Toxic effects of an organophosphate pesticide, envoy 50 SC on the histopathological, hematological, and brain acetylcholinesterase activities in stinging catfish (Heteropneustes fossilis)

Rabeya Akter,A H M Mohsinul Reza,Sharmin Ferdewsi Rakhi,Halima Jahan,Mst Arzu Pervin,Zakir Hossain

doi:10.1186/s41936-020-00184-w

Abstract

BackgroundFreshwater fish in Bangladesh are adversely affected by the washed off pesticides, used in agriculture. The aim of this study was to evaluate the impacts of a commonly used organophosphate pesticide on freshwater stinging catfish, Heteropneustes fossilis, which envisioned that the possible threats might occur by this organophosphate group to other species in the wild.MethodologyTo study the potential hazards of Envoy 50 SC on H. fossilis, fry of the fish were exposed to the acute toxicity tests. Changes in the hematological parameters, organ-specific histomorphologies, and brain acetylcholinesterase (AChE) activities were determined by treating the fish with agricultural recommended dose and below that dose of 0.015 and 0.0075 ppm, respectively.ResultsLC50 of Envoy 50 SC for the fish was determined as 0.151 (0.014–0.198) ppm. Pesticide abruptly altered the normal tissue structures of the gill, liver, and kidney. The major alterations included were the gill lamellae missing, gill clubbing, hyperplasia, nuclear hypertrophy, vacuolation, glomerular expansion, increasing diameter of the renal tubules, hemorrhage, necrosis, and pyknosis. In blood cells, changes observed in the peripheral nuclear erythrocyte were large lymphocyte, dead cell, fusion of the cells, binucleated cells, tear-shaped cells, ghost cells, senile cells, and abnormal structures of the cells. Significantly lower (P < 0.05) red blood cell (RBC) count and AChE activities in fish brain due to the pesticide exposure suggested the reasons of abrupt behavior, increased oxygen consumption, and fish mortality at higher concentration of this organophosphate pesticide.ConclusionThe presence of pesticides, even at low concentrations, caused deleterious effects on the earlier life stages of a comparatively harder and robust fish, suggesting a wider range effect on the more sensitive wild life, in particular decrease in survival in their native environment. Therefore, measures should be taken to minimize the risk of contamination of the aquatic environment by such toxic chemicals.

Highlights

Freshwater fish in Bangladesh are adversely affected by the washed off pesticides, used in agriculture
Data of the oxygen concentration (Table 1) in the aquaria exhibited a declining trend in the dissolved oxygen (DO) content with the increasing concentration of pesticide exposure in comparison to the control group that was consistent until the starting of the mortality
This study was conducted on a freshwater stinging catfish, H. fossilis, to understand the possible effects of the commonly used organophosphate pesticides on the early life stages of this comparatively resilient fish species

Summary

Introduction

Freshwater fish in Bangladesh are adversely affected by the washed off pesticides, used in agriculture. Lower (P < 0.05) red blood cell (RBC) count and AChE activities in fish brain due to the pesticide exposure suggested the reasons of abrupt behavior, increased oxygen consumption, and fish mortality at higher concentration of this organophosphate pesticide. Fish and other aquatic biota, exposed to the pesticide-contaminated water are at much higher risk of dying (Katagi, 2010; Reza, Rakhi, Hossen, & Hossain, 2017). Pesticides can accumulate in water bodies and affect the source of food for young fish by actively altering the trophic levels (Lew, Lew, Biedunkiewicz, & Szarek, 2013; Hossain, Rahman, & Mollah, 2001). Pesticides can abruptly alter the lower trophic levels that instigate the fish to forage further, exposing them to greater risks of predators. The sooner a pesticide degrades in the atmosphere, the less menace it might cause to aquatic life (Gill & Garg, 2014)

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