Biological Control

A concerted effort to identify and evaluate a complex of non-native natural enemies as potential biological controls of the hemlock woolly adelgid (HWA) has been ongoing since the mid-1990s. To date, three imported natural enemies have been released in the eastern United States. Sasajiscymnus tsugae, a lady beetle from Japan, has been released in high numbers across the eastern United States since 1999 and in Connecticut as early as 1995. Laricobius nigrinus, a derodontid beetle from western North America,was first released in five states in 2003 and continues to be reared and released throughout the introduced range of the adelgid.  Release of a third predator Scymnus sinuanodulus, a lady beetle from China, began in 2004 at multiple release sites throughout the infested region.  Foreign exploration efforts to identify other potential natural enemies are underway and have generated some promising new leads including new biological control candidates from Japan and China that are currently in quarantine for further study. Research is focusing on tracking the establishment and impact of already released species and on evaluating the potential of new biological control candidates.

Selected Research Studies

• Release and Evaluation of Scymnus ningshanensis
• Release and Evaluation of Scymnus sinuanodulus
• Using Computer Models to Identify Vulnerabilities in the Adelgid Life-Cycle
• Scymnus coniferarum: A Predator of Hemlock Adelgids in Western North America
• Scymnus camptodromus Rearing and Evaluation
• Hemlock Woolly Adelgid Biocontrol Research in Japan
• Hemlock Woolly Adelgid Biocontrol Research in China
• Genetics and Taxonomy of Laricobius
• Silver fly Predators of the Hemlock Woolly Adelgid in the Pacific Northwest
• Evaluation of Temperature Effects on Feeding by Adelgid Biological Controls