title: Acute and chronic toxicity of Roundup Weathermax and Ignite 280 SL to larval Spea multiplicata and S. bombifrons from the Southern High Plains, USA.
abstract: Pesticides have been implicated in widespread amphibian declines. We assessed acute and chronic toxicity of two widely used herbicides to larval New Mexico (Spea multiplicata) and Plains (S. bombifrons) spadefoots from cropland and native grassland playas. Roundup WeatherMAX (WM) toxicity estimates (48- and 216-h LC(50); 48-h LC(1)) for both species were similar to environmental concentrations expected from accidental overspray. Chronic (30-day) exposure to WM at predicted environmental concentrations (2.0 and 2.8 mg glyphosate acid equivalents/L) reduced survival of both species. Ignite 280 SL (IG) toxicity estimates (48-h LC(50) and LC(1)) for both species were above predicted environmental concentrations of 1.0 mg glufosinate/L. Chronic exposure to predicted environmental concentrations of IG did not reduce survival of either species. Toxicity test results suggest that at predicted environmental concentrations IG would not cause extensive mortalities among larval New Mexico and Plains spadefoots. However, WM may cause extensive mortality among larvae of these species.
authors.affiliation: Department of Zoology, Oklahoma State University, Stillwater, OK 74078, USA. simon.dinehart@okstate.edu
authors.forename: Simon K
authors.initials: SK
authors.lastname: Dinehart
authors.forename: Loren M
authors.initials: LM
authors.lastname: Smith
authors.forename: Scott T
authors.initials: ST
authors.lastname: McMurry
authors.forename: Philip N
authors.initials: PN
authors.lastname: Smith
authors.forename: Todd A
authors.initials: TA
authors.lastname: Anderson
authors.forename: David A
authors.initials: DA
authors.lastname: Haukos
mesh_terms: D000613:Aminobutyrates / Q000633:toxicity*; D000818:Animals; D001001:Anura / Q000254:growth & development*; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000633:toxicity*; D005998:Glycine / Q000031:analogs & derivatives* / Q000633:toxicity; D006540:Herbicides / Q000633:toxicity*; D007814:Larva / Q000187:drug effects; D009516:New Mexico; D023382:Toxicity Tests, Acute; D036401:Toxicity Tests, Chronic; D000097797:Glyphosate
chemical_list: D000613:Aminobutyrates; D004785:Environmental Pollutants; D005998:Glycine; D006540:Herbicides; D000097797:Glyphosate; C003121:phosphinothricin