Exploration for native parasitoids of Asian longhorned beetle in China as prospective biological control agents

1. Native to China and the Korean Peninsula, the Asian longhorned beetle (ALB) Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) is a high-risk invasive pest of hardwood trees.2. To explore the potential of biological control of ALB in the United States, we conducted surveys of ALB parasitoids using sentinel logs in five geographical regions (Beijing, Gansu, Guizhou, Shanghai, and Yunnan) in China from 2019 to 2022.3. Seven hymenopteran larval parasitoid species, Bracon planitibiae Yang, Eurytoma chinensis Yang, Heydenia sp., Oxysychus glabripennis Yang, Sclerodermus guani Xiao et Wu, Spathius anoplophorae Yang, and Zolotarewskya anoplophorae Yang, were collected in Beijing. Four, three and two of these species were also found in Shanghai, Guizhou, and Yunnan, respectively. No parasitoid was found in Gansu.4. Mean parasitism rates by all parasitoid species were 3.6%-15.8% in Beijing, 1.4%-16.4% in Guizhou, 1.6%-7.1% in Shanghai, and 5.8% in Yunnan.5. Spathius anoplophorae and O. glabripennis were the two most dominant parasitoids collected consistently in the four different regions and may be considered as prospective agents for biological control introduction against ALB in the United States.6. We discuss some underlying ecological mechanisms that might contribute to the rarity of egg parasitoids and future opportunities and challenges for biological control of ALB.