Genetic diversity and origins of Halyomorpha halys in the U.S. and of its potential biocontrol agent unexpectedly recovered from the wild in the United States

Authors: BON, MARIE-CLAUDE - European Biological Control Laboratory (EBCL); Hoelmer, Kim; Talamas, Elijah; Buffington, Matthew; GUERMACHE, FATIHA - European Biological Control Laboratory (EBCL); Weber, Donald

Submitted to: International Symposium on Biological Control of Arthropods
Publication Type: Proceedings
Publication Acceptance Date: 7/3/2017
Publication Date: 9/11/2017
Citation: Bon, M., Hoelmer, K.A., Talamas, E.J., Buffington, M.L., Guermache, F., Weber, D.C. 2017. Genetic diversity and origins of Halyomorpha halys in the U.S. and of its potential biocontrol agent unexpectedly recovered from the wild in the United States. Proceeding of the 5th International Symposium on Biological Control of Arthropods, September 11-15, 2017, Langkawi, Malaysia. p. 3.

Interpretive Summary: The brown marmorated stink bug (BMSB) (Halyomorpha halys) has invaded the U.S. from its origin in Asia, and it poses an increasing nuisance to people and threat to agricultural industry because it attacks a wide range of vegetable crops, fruit trees, and ornamentals and aggregates to overwinter in houses. BMSB first appeared in Pennsylvania in 1996 and now occurs in 43 states. In order to develop an effective biological control program, we compared the genetic diversity of BMSB in western U.S., which was invaded later, with the previously published genetic diversity of BMSB in eastern U.S. and Asia in order to identify the origin of the western invasion. Our results indicate that BMSB in western U.S. comes from multiple sources, including China and possibly Japan whereas there is a single source in the Bejing region in China, for BMSB in the eastern U.S. A parasitoid from Asia, Trissolcus japonicus that is being studied as a prospective biological control agent in quarantine laboratories was discovered in field samples in 2014 in Beltsville, MD. Molecular genetic analysis showed that the T. japonicus individuals recovered from the wild in the U.S. did not escape from the US quarantine facilities, but came predominantly from China. Thus both the pest and a potentially effective biological control agent have been accidentally introduced to the U.S. The parasitoid may help to reduce populations of BMSB, but its impact on other species of pentatomid bugs is unknown.

Technical Abstract: The brown marmorated stink bug (BMSB), Halyomorpha halys (Hemiptera: Pentatomidae) is a highly polyphagous pentatomid that is native to Eastern Asia (China, Japan, Korea and Taiwan). Its pest status stems from feeding damage on a wide range of vegetable crops, fruit trees, and ornamentals. The first documentation of this pest in eastern North America occurred in Pennsylvania in 1996, and in western North America in 2004 in Oregon. It now has been detected in 43 states and is reported as a nuisance or agricultural pest in at least 26 states. Using two mitochondrial markers we conducted a comparison of the genetic diversity of BMSB in western U.S. with the previously published genetic diversity of BMSB in eastern U.S. and Asia in order to identify the origin of the western invasion. We detected a total of five haplotypes, two of them being already found in the eastern U.S. by others. While the eastern U.S. pest populations match a single source in the Bejing region in China, the overall genetic structure observed in the western U.S. suggested a more complex invasion scenario, encompassing several introduction events from different sources in China, including the Beijing area and also potentially from Japan and Eastern U.S. Proactive research in the BMSB invaded states has joined national efforts led by the U.S. Department of Agriculture and academic research institutions to develop a classical biological control program for BMSB. One Asian egg parasitoid, Trissolcus japonicus, (Hymenoptera, Scelionidae) has been under study in U.S. quarantine facilities since 2007 to evaluate its efficacy as a candidate classical biological control agent. Domestic surveys of egg parasitoids using sentinel egg masses of BMSB revealed that T. japonicus was already present in the wild in 2014 in Beltsville, MD. Genotyping analyses based on microsatellites determined that the specimens collected in Beltsville do not match those from the U.S. quarantine colonies. Therefore the T. japonicus individuals unexpectedly recovered from the wild in the US did not escape from the US quarantine facilities, but came predominantly from China. The genotype analysis is expanding to include populations of the wasp recovered in 2015 in Vancouver, WA and 2016 in Marlboro, NY and Mercer, NJ, and a more comprehensive analysis is being done to pinpoint the origin of all recovered wasp populations.