The role of phytochemicals and leaf cushion morphology in host resistance to the hemlock woolly adelgid (Adelges tsugae)

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Description: The Eastern Hemlock Tsuga canadensis Carrière is highly susceptible to the hemlock woolly adelgid (HWA) Adelges tsugae Annand. Conventional modes of pest control such as insecticides and biocontrol have been shown to be either impractical or inefficient. I investigated an alternative form of pest management--the use of naturally-occurring terpenoids, chemicals found in resistant hemlocks in Asia and the western United States. Previous analyses performed on seven species in the genus Tsuga have shown that the Eastern Hemlock contains statistically different levels of certain common terpenoids that are also in the Asian and western species. Building upon this previous work, I found that: (1) α-humulene is a possible deterrent of the HWA, while α-pinene and β-carophyllene are not; (2) terpenes can be successfully infused into Eastern Hemlock clippings; and (3) there are no measurable differences in lignin concentration between the susceptible T. chinensis and the resistant T. canadensis.
Language: English
Format: Degree Work