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 (and sometimes agricultural fields) where they mate and lay eggs on suitable host plants. By June or July eggs have hatched and many of these 1st-generation BMSB invade fruit and vegetable plots. Later in the season they may move into soybeans and other field crops. 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. Current projects in North Carolina include:
Optimizing trap designs and developing models for their use. Very effective pheromone attractants and black pyramid “Tedders” traps were developed for monitoring BMSB in the first years of research. Despite their effectiveness, pyramid traps were large, cumbersome, and not suited to all cropping systems. Further research has found that sticky card traps are equally effective. We are now working to develop correlations between the numbers of BMSB captured on sticky cards and the amount of damage occurring in crops. The goal is to develop a simplified trapping system that uses BMSB trap counts in conjunction with degree-day models to better forecast the need for and timing of insecticide applications. Such models could substantially reduce the number of sprays needed, just as they have with other insect pests.
Studying BMSB phenology and host plant availability in different regions. To help predict specific locations and habitats where BMSB is most likely to establish, we are studying the effects that biotic and abiotic factors (such as climate, host plant suitability and distribution, and agricultural and landscape ecology) have on BMSB populations as measured by sticky trap captures. The fact that BMSB are highly aggregated in different ecoregions of North Carolina suggests that factors specific to those regions are important in regulating population size. In addition, our trap counts are added to a nationwide database used by landscape modelers at Washington State University to determine the likelihood and severity of future BMSB invasions throughout the United States.
Identifying natural enemies and incorporating 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 yellow sticky traps as well as “sentinel” BMSB egg masses on a variety of host trees and crops. Parasitoids that hatch from sentinel eggs are identified to species. So 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 in Asia and is much more effective at controlling it. In 2015, T. japonicus was found in the US, presumably having arrived with BMSB. It has since been found in more than ten states and is being studied in quarantine at the USDA. By law, T. japonicus may be released in states where it has been naturally found, but not in states where it hasn’t. If T. japonicus is found in NC, we can start researching the best ways to harness its potential as a biocontrol agent.
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.
Increasing the number of pesticides available for BMSB control, and refining 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.