Environmentally Relevant Concentrations of the Insecticide Fipronil Modulated Molecular Response in Chironomus riparius

• Published in: Environmental toxicology and chemistry Vol. 43; no. 2; pp. 405 - 417
• Main Authors: Pinto, Thandy Junio da Silva, Martínez‐Guitarte, José‐Luis, Amaral Dias, Mariana, Montagner, Cassiana Carolina, Espindola, Evaldo Luiz Gaeta, Muñiz‐González, Ana‐Belén
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.02.2024
• Subjects: Acetylcholinesterase; Acetylcholinesterase - metabolism; Animals; Aquatic animals; Aquatic environment; Aquatic fauna; Aquatic organisms; Aquatic toxicity; Biomarkers; Catalase; Chironomidae - genetics; Chironomids; Chironomus riparius; Detoxification; Ecotoxicology; Enzymatic activity; Exposure; Fipronil; Freshwater organisms; Gene expression; Genes; Glutathione; Immune response; Impact damage; Insecticides; Insecticides - toxicity; Insects; Larva - metabolism; Larvae; Metabolic pathways; Mode of action; Molecular response; mRNA; Nervous system; Organisms; Pesticides; Plant protection; Polymerase chain reaction; Pyrazoles; Real‐time polymerase chain reaction (RT‐PCR); Risk factors; Toxicity; Toxicity testing; Toxicology; Water Pollutants, Chemical - toxicity; Insecticides; Real-time polymerase chain reaction (RT-PCR); Aquatic toxicity; Chironomids; Molecular response; Pesticides
• ISSN: 0730-7268; 1552-8618
• DOI: 10.1002/etc.5798

Pesticides employed worldwide for crop protection easily reach aquatic systems, which act as the main reservoirs, and become a risk factor for aquatic fauna. Fipronil is a broad‐spectrum insecticide acting on the insect nervous system; however, other effects and systems unrelated to this mechanism could be affected in non‐target organisms. Thus, the present study aimed to assess the impact of fipronil on the suborganismal response (gene expression and enzymatic activity) of Chironomus riparius larvae as a model organism in ecotoxicology. To this end, short‐term toxicity tests were carried out with fourth‐instar larvae exposed to 0.001, 0.01, and 0.1 µg L−1 of fipronil for 24 and 96 h. Messenger RNA levels of 42 genes related to diverse metabolic pathways were analyzed by real‐time polymerase chain reaction, complemented with catalase (CAT), glutathione S‐transferase (GST), and acetylcholinesterase (AChE) activities. Few effects were observed at 24 h; however, after longer exposure (96 h), genes involved in the endocrine, detoxification, stress, and immune response pathways were altered. Moreover, fipronil at 96 h increased CAT and GST activity at 0.01 µg L−1 and AChE at the highest concentrations. The results demonstrate that even low environmentally relevant fipronil concentrations can modulate the molecular response of several cellular pathways in C. riparius after short‐term exposure. These results bring new information about the underlying response of fipronil and its mode of action on a key aquatic invertebrate. Despite no effects on mortality, strong modulation at the suborganismal level emphasizes the advantage of biomarkers as early damage responses and the harmful impact of this pesticide on freshwater organisms. Environ Toxicol Chem 2024;43:405–417. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Fipronil alters molecular response in Chironomus riparius. PCR, polymerase chain reaction; GST, glutathione S‐transferase; shsp, small heat shock protein; ATM, ataxia telangiectasia mutated; Dis, disembodied; E93, ecdysone‐induced protein 93; EcR, ecdysone receptor; JHAMT, juvenile hormone acid methyltransferase; Cyp, cytochrome P450; hsp, heat shock protein; def, defensin; Krh1, Krüppel homolog 1; MAPR, membrane‐associated progesterone receptor; MRP‐1, multidrug resistance–associated protein 1; CAT = catalase; SOD = superoxide dismutase.