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CC BY-NC V4.0, Open Access
Dissertation
EFFECTS OF ENVIRONMENTAL VARIATION ON POTATO PSYLLID VECTORS AND A BACTERIAL PLANT PATHOGEN
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000005449
Handle:
https://hdl.handle.net/2376/119076
Abstract
Environmental context affects ecological communities across all scales, from plants to animals to microorganisms. Studying how the environment effects plant-vector-pathogen systems increases our understanding of vector and pathogen movement across landscapes and vector-host interactions. This dissertation addresses these questions within a local crop system. The first chapter is an observational study of population dynamics of an agricultural pest and pathogen vector, the potato psyllid (Bactericera cockerelli Sülc) of potatoes in the Columbia River Basin. Growers have increased pesticide use to control for outbreaks of B. cockerelli and it’s associated pathogen, Candidatus Liberibacter psyllarous, which causes the disease known as zebra chip. This study found that the population dynamics were closely tied with temperature, and that winters with extended cold periods could decrease overwintering survival and decrease population abundance in successive years. The second chapter uses sampling data for four common potato pests collected from 2007-2017: (i) potato tuberworm (Phthorimaea operculella Zeller), (ii) beet leafhopper (Circulifer tenellus Baker), (iii) green peach aphid (Myzus persicae Sulzer), and (iv) potato psyllid (Bactericera cockerelli Šulc). An interpolation model was created to map predicted weekly pest abundance across the entire sampling region and validated to quantify its efficacy. Three data transformations, five power parameters, and three nearest neighbor parameters were tested to quantify sensitivity and determine best fit for each insect. The model performs with a high degree of precision and is robust to changes in parameter, due a wider range of spatial autocorrelation than initially assumed. The third chapter tests the precision of a phenological model for B. cockerelli development against field data. This model is also precise enough for use in guiding management decision. Finally, chapter four tests the effect of water stress on pathogen transmission success, and studies potential chemical and physical mechanisms that may drive that interaction. While we found clear evidence that water stress is associated with decreased pathogen titer, more work needs to be done to untangle the overlapping chemical and physical plant responses. This dissertation has led to the creation and improvement of the potato decision aid tool and will inform future research into the B. cockerelli-Liberibacter system.
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Details
- Title
- EFFECTS OF ENVIRONMENTAL VARIATION ON POTATO PSYLLID VECTORS AND A BACTERIAL PLANT PATHOGEN
- Creators
- Abigail Lienhard Cohen
- Contributors
- David Crowder (Advisor)John P Reganold (Committee Member)Vincent P Jones (Committee Member)William R Cooper (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Entomology
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 134
- Identifiers
- 99900592258001842
- Language
- English
- Resource Type
- Dissertation