The toxicity of glyphosate and several glyphosate formulations to four species of southwestern Australian frogs

The acute toxicity of technical-grade glyphosate acid, glyphosate isopropyl amine, and three glyphosate formulations was determined for adults of one s pecies and tadpoles of four species of southwestern Australian frogs in 48- h static/renewal tests. The 48-h LC50 values for Roundup(R) Herbicide (MON 2139) tested against tadpoles of Crinia insignifera, Heleioporus eyrei, Lim nodynastes dorsalis, and Litoria moorei ranged between 8.1 and 32.2 mg/L (2 .9 and 11.6 mg/L glyphosate acid equivalent [AE]), while the 48-h LC50 valu es for Roundup(R) Herbicide tested against adult and newly meta-morphosed C . insignifera ranged from 137-144 mg/L (49.4-51.8 mg/L AE). Touchdown(R) He rbicide (4 LC-E) tested against tadpoles of C, insignifera, H. eyrei, L. do rsalis, and L. moorei was slightly less toxic than Roundup(R) with 48-h LC5 0 values ranging between 27.3 and 48.7 mg/L (9.0 and 16.1 mg/L AE). Roundup (R) Biactive (MON 77920) was practically nontoxic to tadpoles of the same f our species producing 48-h LC50 values of 911 mg/L (328 mg/L AE) for L. moo rei and >1,000 mg/L (>360mg/L AE) for C. insignifera, H. eyrei, and L. dors alis. Glyphosate isopropylamine was practically nontoxic, producing no mort ality among tadpoles of any of the four species over 48 h, at concentration s between 503 and 684 mg/L (343 and 466 mg/L AE). The toxicity of technical -grade glyphosate acid (48-h LC50, 81.2-121 mg/L) is likely to be due to ac id intolerance. Slight differences in species sensitivity were evident, wit h L. moorei tadpoles showing greater sensitivity than tadpoles of the other four species. Adult and newly emergent metamorphs were less sensitive than tadpoles.