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UBC Theses and Dissertations
Acute, sublethal and synergistic effects of some essential oil constituents against the Asian armyworm, spodoptera litura (lepidoptera: noctuidae) | Hummelbrunner, Laurin Arthur
Abstract
Public concerns over synthetic pesticides have stimulated the search for alternative methods of control. Plant essential oils are the odorous components and secondary metabolites that can be separated from other plant tissues through steam distillation. Generally regarded as plant defenses against herbivory, they have demonstrated acute toxicity to various insect species and are of interest for the development of 'ecologically friendly' pesticides. After identifying three main active ingredients in several samples of commercial fragrance oils against the Asian armyworm, Spodoptera litura, a number of related compounds were also tested for acute toxicity (measured as LD5 0). The most toxic was thymol (LD50=25.4 jj.g/larva). Compounds were then tested for sublethal effects. Growth inhibition after topical application and feeding deterrence using leaf-disc choice experiments were determined. An LD1 0 dose reduces growth by 20% on average three days after topical application, and the most deterrent compound to feeding was thymol, with a DC5 0 of 85.6 u.g/cm2 leaf disc area. Since minor constituents in complex essential oils are thought to act as synergists, binary mixtures of the compounds were tested for synergy vis a vis acute toxicity and feeding deterrence. Trans-anethole acts synergistically with thymol, citronellal and a-terpineol. Based on these findings, several complex mixtures were developed and tested as leads for effective control agents. Candidate mixtures demonstrated good synergistic effects. The observed LD5 0 of Mixture 3 was 40.6 u.g/larvae compared to an expected value of 74.6 (.ig/larvae. The result of this research is a proprietary product soon to enter commercial production.
Item Metadata
Title |
Acute, sublethal and synergistic effects of some essential oil constituents against the Asian armyworm, spodoptera litura (lepidoptera: noctuidae) |
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2000
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Description |
Public concerns over synthetic pesticides have stimulated the search for
alternative methods of control. Plant essential oils are the odorous components
and secondary metabolites that can be separated from other plant tissues
through steam distillation. Generally regarded as plant defenses against
herbivory, they have demonstrated acute toxicity to various insect species and
are of interest for the development of 'ecologically friendly' pesticides. After
identifying three main active ingredients in several samples of commercial
fragrance oils against the Asian armyworm, Spodoptera litura, a number of
related compounds were also tested for acute toxicity (measured as LD5 0). The
most toxic was thymol (LD50=25.4 jj.g/larva). Compounds were then tested for
sublethal effects. Growth inhibition after topical application and feeding
deterrence using leaf-disc choice experiments were determined. An LD1 0 dose
reduces growth by 20% on average three days after topical application, and the
most deterrent compound to feeding was thymol, with a DC5 0 of 85.6 u.g/cm2 leaf
disc area. Since minor constituents in complex essential oils are thought to act
as synergists, binary mixtures of the compounds were tested for synergy vis a vis
acute toxicity and feeding deterrence. Trans-anethole acts synergistically with
thymol, citronellal and a-terpineol. Based on these findings, several complex
mixtures were developed and tested as leads for effective control agents.
Candidate mixtures demonstrated good synergistic effects. The observed LD5 0
of Mixture 3 was 40.6 u.g/larvae compared to an expected value of 74.6
(.ig/larvae. The result of this research is a proprietary product soon to enter
commercial production.
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Extent |
2948796 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-07-06
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0099489
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2000-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.