Photoenhanced toxicity of a carbamate insecticide to early life stage anuran amphibians

Authors

  • Angela Zaga,

    1. Department of Fisheries and Wildlife, University of Missouri, Columbia, Missouri 65211, USA
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  • Edward E. Little,

    Corresponding author
    1. U.S. Geological Survey Biological Resources Division Environmental and Contaminants Research Center 4200 New Haven Columbia, Missouri 65201
    • .S. Geological Survey Biological Resources Division Environmental and Contaminants Research Center 4200 New Haven Columbia, Missouri 65201
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  • Charles F. Rabeni,

    1. Missouri Cooperative, Fisheries Research Unit, University of Missouri, Columbia, Missouri 65211, USA
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  • Mark R. Ellersieck

    1. Agricultural Experimental Station, University of Missouri, Columbia, Missouri 65211, USA
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Abstract

Aican clawed frog (Xenopus laevis) and gray tree frog (Hyla versicolor) embryos and tadpoles were exposed to sublethal levels of carbaryl, a broad-spectrum insecticide, and ultraviolet radiation to determine interactive and sublethal effects. Ultraviolet intensity (UV-B [285–320 nm] plus UV-A [321–400 nm]) was controlled with various types of plastic filters and quantified with a scanning spectroradiometer. Significant differences in swimming activity and mortality of both species were evident during the 96-h experiments. Ultraviolet-B radiation alone and carbaryl in the presence of UV-B significantly decreased swimming activity of both species. As little as 1.5% intensity of ambient solar UV-B radiation photoactivated carbaryl. Toxicity of 7.5 mg/L carbaryl increased by 10-fold in the presence of UV-B in all species and life stages tested. Our results indicate that photoenhancement by solar UV-B radiation should be considered when evaluating the toxicity of contaminants to amphibians and other organisms.

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