Haemato-biochemical Responses in Cyprinus carpio (Linnaeus, 1758) Fry Exposed to Sub-lethal Concentration of a Phenylpyrazole Insecticide, Fipronil

Chronic cypermethrin induced toxicity and molecular fate assessment within common carp (Cyprinus carpio) using multiple biomarkers approach and its novel therapeutic detoxification

Cypermethrin (CYP) is a chemical of emerging concern which has persistent and bioaccumulating impacts as it can be found extensively in freshwater ecosystem and agricultural products. It has exposure risk and toxic effects over human edible fish, as common carp. Four groups were designed for toxicity assessment and detoxification approach: control group (CL), CYP exposure group (CYP), CYP + 10% M. oleifera leaves and 10% M. oleifera seeds (CMO group), 10% M. oleifera leaves and 10% M. oleifera seeds (MO group). Trial period was forty days during which cohort of 240 fish in CYP and CMO group was exposed to 1/5 of 96h LC50 of CYP (0.1612 μg/L). CYP-exposed carp exhibited lower growth parameters, but carp fed with 10% M. oleifera seeds and leaves showed significant improvement in growth rate (SGR, RGR) and weight gain (WG) as compared to the control group. CYP exposure negatively affected haemato-biochemical parameters. Moreover, CYP exposure also led to oxidative stress, damaged immunological parameters, genotoxicity and histopathological damage in liver and intestinal cells. Whereas, M. oleifera supplementation has ameliorated these conditions. Thereby, supplementation with M. oleifera is potential and novel therapeutic detoxication approach for common carp and human health against persistent and bioaccumulating emerging chemicals.

Effects of exposure to sediment-associated fipronil on cardiac function of Neotropical armored catfish Hypostomus regani

Fipronil is widely used as a broad-spectrum insecticide in agriculture, urban environments, and veterinary medicine. Fipronil can enter aquatic ecosystems and spread to sediment and organic matter, representing a risk to non-target species. This study aimed to evaluate the effects of short-term (96 h) exposure to a low and realistic concentration of sediment-associated fipronil (4.2 µg.kg^-1 of Regent® 800 WG) on myocardial contractility of armored catfish Hypostomus regain, a benthic fish species. Fipronil exposure induced increased inotropism and acceleration of contractile kinetics, although no alterations in the relative ventricular mass were observed. This better cardiac function was associated with an elevated expression and/or function of the Na⁺/Ca²⁺ exchanger and its marked contribution to contraction and relaxation, probably due to a stress-induced adrenergic stimulation. Ventricle strips of exposed fish also exhibited a faster relaxation and a higher cardiac pumping capacity, indicating that armored catfish were able to perform cardiac adjustments to face the exposure. However, a high energetic cost to maintain an increased cardiac performance can make fish more susceptible to other stressors, impairing developmental processes and/or survival. These findings highlight the need for regulations of emerging contaminants, such as fipronil, to ensure adequate protection of the aquatic system.

β-1,3-glucan improved the health and immunity of juvenile African catfish (Clarias gariepinus) and neutralized the histological changes caused by lead and fipronil pollutants

BACKGROUND

Water pollutants cause adverse effects in aquatic ecosystems. The immunomodulatory and mitigating effects of dietary 1,3-glucan on fipronil and lead-induced intoxication in African catfish (Clarias gariepinus) were investigated. Two hundred forty catfish were randomly divided into four equal groups: those in the first group were fed basic diet and served as controls; those in the second group were supplemented with β-1,3-glucan (0.1%); those in the third group were exposed to combination of lead nitrate at 0.041 mg/L (1/10 96 h LC50) and fipronil at 2.8 mg/l (1/10 96 h LC50); and those in the fourth group were exposed to combination of fipronil, lead, and β-1,3-glucan. The health status, haematological, immunological, and histological changes were all evaluated.

RESULT

Swelling on the dorsolateral side, spinal column deviation, sluggish movement, skin bleaching, excessive mucus secretion, significant variations in blood indices-related measures, and a 45% death rate were observed in the third group. There was a significant reduction in interleukin-1 (IL-1) and interleukin-6 (IL-6) and immunoglobulin M (IgM) concentrations, as well as decrease in their corresponding gene expression, indicating that fipronil and lead had immunosuppressive activity. Severe catarrhal enteritis and mucinous degeneration of the lining epithelium, and notable depletion of white pulp, congested red pulp and hemosiderosis were common pathological findings in the spleen. β-1,3-glucan alone or in combination with fipronil and lead provoked physical activity, blood indices, with elevations in IL-1β, IL-2, IL-6, and IgM concentrations, as well as up-regulation in their genes' expression in splenic tissues, when compared to the third group. The spleen and intestine had normal histological architecture with 5% mortalities. There were no fish deaths in the β-1,3-glucan-alone or control groups.

CONCLUSION

The use of β-1,3-glucan (0.1%) as dietary supplement could be implemented to protect against the toxic effects of fipronil and lead toxicity by improving the health and immunological parameters of intoxicated catfish.

Dietary supplementation with Moringa oleifera leaves extract reduces the impacts of sub-lethal fipronil in Nile tilapia, Oreochromis niloticus

This study assessed the restorative dietary effects of Moringa oleifera (MO) leaves extract against the negative impacts of sub-lethal fipronil (FIP) toxicity in Nile tilapia. To achieve this purpose, the growth, body composition, haemato-biochemical measurements, serum immunity, and antioxidant condition of Nile tilapia have been examined. Fish were arranged into 6 experimental groups in quadruplicates. Three groups were fed on diets supplemented with 0.0 (reference group), 1.0 (MO1), and 2.0 (MO2) g kg^-1 of MO leaf extract. The other three groups were fed on the same MO levels and concomitantly subjected to a sub-lethal FIP concentration (4.2 µg L^-1 for 3 h only per day) and defined as FIP, FIP + MO1, and FIP + MO2. The experiment lasted for 8 weeks. Results unveiled that growth parameters were significantly decreased alongside an increased feed conversion ratio in the FIP-intoxicated group. The moisture and crude protein (%) were decreased significantly together with a significant increase of the crude lipids (%) in the fish body of the FIP group. Sub-lethal FIP toxicity induced hypochromic anemia, leukopenia, hypoproteinemia, hypoalbuminemia, hypoglobulinemia, and hepato-renal failure (increased urea and creatinine concentrations, as well as ALT and AST enzymes). Exposure to sub-lethal FIP also induced (a) immunosuppression manifested by a decline in total IgM, complement C3, and lysozyme activities, (b) enzymatic antioxidant misbalance manifested by decreases in SOD and CAT activities, and (c) oxidative stress (declined T-AOC and elevated of MDA concentrations). On the other side, dietary supplementation with MO leaf extract in FIP + MO1 and FIP + MO2 groups noticeably modulated the aforementioned parameters. Therefore, we can conclude that dietary MO could reduce sub-lethal FIP toxicity in Nile tilapia with a possible recommendation for regular prophylaxis supplementation in Nile tilapia diets.

A rapid evidence assessment of the potential risk to the environment presented by active ingredients in the UK's most commonly sold companion animal parasiticides

A number of parasiticides are commercially available as companion animal treatments to protect against parasite infestation and are sold in large volumes. These treatments are not intended to enter the wider environment but may be washed off or excreted by treated animals and have ecotoxic impacts. A systematic literature review was conducted to identify the existing evidence for the toxicity of the six most used parasiticides in the UK: imidacloprid, fipronil, fluralaner, afoxolaner, selamectin, and flumethrin. A total of 17,207 published articles were screened, with 690 included in the final evidence synthesis. All parasiticides displayed higher toxicity towards invertebrates than vertebrates, enabling their use as companion animal treatments. Extensive evidence exists of ecotoxicity for imidacloprid and fipronil, but this focuses on exposure via agricultural use and is not representative of environmental exposure that results from use in companion animal treatments, especially in urban greenspace. Little to no evidence exists for the ecotoxicity of the remaining parasiticides. Despite heavy usage, there is currently insufficient evidence to understand the environmental risk posed by these veterinary treatments and further studies are urgently needed to quantify the levels and characterise the routes of environmental exposure, as well as identifying any resulting environmental harm.

Dietary Exposure to Bifenthrin and Fipronil Impacts Swimming Performance in Juvenile Chinook Salmon (Oncorhynchus tshawytscha)

Two commonly used insecticides, bifenthrin and fipronil, can accumulate in the prey of juvenile Chinook salmon, yet the effects of dietary exposure are not understood. Therefore, to better characterize the effect of a dietary exposure route, juvenile Chinook salmon were fed chironomids dosed with a concentration of 9 or 900 ng/g of bifenthrin, fipronil, or their mixture for 25 days at concentrations previously measured in field-collected samples. Chinook were assessed for maximum swimming performance (U_max) using a short-duration constant acceleration test and biochemical responses related to energetic processes (glucose levels) and liver health (aspartate aminotransferase (AST) activity). Chinook exposed to bifenthrin and bifenthrin and fipronil mixtures had a significantly reduced swimming performance, although not when exposed to fipronil alone. The AST activity was significantly increased in bifenthrin and mixture treatments and glucose levels were increased in Chinook following a mixture treatment, although not when exposed to fipronil alone. These findings suggest that there are different metabolic processes between bifenthrin and fipronil following dietary uptake that may influence toxicity. The significant reductions in swimming performance and increased levels of biochemical processes involved in energetics and fish heath could have implications for foraging activity and predator avoidance in wild fish at sensitive life stages.

Realistic exposure to fipronil, 2,4-D, vinasse and their mixtures impair larval amphibian physiology

Expansion of sugarcane crops may have contributed to the increased contamination of native habitats in Brazil. Several species of amphibians inhabit ponds formed in flooded farmlands, where pesticide concentrations are usually high. This study evaluated the ecotoxicological effects of the sugarcane pesticides fipronil and 2,4-D, as well as the fertilizer vinasse (isolated and mixed), on physiological responses of Leptodactylus fuscus and Lithobates catesbeianus tadpoles. In situ assays were conducted in mesocosms with concentrations based on the doses recommended by the manufacturer. Vinasse (1.3% dilution) caused 100% tadpoles' mortality immediately after its application. Fipronil and/or 2,4-D altered antioxidant and biotransformation responses, induced neurotoxicity and changed lipid contents in tadpoles. A multivariate approach indicated that the mixture of pesticides induced most of the sublethal effects in both tadpole species, in addition to the isolated fipronil in L. fuscus. Fipronil alone increased glucose-6-phosphate dehydrogenase (G6PDH) activity, decreased acetylcholinesterase (AChE) and total lipid contents, and altered some individual lipid classes (e.g., free fatty acids and acetone-mobile polar lipids) in L. fuscus. The interaction between fipronil and 2,4-D in this species were more evident for lipid contents, although enzymatic alterations in G6PDH, AChE and glutathione-S-transferase (GST) were also observed. In L. catesbeianus, the mixture of pesticides reduced triglycerides and total lipids, as well as increased GST and decreased AChE activities. The detoxifying enzyme carboxylesterase was reduced by 2,4-D (alone or in mixture) in both species. Isolated pesticides also modulated specific lipid classes, suggesting their disruptive action on energy metabolism of tadpoles. Our study showed that fipronil, 2,4-D, and vinasse, individually or mixed, can be harmful to amphibians during their larval phase, causing mortality or impairing their functional responses.

Acute exposure of embryo, larvae and adults of Danio rerio to fipronil commercial formulation reveals effects on development and motor control

The insecticide fipronil, one of the main pesticides used in Brazil, is often detected in natural aquatic environments, and causes neuronal hyperexcitation by inhibiting GABAergic neurotransmission, leading to putative alterations in behaviour and development. This work sought to analyse the toxicity of formulated Regent^® 800WG (80% fipronil) on development (fish embryo toxicity test, FET), morphology, and swimming behaviour of larvae and adults of zebrafish (Danio rerio). FET was performed following OECD236 guidelines at concentrations ranging from 0.002 to 1600 μg.L^-1 of formulated Regent^® 800WG. Adults were exposed to 0.2, 2 and 20 μg.L^-1 of the product for 24 and 96 h, and were submitted to the light-dark, novel tank and swimming endurance tests No lethal parameters were observed in larvae, but in concentrations above 400 µg.L^-1, there was shortening of the body axis and decreased swimming behavior. In adults, exposure to the pesticide did not lead to changes in free swimming parameters. However, a marked decrease of swimming endurance was observed at all experimental treatments, although probably not in consequence of energetic depletion, since baseline blood glucose levels and condition factor were similar at all conditions. Furthermore, zebrafish adults did not show their natural preference for the dark environment. The pesticide likely has anxiolytic effects on zebrafish, as well as a compromising effect on locomotor control, illustrating that behavioural changes, which could affect activities on the natural environment, such as escape and predation, may occur even in environmentally relevant concentrations of this pollutant.

Hematological and immunological responses in the African catfish Clarias gairepinus exposed to sublethal concentrations of herbicide Ronstar®

The aim of the study was to investigate the effects of sublethal concentrations (0.3, 0.6 and 1.2 mg L^-1) of the herbicide Ronstar on the hematology and some immune parameters in Clarias gariepinus juvenile (mean weight and length 58.72 ± 2.46 g and 27.60 ± 1.62 cm, respectively). The hematological and some immune parameters were studied for 21 days in a static renewal bioassay system in which the water and the herbicide were changed daily. The erythrocyte count, hemoglobin concentration (Hb), and packed cell volume (PCV) were significantly (p < 0.05) reduced in the treatment groups. When compared with the control, there were significant (p < 0.05) leucocytosis, lymphocytosis, neutropenia and monocytopenia in the treatment groups. Both the mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV) were reduced ((p < 0.05) in the Ronstar-exposed fish. The result showed that the treated fish suffered hypochromic microcytic anemia. The total immunoglobulin and phagocytic indices (phagocytic capacity and phagocytic index) were significantly (p < 0.05) reduced in the treatment groups. while the respiratory burst was significantly (p < 0.05) increased in the treatment groups. The result showed that exposure to Ronstar had adverse effects on the hematology and immunocompetency of the fish.

Avaliação neurocomportamental e níveis de acetilcolinesterase cerebral em ratos expostos subcronicamente ao fipronil

RESUMO O fipronil é um inseticida de toxicidade seletiva amplamente empregado na agricultura e na medicina veterinária. Porém, há relatos de efeitos neurotóxicos dessa substância, que geram prejuízos para vertebrados. Avaliou-se a atividade locomotora, a coordenação motora e a atividade da enzima acetilcolinesterase cerebral em ratos expostos ao fipronil. Ratos Wistar machos adultos (n=15) receberam fipronil em dose de 30mg/kg, por via oral, durante 15 dias; o grupo controle (n=15) foi tratado com solução fisiológica, por via oral, no mesmo período. No 16° dia de experimentação, os animais foram submetidos aos testes de arena de campo aberto e hole board. No 17° dia, foram anestesiados e eutanasiados, procedendo-se à coleta de órgãos, e posteriormente foi feita a avaliação da AChE cerebral. A exposição ao fipronil não provocou alterações significativas sobre a coordenação motora e a atividade locomotora, porém gerou inibição significativa da atividade da acetilcolinesterase cerebral. Esses achados sugerem que o fipronil pode provocar efeitos neurotóxicos em curto prazo, os quais podem ser exacerbados caso a exposição seja prolongada.

Immune-protective, antioxidant and relative genes expression impacts of β-glucan against fipronil toxicity in Nile tilapia, Oreochromis niloticus

Our study is considered to attempt reducing the immune-toxic and antioxidant impacts of exposure to fipronil (FP) on Nile tilapia, Oreochromis niloticus using the β-glucan (βG). Two hundred and seventy fingerlings of Nile tilapia were divided randomly into six groups (45 tilapias of each, in 3 replicates): group I control (CT) group nourished on a basal diet. Group II (βG) nourished a basal diet supplemented with 0.4% βG. Groups III (1/20 FP) and V (1/10 FP) was exposed to 1/20 and 1/10 of the 96 h LC₅₀ of FP in water and nourished the basal diet respectively. Groups IV (1/20 FP+ βG) and VI (1/10 FP+ βG) were exposed to 1/20 and 1/10 FP concomitantly with 0.4% βG supplementation for 90 successive days. Growth performance metrics were higher in βG group than CT. While those metrics were fallen at exposure to 1/20 or 1/10 FP. Supplementation with βG elevated the IgM and lysozyme levels.Whereas, tilapias exposed to FP only at different concentration showed lowering of those compared to CT. Supplementation with βG was effectively augmented IgM and lysozyme in 1/20 FP exposed tilapias. Furthermore, in a minor grade at 1/10 FP exposed tilapias. Exposure to FP increased the activities of hepatic markers chiefly at 1/10, however the βG supplementation was successfully improved these markers. There was imbalance of cortisol level at FP exposure where, βG combining to FP alleviate this disparity. There was fallen in LDH, MDH and FDPase in βG tilapias where continuing raise in 1/10 FP followed by 1/20 FP. βG supplementation raise the level of GSH, without significant variations in MDA conversely occurs in FP alone. Genes expression of βG caused raise of both GPx and GR, without fluctuations in CAT and SOD. Exposure to FP diminishes all evaluated antioxidant genes. It could fulfilled that supplementation with βG successfully alleviated the immune-toxic and antioxidant impact of FP in tilapias.

Effects of silver nanoparticles on stress biomarkers of Channa striatus: immuno-protective or toxic?

Nanotechnology is a novel arena with promising applications in the field of medicine, industry, and agriculture including fisheries. Cross-disciplinary interactions and the application of this technology in biological systems have led to the innovation of novel nanoparticle antioxidants, which are the subject of our study. In context with above background, we designed an experiment on nano-silver to elucidate its role for mitigation of abiotic and biotic stress. Three diets were formulated viz. silver nanoparticles (Ag-NPs) incorporated at 0.5 and 1 mg/kg diet and control diet (Ag-NPs at 0 mg/kg). Fish were exposed to sublethal level of 1/25th of LC₅₀ (4 ppm) of lead (Pb) and temperature at 34 °C. The effect of Ag-NPs on productive performance (weight gain %, feed conversion ratio, protein efficiency ratio, and specific growth rate), stress biomarkers (catalase, super oxide dismutase, glutathione-s-transferase, acetylcholine esterase, cortisol, heat shock protein), biochemical and immunological response (protein and carbohydrate metabolic enzymes, phagocytic activity, serum total protein and albumin: globulin ratio), histopathology alterations in the liver and gill as well as survival of Channa striatus, following challenge with pathogenic bacteria were evaluated. Dietary Ag-NPs at 0.5-mg supplementation improved growth performance, immunity, survival, and reduced stress biomarker such as HSP 70, cortisol, and blood glucose in various fish tissues. Exposure to Pb and high temperature and group fed with Ag-NPs (1 mg/kg diet) demonstrated remarkable changes in the histo-architect of liver such as pyknotic nuclei, pyknosis, leucocyte infiltration, hemorrhage and karyokinesis, blood vessels with nucleated, lipid vacuoles in the liver tissue. Histology of gill displayed hyperplasia, aneurism, blood congestion, severe telengiectiasis, epithelial lifting, curling of secondary lamella, hyperplasia of epithelial cell of secondary lamella in the group exposed to lead and high temperature and supplemented with Ag-NPs at 1 mg/kg diet. In addition to histopathology, feeding with Ag-NPs at 1 mg/kg diet deteriorated and altered all studied parameters including reduced growth performance. Results obtained in the present study suggest that supplementation of Ag-NPs at 0.5 mg/kg diet has a definitive role to play in the mitigation of abiotic and biotic stress in C. striatus.

Acute toxicity, biochemical and histopathological responses of endosulfan in Chanos chanos

This study investigated 96h median lethal concentration of endosulfan (99%, pure α: β ratio of 7:3) by conducting static non-renewable acute toxicity bio-assay in Chanos chanos juvenile with average weight (110±5.65g). Further, the effect of different definitive doses (18.5, 19.5, 20.5, 21.5 and 22.5µg/L) of endosulfan on metabolic, heamato-immunoligcal and histopathological response were probed. Anti-oxidative enzymes CAT, SOD and GST showed significant (p<0.01) increase of activity in the liver, gill and brain during exposure to endosulfan in a dose and time dependent manner. The brain AChE activity showed significant (p<0.01) inhibition from 18.5 to 22.5µg/L exposure of endosulfan than the control group. LDH and MDH activity gradually increased with consequent increasing dose of endosulfan exposure in the liver, gill and brain. Similarly, ALT, AST and G6PDH activities in both liver and gill increased with consequent increases in the dose of endosulfan exposure. Immunological profile such as blood glucose and serum cortisol level significantly enhanced while respiratory burst activity declined with consequent increasing doses of endosulfan exposure. Histopathological alteration in the gill demonstrated curling of secondary lamellae, thickening of primary epithelium, shorting of secondary lamellae, epithelial hyperplasia, fusion of secondary lamellae, aneurism, and collapsed secondary lamellae due to dose dependent exposure of endosulfan. Liver histology illustrated cloudy swelling and necrosis with pyknotic nuclei to the moderate dose of endosulfan, whereas higher dose of endosulfan (21.5µg/L) displayed severe necrosis of hepatic cells. Overall results clearly indicate that acute exposure of endosulfan led to pronounced deleterious alterations on biochemical, heamato-immunological, and histopathological responses of C. chanos juvenile.

Dietary pyridoxine potentiates thermal tolerance, heat shock protein and protect against cellular stress of Milkfish (Chanos chanos) under endosulfan-induced stress

We herein report the protective role of pyridoxine in enhancing thermal tolerance of Milkfish Chanos chanos reared under endosulfan-induced stress. Four isocaloric and isonitrogenous diets were prepared with graded levels of pyridoxine (0, 50, 75 and 100 mg/kg). Two hundred and twenty five fishes were randomly distributed into four treatment groups in triplicate, reared under endosulfan-treated water, which were fed with pyridoxine supplemented diet, while the negative control group was reared without endosulfan-treatment and control fed. The concentration of endosulfan in treated water was maintained at a level of 1/40th of LC50 i.e. 0.52 μg/L. Dietary pyridoxine supplementation had significant (p < 0.01) effect on temperature tolerance viz. CTmax (Critical temperature maxima), LTmax (Lethal temperature maxima), CTmin (Critical temperature minima) and LTmin (Lethal temperature minima) of milkfish. The positive correlation was observed between CT max and LTmax (Y = -1.54 + 15.6x, R(2), 0.943) as well as CTmin and LTmin (Y = -1.44 + 1.021x, R(2), 0.941). At the end of the thermal tolerance study, antioxidative status and HSP 70 were significantly reduced in pyridoxine supplemented groups, whereas brain AChE was significantly (p < 0.01) elevated compared to positive and negative control. It is concluded that CTmax, LTmax, CTmin and LTmin, antioxidative status, neurotransmitter enzyme and HSP 70 strengthened the enhancement of thermal tolerance of Milkfish.