278 Invasive Stink Bugs and Related Species (Pentatomoidea)
to introduce exogenous dsRNA into cells with the goal of silencing host cells involved in the production
of critical proteins or causing modulations in the protein level produced (Ambrose 2004, Mello and
Conte 2004). Ghosh et al. (2017) have taken the first step toward the use of this technique by developing
a system to deliver dsRNA into H. halys using oral ingestion that significantly reduces the expression of
genes such as JHAMT and Vg.
4.7 What Does the Future Hold?
Going forward, Halyomorpha halys has the potential to continue to invade new areas of the world fol-
lowing a pattern of population buildup in urban areas first followed by expansion into agricultural areas.
In North America, H. halys continues to spread across the southern and midwestern United States and
throughout California and the Pacific Northwest. In Canada, its spread may occur around the Great
Lakes area, the Maritime Provinces, and British Columbia. In Europe, it is continuing to invade new
areas and may increase its range into more European countries. Other potential expansions into areas
such as New Zealand and Australia, where H. halys has been intercepted previously at ports but not
become established, will continue to be a possibility because of international movement of cargo and
people from invaded areas. It currently is unknown whether or not H. halys will invade Central America
and the Caribbean, or more of South America; however, the potential exists. As this bug invades areas
outside of North America and Asia, it can be expected to expand the list of host plants and resultant dam-
age to agricultural commodities because of the unique crops grown in those areas.
One question that needs to be examined is the current reduction that is occurring in the mid-Atlantic
United States (Leskey and Hamilton 2015). Following the appearance of peak populations through-
out the area, populations, although continuing to cause agricultural damage, have declined markedly.
Hypotheses including the heavy use of insecticides by growers, and changes in weather patterns (summer
and winter maximum and minimum temperatures and hurricane patterns), have been proposed but, at
present, have not been investigated.
Management of Halyomorpha halys should continue to improve in invaded areas. The development of
conservation biological control options such as companion plantings (i.e., the practice of planting flowering
plants in conjunction with crops to attract and retain natural enemies in infested fields) and trap crops, and the
identification, release, and manipulation of biological agents, should reduce the use of current broad-spectrum
insecticides to control this bug, which are disrupting historical integrated pest management (IPM) programs
in agricultural systems such as tree fruit. The establishment of Asian egg parasitoids such as Trissolcus japon-
icus, whether due to adventive or deliberate introductions following regulatory review, should help suppress
H. halys populations in habitats that cannot be actively managed. The identification of more effective, selec-
tive insecticides also will improve management and reduce current environmental issues.
4.8 Acknowledgments
The authors thank J.E. McPherson for his dedication to this book and for his keen eye for detail and his
proofreading skill without which this chapter would have been a lesser contribution. The authors also thank
the following people for supplying information referenced in this chapter. We wish to thank Angelita Acebes
(Department of Entomology, Virginia Tech University, Winchester), J. Christopher Bergh (Department of
Entomology, Virginia Tech University, Winchester), Brett R. Blaauw (Department of Entomology, Rutgers
University, Upper Deerfield, New Jersey), Marie-Claude Bon (USDA ARS, Montferrier, France), Christine
Dieckhoff (USDA ARS, Newark, DE), Daniel L. Frank (Agriculture & Natural Resources, West Virginia
University, Morgantown), Ann Hajek (Cornell University, Ithaca, New York), Torri J. Hancock (Department of
Entomology, Virginia Tech University, Blacksburg), and Tim Haye (CABI, Delémont, Switzerland) for allow-
ing their unpublished data to be cited. We also are grateful to Julieta Brambila (USDA APHIS, Gainesville,
Florida), Galen P. Dively (Department of Entomology, University of Maryland, College Park), Charles
Pickett (California Department of Food and Agriculture, Sacramento), and David A. Rider (Department of
Entomology, North Dakota State University, Fargo) for providing personal communications that we cited.