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Acute and chronic toxicity of Roundup Weathermax and Ignite 280 SL to larval Spea multiplicata and S. bombifrons from the Southern High Plains, USA |
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| Authors: | Simon K Dinehart Loren M Smith Philip N Smith David A Haukos |
| Institution: | a Department of Zoology, Oklahoma State University, Stillwater, OK 74078, USA b The Institute of Environmental and Human Health, Texas Tech University, Box 41163, Lubbock, TX 79409, USA c U.S. Fish and Wildlife Service, MS 2125, Texas Tech University, Lubbock, TX 79409, 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 LC50; 48-h LC1) 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 LC50 and LC1) 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. |
| Keywords: | Amphibian decline Glyphosate Herbicide Roundup |
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