Toxicity Of Fenitrothion Research Articles

Solanum Nigrum Fruit Extract Increases Toxicity of Fenitrothion-A Synthetic Insecticide, in the Mealworm Beetle Tenebrio Molitor Larvae.

Synthetic insecticides are widely used for crop protection both in the fields and in the food stored facilities. Due to their toxicity, and assumptions of Integrated Pest Management, we conducted two independent experiments, where we studied the influence of Solanum nigrum unripe fruit extract on the toxicity of an organophosphorus insecticide fenitrothion. In the first variant of the experiment, Tenebrio molitor larvae were fed with blended fenitrothion (LC50) and the extract in four concentrations (0.01, 0.1, 1 and 10%) in ratio 1:1 for 3 days. In the second variant, a two-day application of fenitrothion (LC40) was preceded by a one-day extract treatment. The first variant did not show any increase in lethality compared to fenitrothion; however, ultrastructure observations exhibited swollen endoplasmic reticulum (ER) membranes in the midgut and nuclear and cellular membranes in the fat body, after application of blended fenitrothion and extract. An increased amount of heterochromatin in the fat body was observed, too. In the second variant, pre-treatment of the extract increased the lethality of larvae, decreased the level of glycogen and lipids in the fat body and disrupted integrity of midgut cellular membranes. S. nigrum extract, applied prior to fenitrothion treatment can be a factor increasing fenitrothion toxicity in T. molitor larvae. Thus, this strategy may lead to decreased emission of synthetic insecticides to the environment.

Amelioration of fenitrothion induced oxidative DNA damage and inactivation of caspase-3 in the brain and spleen tissues of male rats by N-acetylcysteine

N-acetylcysteine (NAC) has largely been used as an effective chemo- protective agent owing to their beneficial effect in restoring several physiological parameters and relieving oxidative stress. Interestingly, it has been suggested that NAC mechanisms of action extend beyond being a precursor to the antioxidant glutathione and that they may involve several neurotropic and inflammatory pathways. Exposure to fenitrothion, an organophosphorus insecticide, promotes oxidative stress and induces several deleterious changes in the immune response and various tissues including cerebrum and spleen. The main objective of our study was to investigate ameliorative efficacy of N-acetylcysteine for immunological and neurological alterations and oxidative DNA damage induced by fenitrothion toxicity in cerebrum and spleen tissues of male rats. Our results revealed that oral exposure to fenitrothion for 30 days caused a reduction in the erythrocyte count in addition to leukocytosis, lymphocytosis, and neutrophilia. Also, this route of administration increased the serum levels of LDH, TNF-α, and IL-2 with reduction in serum immunoglobulins (IgG & IgM) concentrations. Furthermore, a significant downregulation in the antioxidant markers (GSH & SOD) with an elevation of free radical (MDA) levels were noticed. Regarding the brain, fenitrothion administration inhibited AchE activity and increased brain GABA, serotonin and dopamine levels. Moreover, it induced an elevation in oxidative DNA damage indicated by 8-hydroxy 2-deoxyguanosine (8OH2dG) and mRNA expression of pro-apoptotic genes, including Bax, and p53, but Bcl-2 expression was reduced. N-acetylcysteine co-treatment restored the normal physiological tone in most of these parameters. Immunostaining for GFAP and Caspase-3 markers in the brain and spleen tissues were increased respectively. In conclusion, N-acetylcysteine supplementation has an ameliorative effect against immunotoxic, neurotoxic and oxidative DNA damage induced by fenitrothion exposure.

THE EFFECTS OF EXPOSURE TO ORGANOPHOSPHOROUS COMPOUNDS ON SOME ASPECTS OF CARBOHYDRATE METABOLISM IN Tilapia zillii

The Effect of organophosphorous insecticides compounds (Malathion and Fenitrothion) on certain aspects of carbohydrate metabolism in the freshwater fish Tilapia zillii exposed to 1/3 LC50 of both insecticides for 96 hours was studied. Organophosphorous compounds were found to affect some parameters of carbohydrate metabolism. Muscle and liver glycogen decreased significantly accompanied with significant increase of the plasma glucose and the specific activity of phosphorylase enzyme in both liver and muscles. The activity of Succinate dehydrogenase (SDH), lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) showed a significant decrease in liver and muscle tissues. Alanine transferase (ALT) and Aspartate transferase (AST) in liver and muscles also showed a significant decrease. Significant alterations in the content of metabolites and enzyme activity under malathion and fenitrothion toxicity seemed to suggest marked shift from aerobic to anaerobic condition.

THE EFFECTS OF EXPOSURE TO ORGANOPHOSPHOROUS COMPOUNDS ON SOME ASPECTS OF CARBOHYDRATE METABOLISM IN Tilapia zillii

The Effect of organophosphorous insecticides compounds (Malathion and Fenitrothion) on certain aspects of carbohydrate metabolism in the freshwater fish Tilapia zillii exposed to 1/3 LC50 of both insecticides for 96 hours was studied. Organophosphorous compounds were found to affect some parameters of carbohydrate metabolism. Muscle and liver glycogen decreased significantly accompanied with significant increase of the plasma glucose and the specific activity of phosphorylase enzyme in both liver and muscles. The activity of Succinate dehydrogenase (SDH), lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) showed a significant decrease in liver and muscle tissues. Alanine transferase (ALT) and Aspartate transferase (AST) in liver and muscles also showed a significant decrease. Significant alterations in the content of metabolites and enzyme activity under malathion and fenitrothion toxicity seemed to suggest marked shift from aerobic to anaerobic condition.

Effects of fenitrothion on Gryon japonicum (Hymenoptera: Platygastridae) parasitizing non-viable, refrigerated eggs of Riptortus pedestris (Hemiptera: Alydidae)

Gryon japonicum (Ashmead) is an egg parasitoid of Riptortus pedestris (Fabricius), an economically important pest of soybean in Korea and Japan. One conservation biological control tactic for this pest is to release refrigerated, non-viable eggs of R. pedestris in a soybean field to enhance natural parasitism by G. japonicum. Since fenitrothion is commonly used against R. pedestris, in this study we investigated its potential effects on the parasitization of refrigerated host eggs by G. japonicum. The acute toxicity of fenitrothion was compared with that of eight other pesticides by direct spray, exposure to residues, and oral ingestion. Fenitrothion, spinosad, cyfluthrin, etofenprox, carbosulfan, and thiamethoxam all caused 100% mortality of the parasitoid adults within 24h following direct spray or exposure to residues. Fenitrothion was also highly toxic to G. japonicum if ingested orally. There were no significant sublethal effects of fenitrothion on G. japonicum emerging between refrigerated and unrefrigerated host eggs although adult emergence of G. japonicum was reduced by 13 and 35%, respectively, compared to the control when fenitrothion was applied to eggs on the 8th day after parasitization. Parasitism of refrigerated and unrefrigerated eggs was not statistically different, but decreased significantly when the parasitoids were provided with fenitrothion-sprayed eggs 1h after application. In conclusion, while fenitrothion is detrimental to the parasitoid in the acute toxicity assay, the negative effects of fenitrothion on parasitization by G. japonicum did not differ between refrigerated and unrefrigerated eggs, suggesting that refrigerated eggs can be used in soybean fields to enhance parasitism.

Cyp35a2 gene expression is involved in toxicity of fenitrothion in the soil nematode Caenorhabditis elegans

In this study, the effect of organophosphorous (OP) pesticide, fenitrothion (FT), on the non-target organism was investigated using the soil nematode, Caenorhabditis elegans. Toxicity was investigated on multiple biological levels, from organism to molecular levels, such as, immoblity, growth, fertility, development, acetyl cholinesterase (AChE) activity and stress-response gene expressions. FT may provoke serious consequences on the C. elegans population, as it induced significant developmental disturbance. As expected, FT exposure inhibits AChE activity of C. elegans. The increased expression of the cytochrome p450 family protein 35A2 ( cyp35a2) gene was also observed in FT exposed worms. To experimentally demonstrate the relationships between organism-level effects and the cyp35a2 gene expression in FT-exposed C. elegans, the integration of the gene expression with biochemical-, and organism level endpoints were attempted using a C. elegans cyp35a2 RNA interference (RNAi) and cyp35a2 mutant ( gk317). The 24 h-EC50s of C. elegans on FT exposure were in the order of cyp35a2 RNAi in cyp35a2 mutant ( gk317) > cyp35a2 mutant ( gk317) > cyp35a2 RNAi in wildtype ( N2) > wildtype ( N2). The higher EC50 values of cyp35a2 RNAi and cyp35a2 mutant ( gk317) compared to that of wildtype C. elegans strongly supported that cyp35a2 gene plays an important role in the toxicity of FT towards C. elegans. The experiments with cyp35a2 RNAi also indicated that the development disturbance and decreased AChE activity, which were observed in FT exposed wildtype C. elegans were significantly rescued in the cyp35a2 RNAi C. elegans. Overall results suggest that the cyp35a2 may be an important gene for exerting FT toxicity in C. elegans.

Acute oral toxicity of the organophosphorus pesticide fenitrothion to fat‐tailed and stripe‐faced dunnarts and its relevance for pesticide risk assessments in Australia

The scarcity of information on the effects of pesticides on native Australian vertebrates constrains the development of biologically relevant risk assessments in Australia for the registration of pesticides. The concern that endemically old and unique Australian vertebrate fauna might display high sensitivity to pesticides used for locust control provoked examination of the acute oral toxicity of the organophosphorus pesticide fenitrothion for the fat-tailed dunnart, Sminthopsis crassicaudata (Gould 1844), and the stripe-faced dunnart, S. macroura (Gould 1845). By using the up-and-down method for determining acute oral toxicity, S. crassicaudata and S. macroura were found to have estimated median lethal doses (LD50s) of 129 mg/kg (95% confidence interval [CI] = 74.2-159.0) and 97 mg/kg (95% CI = 88.3-120.0), respectively. These values are 10 to 14 times lower than the reported LD50 values for a similar-sized eutherian mammal, Mus musculus (L. 1758; LD50 = 1,100-1,400 mg/kg) and lower than all other reported mammalian LD50 values. Such wide interspecific variation in sensitivity to fenitrothion may be a consequence of underlying differences in the metabolic pathway for fenitrothion detoxification in mammals and a possible explanation for the increased toxicity of fenitrothion to dunnarts, compared with other mammals, is proposed. The unexpectedly high sensitivity of these Australian marsupials to fenitrothion emphasises the importance of adequately evaluating the risks of pesticides to endemic Australian fauna.

The acute toxicity of fenitrothion on narrow‐clawed crayfish (Astacus leptodactylus Eschscholtz, 1823) in association with biomarkers of lipid peroxidation

The aim of this research was to evaluate the acute toxicity of fenitrothion to the crayfish (Astacus leptodactylus Eschscholtz, 1823), which is chosen as an alternative aquatic organism to fish by using the static test system and evaluate the basic lipid peroxidation parameters for the first 24 h. Crayfish of 27.3 ± 0.56 g mean weight and 10.0 ± 0.72 cm mean length were selected for the bioassay experiments. The experiments were repeated three times in 20 liters of tap water. The temperature of water was 21 ± 1°C. The data obtained were statistically evaluated by using a computer program developed by the United States Environmental Protection Agency, based on Finney's probit analysis method and the 96-h LC(50) value for crayfish was calculated to be 15.75 μg/L. The 95% lower and upper confidence limits for the LC(50) were 9.45 to 25.01 μg/L. In addition to the acute toxicity bioassay experiments, 24-h oxidative stress parameters such as malondialdehyde (MDA) levels and ferrous oxidation assay (FOX HP [hydrogen peroxide] equivalents) were also determined. Only MDA levels of hepatopancreas decreased at 5, 10, and 20 μg/L of fenitrothion doses. We can conclude that fenitrothion is highly toxic to crayfish, a nontarget organism in the ecosystem, and the lipid peroxidation indicators can be easily used for monitoring environmental effects.

Effect of ginger supplementation on developmental toxicity induced by fenitrothion insecticide and/or lead in albino rats

Evaluation of the antioxidant and antiteratogenic role of ginger Zingiber officinale polyphenols against the toxicity induced by fenitrothion and/or lead in female albino rats were investigated. Adult virgin females were divided into 8 groups and were orally treated as follow: control (C), 1% w/w of ginger (G), 120 μg/animal lead as lead acetate (L), 10 mg/kg of fenitrothion (F), lead (120 μg/animal) fenitrothion (10 mg/kg) (LF), ginger (1%w/w) + fenitrothion (10 mg/kg) (GF), ginger (1%w/w) + lead (120 μg/animal) (GL), ginger (1%w/w) + lead (120 μg/animal) + fenitrothion (10 mg/kg) (GLF). Treatments were expanded for 28 days before pregnancy and during gestation period from zero to 6th day. Blood samples were taken at the day 20th of gestation and animals were sacrificed to investigate the effect of tested substances on dams and development of their fetuses. Inhibition in AchE in (F) and (LF) groups and elevation in plasma AchE in (L) groups were observed. Elevation in oxidative stress biomarker malondialdehyde (MDA) was recorded in all intoxicated groups concomitants with reduction in total reduced glutathione (GSH) and reduction in the activity of glutathione S-transferase (GST). Elevation in liver function biomarkers alanin amintransferase (ALT) and aspartate aminotransferase (AST) and reduction in plasma total protein and albumin were recorded in (F), (L) and (LF). Supplementation with ginger in diet attenuates the alteration in MDA, GSH, GST, ALT and AST, however, it failed to counteract the effect of F, L and LF on AchE, total protein and albumin. Significant alterations in maternal toxicity were recorded in (GF, GL, LF and GLF) compared with control group. Also, parameters of embryotoxicity and fetotoxicity indicated significant decrease in litter number that observed in F and L and the number of dead fetus/dam and litters number increased in L group. Supplementation with ginger decreased each of the number of died fetus, growth retardation and fetal length, while, it increased fetal weight. As regards to, teratological aspects, the percentage of skeletal malformations and visceral anomalies were observed in all feti obtained from treated groups with different percentages. Supplementation with ginger slightly attenuates the developmental toxicity of fenitrothion and/or lead.

Ecotoxicological effect of fenitrothion on Trissolcus nigripedius (Hymenoptera: Scelionidae) an egg parasitoid of Dolycoris baccarum (Hemiptera: Pentatomidae)

Trissolcus nigripedius Nakagawa (Hymenoptera: Scelionidae) is an egg parasitoid of Dolycoris baccarum L. (Hemiptera: Pentatomidae), a polyphagous insect pest of many crops. Application of chemical insecticides is the most common control method against stink bugs in soybean. As a part of studies to investigate the potential of T. nigripedius as a biocontrol agent of D. baccarum, we assessed ecotoxicological effects of fenitrothion on T. nigripedius. The acute toxicity of fenitrothion was compared with five pesticides by topical application, exposure to residue, and oral ingestion in field recommended rate. Fenitrothion, spinosad, and milbemectin caused 100% mortality within 24 h by topical application or exposure to residue. Fenitrothion was also highly toxic to T. nigripedius when ingested. T. nigripedius was less susceptible to thiamethoxam a neonicotinoid insecticide in topical application or exposure to residue than oral ingestion. Sublethal effects of fenitrothion on T. nigripedius were also assessed. Emergence rate was significantly reduced in the insecticide treatments at 4 and 6 days after the parasitization. The proportion of inviable eggs increased when fenitrothion was applied before the parasitization, but was not affected when it was applied after the parasitization. Since higher proportion of males emerged from the host eggs sprayed with the fenitrothion, the female parasitoid may be more susceptible to the insecticide. Furthermore, T. nigripedius progeny that emerged from host eggs exposed to fenitrothion parasitized fewer host eggs. Therefore, for the conservation of T. nigripedius as a biological control agent of D. baccarum, use of fenitrothion should be minimized.

Acute toxicity and effect of fenitrothion on liver esterase of fish

The acute toxicity of fenitrothion (FNT) alone and combined with piperonyl butoxide (PBO) or triphenyl phosphate (TPP), and their effect on liver esterase (LE) activity of Gambusia holbrooki, Pseudorasobora parva and Oncorhynchus mykiss was studied in aquaria for 96h. The results indicated that fenitrothion is moderately toxic to the three species of fish tested, the toxicity being highest to O. mykiss followed by P. parva and G. holbrooki. Both FNT concentrations and the exposure time on the activity of LE and FNT (two way ANOVA P

Seletividade de inseticidas a Podisus rostralis (Stal) (Heteroptera: Pentatomidae) predador de lagartas desfolhadoras de eucalipto

O objetivo deste trabalho foi estudar a seletividade fisiológica dos inseticidas deltametrina, fenitrotiom, malatiom e permetrina em favor de ninfas (3º e 5º instares) e adultos (fêmeas e machos) do predador Podisus rostralis, empregando-se 50 (subconcentração) e 100% da concentração usada no controle de lagartas desfolhadoras de eucalipto. Deltametrina foi seletivo em favor de ninfas de 3º e 5º instares e adultos (1,94, 0,00 e 7,87% de mortalidade, respectivamente) do predador. Permetrina foi seletivo em favor de ninfas de 5º instar (3,55% de mortalidade) e medianamente seletivo em favor de ninfas de 3º instar e adultos (28,22 e 32,08% de mortalidade, respectivamente) do predador. Malatiom foi medianamente seletivo em favor de ninfas de 5º instar (49,38% de mortalidade) e não-seletivo em favor de ninfas 3º instar e adultos (95,34 e 88,99% de mortalidade, respectivamente) do predador. Fenitrotiom não foi seletivo em favor de nenhum dos instares do predador (100% de mortalidade). A alta toxicidade do fenitrotiom a P. rostralis não foi reduzida quando o predador foi exposto a 50% da concentração recomendada deste inseticida. O impacto do malatiom (a ninfas de 3º instar e adultos) e permetrina (a fêmeas) sobre P. rostralis diminuiu quando estas fases do predador foram expostas à metade das concentrações desses inseticidas. O impacto do deltametrina não foi afetado por sua concentração. Ninfas de 3º instar e adultos foram menos tolerantes do que ninfas de 5º instar ao malatiom e permetrina. As fêmeas de P. rostralis foram mais tolerantes que os machos à concentração do malatiom e à subconcentração de permetrina.

The multidrug resistance-associated protein 1 transports methoxychlor and protects the seminiferous epithelium from injury

We examined the ability of the multidrug resistance-associated protein 1 (MRP1/ABCC1) to transport pesticides, as this transporter mediates the cellular efflux of a variety of xenobiotics, typically as glucuronide, sulfate, or glutathione conjugates. NIH3T3 cells stably expressing MRP1 were 3.37-fold more resistant to the toxicity of fenitrothion, 3.12-fold more resistant to chlorpropham, and 2.5-fold more resistant to methoxychlor, a pesticide with estrogenic and anti-androgenic metabolites. The cells expressing MRP1 also eliminated methoxychlor two times more rapidly than their mock-transfected counterparts. We then examined whether mrp1 expression could alter the toxicity of methoxychlor in vivo using male FVB/mrp1 knockout mice (FVB/mrp1 −/−). Both control and knockout mice were fed 25 mg/kg methoxychlor in honey for 39 days, and its effects on testicular morphology were examined. Methoxychlor treatment did not significantly affect testicular morphology in the FVB mice, but markedly reduced the number of developing spermatocytes in the FVB/mrp1 −/− mice. These results suggest that MRP1 may play a role in protecting the seminiferous tubules from methoxychlor-induced damage.

Studies on some enzymes involved in insecticide resistance in fenitrothion-resistant and -susceptible strains of Musca domestica L. (Dipt, Muscidae)

Abstract: The toxicity of fenitrothion and fenitrothion plus synergists was determined by topical application to adults of fenitrothion-resistant (571ab) and -susceptible (Cooper) strains of Musca domestica L. The strain 571ab was 232-fold resistant to fenitrothion when compared with the Cooper strain. Co-administration of fenitrothion with three synergists, namely piperonyl butoxide (PBO), tributylphosphorotrithioate (DEF) and diethyl maleate (DEM) was investigated, respectively, at 1 : 5, 1 : 5 and 1 : 10 ratio. This co-administration of fenitrothion with PBO, DEF and DEM caused a decrease in the doses which produced 50% lethality (LD50s) in 571ab but had no synergistic effect on fenitrothion toxicity was observed in the Cooper strain. The effect of topical application of fenitrothion alone and in combination with PBO, DEF and DEM at the LD50 level on some enzyme activities in 571ab and Cooper strains was examined. The application of fenitrothion alone and in combination with DEF and DEM at LD50 level caused a significant decrease in activities of total esterases, acetylcholinesterase (AChE) and glutathione S-transferase (GST) in the 571ab strain. The decrease in GST activity was not significant in treated flies of the Cooper strain when compared with GST activity of control flies. A non-significant effect on total cytochrome P450 level was observed with fenitrothion alone and the fenitrothion + PBO treatment. No increase in activity level of total esterases, AChE and GST was found, which might suggest that changes in activity level of these enzymes are not related to fenitrothion resistance in the 571ab strain.

Analytical and microscopical studies on the protective effect of ascorbic acid (vitamin C) and beta-carotene against the toxicity induced by fenitrothion on the liver of female albino rats

The organophosphate insecticide feneitrothion is a contact insecticide and selective acaricide. It is used as a fly, mosquito and cockroach, residual contact spray for farms and public health programs. The objectives of the present study were to evaluate the toxicity of fenitrothion on the female rate and the possible protective effects of ascorbic acid (vitamine C) and beta–carotene as antioxidant agents against the toxicity induced by fenitrothion. Sixty of adult female albino rats were randomly assigned to six equal groups including control group and groups treat
          
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  ! successive days. Ingestion of fenitrtothion caused a significant increase in ALT (alanine transferase), AST (aspartate transferase), and AP (alkaline phosphatase). It decreased signifiantly GL (glucose) level, AchE (acetyle cholinesterase) and GSH (glutathion reductase) activities, while, it had insignificant effects on TB (total bilirubine) and a slight decrease in TP (total protein). The histological study of female rat liver tissues by Hx & Eosin,P.A.S, and Methyl Green Pyronine revealed that, fenitrothion showed vascular and degenrative changes in the hepatic cells, Also, it caused a significant decrease in glycogen contents and depletion in of nucleic acids in hepatic cells. Treatments with ascorbic acid and beta–carotene plus fenitrothion hasn’t been caused any significant changes in all parameters in serum of female rats. Treatment with ascorbic acid plus fenitrothion resulted a significant improvement in all parameters tested regarding to the histological study, while, beta-carotene plus fenitrothion showed the same improvement except in glycogen content in hepatic cells .

Analytical and microscopical studies on the protective effect of ascorbic acid (vitamin C) and beta-carotene against the toxicity induced by fenitrothion on the liver of female albino rats

The organophosphate insecticide feneitrothion is a contact insecticide and selective acaricide. It is used as a fly, mosquito and cockroach, residual contact spray for farms and public health programs. The objectives of the present study were to evaluate the toxicity of fenitrothion on the female rate and the possible protective effects of ascorbic acid (vitamine C) and beta–carotene as antioxidant agents against the toxicity induced by fenitrothion. Sixty of adult female albino rats were randomly assigned to six equal groups including control group and groups treat
          
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  !" successive days. Ingestion of fenitrtothion caused a significant increase in ALT (alanine transferase), AST (aspartate transferase), and AP (alkaline phosphatase). It decreased signifiantly GL (glucose) level, AchE (acetyle cholinesterase) and GSH (glutathion reductase) activities, while, it had insignificant effects on TB (total bilirubine) and a slight decrease in TP (total protein). The histological study of female rat liver tissues by Hx & Eosin,P.A.S, and Methyl Green Pyronine revealed that, fenitrothion showed vascular and degenrative changes in the hepatic cells, Also, it caused a significant decrease in glycogen contents and depletion in of nucleic acids in hepatic cells. Treatments with ascorbic acid and beta–carotene plus fenitrothion hasn’t been caused any significant changes in all parameters in serum of female rats. Treatment with ascorbic acid plus fenitrothion resulted a significant improvement in all parameters tested regarding to the histological study, while, beta-carotene plus fenitrothion showed the same improvement except in glycogen content in hepatic cells .

Fenitrothion toxicity intriatoma infestanssynergized by quercetin or thymol blue

Quercetin and thymol blue were shown to synergize the toxicity of fenitrothion to Triatoma infestans with synergistic ratios of 1.89 and 2.65 respectively. These synergistic ratios were statistically significant at P < 0.05. Both compounds inhibited glutathione S-transferases (GST) in vitro, with pI 50 values of 6.1 and 5.1 respectively. Quercetin or thymol blue caused in-vivo GST inhibition without affecting non-specific esterase (NSE) or acetylcholinesterase (AChE) activity. Incubation of [ 14 C]fenitrothion with T. infestans or rabbit liver GST produced desmethylfenitrothion as the major metabolite, which was specifically diminished in the presence of 0.3 mM quercetin. [ 14 C]Fenitrothion toxicokinetics study showed a significant decrease (P < 0.05) in radioactivity due to polar metabolites when insects were pre-treated with quercetin. These facts suggest that both assayed chemicals may be active in synergizing fenitrothion toxicity due to their ability to prevent the detoxification of organophosphorus insecticides by GSH conjugation.

Effect of an organophosphorus insecticide, fenitrothion, on survival and osmoregulation of various developmental stages of the shrimp Penaeus japonicus (Crustacea: Decapoda)

The toxicity of fenitrothion was determined in larvae (nauplii, Zoeae 1 to 3, Mysis 1 to 3), postlarvae (PL stages) and juvenile shrimp (Penaeus japonicus Bate), in two media, seawater (SW) and diluted seawater (DSW) (1100 and 550 mosM kg−1, ≃ 37 and 19‰ S). The effects of fenitrothion on the osmoregulatory capacities (OC) of juveniles were recorded. A gill and epipodite histopathological study was also conducted. For larvae in seawater, 24 and 48 h LC50s ranged from 32.9 μg l−1 (Zoeae 2) to 10.7 μg l−1 (Mysis 3), and from 3.9 μg l−1 (Zoeae 3) to 2.0 μg l−1 (Mysis 3), respectively; 48 and 96 h LC50s in postlarvae (PL) at the same salinity ranged from 1.8 μg l−1 (PL1) to 0.6 μg l−1 (PL5), and from 0.3 μg l−1 (PL7) to 0.4 μg l−1 (PL15). In juveniles, 96 h LC50s were 0.8 μg l−1 in seawater and 1.5 μg l−1 in diluted seawater. From hatching to juvenile stages, the overall trend was a rapid decrease (from nauplii to PL5–PL7) followed by a slight increase (from PL7 to PL15 and juveniles) in the shrimp's ability to tolerate the insecticide. In juveniles kept in seawater and in diluted seawater, fenitrothion decreased the osmoregulatory capacity (OC = difference between the hemolymph osmotic pressure and the osmotic pressure of the medium) at both lethal and sublethal concentrations. This effect was time- and dose-dependent. In SW, the decrease in hypo-OC was ˜ 25% at sublethal concentrations and ˜ 35% at the 96 h LC50. In DSW, the decrease in hyper-OC was ˜ 10 to 15% at sublethal concentrations. In SW, shrimp were able to recover their OC in less than 48 h when transferred to water free of pesticide. In DSW, recovery at 48 h was only possible after exposure to the lowest tested sublethal concentration. Haemocytic congestions (thrombosis) of the gills, lamellae necrosis and other alterations of gills and epipodites (breakage of the cuticle, reduction of the hemolymph lacunae) were noted in juveniles exposed to lethal and sublethal concentrations of fenitrothion.

A safety study on rat's eye after 13-week oral administration with fenitrothion.

The potential of ocular toxicity of fenitrothion (O,O-dimethyl O-4-nitrom-tolyl phosphorothioate) was assessed in Sprague-Dawley (Crj:CD) rats of both sexes receiving a diet containing the test compound at concentrations of 0, 2.5, 5, 10, or 30 ppm for 13 weeks. The animals were observed daily for clinical signs and their body weights and food consumption were measured weekly during the study. At termination of treatment, surviving animals were subjected to ophthalmoscopy, electroretinography, and biochemical analyses of plasma, erythrocyte, and brain cholinesterase (ChE). Histopathological examinations of ocular tissues were performed on all animals by light microscopy and on two animals/sex/dose by electron microscopy. There were no treatment-related changes in clinical signs, body weights, and food consumption. A significant inhibition of ChE activity was observed in males (plasma and erythrocyte ChE) and females (plasma, erythrocyte, and brain ChE) at 30 ppm and in females (plasma ChE) at 10 ppm. Ophthalmological and histopathological examinations revealed neither functional nor morphological alterations in the visual system at any dose level. Under the conditions of the present study, there was no evidence of ocular toxicity of fenitrothion for male and female rats at dose levels up to 30 ppm (1.70 mg/kg/day for males and 1.96 mg/kg/day for females) where distinct inhibition of ChE activity was observed.

Effect of GSH depletion mediated by l-BSO on the insecticidal activity of DDT and fenitrothion in Triatoma infestans (Hemiptera)

l-BSO injected at a sublethal dose in nymph V of Triatoma infestans produces a transient GSH depletion in the abdomen. A depletion of the total content of GSH was observed in nymph II fed with a sublethal concentration of l-BSO. Either ingestion or injection pretreatments of T. infestans nymph V with sublethal concentrations of l-BSO produced a slight synergism on the toxicity of fenitrothion. Feeding adminstration of a sublethal concentration of l-BSO to nymphs II of T. infestans resulted in a weak potentiation of the acute toxicity of DDT.