Fipronil and 2,4-D effects on tropical fish: Could avoidance response be explained by changes in swimming behavior and neurotransmission impairments?

• Published in: Chemosphere (Oxford) 2021-01, Vol.263, p.127972, Article 127972
• Main Authors: Moreira, Raquel Aparecida, Araújo, Cristiano V.M., Junio da Silva Pinto, Thandy, Menezes da Silva, Laís Conceição, Goulart, Bianca Veloso, Viana, Natália Prudêncio, Montagner, Cassiana Carolina, Fernandes, Marisa Narciso, Gaeta Espindola, Evaldo Luiz
• Format: Article
• Language: English
• Subjects: 2,4-D; 2,4-Dichlorophenoxyacetic Acid - toxicity; Acetylcholinesterase; Acetylcholinesterase - metabolism; Animals; avoidance behavior; Behavior, Animal - drug effects; biomarkers; Brazil; chemical control; Danio rerio; environmental assessment; fipronil; Habitat disturbance; Herbicides - pharmacology; Hyphessobrycon eques; insecticides; Insecticides - toxicity; neurotoxicity; Pesticides; Pesticides - toxicity; Pyrazoles - chemistry; sugarcane; Swimming; Synaptic Transmission; tropical fish; Water Pollutants, Chemical - toxicity; Zebrafish - metabolism; Zebrafish - physiology
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.127972

Brazil is the largest producer of sugarcane, a crop largely dependent on chemical control for its maintenance. The insecticide fipronil and herbicide 2,4-D stand out among the most commonly used pesticides and, therefore, environmental consequences are a matter of concern. The present study aimed to investigate the toxicity mechanisms of Regent® 800 WG (a.i. fipronil) and DMA® 806 BR (a.i. 2,4-D) pesticides using forced and non-forced exposures through an integrative approach: firstly, to assess whether contamination by fipronil and 2,4-D can trigger the avoidance behavior of the fish Danio rerio (zebrafish) and Hyphessobrycon eques (serpae tetra or mato-grosso). Additionally, the effects on fish were analyzed considering the swimming behavior together with a biomarker of neurotoxicity, the activity of acetylcholinesterase (AChE). In avoidance tests with pesticide gradients, D. rerio avoided the highest concentrations of the two compounds and H. eques avoided only the highest concentration of 2,4-D. The swimming behavior (distance moved) was reduced and AChE was inhibited when D. rerio was exposed to fipronil. The 2,4-D affected the swimming (maximum speed) of H. eques, but AChE was not altered. Avoidance response seemed not to have been affected by possible effects of contaminants on swimming behavior and Ache activity. This study showed the importance of knowing the avoidance capacity, swimming behavior and neurotoxic effects of pesticides on fish in an integrated and realistic context of exposure in environments contaminated with pesticides and can be useful as ecologically relevant tools for ecological risk assessment. [Display omitted] •Toxicity and avoidance of fipronil and 2,4-D were studied in D. rerio and H. eques.•Environmentally relevant concentrations of fipronil were repellent for D. rerio.•D. rerio and H. eques avoided 2,4-D concentrations.•Fipronil affected the swimming behavior of D. rerio and 2,4-D of H. eques.•Fipronil inhibited the enzymatic activity of AChE in D. rerio but not in H. eques.