Molecular ecology of hemlock woolly adelgid, its hosts, and its natural enemies

Abstract

Molecular analyses show that the hemlock woolly adelgid (HWA) has distinct native lineages in western North America, Japan, China, and Taiwan, while in eastern North America, HWA is not native and was introduced from Japan some time before 1951 (Havill et al. 2006 and 2007). The typical holocyclic lifecycle in the family Adelgidae involves primary hosts in the genus Picea and secondary hosts in other conifer genera (Havill and Foottit 2007). It is therefore feasible that in the regions where it is native, HWA alternates between Tsuga and Picea species. A database of DNA barcodes (approximately 650 base pairs from the COI gene) being compiled at the Canadian Centre for DNA Barcodes (Guelph, Ontario) includes HWA as well as adelgid samples collected from various Asian Picea species. We found an exact match between Chinese HWA and adelgids from galls on Picea likiangensis (Franch.) Pritzel and between Japanese HWA and adelgids from galls on Picea torano (K. Koch) Koehne. This confirms that HWA host alternates in at least part of its ranges in China and Japan. We are currently working to further understand HWA lifecycles and the relationships between HWA and its hosts with population genetic methods using microsatellites.

Citation

Havill, Nathan P.; Montgomery, Michael E.; Foottit, Robert. 2008. Molecular ecology of hemlock woolly adelgid, its hosts, and its natural enemies. In: Onken, Brad; Reardon, Richard, comps. Fourth Symposium on hemlock woolly adelgid in the eastern United States; 2008 February 12-14; Hartford, CT. FHTET 2008-01. Morgantown, WV: U.S. Forest Service, Forest Health Technology Enterprise Team: 147-148.