Evaluation of toxic effects of lambdacyhalothrin on the haematology and selected biochemical parameters of African catfishClarias gariepinus

Chronic effects of a binary insecticide Acer 35 EC on Nile tilapia Oreochromis niloticus through a multi-biomarker approach

Acer 35 EC is a widely used insecticide (a binary mixture of lambda-cyhalothrin and acetamiprid) in pest control in many West African countries, particularly in the cotton culture in north Benin. The aim of this study was to investigate the chronic effects of Acer 35 EC on Nile tilapia Oreochromis niloticus juveniles using a multi-biomarker approach under laboratory conditions. For this purpose, fish were exposed to sublethal concentrations of Acer 35 EC (0, 1 and 10% of LC₅₀- 96 h value). After 28 and 56 days of exposure, several biomarkers were measured in males and females including enzymatic activities related to detoxification and oxidative stress, neurotoxicity and immune responses, sex steroid hormones (testosterone, 17β-estradiol and 11-keto-testosterone) and histological alterations of liver, kidney and gonads. An Integrated Biomarker Response (IBR) was then calculated. The results showed a reduction of cholinesterase activity in muscles, and intercellular superoxide anion production in both sexes. Female steroidogenesis and gametogenesis were affected, especially testosterone levels and oocyte growth. More alterations were observed in liver after exposure to Acer 35 EC. In both sexes, IBR values were higher after 56 days than after 28 days of exposure. In conclusion, based on a large set of biomarkers and IBR values, the chronic exposure to low doses of insecticide Acer 35 EC seems to impair different physiological functions in Nile tilapia juveniles on a time-dependent manner, with a stronger impact on females than on males.

Dual immunological and oxidative responses in Oreochromis niloticus fish exposed to lambda cyhalothrin and concurrently fed with Thyme powder (Thymus vulgaris L.): Stress and immune encoding gene expression

The present study was performed to explore the immunotoxicological effects of the lambda cyhalothrin (LCH) insecticide and evaluate the efficiency of Thyme powder (TP) as a fish supplement in attenuation of LCH impact on Oreochromis niloticus (O. niloticus) fish. Fish was sampled following 30-days exposure to LCH (¹/₆ LC50: 0.48 μg/L) and TP (2%) supplementation, individually or in combination. The growth performance, immune status, biochemical indices, and mRNA expression pattern changes of stress and immune-encoding genes in the liver and spleen tissues, respectively, through real-time polymerase chain reaction (RT-PCR) analysis, were evaluated. The findings showed that LCH exposure caused a significant lowering in most of the estimated variables including growth performance, hematological and immunological indices. Moreover, LCH disrupted the oxidant/antioxidant status and dysregulated the expression of stress and immune-related genes, downregulating the mRNA transcript level of Immunoglobulin M heavy chain (IgM), Interferon (IFN-γ), CXC-chemokine, and Toll-like receptors (TLR-7) in the spleen. However, mRNA expression of Myxovirus resistance (Mx) gene remained unaffected. In liver tissue, the heat shock protein (HSP-70) expression was upregulated, while that of cytochrome P450 1A (CYP 1A) was downregulated. TP (2%) supplementation elicited a significant modulation in aforementioned indices; however, their levels did not attain that of the control values. Our findings concluded that LCH affects the O. niloticus immune response through the negative transcriptional influence on genes linked to immunity and induction of oxidative injury of the immune organs. Besides, dietary TP (2%) could be a proper candidate to modulate the compromised immunity in response to LCH exposure in O. niloticus aquaculture.

Comparative acute toxicity of two phytosanitary molecules, lambda-cyhalothrin and acetamiprid, on Nile Tilapia (Oreochromis Niloticus) juveniles

This study aimed to compare the toxicity for fish of two active ingredients (lambda-cyhalothrin-20 g L^-1, a pyrethroid, and acetamiprid-15 g L^-1, a neonicotinoid) which are components of a commercial insecticide (Acer 35 EC) used in cotton crop in many West African countries. The juveniles of Oreochromis niloticus (4.01 ± 0.34 g, mean body weight) were exposed for 96 h to increasing concentrations of active ingredients (lambda-cyhalothrin and acetamiprid) or a mixture similar to Acer 35 EC (composed by 20 g of chemical compound lambda-cyhalothrin and 15 g of acetamiprid dissolved in 1 L of acetone). The experiments were carried out under controlled conditions in aquaria according to OECD Guidelines. During the experiments, the behavioral responses (loss of balance, color change, hyperactivity, etc.) that usually precede death were observed in exposed fish. Mortalities were recorded in each aquarium and the LC₅₀-96h of each chemical was determined. The LC₅₀-96h obtained were respectively 0.1268, 0.0029, 182.9 and 0.5685 ppm for Acer 35 EC, lambda-cyhalothrin, acetamiprid and mixture. All insecticides used in this study had profound impact on Nile tilapia behavior which may confirm the neurotoxicity of each single active compound as well as of their mixture.

The pyrethroid λ-cyhalothrin induces biochemical, genotoxic, and physiological alterations in the teleost Prochilodus lineatus

The λ-cyhalothrin (CL) is a globally used pyrethroid insecticide that has been detected in different water bodies worldwide. However, studies on the effects of CL on freshwater fishes are still incipient. In this context, we evaluated the acute effects of a commercial formulation containing CL (Karate Zeon^® CS 50) in juveniles of the teleost Prochilodus lineatus exposed for 96 h to four concentrations of the active ingredient (5, 50, 250 and 500 ng.L^-1). Biochemical, physiological, and genotoxic biomarkers were evaluated in different organs of the fish. Exposure to CL induced significant changes in the enzymatic profiles of P. lineatus, with specific alterations in biotransformation enzymes and antioxidant defence in different tissues. Lipid peroxidation was observed in fish gills and kidney. Increases in esterases were observed in the liver of fish exposed to all CL concentrations evaluated, whereas acetylcholinesterase activity decreased in the muscles of fish at all concentrations. CL also promoted osmoregulatory disorders, with decreases in calcium and magnesium gill ATPases, with consequent hypocalcaemia, in addition an increase in sodium-potassium ATPase activity was observed in the gills of fish exposed to the highest CL concentration, probably in order to compensate a reduction in plasma sodium. Besides, increases in DNA damage were observed in the erythrocytes of fish exposed to all CL concentrations. Thus, despite the low CL concentrations and the short exposure time, this pyrethroid caused hematological adjustments, oxidative stress, osmoregulatory disorders, and DNA damage in P. lineatus, showing that the species is highly sensitive to the deleterious effects of CL.