Toxicity Of Methomyl Research Articles

Propolis attenuated the toxicity of methomyl on rat fetuses and pups during pregnancy and lactation.

Propolis attenuated the toxicity of methomyl on rat fetuses and pups during pregnancy and lactation.

Toxicity of methomyl insecticides to testicular cells and protective effect of folic acid.

Methomyl is a carbamate insecticide with confirmed testicular toxicity. This study intended to observe the effect of methomyl on testicular cells and the protective effect of folic acid through in vitro experiments. The GC-1 spermatogonia, TM4 Sertoli cells, and TM3 Leydig cells were treated with methomyl (0, 250, 500, and 1000μM) with or without folic acid (0, 10, 100, and 1000nM) for 24h. It was found that methomyl increased cytotoxicity to testicular cells in a dose-dependent manner. In spermatogonia, methomyl significantly inhibited the expression of proliferation genes Ki67 and PCNA at 1000μM, and increased the expression of apoptosis genes Caspase3 and Bax at each dose. In Sertoli cells, methomyl dose-dependently inhibited the expression of blood-testis barrier function genes TJP1, Cx43, and N-cadherin, but did not affect Occludin and E-cadherin. In Leydig cells, methomyl inhibited the expression of steroid synthase P450scc, StAR, Hsd3b1 and down-regulated the level of testosterone, but did not affect Cyp17a1 and Hsd17b1. Further, folic acid could basically reduce the damage caused by methomyl. This study provided new insights into the toxicity of methomyl and the protective effect of folic acid.

Monitoring resistance to methomyl and synergism in the non-target Musca domestica from cotton fields of Punjab and Sindh provinces, Pakistan

Insecticides are an integral part of most of the cropping systems worldwide; however, these usually exert negative impact on the environment and non-target insects as well. Non-target insects are prone to develop resistance to insecticides due to prolonged and repeated lethal and sublethal exposures. Musca domestica is a common non-target, pollinator and nectar feeder species in cotton ecosystem, besides its status as a public health pest in human habitations. In the present work, resistance to methomyl, one of the major insecticides used for cotton pest management, was assessed in 20 M. domestica strains from the major cotton producing areas of the Punjab and Sindh provinces of Pakistan. The results revealed that toxicity values of methomyl for Punjabi and Sindhi strains ranged from 28.07 to 136.16 µg fly−1 and 29.32 to 136.87 µg fly−1, respectively. Among Punjabi strains, D.G. Khan, Lodhran, Bahawalpur, Toba Tek Singh, Bahawalnagar, Rajanpur and Jhang strains exhibited very high levels of resistance (RR > 100) to methomyl; Bhakkar, Kasur, Vehari, Layyah, Muzaffargarh and R.Y. Khan showed high resistance (RR = 51–100 fold), while the Mianwali strain showed a moderate level of resistance to methomyl (RR = 36.45 fold). In case of Sindhi strains, very high levels of resistance (> 100 fold) were reported for Sukkar and Sanghar strains, high levels of resistance (RR 51–100 fold) for Khairpur, Jamshoro and Ghotki, and moderate resistance to methomyl (38.08 fold) in the Dadu strain. There was a significant synergism of methomyl toxicity in all field strains when methomyl bioassayed along with piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF) providing clues of metabolic-based mechanisms of resistance to methomyl. In conclusion, insecticides used in crop farming can cause resistance development in non-target M. domestica. It is necessary to adopt the pest management activities that are safe for the environment and non-target insect species.

Human Poisoning with Methomyl and Cypermethrin Pesticide Mixture.

There is limited literature analyzing the outcome of human poisoning with methomyl and cypermethrin pesticide mixture. Between 2002 and 2018, a total of 63 patients intoxicated with methomyl, cypermethrin, or their pesticide mixture were treated at Chang Gung Memorial Hospital. The patients were categorized into three groups based on the type of pesticide, as methomyl (n = 10), cypermethrin (n = 31), or methomyl and cypermethrin (n = 22). Demographic, clinical, laboratory, and mortality data were obtained for analysis. The patients were aged 54.9 ± 18.9 years. Following ingestion, the patients experienced a wide range of clinical symptoms, including aspiration pneumonia (50.8%), acute respiratory failure (41.3%), acute kidney injury (33.3%), multiple organ failure (19.0%), emesis (19.0%), acute hepatitis (12.7%), diarrhea (7.9%), seizures (4.8%), lacrimation (4.8%), etc. After analysis, it was found that patients with methomyl and cypermethrin poisoning suffered higher incidences of acute respiratory failure (p < 0.001), aspiration pneumonia (p = 0.004), acute kidney injury (p = 0.011), and multiple organ failure (p < 0.001) than the other groups. Laboratory analyses revealed that patients with methomyl and cypermethrin poisoning had a higher creatinine level (p = 0.011), white blood cell count (p < 0.001), and neutrophil count (p = 0.019) than the other groups. A total of seven (11.1%) patients died. The average duration of hospitalization was 9.8 ± 10.0 days. In a multivariate logistic regression model, it was revealed that methomyl pesticide (p = 0.045) or methomyl and cypermethrin pesticide mixture (p = 0.013) were significant risk factors for acute respiratory failure. Nevertheless, no mortality risk factor could be identified. Therefore, the analytical results suggest that methomyl pesticide is the major contributor to the toxicity of methomyl and cypermethrin pesticide mixture poisoning. More research is needed.

Toxic effects of methomyl on mouse oocytes and its possible mechanisms.

Methomyl is a broad-spectrum carbamate insecticide that has a variety of toxic effects on humans and animals. However, there have been no studies on the toxicity of methomyl in female mammalian oocytes. This study investigated the toxic effects of environmental oestrogen methomyl exposure on mouse oocyte maturation and its possible mechanisms. Our results indicated that methomyl exposure inhibited polar body extrusion in mouse oocytes. Compared with that in the control group, in the methomyl treatment group, superoxide anion free radicals in oocytes were significantly increased. In addition, the mitochondrial membrane potential of metaphase II stage oocytes in the methomyl treatment group was significantly decreased, resulting in reduced mouse oocyte quality. After 8.5 h of exposure to methomyl, metaphase I stage mouse oocytes displayed an abnormal spindle morphology. mRNA expression of the pro-apoptotic genes Bax and Caspase-3 in methomyl-treated oocytes increased, which confirmed the apoptosis. Collectively, our results indicated that mouse oocyte maturation is defective after methomyl treatment at least through disruption of spindle morphology, mitochondrial function and by induction of oxidative stress.

The Hepatoprotective Role of Balanites aegyptiaca Extract and its Nano-Formulation Against Methomyl-Induced Toxicity and Oxidative Stress in Mice via Overexpression of Nrf2

IntroductionMethomyl (MET) is a monomethyl carbamate insecticide that is widely used around the world. MET is highly toxic to humans via oral exposure and mainly affects the liver tissue. It actually induces toxicity through overproduction of Reactive Oxygen Species (ROS) leading to oxidative stress with subsequent destruction of lipids, proteins, and nucleic acids.Materials and MethodsVarious plant extracts have been primarily screened for their antioxidant activities by measuring the free radical scavenging ability. Later, the plant extract with the highest antioxidant efficacy has been further formulated into a nanosuspension and the antioxidative effect has also been investigated against MET. Additionally, liver, kidney, and heart function biomarkers, liver tissue oxidative stress parameters, and total antioxidant capacity were assessed. Moreover, RT-PCR was applied to measure the Nrf2 expression.ResultsThe antioxidant screening data showed that balanites extract (BLT, Balanites aegyptiaca) had the most potent antioxidant activity. Besides, BLT showed dose-dependent improvement in liver, heart, and kidney functions in experimental mice treated with MET. The antioxidant biomarkers in liver tissue and total antioxidant capacity were elevated as compared to the MET-treated group. Furthermore, BLT significantly ameliorated MET-induced toxicity via the induction of Nrf2 and MET hepatic clearance. This study suggests the potential use of BLT extract as a natural antioxidant for the safe management of MET-induced hepatotoxicity and oxidative stress.ConclusionsBased on the presented data in this study, it can be concluded that BLT or BLT-NS can be used as a safe drug for methomyl toxicity.

ACUTE TOXICITY OF SOME INSECTICIDES ON HONEYBEE, Apis mellifera L.

This work was conducted to evaluate the toxicity of some insecticides against honeybee workers under laboratory conditions. Among the tested insecticides, Deltamethrin was the most toxic compound followed by Methomyl while Chlorpyrifos was the least one followed by Profenfos after 24, 48, and 72 hr., of topical exposure. The results indicated that there was negative relationship between the time post treatment and lechal concentration (LC50) values of all the tested insecticides. The LD50 values were 9.5, 10.45, 3.68, 18.33 and 12.55 μg/bee for Methomyl, Cyhalothrin, Deltamethrin, Chlorpyrifos and Profenfos, respectively after 24 hr., of exposure. In this respect, the toxicity of the insecticide Deltamethrin was 2.58 times more than Methomyl, 2.83 times than Cyhalothrin, 4.98 times than Chlorpyrifos and 3.41 times than Profenfos. On the other hand, the toxicity of Methomyl was 1.93 times, more than Chlorpyrifos 1.37 times than Profenfos and 1.1 times than Cyhalothrin. The toxicity of the tested insecticides against the workers of honeybee after 48 hr., of topical exposure showed LD50 values range from 2.44 to 12.32 μg/bee. The insecticide Deltamethrin was the highest toxic compound where as the Chlorpyrifos was the least toxic one. The other insecticides occupied intermediate degree of toxicity. Deltamethrin toxicity in comparision to the other tested insecticides revealed that it was more toxic than Methomyl by 2.21 times, 2.93 times than Cyhalothrin, 5.01 times than Chlorpyrifos and 3.82 times than Profenfos. The LD50 of Deltamethrin was 1.01 mg/l, 0.1mg/l to Methomyl, 5.21 μg/bee to Cyhalothrin, 7.58 mg/l to Chlorpyrifos and 6.11 mg/l to Profenfos. On the other hand, the corresponding LD90 were 2.31 to Deltamethrin, 8.71 to Methomyl, 9.98 to Cyhalothrin, 13.75 to Chlorpyrifos and 15.73 μg/bee to Profenfos. The tested insecticides could be arranged descendingly as follows: Deltamethrin > Methomyl > Cyhalothrin > Profenfos > Chlorpyrifos.

Protective Effects of Pelargonium graveolens Essential Oil on Methomyl-Induced Oxidative Stress and Spatial Working Memory Impairment in Association with Histopathological Changes in the Hippocampus of Male Wistar Rats.

Introduction:Methomyl (MET) is a carbamate insecticide, used in agriculture and public health to eliminate harmful insects. Besides its advantages in agriculture, it causes neurotoxic effects. The aim of this study was to evaluate the effect of MET on Spatial Working Memory (SWM), oxidative stress parameters, and histopathological changes in the hippocampus, as well as the possible protective role of Pelargonium graveolens Essential Oil (EO).Methods:Male Wistar rats were randomized into four groups of six animals: group I as the control that received the vehicle; group II received EO (75 mg/kg b.w), group III received MET (2 mg/kg b.w); and group IV received both MET and EO. The rats were administered the respective doses orally by gavage for 28 days. SWM was assessed using Y-maze on the day before the first treatment and day 28 after the last dose. They were sacrificed by decapitation and their brains were taken for assessing oxidative stress parameters and histopathological analysis.Results:MET treatment caused SWM deficits. Furthermore, drastic changes were observed in aspartate transaminase, alanine aminotransferase, and alkaline phosphatase activities. The level of malondialdehyde significantly increased, whereas antioxidant (glutathioneS-transferase and catalase) enzyme activities significantly decreased. The CA1 region of the hippocampus of rats exposed to MET revealed severe histological alterations. However, supplementation with EO improved SWM and partially restored the activities of antioxidant systems and prevented neuronal cell damage.Conclusion:P. graveolens EO has the potential in mitigating most of the adverse effects in the hippocampus and prevents SWM impairment induced by MET toxicity.

Methomyl induced effect on fortilin and S100A1 in serum and cardiac tissue: Potential biomarkers of toxicity.

Methomyl toxicity has been reported as a cause of several accidental and suicidal fatalities. The study is evaluating the effect of lethal methomyl toxicity on fortilin and S100A1 in serum and cardiac tissues. Adult 96 female Sprague-Dawley rats were divided equally into a control (euthanized by cervical dislocation) and a study group (overdosed with methomyl). The levels of fortilin and S100A1 in serum were measured antemortem (to establish the basal levels in serum) and postmortem (to evaluate changes after methomyl exposure) using enzyme-linked immunoassay. S100A1 was immunostained in sections from cardiac tissues. Both proteins in the control were not significantly different (p > 0.05) compared with the antemortem levels. On the contrast, both biomarkers levels in the intoxicated group were remarkably higher (p < 0.001) than the control and the antemortem levels. Ventricular tissues from the intoxicated rats presented depleted S100A1 immunostain in cardiomyocytes localized mainly in the epicardium with deeply stained adjacent cardiac fibroblasts. The cardiomyocytes were damaged with a prominent loss of striations compared to normal cardiac tissues from the control. The present outcomes explain to a certain degree the potential toxic effect of methomyl poisoning on the cardiac tissue. Both proteins could be added to the currently available battery of markers for assessing methomyl toxicity.

1H-NMR-based metabolomic study on toxicity of methomyl and methidathion in fish

ABSTRACTA 1H-nuclear magnetic resonance (NMR) spectroscopy with multivariate analysis was applied to detect the toxicity of antiacetylcholinesterase insecticides, methomyl (methyl (1E)-N-(methylcarbamoyloxy)ethanimidothioate) and methidathion (3-(dimethoxyphosphinothioyl sulfanylmethyl)-5-methoxy-1,3,4-thiadiazol-2-one), using zebrafish (Danio rerio) and Chinese bleak (Aphyocypris chinensis). Generally, methomyl and methidathion have been believed not to highly accumulate in fish tissues. However, these pesticides showed their toxicity by altering patterns of whole-body metabolites in neurotransmitter balance, energy metabolism, oxidative stress, and muscle maintenance in low concentrations. We used Pearson correlation analysis to contextualize the metabolic markers in pesticide treated groups. We observed that the positive correlations of choline with acetate and betaine in untreated control were shifted to null correlations showing acetylcholinesterase specific toxicity. This research demonstrated the applicability and potential of NMR metabolomics in detecting toxic effects of insecticide with a modicum of concentrations in aquatic environment.

Role of Nicotinic Acid in Mitigating Methomyl Induced Acute Toxicity in Albino Rats

Methomyl has a significant animal and public health problem. The present study was designed to evaluate the protective effect of nicotinic acid against the acute toxic effects induced by methomyl in albino rats. Four groups were divided into control, nicotinic acid (NA) (100 mg/kg b.wt./twice daily) for 7 successive days, methomyl (MET) (8 mg/kg b.wt.) and nicotinic acid plus methomyl (NA+MET) treated groups. Red blood cells-RBCs count; hemoglobin- Hb, packed cell volume-PCV and blood indices were measured. Hepatic marker enzymes (aspartate aminotransferase-AST, alanine aminotransferase-ALT and alkaline phosphatase-ALP), proteinogram (total protein, albumin, globulin and albumin/ globulin ratio), serum bilirubin (total, direct and indirect) and serum urea and creatinine were measured. Acute MET toxicity resulted in normocytic normochromic anemia with a significant (P<0.05) increase in the AST, ALT and ALP activities. Serum protein and globulin were significantly (P<0.05) decreased with an increase in albumin globulin ratio (A/G ratio) in MET treated rats. Bilirubin (total and direct) and kidney markers were significantly (P<0.05) increased. The NA pretreatment showed an improvement in the erythrocytic parameters. It restored the hepatic and renal markers. This is the first study investigating the effects of NA supplementation on the hematological and biochemical parameters of methomyl intoxicated rats. These findings suggest that the nicotinic acid could be used in amelioration of the methomyl toxicity.

Renal and hepatic toxicity of methomyl and ameliorative effects of green tea (Camellia sinensis) administration

This study was conducted to test the toxicity of the carbamate insecticide (methomyl) and to evaluate the ameliorative effect of green tea (Camellia sinensis) administration. Male albino rats (Rattus norvegicus) were used as test animal model organism. A total of 30 rats were divided into 6 groups and assigned as: G1 (control), G2 (green tea in drinking water at a rate of 6 g/300 ml), G3 (methomyl at a dose of its corresponding ADI; 0.025 mg/kg b.w.), G4 (methomyl at a dose of 10X- ADI; 0.25 mg/kg b.w.), G5 (methomyl ADI + green tea), and G6 (methomyl 10X- ADI + green tea). Methomyl was given daily by gavages. Compared to control results, the body weights in G2 had recorded slight decrease, while that of G5 & G6 recorded high significant decrease. The two later groups showed significant increase of liver and spleen weights, and decrease of kidney, heart and testes weights. In control group, ALT and AST were 25.0 and 63.06 U/mL, respectively, while G4 were 74.61 and 75.53 U/mL, respectively. Lipid peroxidation (LPO) as MDA was highly elevated in methomyl treatments (G3 &G4), while SOD was strongly decreased in these treatments. Based on MDA results, the "Ameliorative Index; AI" for green tea in conjunction with methomyl, equaled to 1.2 and 1.1 for the low and high doses, respectively. In the case of SOD, the AI reached 0.74 and 0.7, respectively. These results revealed the ameliorative effect of green tea against methomyl intoxication. Also, the other measured biochemical parameters (e.g., ALT, AST, ALP, TAC, Creatinine, Urea, BuChE) were normalized due to administration of green tea when given with the insecticide. In conclusion, green tea achieved some body weight decrease. However, it alleviated the oxidative stress induced by methomyl.

Effects of methomyl on acetylcholinesterase in erythrocyte membrane and various brain areas

To study the toxicity of methomyl to acetylcholinesterase (AChE) in different regions. The optimal temperature and time for measurement of AChE activity were determined in vitro. The dose- and time-response relationships of methomyl with AChE activity in human erythrocyte membrane, rat erythrocyte membrane, cortical synapses, cerebellar synapses, hippocampal synapses, and striatal synapses were evaluated. The half maximal inhibitory concentration (IC50) and bimolecular rate constant (K) of methomyl for AChE activity in different regions were calculated, and the type of inhibition of AChE activity by methomyl was determined. AChE achieved the maximum activity at 370 °C, and the optimal time to determine initial reaction velocity was 0-17 min. There were dose- and time-response relationships between methomyl and AChE activity in the erythrocyte membrane and various brain areas. The IC50 value of methomyl for AChE activity in human erythrocyte membrane was higher than that in rat erythrocyte membrane, while the Ki value of methomyl for AChE activity in rat erythrocyte membrane was higher than that in human erythrocyte membrane. Among synapses in various brain areas, the striatum had the highest IC50 value, followed by the cerebellum, cerebral cortex, and hippocampus, while the cerebral cortex had the highest Ki value, followed by the hippocampus, striatum, and cerebellum. Lineweaver-Burk diagram demonstrated that with increasing concentration of methomyl, the maximum reaction velocity (Vmax) of AChE decreased, and the Michaelis constant (Km) remained the same. Methomyl is a reversible non-competitive inhibitor of AChE. AChE of rat erythrocyte membrane is more sensitive to methomyl than that of human erythrocyte membrane; the cerebral cortical synapses have the most sensitive AChE to methomyl among synapses in various brain areas.

Toxicity of methomyl, copper hydroxide and urea fertilizer on some land snails

Terrestrial gastropods have become important economic pests attacking various vegetations in Egypt. According to this study, the molluscicidal activity of methomyl, urea, and copper hydroxide against the brown garden snail Eobania vermiculata and the small white garden snail, Theba pisana was investigated.The obtained results indicated that copper hydroxide was the most toxic compound against E. vermiculata followed by methomyl and urea after 72h of evaluation where LC50 values were 3.31%, 3.75% and 40.88%, respectively. Methomyl was also the most toxic compound when it was tested against T. pisana followed by copper hydroxide followed by urea. The LC50 values were 3.76%, 4.63% and 40.13%, with respect. The brown garden snail was more susceptible to copper hydroxide and methomyl than the second one. There was no difference in the susceptibility of the two tested snails to urea. The toxicity of the compounds was enhanced as increasing the exposure time. This study showed that the land snails may be controlled using urea fertilizer at concentration of 8%, to give % mortality in a range of (67–100)%.

Toxicity of essential plant oils, in comparison with conventional insecticides, against the desert locust, Schistocerca gregaria (Forskål)

Essential oils extracted from ten different plants belonging to five families were tested against the 3rd nymphal instars of the desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae) by topical application technique. Also, the toxicity of four chemical insecticides, as well as the joint action resulted from mixing botanicals and insecticides were evaluated. Either at LD50 or LD90 values, the Allium cepa-oil proved to be the most toxic where the above mentioned values equaled to 1.11 and 1.42ppm, respectively followed by the Petroselinum sativum (1.34 and 1.61ppm, respectively). The LD50 and LD90 values for the oils of Pelargonium radula, Cuminum cyminum, Ocimum basilicum, Origanum vulgare and Matricaria chamomilla ranged between 1.54–1.59ppm and between 1.84–1.91ppm, respectively. GC/MS analyses revealed the presence of known biologically active compounds such as p-Cymene, Linalool, Thymol, Caryophyllene and Carvacrol in some of the analyzed oils. Fenitrothion was the most toxic (LD50=0.33ppm), while fenvalerate was the least (LD50=1.48ppm). The other 2 insecticides possessed intermediate and nearly equitoxic values (LD50=1.2ppm). Surprisingly, the A. cepa oil was more toxic than methomyl, and the other plant oils possessed toxicity accounted to 74–80% and 83–98% of methomyl toxicity when comparisons were made at the LD50 and LD90 levels, respectively. Combining plant oils with insecticides resulted in different types of interaction (e.g., synergism, additive and antagonism). Such results may be considered as novel findings in the course of searching for potent botanical insecticides against the locust, S. gregaria, and magnify the industrial value of such plant oils in the era of biopesticides.

Interaction of Methomyl with Brown Garden Snail, Eobania vermiculata (Müller), and White Snail, Theba pisana (Müller) Acetylcholinesterase Activity

Comparative toxicity of methomyl against two land snails Eobania vermiculata and Theba pisana was investigated. The Michaelis constant(Km) and maximal velocity(Vmax) valuesof E. vermiculata and T. pisana AChE were compared. Finally, the in vivo and in vitro inhibition of E. vermiculata and T. pisana acetylcholinesterase by methomyl was studied. Results revealed that, the median lethal concentrations (LC50s values) of methomyl against T. pisana were 58.85, 18.71 and 3.87 % after 24, 48 and 72hrs post-treatment,respectively. On the other hand, LC50s values of methomyl against E. vermiculata were 2.94, 0.92 and 0.38 % after the same time, respectively. The Km values were 0.098 and 0.042 mM and Vmax values were 0.042 and 0.052 mmole/min for E. vermiculata and T. pisana AChE, respectively. Specific activity of T. pisana AChE is 1.43 times the E. vermiculata AChE specific activity. When T. pisana was exposed to methomyl at concentrations of 375, 750 and 1875 ppm the inhibition percentages of AChE were 88.74, 89.44 and 92.25%, respectively. On the other hand, methomyl revealed inhibition percentages of 42.3, 51.4 and 75.3% of E. vermiculata AChE activity at concentrations of 37.6, 75.2 and 188.0 ppm, respectively. The in vitro studies showed that, the sensitivity of T. pisana AChE (I50 = 1.3 µM) is 4.1 times more than the sensitivity of E. vermiculata AChE (I50 = 5.3 µM) to methomyl.

ACUTE AND CHRONIC TOXICITY OF METHOMYL AND LANTANA CAMARA (VERBENACEAE) TO FIVE BIOLOGICAL CONTROL AGENTS OF AGRICULTURE PEST IN PERU

Methomyl is a systemic-contact carbamate insecticide acetylcholinesterase inhibitor. Lantana camara is a plant that presents antimicrobial, insecticidal, repellent and nematicide properties. The aim of this study was to evaluate the acute and chronic toxicity of methomyl and L. camara on five biological controls of agricultural pests of Peru. Toxicity tests for Cereaochrysa cincta, Chrysoperla asoralis, Trichogramma pretiosum, Trichogramma pintoi and Trichogrammatoidea bactrae used methomyl and L. camara with five concentrations plus control. C. asoralis relative to first instar larval mortality and no hatching of eggs were more sensitive to methomyl in relation to C. cincta. Instead C. cincta was slightly more sensitive to C. asoralis relating to lantana at first instar larval mortality and to non-egg hatching. The sequence descending of methomyl toxicity in adults and not emerged was: T. pretiosum &gt; T. bactrae &gt; T. pintoi. Regarding these three parasitoids, the aqueous extract of lantana had no significant effect on adult survival and only produced a significant decrease in the emergence of T. pintoi and T. bactrae. Methomyl showed harmful effects on the five species of beneficial fauna compared with lantana, which proved to be harmless.

Protective Effects of Tannic Acid against Methomyl-Induced-Oxidative Stress

Methomyl carbamate is a pesticide widely used in the control of insects. The present work aims at studying the effect of tannic acid on the antioxidant system of methomyl-treated-mice. Swiss albino mice were intraperitoneally administered a single dose of methomyl (7 mg/Kg b.wt). Mice of another group were injected with tannic acid (20 mg/ Kg b.wt.) 3 hrs before methomyl intoxication. After 24 hours, methomyl exposure resulted in significant increase in lactic dehydrogenase activity (LDH). The antioxidant capacity of hepatic cells in terms of the activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione-S-transferase (GST) and glutathione (GSH) content was diminished. It appears that methomyl exerts its toxic effect via peroxidative damage to hepatic, renal and splenic cell membranes. Also, methomyl induced DNA damage in these organs as detected by alkaline filter elution technique. The distribution of methomyl in different organs of mice was detected by HPLC. Tannic acid administration prior to methomyl injection produced pronounced protective action against methomyl effects. It is observed that tannic acid enhances the endogenous antioxidant capacity of the cells by increasing the activities of SOD, CAT, GR and GST as well as increasing GSH content. The activity of LDH was decreased in liver and the damage of DNA was suppressed comparable to controls. In conclusion, this study concludes that tannic acid has a potential in mitigating most of the adverse effects induced by methomyl toxicity.

Reproductive toxicity of methomyl insecticide in male rats and protective effect of folic acid

The acute toxicity (LD 50) of insecticide methomyl and its effects on male reproduction in rats were carried out. Methomyl was given orally to male rats daily for 65 successive days at two doses (0.5 and 1.0 mg kg −1 b.wt., corresponding to 1/40 and 1/20 LD 50) alone and in combination with folic acid (1.1 mg kg −1 b.wt., corresponding to acceptable daily intake, ADI). Fertility index, weight of sexual organs, semen picture, serum testosterone level and histopathology of testes were the parameters used to evaluate the reproductive efficiency of treated rats. The reversibility of methomyl effects was also studied after 65 days post-administration. The oral LD 50 of methomyl was 20.0 mg kg −1 b.wt. in male rats. Methomyl significantly decreased the fertility index, weight of testes and accessory male sexual glands, serum testosterone level and sperm motility and count, but increased sperm cell abnormality. It induced testicular lesions characterized by moderate to severe degenerative changes of seminiferous tubules and incomplete arrest of spermatogenesis. These toxic effects were not persistent (reversible). Coadministration of folic acid with methomyl decreased its reproductive toxicity. A great attention should be taken during field application of methomyl to avoid its deleterious effects in farm animals and occupationally exposed humans.

Toxicidad aguda de metomilo en poecilia latipinna (lesueur 1821) (poecilidae)

Methomyl is a chemical compound acetylcholinesterase inhibitor that acts by contact system and is one of the most widely used chemicals such as insecticide-acaricide for control of a wide range of agricultural pests. The following study aims to assess the acute toxicity of methomyl on introduced fish Poecilia latipinna (Lesueur 1821) (Poecilidae) at 2, 4, 6, 8, 24, 48, 72 and 96 h of exposure. Bioassays were carried out with 5 levels and 4 treatments, temperature was 21.8 ° C ± 1, pH 7.34 ± 0.31, conductivity 0.54 mS ± 0.03, and average dissolved solutes in the middle 267.39 mg.L-1. The data obtained during tests were evaluated using the statistical method analytic Probit ver. 1.5. The results of the median Lethal Concentration (LC ) of methomyl on P. latipinna were: 2 h = 13.95 mg IA.L-1, 4 h 50 =10.39 mg IA.L-1, 6 h = 8.12 mg IA.L-1, 8 h = 5.81 mg IA.L-1, 24 h 3.99 mg IA.L-1, 48 h = 2.61 mg IA.L-1, 72 h = 2.24 mg IA.L-1 and finally 96 h = 2.08 IA.L mg-1. At the highest concentration was observed a change of skin color intensity of silver to black.