Red alder (Alnus rubra) is the most commercially important hardwood tree species in the Pacific Northwest and has a long history of traditional medicinal use as a source of fungicide and insecticide. Chemical analysis has shown that the diarylheptanoid oregonin ((5S)-1,7-bis(3,4-dihydroxyphenyl)-5-(β-D-xylopyranosyloxy)-heptan-3-one) is the dominant phytochemical contributing to medicinal activity. It was recently discovered that high oregonin concentration in alder leaves is associated with enhanced resistance to western tent caterpillar (Malacosoma californicum), a leaf eating lepidopteran herbivore; however, oregonin has never been directly tested on insects, or red alder-associated fungal species. In this thesis, a novel purification method was developed for the preparative extraction of oregonin from red alder leaf and bark material to directly test its biological activity. A battery of insect feeding and toxicity bioassays were carried out with several tree-defoliating caterpillars, and fungal inhibition was tested against a range of plant-associated fungal species, including several alder-associated species. This research represents the first evaluation of oregonin biological activity on insects, plant-associated fungi of the phyla Basidiomycota, and fungal-like pathogens of the phyla Oomycota. Oregonin exhibited promising insect feeding deterrent activity against generalist lepidopteran pests, including cabbage loopers (Trichoplusia ni), white-marked tussock moths (Orgyia leucostigma), and fall webworm (Hyphantria cunea) at similar concentrations shown to reduce western tent caterpillar herbivory in alder leaf bioassays. The results suggest that oregonin concentration has potential for selection as a breeding trait in managed populations of red alder to improve host resistance to leaf-eating pests. / Graduate / 2021-08-10
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/12038 |
| Date | 27 August 2020 |
| Creators | Lea, Carmen |
| Contributors | Constabel, Carsten Peter |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Available to the World Wide Web |
Page generated in 0.0202 seconds