Acute toxicity and cholinesterase inhibition of the nematicide ethoprophos in larvae of gar &lt;i&gt;Atractosteus tropicus&lt;/i&gt;(Semionotiformes: Lepisosteidae).

Freylan Mena Torres,María De Jesús Arias Andrés,Adrián Sevilla,Sacsha Pfennig,Gabriel Márquez-Couturier,C Maurizio Protti Q

doi:10.15517/rbt.v60i1.2769

Acute toxicity and cholinesterase inhibition of the nematicide ethoprophos in larvae of gar <i>Atractosteus tropicus</i>(Semionotiformes: Lepisosteidae).

Freylan Mena Torres, María De Jesús Arias Andrés + Show 4 more

Open Access

https://doi.org/10.15517/rbt.v60i1.2769

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Abstract

Biomarkers are a widely applied approach in environmental studies. Analyses of cholinesterase (ChE), glutathione S-transferase (GST) and lipid peroxidation (LPO) are biomarkers that can provide information regarding early effects of pollutants at different biochemical levels on an organism. The aim of this study was to evaluate the biomarker approach on a Costa Rican native and relevant species. For this, larvae of gar (Atractosteus tropicus) were exposed to the organophosphorus nematicide, ethoprophos. Acute (96hr) exposure was conducted with pesticide concentrations ranging from 0.1 microg/L to 1 500 microg/L. The 96hr LC50 calculated was 859.7 microg/L. After exposure, three biomarkers (ChE, GST and LPO) were analyzed in fish that survived the acute test. The lowest observed effect concentration (LOEC) regarding ChE activity inhibition was 50 microg/L. This concentration produced a significant inhibition (p<0.05) of the enzyme by 20%. The highest concentration tested without showing any effect on ChE activity and therefore considered as no observed effect concentration (NOEC) was 10 microg/L. Ethoprophos concentration of 400 microg/L caused a ChE inhibition by 79%. In this study, no significant variations (p>0.05) in GST activity and LPO were observed in A. tropicus larvae after exposure to ethoprophos.

Highlights

The application of large amounts of agricultural pesticides is a serious environmental problem in Costa Rica, that has increased its imports during the last 30 years (Ramírez et al 2009)
ChE was significantly inhibited (p
The 96hr LC50 value calculated for ethoprophos on A. tropicus demonstrated a high toxicity of the pesticide for this species according to data from the Pesticide Action Network (PAN) of North America

Summary

Introduction

The application of large amounts of agricultural pesticides is a serious environmental problem in Costa Rica, that has increased its imports during the last 30 years (Ramírez et al 2009). Studies developed with other species of gar fish have demonstrated the potential of these fish for monitoring the effects of pollutants, including pesticides, heavy metals and endocrine disruptors (Osborne & Rulifson 2010, Aguilera et al 2010) These studies have evaluated the bioaccumulation of metals and the response of biomarkers. Considering the intensive use of organophosphates in Costa Rican agriculture and the use of this kind of pesticides in the Caño Negro area (Soto & Ramírez 2002), ChE stands out as an ideal biomarker to evaluate agriculture-related pollution effects in the area. Biotransformation and oxidative stress biomarkers such as Glutathione S-transferase (GST) and lipid peroxidation (LPO) are widely applied in environmental studies (Mdegela et al 2006, Guilhermino 2006, Sanchez et al 2007); these markers are more unspecific, but still useful signals of environmental stress as they might respond to a broad diversity of pollutants

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