Thesis
Effects of a Graminicide on three Euphydryas species, surrogates for endangered and at-risk checkerspots
Washington State University
Master of Science (MS), Washington State University
2015
Handle:
https://hdl.handle.net/2376/102153
Abstract
Habitat degradation is a major contributor to butterfly population decline worldwide. Agencies and land managers often elect herbicides to reduce invasive flora and improve native plant community in habitat restoration and maintenance. These herbicides may harm butterfly larvae and are sometimes the impetus for management of invasive flora. Butterfly larvae are commonly present during spring and fall when herbicides are most effective. We examine larval response to a grass-specific herbicide using three, common and closely-related surrogates within a genus that includes many endangered and at-risk butterfly species. We detect fitness and behavioral treatment effects in our three Euphydryas surrogates; each species responded distinctively. In one species, we find a reduction in diapause biomass, a proxy for survival to adulthood and overall fitness. In two species, we detect a reduction in group size, with the potential to affect larval survival in the field. Additionally, there is significant interactive effect between herbicide exposure and novel hostplant in two butterfly species, and marginal effect in the third. These factors could contribute to reduction in metapopulation viability and overall population decline if larvae are exposed to this herbicide in the field. Scheduling herbicide application to avoid the vulnerable pre-diapause larval stage may allow land stewards to use this tool conscientiously in habitat management and land conservation where endangered and at-risk species reside.
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Details
- Title
- Effects of a Graminicide on three Euphydryas species, surrogates for endangered and at-risk checkerspots
- Creators
- Jessica Lee Zemaitis
- Contributors
- Cheryl Barbara 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
- 99900525066101842
- Language
- English
- Resource Type
- Thesis