By Tim Widmer, National Program Leader-Plant Diseases, USDA ARS
The study and control of the exotic brown marmorated stink bug is a prime example of how international collaborative efforts lead to solutions to invasive pests. A natural enemy of the stink bug was identified at an overseas biological control laboratory (OBCL), which is part of the U.S. Department of Agriculture’s Agricultural Research Service (ARS).
The OBCL facilities provide a year-round base for studying invasive pests in their native ranges and discovering natural enemies that potentially can be introduced safely into the United States. As a leader in invasive species research, ARS has established OBCLs through cooperative agreements with Argentina, Australia, China, and Greece. In addition, ARS owns and operates the European Biological Control Laboratory (EBCL) in France. These overseas laboratories collaborate with and contribute to the goals of ARS labs in the United States to protect U.S. agriculture.
The brown marmorated stink bug is particularly devastating because it feeds on a wide variety of different host plants of economic and landscape value. In the mid-Atlantic region, some apple and peach growers reported total losses. In addition, it is a nuisance as it invades homes in large numbers to shelter for the winter.
To find a solution to the brown marmorated stink bug, scientists at the ARS lab in Newark, Delaware, began exploring in Asia with the assistance of researchers at the OBCL facility in China. This resulted in the identification of an important parasitoid wasp species that was attacking brown marmorated stink bug eggs in their native Asian range. This discovery led to further taxonomic study of the parasitoid wasps, revealing that their current scientific name was not valid. The name was corrected, an important step, because precise identities are required in biological control for insight into the biological features and adaptive evolution of invasive agricultural pests.
International collaboration continued as molecular studies of the Asian collections of this parasitoid wasp were conducted at the EBCL in France. Interestingly, populations of this gnat-sized wasp have been found in the United States, although it is not known how they arrived. The molecular characterization initially conducted at EBCL confirmed there are three genetically distinct groups present in the United States, all of which are different from the Asian parasitoid wasps brought in for evaluation. Fortunately, these U.S. parasitoid populations are well established, and researchers soon should have the opportunity to assess their impacts. Because these parasitoid wasp populations are already established in the United States, some states have already permitted redistribution of existing populations as a management option for the stink bug.
Surveys to identify natural enemies of the brown marmorated stink bug are complete, but work continues to determine which ones will be most effective. In addition, the OBCLs and the EBCL continue to lead ARS searches for new biological control agents for other invasive pests, such as spotted wing drosophila, spotted lanternfly, and roseau cane scale, in their native ranges.