Investigating the interactive effects of ultraviolet-B radiation and pesticides in amphibians

Amphibian populations are decreasing world-wide, which will not only lead to significant biodiversity loss but will also affect the structure and function of the ecosystems. Several causing factors have been proposed, including pesticide contamination and UVB radiation. However, amphibian declines are likely caused by a combination of these factors. For two of these stressors that co-occur in aquatic habitats, little is known about the interactive effects of pesticides and UVB radiation in amphibians. Understanding the potential interaction mechanisms between pesticides and UVB may have important implications in risk assessments and conservation of global amphibian populations. The purpose of this research is to (1) evaluate acute toxicity of some commonly used pesticides in the African clawed frog (Xenopus laevis), and (2) characterize the joint effects of these pesticides and UVB radiation and determine the potential mechanisms. My experiments have revealed that (1) α-cypermethrin (pyrethroid insecticide) and chlorothalonil (organochlorine fungicide) are most toxic to X. laevis embryos and larvae; (2) X. laevis larvae can be used as a surrogate species for endemic amphibians in risk assessments of pesticides; (3) α-cypermethrin and UVB had synergistic effects on larval growth; and (4) pesticides can increase the exposure and risk of UVB radiation in amphibians by impairing repair of UVB-induced DNA lesions and UVB avoidance behavior. Adverse effects were observed at environmentally relevant levels of UVB radiation and pesticides, suggesting that pesticides and UVB radiation may play a role in the global amphibian declines.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Environmental Toxicology

Grantor

Texas Tech University

Year dc:date.issued

2014

Author dc:creator

• Yu, Shuangying

Chair dc:contributor.committeechair

• Maul, Jonathan D.

Committee members dc:contributor.committeemember

• Cobb, George P.
• Mayer, Gregory D.
• Carr, James A.

• Amphibians
• Pesticides
• Ultraviolet-B radiation (UVB)

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/2346/58657

OAI identifier oai:identifier

oai:ttu-ir.tdl.org:2346/58657