Organophosphorus Insecticides Dimethoate Research Articles

The gut bacterium Serratia marcescens mediates detoxification of organophosphate pesticide in Riptortus pedestris by microbial degradation

AbstractOrganophosphate insecticides have been widely used in agriculture to control insect pests and raised growing problems including insecticide resistance. According to recent studies, microbial symbionts play important roles in developing insecticide resistance. The bean bug Riptortus pedestris is a notorious pest of leguminous crops, harbouring diverse microorganisms in their insect midguts. However, the potential biological roles of many gut‐associated bacteria are largely unknown. In this study, we isolated a bacterial strain from the midgut of R. pedestris and identified it as Serratia marcescens based on its morphological characteristics and the phylogenetic analysis of the 16S rRNA gene sequence. A halo of phosphorus‐solubilizing bacteria was observed on a medium containing lecithin and an organophosphorus insecticide dimethoate. Subsequently, the microbial degradation of dimethoate was determined using Gas Chromatography with Mass Spectroscopy (GC–MS). Further analysis indicated that the S. marcescens contained organophosphorus‐degrading MBL‐fold metallo‐hydrolase gene. Additionally, we discovered that the bacterium could colonize the insect midgut stably and enhance the host survivorship when exposed to dimethoate. Our results revealed that an insect gut‐associated bacterium could degrade organophosphorus compounds, thereby reducing related insecticide toxicity to the insect hosts. These findings provided further insights into the host‐microbiota interactions underpinning the development of insecticide resistance.

Amino-functionalized Al-MIL-53 for dimethoate pesticide removal from wastewater and their intermolecular interactions

Aluminum-organic framework was reformed with various amount of amino-group (Al-(BDC)x(BDC-NH2)1-x, x = 0.00, 0.25, 0.50, 0.75 and 1.00). The technique used to modify the aluminum-based metal-organic framework was the mixed bonding method. All prepared metal-organic frameworks exhibited the same structure as that of Al-MIL-53. The surface areas of amino-functionalized aluminum-based metal-organic framework showed (SBET = 866, 1105, 1260, 1100 and 1060 m2g−1) for Al-BDC, [Al-(BDC) 0.75(BDC-NH2)0.25], [Al-(BDC) 0.5(BDC-NH2)0.5], [Al-(BDC) 0.25(BDC-NH2)0.75] and Al-BDC-NH2, respectively. Amino groups have a great effect on organophosphorus insecticide dimethoate adsorption capability. Pesticide adsorption capacities of Al-BDC, [Al-(BDC) 0.75(BDC-NH2)0.25], [Al-(BDC) 0.5(BDC-NH2)0.5], [Al-(BDC) 0.25(BDC-NH2)0.75] and Al-BDC-NH2 were 154.8, 267.2, 513.4, 344.7 and 266.9 mg g−1, respectively. Fortunately, the results show that Al-(BDC) 0.5(BDC-NH2)0.5 is the best absorbent Al-MOF ratio to reduce dimethoate residue in wastewater. Monte Carlo simulation was used for evaluation of the dimethoate adsorption mechanism.

Sorption and leaching potential of organophosphorus insecticide dimethoate in Croatian agricultural soils

Dimethoate is an organophosphorus insecticide still used in Croatia and worldwide, with polar structure and high water solubility that make it prone to leaching. This study analyzed how physico-chemical properties of soils affected dimethoate sorption and mobility. For that purpose, five soil samples were collected from three Croatian regions (two coastal and one mountain region). Dimethoate sorption process was analyzed using the batch procedure while its mobility and leaching potential was investigated by column experiment. The results showed that dimethoate sorption can be adequately described by Freundlich model. All isotherms were of L-type with varying degrees of non-linearity, indicating different sorption efficiencies and distribution of sorption sites energies among the soils. Energy distribution was broader in soils richer in organic matter (OM). KF values indicated relatively low sorption efficiency for all soils, with an increase of KF values proportional to OM content. Mechanisms involved in dimethoate sorption and mobility were analyzed by fitting the breakthrough curves (BTCs) with two mathematical models, namely one-site equilibrium (ELM) and two-site nonequilibrium sorption model (NELM). Correlations were quantified by Kendall-Tau test, which revealed the strongest correlation of KF value with OM content, cation exchange capacity and the humic acid content, while correlations with pH, clay content and A465nm/A665nm ratio were negative and insignificant. Based on these findings, a model for prediction of leaching potential was formed. A simplified model for dimethoate sorption/transport was proposed.

The organophosphorus pesticide dimethoate decreases cell viability and induces changes in different biochemical parameters of rat pancreatic stellate cells

In the present study we employed cultured pancreatic stellate cells to study the effect of the organophosphorus insecticide dimethoate on pancreatic cell physiology. Esterase activity, cell viability, reactive oxygen species generation and Ca2+ mobilization were examined. Our results show that dimethoate (0.1, 1 and 10 μM) induced a concentration-dependent inhibition of cholinesterase enzymatic activity at all concentrations tested. A drop in carboxylesterase activity was noted in the presence of 10 μM dimethoate. In the presence of the pesticide a decrease in cell viability was detected. The clearer effect could be observed when the cells had been incubated during 96 h in the presence of dimethoate. The pesticide induced a slight but statistically significant increase in the production of reactive oxygen species in the mitochondria. Incubation of cells with dimethoate, in the presence of Ca2+ in the extracellular medium, led to a slow and progressive increase in [Ca2+]c towards an elevated value over the prestimulation level. A similar behavior was observed in the absence of extracellular Ca2+, indicating that dimethoate releases Ca2+ from the intracellular stores. Our results suggest that dimethoate might alter intracellular pathways that are critical for pancreatic physiology, creating a situation potentially leading to dysfunction in the exocrine pancreas.

Sex Differences and Effects of Estrogenic Compounds on the Expression of Inflammatory Molecules by Astrocytes Exposed to the Insecticide Dimethoate

A low dose of the organophosphorus insecticide dimethoate (DMT) produces oxidation of lipids and proteins and impairs mitochondrial function in the brain of male rats, together with a reduction of gonadal hormones in plasma. Here, we have assessed whether DMT affected the expression of inflammatory molecules, the production of reactive oxygen species (ROS), and the expression of steroidogenic proteins and estrogen receptors in cortical astrocyte-enriched cultures obtained separately from male and female CD1 mice pups. Furthermore, we have analyzed whether estradiol may counteract the effects of DMT. A dose of DMT (2 μg/mL) did not affect cell viability, increased interleukin (IL) 6, IL1β, tumor necrosis factor (TNF)α, interferon-γ-inducible protein 10 (IP10), ERβ, steroidogenic acute regulatory protein, and aromatase mRNA levels and ERα protein levels in male but not in female cultures. Estradiol decreased the mRNA levels of IL6, IP10, TNFα, and IL1β in male but not in female cultures treated with DMT. The effect of estradiol was prevented by the ER antagonist ICI 182,780, fully imitated by an ERβ agonist and partially imitated by an ERα agonist. Furthermore, DMT increased the production of ROS in male astrocytes while estradiol reduced ROS production to control levels. These findings indicate that a sublethal dose of DMT alters astrocyte function. The selective action of estradiol on male astrocytes and the sexually dimorphic action of DMT suggest that the pesticide may have different neurological outcomes in males and females.

Photosynthetic and fluorescence responses of Solanum melangena L. to field application of dimethoate

The organophosphorus insecticide dimethoate, at field concentration (1.419±0.086 mg a.i. g −1 fr.wt. of leaf tissue) did not cause any significant degradation of chlorophylls and carotenoids in Solanum melangena L. On the other hand, there was significant reduction of photosynthesis, transpiration and stomatal conductance during 6 h after spray application of the insecticide. Distinct change of OJIP fluorescence transient with increase of J and I rise and corresponding decrease in P rise was observed during 6 h after insecticide application. The fluorescence parameters, viz., relative variable fluorescence at J level ( V j), net rate of PS II closure ( M 0), energy dissipation (DI 0/RC) and maximum trapping rate of active PS II (TR 0/RC), during the same treatment period, showed significant increase but variable fluorescence ( F v), fluorescence yield (TR 0/Abs), electron transport probability (ET 0/TR 0), and activity of RC (ET 0/RC) showed significant decrease. All physiological and fluorescence parameters, and the OJIP fluorescence transient recovered steadily to the control level during 48 h after insecticide application. There was continuous reduction in the insecticide content of the leaf tissue during the observation period.

Effects of 90-day oral dimethoate exposure on glutamatergic system and neurobehavioral performance in rats

To investigate the spatial learning and exploration along with the CNS excitatory amino acid neurotransmitters profiles in adult rats subchronically exposed to the anticholinesterase organophosphorus insecticide dimethoate. Rats were gavaged daily with dimethoate (0, 5, 10 or 20 mg/kg via oral) in NS. for 90 days. Morris water maze tasks were used to test the spatial learning and memory in the rats after the dimethoate exposure. Simultaneously, rats were decapitated for the determination of brain cholinesterase AChE activities, glutamate concentrations, and the NMDA receptor NMDA-R densities and affinities in hippocampus. Latencies to find a hidden escape platform were significantly longer in dimethoate dosed groups than that of the control group in the place navigation tests. Subsequently, the times of crossing the location of platform which had been removed obviously decreased in the highest dose group compared with that of the control in the spatial probe tests (P < 0.05). AChE activity was significantly reduced 42% approximately 78% by all three doses of dimethoate (P < 0.05). Glutamate concentrations were increased significantly 132.9% approximately 134.5% by the two highest doses of dimethoate (P < 0.05). In addition, the NMDA receptor bindings were reduced 21.2% approximately 23.2% with the statistical significance at the same two highest doses (P < 0.05). Furthermore, the receptor affinities was reduced 33.1% by the highest dose group (P < 0.05). The lesions of spatial memory were statistically corrected with the decrease of the NMDA-R affinities (P < 0.05). The cholinergic lesion as well as the excitatory amino acid system alteration might attribute to the inferior ability in spatial learning and memory in dimethoate subchronically exposed rats.

Effect of ascorbic acid in the detoxification of the insecticide dimethoate in the bone marrow erythrocytes of mice

The antimutagenic potential of ascorbic acid in the detoxification of the organophosphorus insecticide dimethoate was evaluated in female Swiss albino mice using the in vivo bone marrow micronucleus test. Groups of three mice were treated with distilled water (control), 1% dimethyl sulphoxide (solvent control), or 86, 129.5 or 259 mg ascorbic acid/kg body weight, with or without the concurrent administration of 150 mg dimethoate/kg. There was a statistically significant increase in the frequency of micronuclei in dimethoate-treated mice. However, in mice that were given dimethoate and ascorbic acid simultaneously, the numbers of micronuclei did not differ significantly from control values, thus indicating the protective role of ascorbic acid.

A Case of Unusual Suicidal Poisoning by the Organophosphorus Insecticide Dimethoate

A 20-year-old male who attempted suicide by injecting subcutaneously 10 ml of Sistemin 40 (40% dimethoate) was admitted 16 h later. General weakness, muscular fibrillations and a marked inhibition of red blood cell and serum cholinesterases were the prominent signs of intoxication. The antidotal treatment of intermittent boluses of atropine, oxime HI-6 and diazepam was combined with symptomatic therapy. Cholinesterase activity decreased within the next 3 d. In contrast to the marked general improvement of the patient, the return of cholinesterase activities was very slow. The patient was discharged 24 d after the poisoning with no notable consequences which could be ascribed to the intoxication.

Indication for weak mutagenicity of the organophosphorus insecticide dimethoate in Drosophila melanogaster

The organophosphorus insecticide dimethoate was tested for induction of genetic damage in male germ cells of Drosophila melanogaster. Sex-linked recessive lethals, sex-chromosome loss and non-disjunction induction were studied following different routes of administration: adult feeding, injection and larval feeding. Our results show that, after injection, dimethoate induces a slight but significant increase in the frequency of point mutations.

Determination of Dimethoate in Waste Water, Soil and Sediment Using Gel Permeation Chromatography for Sample Clean-up

Abstract A method for the determination of trace amounts of the organophosphorus insecticide dimethoate in waste water, soil and sediment is presented. Sediment and soil samples are extracted by soxhelt with acetone/hexane followed by partition of the extract between methylene chloride and water. Separation of dimethoate from other compounds is carried out using gel permeation chromatography with Bio-Beads SX-3. Dimethoate is determined by capillary gas chromatography with a nitrogen-phosphorus detector. Detection limits are 10, 30 and 130ppt for surface water, waste water and soil/sediment respectively. Recoveries are 70.6–75.2% with standard deviations between 5.4 and 9.2%.

Effect of Toxogonin and P2S on the Toxicity of Carbamates and Organophosphorus Compounds

Toxogonin (80 mg/kg intraperitoneally) given 15 min. prior to the administration of organophosphorus insecticides dimethoate, malathion, parathion and azinphos-methyl, organophosphorus warfare agents soman and tabun, or carbamates physostigmine, pyridostigmine and aldicarb, reduced the toxicity in mice of these agents by increasing their LD50 dose 1.5-3 fold. The toxicity of the carbamate insecticide carbaryl, however, was significantly increased by toxogonin. Similar results were obtained for P2S (150 mg/kg intraperitoneally) with respect to the toxicity of dimethoate, soman and pyridostigmine, whereas no effect could be detected on the toxicity of tabun. Only a slight reduction in the toxicity of physostigmine was observed. The acetylcholinesterase activity in erythrocytes, cerebrum and diaphragm of surviving mice 20 hours after organophosphate intoxication was similar both in toxogonin and P2S treated animals and untreated animals.

Effect of phenobarbital on the toxicity of several organophosphorus insecticides

The toxicity of the organophosphorus insecticides dimethoate, O,O-dimethyl S-( N-methylcarbamoylmethyl) phosphorodithioate; phosphamidon, dimethyl phosphate, ester with 2-chloro- N,N-diethyl-3-hydroxy-crotonamide; Bidrin, dimethyl phosphate, ester with cis-3-hydroxy- N,N-dimethylcrotonamide; and their N-dealkylated derivatives was compared in mice. The toxicity of dimethoate to mice was increased from an LD 50 of 198 mg/kg to 58.5 mg/kg by pretreatment of mice for 3 days with 75 mg/kg of sodium phenobarbital per day. The toxicity of phosphamidon, Bidrin, and their N-dealkylated derivatives was decreased by approximately one-half by the same pretreatment with phenobarbital.