title: Temperature-dependent acute toxicity of methomyl pesticide on larvae of 3 Asian amphibian species.
abstract: Relative to other animal taxa, ecotoxicological studies on amphibians are scarce, even though amphibians are experiencing global declines and pollution has been identified as an important threat. Agricultural lands provide important habitats for many amphibians, but often these lands are contaminated with pesticides. The authors determined the acute toxicity, in terms of 96-h median lethal concentrations, of the carbamate pesticide methomyl on larvae of 3 Asian amphibian species, the Asian common toad (Duttaphrynus melanostictus), the brown tree frog (Polypedates megacephalus), and the marbled pygmy frog (Microhyla pulchra), at 5 different temperatures (15 °C, 20 °C, 25 °C, 30 °C, and 35 °C) to examine the relationships between temperature and toxicity. Significant interspecific variation in methomyl sensitivity and 2 distinct patterns of temperature-dependent toxicity were found. Because high proportions of malformation among the surviving tadpoles were observed, a further test was carried out on the tree frog to determine effect concentrations using malformation as the endpoint. Concentrations as low as 1.4% of the corresponding 96-h median lethal concentrations at 25 °C were sufficient to cause malformation in 50% of the test population. As the toxicity of pesticides may be significantly amplified at higher temperatures, temperature effects should not be overlooked in ecotoxicological studies and derivation of safety limits in environmental risk assessment and management.
authors.affiliation: School of Biological Sciences, Swire Institute of Marine Science, Faculty of Science, The University of Hong Kong, Hong Kong, People's Republic of China.
authors.forename: Edward Tak Chuen
authors.initials: ET
authors.lastname: Lau
authors.affiliation: Department of Natural Resources Science, University of Rhode Island, Kingston, Rhode Island, USA.
authors.forename: Nancy Elizabeth
authors.initials: NE
authors.lastname: Karraker
authors.affiliation: School of Biological Sciences, Swire Institute of Marine Science, Faculty of Science, The University of Hong Kong, Hong Kong, People's Republic of China.
authors.forename: Kenneth Mei Yee
authors.initials: KM
authors.lastname: Leung
mesh_terms: D000818:Animals; D001001:Anura / Q000502:physiology*; D002025:Bufonidae / Q000502:physiology*; D007814:Larva / Q000187:drug effects; D008724:Methomyl / Q000633:toxicity*; D010575:Pesticides / Q000633:toxicity*; D013045:Species Specificity; D013696:Temperature; D013997:Time Factors; D018675:Toxicity Tests
chemical_list: D010575:Pesticides; D008724:Methomyl
keywords: Amphibian; China; Insecticide; Malformation; Multistressor