Effects of the emulsifiable herbicide Dicamba on amphibian tadpoles: an underestimated toxicity risk?

Abstract

The effects of exposure to the herbicide Dicamba (DIC) on tadpoles of two amphibian species, Scinax nasicus and Elachistocleis bicolor, were assessed. Mortality and biochemical sublethal effects were evaluated using acetylcholinesterase (AChE), glutathione S-transferase (GST), glutathione reductase (GR), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) activities and thyroid hormone (T4) levels. The LC 50 value at 48h was 0.859 mg L −1 for S. nasicus and 0.221 mg L −1 for E. bicolor tadpoles. After exposure to sublethal DIC concentrations for 48 h, GST activity increased in S. nasicus but significantly decreased in E. bicolor with respect to controls. GR activity decreased only in S. nasicus at all the tested DIC concentrations. AChE activity was significantly inhibited in both S. nasicus and E. bicolor tadpoles at 48 h. DIC also caused significant changes in transamination, as evidenced by an increase in AST and ALT activities in both amphibian species. T4 levels were higher in DIC-treated tadpoles of both species than in controls. The DIC-induced biochemical alterations in glutathione system enzymes and transaminases indicate lesions in liver tissues and cellular function. Moreover, the observed AChE inhibition could lead to the accumulation of acetylcholine, excessively stimulating postsynaptic receptors, and the increase in T4 levels in both species may indicate an overactive thyroid. The commercial DIC formulation showed a high biotoxicity in the two amphibian native species after short-term exposure, controversially differing from the toxicity level indicated in the official fact sheet data. This fact highlights the need for an urgent re-categorization and reevaluation of DIC toxicity in native species.

Pesticide-Induced Alterations of Esterase and Antioxidant Enzymes of Aquatic Organisms <i>Oreochromis mossambicus</i> and <i>Xenopus laevis</i>

“…In the tadpoles on the other hand the AChE probably took the role of xenobiotic metabolizing enzymes and the organisms responded to exposure to the pesticides by increasing the synthesis of the enzymes as a protective measure. Attademo et al [34] reported an increase in AChE activity in tadpoles (Elachistocleis bicolor) exposed to the herbicide Dicamba for 48 hours at a concentration of 0.0375 mg•L −1 . However, the herbicide inhibited AChE activity at higher concentrations Attademo et al [34].…”

“…Attademo et al [34] reported an increase in AChE activity in tadpoles (Elachistocleis bicolor) exposed to the herbicide Dicamba for 48 hours at a concentration of 0.0375 mg•L −1 . However, the herbicide inhibited AChE activity at higher concentrations Attademo et al [34]. A similar trend was shown by Van Meter et al [14] who investigated the effects of atrazine on Southern leopard frogs (Lithobates sphenocephala).…”

Sublethal Biochemical Effects of Polyethylene Microplastics and TBBPA in Experimentally Exposed Freshwater Shrimp Palaemonetes argentinus

“…The levels of T4 and T3 were measured using enzyme-linked electro-chemiluminescent immunoassay (ECLIA) kits (COBAS ® , Roche Diagnostics, Indianapolis, IN, USA) following the protocol previously described in Attademo et al [ 40 ]. The detection limits for T3 and T4 were 0.0001 ng g −1 and 2.1 ng g −1 , respectively.…”

The Taxonomic Status of Physalaemus cuqui Lobo, 1993, with the Description of a New Species of Physalaemus (Anura: Leptodactylidae) from Argentina and Paraguay

“…[In part, misidentification.] Viña-Albornoz et al (2020: 277); Antoniazzi et al (2021: 47); Attademo et al (2021: their Table 1); Catalano et al (2021: 635, their Tables 1 and 2); Curi et al (2021: 2, 3); de Oliveira et al (2021: 16); Demartín et al (2021: their Table 2); Empey et al (2021: 796, their Table 1); Ferraro et al (2021: 396, their Fig. 5, their supplementary data S1–S7); González et al (2021: 4, 15, their Figs.…”