Thesis
Characterizing a contentious management tool: the effects of a grass-specific herbicide on the silvery blue butterfly
Washington State University
Master of Science (MS), Washington State University
2014
Handle:
https://hdl.handle.net/2376/100562
Abstract
Land managers of Pacific Northwest prairies are interested in using selective herbicides to reduce invasive grasses and improve habitat for native plants and animals. These prairies support unique butterfly species so it is crucial to understand the cost-benefit tradeoff of using herbicides in this landscape. We evaluate the effect of the grass-specific herbicide fluazifop-pbutyl on behavior and demographic indicators of the silvery blue butterfly (Glaucopsyche lygdamus) in the field and also quantify effects on reproductive behavior in the greenhouse. We find that in the first few months after an early spring application, herbicide decreases vertical grass structure but does not have a positive or negative net effect on adult behavior, egg deposition, larval density, pupal weight, or ant-tending association for the silvery blue. Our greenhouse oviposition choice trials corroborate field findings and indicate that females do not show preference for unsprayed host plants. Selective herbicides create a vegetative structure preferred by butterflies and do not negatively affect the silvery blue when applied in the early spring. Appropriate timing of herbicide application is likely the key to avoiding adverse effects on vulnerable butterfly life stages. Depending on the longevity of the vegetative reduction, strategic herbicide application may be an acceptable tool for restoring prairie communities.
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Details
- Title
- Characterizing a contentious management tool
- Creators
- Rachel Marie Glaeser
- Contributors
- Cheryl B. Schultz (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525009801842
- Language
- English
- Resource Type
- Thesis