespread occurrences by 2015. In some locations, populations have become high enough that frequent pesticide applications are necessary to prevent extensive crop loss.
Life cycle in North Carolina
Brown marmorated stink bugs overwinter as adults in structures, standing dead trees, and other sheltered places. In April and May, these adults leave shelter and move into nearby woods where they mate and lay eggs on suitable host plants. Some of these adults may also enter agricultural plots. By June or July eggs have hatched and 1st-generation BMSB are also in agricultural plots. They generally prefer fruits and vegetables early in the summer, then move to soybeans later in the season. Under ideal conditions (warm temperatures and favorable hosts), a second generation of adults may be produced. As days become shorter in early August, adult BMSB stop laying eggs. In September and early October, adults begin looking for overwintering sites, and by late October most individuals have settled back into sheltered places. The months of September and October, when adults are aggregating on buildings, is usually when invasions to new areas are first observed.
What’s being done?
Since 2011, NC State University has been part of a collaboration of over 50 scientists working on the biology and management of BMSB in the United States. During that time we have introduced emergency measures to minimize crop damage, developed monitoring traps and attractants, gained a clearer understanding of the BMSB life cycle, and identified many of the wild plants that BMSB use to complete their development. We are also identifying native and non-native predators and parasitoids of BMSB, which may hold the most promise for controlling the insect in the future.
Despite the short-term effectiveness of current control methods, they are not sustainable. Broad-spectrum pyrethroids and neonicotinoids have reduced the severity of BMSB damage in many crops, but they have also increased production costs and disrupted IPM programs, resulting in greater risk to non-target organisms and secondary pest outbreaks.
The focus of BMSB research has therefore shifted toward finding management strategies that can be used over the long term. Projects that North Carolina researchers are pursuing and will continue to pursue in the next few years include:
Studying BMSB phenology and host plant availability in different regions of North Carolina. To help growers anticipate BMSB invasions in their crops, and to predict specific locations and habitats where BMSB is most likely to be a problem, we are studying the effects of temperature and host plant suitability on BMSB populations in different regions of NC. The fact that BMSB populations are highly aggregated in different ecoregions of the state suggests that biotic and abiotic factors specific to those regions are important in regulating populations. We are currently examining the effect of temperatures on both overwintering ecology and survivorship during summer months, and how host plant availability affects population density.
Identify natural enemies and incorporate them into management programs. Biological control has the potential to permanently suppress BMSB populations over a large landscape scale. In its native Asia, BMSB is not a major pest, partly because of tiny parasitic wasps (parasitoids) that destroy large numbers of BMSB eggs. To monitor biological control, we deploy “sentinel” BMSB egg masses every season on a variety of host trees and crops, then examine them for parasitization and predation. Parasitoids that hatch from sentinel eggs are identified to species. Thus far, only native species of parasitic wasps have been detected in North Carolina, and they—along with native predators such as katydids, jumping spiders, earwigs, and lady beetles—have had only a modest effect on BMSB populations.
However, our lab is also looking for natural expansion of Trissolcus japonicus into North Carolina. This wasp coevolved with BMSB and is much more effective at controlling it. T. japonicus was detected in 2015 in Maryland and northern Virginia, as well as Washington State, and we expect it to naturally disperse to other areas. It is also being studied in quarantine at USDA, and permits may soon be issued to accelerate its establishment over a wide geographic area.
We also rear lab colonies of native hymenopteran parasitoids for continued research into their ecology and biology, and we perform bioassays on the lethal and sub-lethal effects on native parasitoids of pesticides approved for organic production. Future research will focus on understanding which natural enemies are most effective, where they usually occur, and how management practices can increase their effectiveness in North Carolina agricultural systems.
Optimize trap designs and develop models for their use. Very effective pheromone attractants and Tedders-style (black pyramid) monitoring traps have been developed for BMSB over the last five years. Despite their effectiveness, they are large, cumbersome to use, and not well-suited to all cropping systems. Further research has identified sticky cards as being equally effective. We are continuing to test these cards as well as develop correlations between the numbers of BMSB captured in traps and the amount of damage appearing in crops. The goal is to develop a simplified trapping system that uses the numbers of insects captured as thresholds that trigger insecticide sprays in different cropping systems.
Increase the number of pesticides available for BMSB control, and refine their use. Insecticides will remain a critical component of BMSB management for the foreseeable future, and pyrethroids and neonicotinoids are currently the most effective materials available. However, frequent use of these broad-spectrum chemicals is not compatible with IPM programs, and it may eventually cause the development of resistance in BMSB populations. As new materials with new modes of action are developed, they will be lab- and field-tested for both efficacy against BMSB and minimal impact on natural enemies.
Report a sighting
Since 2011, NC State University has been collecting information about BMSB occurrences through an online survey. If you live in NC and have seen BMSB, please complete the survey.
Frequently asked questions
Click the FAQ page for the most common concerns.
Visit our lab on the web
The bulk of BMSB research in NC is conducted by the Walgenbach Lab at the Mountain Horticultural Crops Research and Extension Center in Mills River.