Effects of 2,4-D-based herbicide (DMA (R) 806) on sensitivity, respiration rates, energy reserves and behavior of tadpoles

Author(s)

Freitas, Juliane Silberschmidt ^[1] ; Girotto, Lais ^[1] ; Goulart, Bianca Veloso ^[2] ; Goncalves Alho, Lays de Oliveira ^[3] ; Gebara, Renan Castelhano ^[3] ; Montagner, Cassiana Carolina ^[2] ; Schiesari, Luis ^[4] ; Gaeta Espindola, Evaldo Luiz ^[1]

Affiliation

^[1] Univ Sao Paulo, Sao Carlos Engn Sch, NEEA CRHEA SHS, Sao Carlos, SP - Brazil

^[2] Univ Estadual Campinas, Analyt Chem Dept, Inst Chem, Campinas, SP - Brazil

^[3] Univ Fed Sao Carlos, Dept Hydrobiol, Sao Carlos, SP - Brazil

^[4] USP Sch Arts Sci & Humanities, EACH, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY; v. 182, OCT 30 2019.
• Web of Science Citations: 0

Abstract

Increased use of sugarcane pesticides and their destination to non-target environments in Brazil has generated concerns related to the conservation of more vulnerable groups, such as amphibians. Besides the high skin permeability, tadpoles are constantly restricted to small and ephemeral ponds, where exposure to high concentrations of pesticides in agricultural areas is inevitable. This study evaluated chronic effects caused by sublethal concentrations of 2,4-dichlorophenoxyacetic acid herbicide on energy storage, development, respiration rates, swimming performance and avoidance behavior of bullfrog tadpoles (Lithobates catesbeianus). Firstly, we conducted acute toxicity test (96 h) to estipulate sub-lethal concentrations of 2,4-D and evaluate the sensitivity of three tadpoles' species to this herbicide. Results showed that Leptodactylus fuscus presented the lowest LC50 96 h, 28.81 mg/L, followed by Physolaemus nattereri (143.08 mg/L) and L. catesbeianus (574.52 mg/L). Chronic exposure to 2,4-D (125, 250 and 500 mu g/L) delayed metamorphosis and inhibited the growth of tadpoles at concentrations of 125 mu g/L. Effects on biochemical reserves showed that 2,4-D increased total hepatic lipids in tadpoles, although some individual lipid classes (e.g. free fatty acids and triglycerides) were reduced. Protein and carbohydrates contents were also impaired by 2,4-D, suggesting a disruption on energy metabolism of amphibians by the herbicide. In addition to biochemical changes, respiration rates and swimming speed were also decreased after chronic exposure to 2,4-D, and these responses appeared to be correlated with the changes detected in the basic energy content. Avoidance test indicated that tadpoles of L. catesbeinus avoided the presence of 2,4-D, however they were unable to detect increasing gradients of the contaminant. Our data showed that chronic exposure to 2,4-D impaired biochemical, physiological and behavioral aspects of tadpoles, which may compromise their health and make them more vulnerable to environmental stressors in natural systems. (AU)

• FAPESP's process: 15/18790-3 - Environmental effects of the pasture-sugarcane conversion and pasture intensification
• Grantee: Luiz Antonio Martinelli
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 17/13377-6 - Evaluation of ecotoxicological effects of livestock products and sugarcane pesticides to amphibians.
• Grantee: Juliane Silberschmidt Freitas
• Support Opportunities: Scholarships in Brazil - Post-Doctoral