title: Acute toxicity of Headline® fungicide to Blanchard's cricket frogs (Acris blanchardi).
abstract: Previous laboratory studies have suggested that pyraclostrobin-containing fungicide formulations are toxic to amphibians at environmentally relevant concentrations. However, it is unknown if all pyraclostrobin formulations have similar toxicity and if toxicity occurs in different amphibian species. We investigated the acute toxicity of two formulations, Headline(®) fungicide and Headline AMP(®) fungicide, to Blanchard's cricket frogs (Acris blanchardi) based on a direct overspray scenario. In addition, we examined body residues of fungicide active ingredients in A. blanchardi following direct exposure to Headline AMP fungicide. Headline fungicide and Headline AMP fungicide had similar toxicity to A. blanchardi with calculated median lethal doses of 2.1 and 1.7 µg pyraclostrobin/cm(2), respectively, which are similar to the suggested maximum label rate in North American corn (2.2 and 1.52 µg pyraclostrobin/cm(2), respectively). Tissue concentrations of pyraclostrobin were lower than predicted based on full uptake of a direct dose, and did not drop during the first 24 h after exposure. Headline fungicides at corn application rates are acutely toxic to cricket frogs, but acute toxicity in the field will depend on worst-case exposure.
authors.affiliation: Department of Integrative Biology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK, 74078-3052, USA. cusaac@ostatemail.okstate.edu.
authors.forename: J Patrick W
authors.initials: JP
authors.lastname: Cusaac
authors.affiliation: Department of Integrative Biology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK, 74078-3052, USA.
authors.forename: Shane A
authors.initials: SA
authors.lastname: Morrison
authors.affiliation: Department of Integrative Biology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK, 74078-3052, USA.
authors.forename: Jason B
authors.initials: JB
authors.lastname: Belden
authors.affiliation: Department of Integrative Biology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK, 74078-3052, USA.
authors.forename: Loren M
authors.initials: LM
authors.lastname: Smith
authors.affiliation: Department of Integrative Biology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK, 74078-3052, USA.
authors.forename: Scott T
authors.initials: ST
authors.lastname: McMurry
mesh_terms: D000818:Animals; D001001:Anura; D002219:Carbamates / Q000633:toxicity*; D005659:Fungicides, Industrial / Q000633:toxicity*; D007928:Lethal Dose 50; D011720:Pyrazoles / Q000633:toxicity*; D000073739:Strobilurins; D023382:Toxicity Tests, Acute
chemical_list: D002219:Carbamates; D005659:Fungicides, Industrial; D011720:Pyrazoles; D000073739:Strobilurins; C513428:pyrachlostrobin
keywords: Acris; Amphibian; Fungicide; Strobilurin; Toxicity