Dissertation
Environmental site conditions and habitat characteristics influence biocontrol insects of yellow starthistle (Centaurea solstitialis) in Washington, USA
Doctor of Philosophy (PhD), Washington State University
01/2018
Handle:
https://hdl.handle.net/2376/111031
Abstract
This dissertation is comprised of three separate field studies which took place in eastern Washington State and occurred between 2014 through 2017. The first, a 2-year (2014-2015) field study quantified the effect of environmental factors on the overwintered Eustenopus villosus (Boheman) and Larinus curtus (Hochhut) adults in relation to the phenology of Centaurea solstitialis L. (Asteraceae: Cardueae). Results suggested that the appearance and increase in frequency of the overwintered E. villosus and L. curtus adults was likely a function of warming temperatures. Both species’ decline in frequency was likely a function of the weevils completing their life cycle in synchrony with the phenological advancement of C. solstitialis and decline of abundant breeding and foraging sites (buds and flowers). The second 2-year field study (2014-2015) examined percent infestation of E. villosus and L. curtus and the species percent seed consumption in Washington compared to studies in California and Greece to determine if differences in macroclimates influence the efficacy of the species. Findings suggested that differences in macroclimates does not appear to influence either species percent infestation or seed consumption. The third, a one-year field study (2017) examined the influence of physical environmental conditions and habitat characteristics on the composition of colonization by biocontrol insects of C. solstitialis biocontrol insects. In addition, this research examined whether different colonization by C. solstitialis biocontrol insects at a site created differences in the percent of C. solstitialis flowerheads infested and seed consumption in the southeastern corner of Washington. Results indicate that different environmental conditions and habitat characteristics which create the effective environment for the insects and reflected by the different plant associations and C. solstitialis seed production between sites, influence the composition of colonization by C. solstitialis biocontrol insects. Different effective environments create opportunity for physiological selection by biological insects of C. solstitialis. In addition, consumptive competition, seasonal emergence, and/or the timing of ovipositing by the overwintering generations may also play a significant role in the composition of colonization. Sequentially, differences in the composition of colonization create differences in the efficacy of control C. solstitialis by biocontrol insects.
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Details
- Title
- Environmental site conditions and habitat characteristics influence biocontrol insects of yellow starthistle (Centaurea solstitialis) in Washington, USA
- Creators
- Steven Edward Woodley
- Contributors
- Benjamin A Zamora (Advisor)Rodney Sayler (Committee Member)Richard Zack (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of the Environment (CAHNRS)
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 95
- Identifiers
- 99900581822401842
- Language
- English
- Resource Type
- Dissertation