Thesis
Compensatory response of black cottonwood to defoliation by cottonwood leaf beetle
Washington State University
Master of Science (MS), Washington State University
2010
Handle:
https://hdl.handle.net/2376/101273
Abstract
Many studies report that species of Populus respond to the negative effects of defoliation by cottonwood leaf beetle (CLB), Chrysomela scripta F. [Coleoptera:Chrysomelidae], through mechanisms of tolerance. Studies that report a physiological response to defoliation often fail to accurately simulate CLB feeding behavior in their experiments. During the summer of 2009, 1) we assessed the treatment techniques used in the literature and developed a set of protocols to simulate CLB feeding behavior and, 2) we measured the physiological and morphological response of P. trichocarpa to CLB and artificial defoliation treatments. We found that CLB avoided apical meristems, fed on young leaves (LPI 0-5) and avoided feeding on leaf midveins and primary lateral veins. To assess the response of P. trichocarpa to defoliation, we assigned two-year old trees a defoliation treatment (CLB or artificial) with individual branches defoliated at different levels (0, 25, 50, or 75% defoliation). Leaf and branch biomass were not different across different levels of defoliation and between types of defoliation due to increased leaf thickness and increased lateral branching. Branches that were defoliated by CLB had 22% lower leaf nitrogen than branches defoliated artificially. We concluded that 1) P. trichocarpa completely compensated for low levels (<30% branch defoliation) by CLB through increased leaf thickness and increased lateral branching and 2) defoliation by CLB caused a decrease in leaf nitrogen content compared to artificial defoliation due to the selective removal of nitrogen rich interveinal tissue by the insects.
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Details
- Title
- Compensatory response of black cottonwood to defoliation by cottonwood leaf beetle
- Creators
- Bryan R. Carlson
- Contributors
- R. Alan Black (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Sciences, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525091601842
- Language
- English
- Resource Type
- Thesis