Physiological and Biochemical Effects of Insecticides on Catla catla from Freshwater Ecosystems: A Biomarker-Based Monitoring System for Yeldari Reservoir, Maharashtra

Abstract

Agricultural insecticides reach freshwater reservoirs through runoff, drainage, leaching and accidental discharge, and fish are exposed continuously through gills, skin and diet. Catla catla (Hamilton), an Indian major carp of high economic and ecological value, is a suitable sentinel species for such contamination. This paper reviews the physiological, haematological, biochemical, oxidative and histopathological responses of C. catla to organophosphate, organochlorine, pyrethroid and neonicotinoid insecticides, and identifies the gaps that limit their use in field risk assessment. Building on this evidence, we present a methodology and a proposed six-module system for Yeldari Reservoir, a hydroelectric and irrigation reservoir on the Purna River, that links catchment pesticide-use surveys, seasonal field monitoring, laboratory bioassays, a multi-biomarker panel, integrated data analysis (Integrated Biomarker Response and risk quotient) and decision support. The approach is intended to show whether agricultural insecticides cause measurable physiological stress in the reservoir’s C. catla population, and to convert that evidence into management advice.

Introduction

The study investigates the potential effects of agricultural insecticides on freshwater fish, particularly Catla catla, in Yeldari Reservoir, Maharashtra, India. Reservoirs support irrigation, drinking-water supply, hydropower, and fisheries, but agricultural runoff can introduce pesticides that threaten aquatic organisms. Although routine water-quality measurements may meet established standards, they may not detect pesticide contamination or reveal its biological effects on fish.

The study reviews the toxicity of several insecticide groups, including organophosphates, organochlorines, pyrethroids, and neonicotinoids. Previous research indicates that these chemicals can cause neurological disturbances, respiratory stress, reduced growth, changes in blood parameters, oxidative stress, liver and kidney damage, and alterations in gene expression in C. catla. Pyrethroids such as cypermethrin have shown particularly high toxicity at low concentrations. Pesticide residues may also accumulate in fish tissues, creating potential concerns for aquatic ecosystems and human consumers.

The research emphasizes that pesticide toxicity depends on factors such as concentration, exposure duration, water temperature, pH, dissolved oxygen, chemical properties, and fish characteristics. Therefore, relying on a single biomarker or routine water-quality measurement is insufficient. An integrated assessment combining physiological, biochemical, haematological, histological, and molecular indicators can provide a more comprehensive understanding of pesticide exposure and its effects.

The proposed methodology combines field monitoring at the Yeldari Reservoir with controlled laboratory experiments. Water, sediment, and fish samples will be collected from inlet, mid-reservoir, and outlet stations across pre-monsoon, monsoon, and post-monsoon seasons over twelve months. Laboratory experiments will assess acute toxicity, sub-lethal exposure, recovery, and selected pesticide mixtures. Analytical techniques such as GC-MS/MS and LC-MS/MS will be used to quantify pesticide residues, while biochemical assays and histopathological examinations will identify biological damage.

The proposed biomarker panel includes acetylcholinesterase (AChE), antioxidant enzymes such as SOD, CAT, and GPx, glutathione-related indicators, malondialdehyde (MDA), blood parameters, liver enzymes, tissue histology, and pesticide residues in water, sediment, and fish tissues. Statistical analyses will be used to investigate relationships between pesticide exposure, environmental conditions, and biological responses.

The study identifies an important research gap: many existing investigations examine individual pesticides under laboratory conditions, while fewer connect real-world reservoir contamination, seasonal variation, multiple exposure pathways, and biological effects. To address this gap, the proposed integrated monitoring system aims to link agricultural pesticide use, environmental contamination, fish exposure, biological responses, and management decisions.

Conclusion

Insecticides from several chemical classes produce behavioural, respiratory, haematological, metabolic, enzymatic, oxidative and histopathological changes in Catla catla, even at sub-lethal concentrations. Because responses are multi-level, a panel of complementary biomarkers linked to measured residues is the most defensible way to judge whether a reservoir population is under pesticide stress. The methodology and six-module system proposed here provide a practical route to do this for Yeldari Reservoir and to turn the results into management action for farmers, fisheries and reservoir authorities. Field validation is the next step.

References

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Copyright

Copyright © 2026 Ms. Pooja Dinkarappa Tarte, Dr. Niwrati Govindrao Popatwar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.