Chlorpyrifos Methyl Research Articles

Metamaterial-Free Flexible Graphene-Enabled Terahertz Sensors for Pesticide Detection at Bio-Interface

There is an increasing recognition that terahertz (THz) spectroscopy can be used for high-sensitivity molecular sensing. Therefore, in recent years, much work has been devoted to developing flexible, compact, and high-sensitivity THz sensors. However, most designs employ metamaterials, which require complicated, and often expensive, fabrication procedures. Also, the metamaterial structures create a gap between the sensor surface and the target surface, which decreases the effective contact area between them, resulting in reduced sensing performance. Here, we fabricated a metamaterial-free graphene-based THz sensor with user-designed patterns for sensing at bio-interfaces. External molecules can strongly interact with π electrons in graphene, which moves the Fermi level and changes the amount of THz absorption. We used this sensor to successfully detect chlorpyrifos methyl with a limit of detection at 0.13 mg/L. We also detected pesticide molecules of a concentration of 0.60 mg/L on the surface of an apple, revealing the flexibility of this sensor. The flexible graphene THz sensor showed high sensing stability and robustness over 1000 cycles of bending. These results show that our graphene-based thin-film sensors are easy to fabricate, flexible, versatile, and suited for a wide range of sensing applications.

Optimization of a Simplified and Effective Analytical Method of Pesticide Residues in Mealworms (Tenebrio molitor Larvae) Combined with GC-MS/MS and LC-MS/MS.

An effective analytical method was optimized for residues including chlorpyrifos–methyl, deltamethrin, fenoxanil, thiobencarb and fludioxonil in mealworms, the larval form of Tenebrio molitor. They are listed for pest control during wheat cultivation and can be found in wheat-bran feed for growing mealworms in South Korea. Analytes were extracted using acetonitrile and salt packet. Four clean-up methods ((1) MgSO4 + 25 mg PSA + 25 mg C18; (2) MgSO4 + 50 mg PSA + 50 mg C18; (3) EMR-lipidTM tube; and (4) 10 mL n-hexane) were investigated and the method (1) was selected due to its robustness. Low-temperature precipitation of fat and proteins improved the recoveries. Recoveries from the Method (1) were satisfying with 70–120% with <20% relative SD at a spiking level of 0.01 mg/kg. With the simultaneous sample preparation, fenoxanil, thiobencarb and fludioxonil were analyzed by liquid chromatography tandem mass spectrometry (LC–MS/MS) and chlorpyrifos–methyl and deltamethrin by gas chromatography tandem mass spectrometry (GC–MS/MS). Quantification limits for LC–MS/MS and GC–MS/MS were 0.5 and 2.5 μg/L, respectively. No pesticides of interest were detected in 30 real samples collected across the nation. However, the data can be provided for establishing maximum residue limits for the pesticides in mealworms in response to the positive list system.

Qualitative enzymatic detection of organophosphate and carbamate insecticides

In this study, new polymers containing amides (TrisPS-Ntaa, and TrisPS-Ntaa-Fc) were synthesized by condensation reaction for qualitative identification of insecticides. The synthesized polymers, including amides were investigated by infrared spectroscopy (IR), scanning electron microscopy-energy dispersion X- ray spectrometry (SEM-EDX), and gel permeation chromatography (GPC). Then, acetylcholinesterase enzyme (AChE) was covalently immobilized on these polymers to improve properties (including activity, reusability, and storage stability). Accordingly, organophosphate (malathion, acephate, chlorpyrifos methyl) and carbamate (carbofuran, methiocarb, methomyl), which are used to prevent harmful organisms in some agricultural products were enzymatically determined based on their inhibitory activity on AChE.

Magnetic Mesoporous Silica Composite for Enhanced Preconcentration of Selected Organophosphorus Pesticides in Fruits

In the present work, MCM-41 coated magnetic particles (Fe3O4-MCM-41) composite was synthesized and employed as an effective adsorbent in magnetic solid phase extraction (MSPE) of three selected organophosphorus pesticides (OPPs) namely chlorpyrifos, diazinon and parathion methyl from grape and strawberry samples prior to high performance liquid chromatography with UV detection (HPLC-UV). The synthesized sorbent was physicochemically and morphologically characterized via Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and N2 adsorption analysis. The main parameters on the extraction efficiency of selected OPPs, including extraction time, desorption solvent, desorption time, and sorbent dosage, were thoroughly optimized. Compared to MCM-41 sorbent, the newly synthesized Fe3O4-MCM-41 adsorbent shows a linear response (0.1-5.00 mg L–1) with good determination coefficients ranging from 0.9900 to 0.9980, low limits detection (LODs), 0.02-0.15 mg L–1 and low limit quantifications (LOQs), 0.06-0.40 mg L–1. The precision as relative standard deviation (%RSD) of the proposed MSPE method was studied at low and high concentration (0.1-5.0 mg L–1) based on intra-day (1.0 to 6.0%, n = 3) and inter-day (1.0 to 7.0%, n = 3), respectively. Fruit matrices were used to assess the field applicability of the sorbents. Comparatively, Fe3O4-MCM-41 achieved excellent percent recovery (85–120%) compared to the MCM-41 (70–110%). The result revealed that the Fe3O4-MCM-41 composite was efficient sorbent with good capability for the preconcentration of selected OPPs from fruit samples.

Identification of Pesticide Residues and Prediction of Their Fate in Agricultural Soil

Fourteen pesticides were screened and determined through quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction process combined with GC-MS/MS in arid agriculture soil. The aims of the current investigation were to account the occurrence of organochlorine (OCP) and organophosphates (OPP) pesticide residues as well as other groups of pyrethroids (PYRs), carbamates, and biopesticides using a combined of QuEChERS and GC-MS/MS techniques in agriculture soils at Al-Kharj region, Saudi Arabia, and to investigate correlation between pesticide losses in soils and some physicochemical characteristics of pesticides including an octanol-water coefficient partition (Kow) and the vapor pressure (Vp). Prediction of pesticide fate by considering both pesticide and soil physio-chemical properties will facilitate the management of pesticide application and minimize the hazards of environmental pollution. The fate of pesticide residue in soils is generally controlled by soil/air exchange, water interaction, and biodegradation. The results indicated that 14 pesticide residues were measured in collected samples of various soils, spinosad, chlorpyrifos methyl, dimethoate, chlorpyrifos, lindane (γ-HCH), permethrin, and methomyl which were the most abundant sources of contamination in the studied region. p,p-DDT, o,p-DDT, bifenthion, β-cyfluthrin, and methidathion were less commonly detected. Single parameter least squares regression equations (sp-LSRE) for Vp and Kow against the loss of each pesticide residue showed a significant change in concentration levels (p < 0.05) between the two seasons. The results showed that vapor pressure and octanol-water partition coefficient data are not enough to model pesticide residue losses in arid low organic carbon soil. More soil-related data is needed to describe the dissipation mechanisms of these pesticide residues in the region.

Revisiting the Tropospheric OH-Initiated Unimolecular Decomposition of Chlorpyrifos and Chlorpyrifos-Methyl: A Theoretical Perspective.

Based on density functional theory (DFT) electronic structure calculations with dispersion correction, we propose new reaction pathways in which no extra reaction step is necessary to account for the formation of 3,5,6-trichloro-2-pyridynol (TCP) within the process of tropospheric OH-initiated unimolecular decomposition of chlorpyrifos (CLP) and chlorpyrifos-methyl (CLPM). Chlorpyrifos and its analogous compound are among the most used organophosphorus pesticides worldwide, and their unimolecular decomposition in the troposphere is a dominant process of removal in the gas phase. The reaction pathways that we put forward have turned out to be the most exergonic ones among the three possible routes for the attack of the hydroxyl radical to the thiophosphoryl (P═S) bond of both CLP and CLPM. The results showed that the reaction is thermodynamically controlled with the formation of P-bonded adducts via a six-membered ring. The unimolecular decomposition of such reactive intermediates takes place with small energy barriers (less than 3 kcal mol-1) and is distinguished by hydrogen transfer to the nitrogen atom of the aromatic ring, resulting in the formation of 3,5,6-trichloro-2-pyridinol (TCP) and dialkyl phosphate radical (DAP·) product complexes in a single step.

Assessment of human exposure to selected pesticides in Norway by wastewater analysis

Pesticides offer many benefits for humanity and agriculture, but at the same time pose a potential risk to human health because of their widespread use and high biological activity. Human biomonitoring (HBM) studies are the main tool to investigate human exposure to pesticides and other chemicals, but face limitations such as sampling biases, long time to complete and high costs. Wastewater-based epidemiology (WBE) is an alternative approach that is centered on the chemical analysis of biomarkers of (pesticide) exposure in urban wastewater. The present study used WBE to assess human exposure to selected classes of pesticides, triazines, pyrethroids and organophosphates, in Norway. Untreated wastewater samples were collected from four cities, covering approximately 20% of the Norwegian population. The highest population weighted mass loads (mg/day/1000 inhabitants) were for alkyl phosphates and the lowest for triazines. Some differences were observed for the two metabolites, 2-isopropyl-6-methyl-4-pyrimidinol (IMPY) and 3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (DCCA), which were higher in the rural city of Hamar. WBE figures were comparable with HBM findings for the specific metabolite of chlorpyrifos and chlorpyrifos methyl (3,5,6-trichloro-2-pyridinol; TCPY) but were different for the alkyl phosphates. Pyrethroid intake was calculated and was lower than the acceptable daily intake in all the cities, indicating low risk for human health. This is the most extensive WBE study performed to date to assess national human exposure to pesticides. This study demonstrated that WBE has the potential to be a useful complementary biomonitoring tool for assessing population-wide exposure to pesticides, overcoming some of the limitations of HBM.

Mixture toxicity of chlorpyrifos-methyl, pirimiphos-methyl, and nonylphenol in Atlantic salmon (Salmo salar) hepatocytes

Pesticide formulations typically contain adjuvants added to enhance the performance of the active ingredient. Adjuvants may modify the bioavailability and toxicity of pesticides. In this study, the aim was to examine to which degree nonylphenol (NP) may interfere with the toxicity of two organophosphorus pesticides found in aquafeeds, chlorpyrifos-methyl (CPM) and pirimiphos-methyl (PPM). Atlantic salmon liver cells were exposed to these compounds singly or in combinations for 48 h using 3D cell cultures. Cytotoxicity, gene expression (RT-qPCR), and lipidomics endpoints were used to assess toxicity. The dose-response assessment showed that NP was the most toxic compound at equimolar concentrations (100 μM). Shotgun lipidomics pointed to a general pattern of elevated levels of saturated 18:0 fatty acids and declined levels of 18:1 monounsaturated fatty acids by the combined treatment. All three compounds had a distinct effect on membrane phospholipids, in particular on phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Lipid species patterns predicted inhibited stearoyl CoA desaturase (SCD) activity and increased Δ6 desaturase (D6D) activity in co-treated cells. While all three compounds alone mitigated increased triacylglycerol (TAG) accumulation, combined treatment resulted in lower total TAG in the cells. Multivariate analysis with PLS regression showed significant combined effects for nine genes (d5d, d6d, scd, srebf2, vtg, esr1, cyp1, ugt1a, and cat) and four lipid species (FFA 22:5, LPC 18:0, TAG52:1-FA16:0, and TAG52:1-FA18:0). In summary, this study demonstrates that the adjuvant can be the main contributor to the toxicity of a mixture of two organophosphorus pesticides with relatively low toxicity in fish cells.

Magnetic Solid Phase Extraction using Magnetic Mesoporous Silica for Preconcentration of Organophosphorus Pesticides

The present study describes the synthesis, characterization and application of two mesoporous silica material based coated magnetic nanoparticles namely Fe3O4-SBA-15 and Fe3O4-MCM-41 for the simultaneous preconcentration of three selected organophosphorus pesticides (OPPs) namely chlorpyrifos, diazinon and parathion methyl from water samples. The resultant sorbent material was physicochemically and morphologically characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and N2 adsorption analysis. OPPs pesticides extraction efficiency of two sorbents were evaluated through magnetic solid phase extraction (MSPE) using high performance liquid chromatography with ultraviolet detector (HPLC/UV). The main parameters affecting the sorbent efficiency namely extraction time and desorption solvent were optimized. Comparatively, Fe3O4-SBA-15 achieved excellent percent recovery (97.5%) compared to the Fe3O4-MCM-41 (87.1%) under optimum condition respectively. The result appealed that the Fe3O4-SBA-15 composite was efficient sorbent with good capability for the preconcentration of selected OPPs from water samples.

Association of prenatal pesticide exposures with adverse pregnancy outcomes and stunting in rural Bangladesh

BackgroundPesticide exposure during pregnancy is thought to adversely affect fetal growth, which in turn may impact child growth, but results have been inconsistent across studies and few have explored these effects in developing countries. ObjectivesTo quantify urinary concentrations of pesticide biomarkers in early pregnancy (<16 weeks’ gestation), and to estimate the association of these concentrations with preterm birth, low birth weight, small for gestational age, and stunting at ~1 and 2 years of age. MethodsEight pesticide biomarkers were quantified in urine collected from 289 pregnant women (aged 18–40 years) participating in a birth cohort study in Bangladesh. Anthropometry measurements were conducted on the index child at birth and approximately 1 and 2 years of age. A directed acyclic graph was used to identify minimal sufficient adjustment sets. Log-binomial regression was used to estimate the relative risk (RR) with 95% confidence intervals (CI). Results3,5,6-trichloro-2-pyridinol (TCPY), a metabolite of chlorpyrifos and chlorpyrifos methyl, and 4-nitrophenol, a metabolite of parathion and methyl parathion, were detected in nearly all women with geometric mean (95% CI) values of 3.17 (2.82–3.56) and 18.66 (17.03–20.46) µg/g creatinine, respectively. 3-phenoxybenzoic acid (3-PBA), a non-specific metabolite of several pyrethroids, and 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPY), a diazinon metabolite, were detected in 19.8% and 16.1% of women, respectively. The remaining four pesticide biomarkers were detected in <10% of women. Women in the highest quartile of 4-nitrophenol were more than 3 times more likely to deliver preterm than women in the lowest quartile: unadjusted RR (95% CI), 3.57 (1.65, 7.73). Women in the highest quartile of 4-nitrophenol were also at increased risk of having a child born small for gestational age: RR (95% CI) adjusted for household income, maternal education, and maternal total energy and meat intake, 3.81 (1.10, 13.21). Women with detectable concentrations of IMPY were at increased risk of having a child born with low birth weight compared to women with non-detectable concentrations: adjusted RR (95% CI), 2.13 (1.12, 4.08). We observed no association between any of the pesticide biomarkers and stunting at 1 or 2 years of age. DiscussionExposure to the insecticides parathion and diazinon during early pregnancy may increase the risk of adverse birth outcomes.

Effects of Agricultural Pesticides in Aquafeeds on Wild Fish Feeding on Leftover Pellets Near Fish Farms.

Screening has revealed that modern-day feeds used in Atlantic salmon aquaculture might contain trace amounts of agricultural pesticides. To reach slaughter size, salmon are produced in open net pens in the sea. Uneaten feed pellets and undigested feces deposited beneath the net pens represent a source of contamination for marine organisms. To examine the impacts of long-term and continuous dietary exposure to an organophosphorus pesticide found in Atlantic salmon feed, we fed juvenile Atlantic cod (Gadus morhua), an abundant species around North Atlantic fish farms, three concentrations (0.5, 4.2, and 23.2 mg/kg) of chlorpyrifos-methyl (CPM) for 30 days. Endpoints included liver and bile bioaccumulation, liver transcriptomics and metabolomics, as well as plasma cholinesterase activity, cortisol, liver 7-ethoxyresor-ufin-O-deethylase activity, and hypoxia tolerance. The results show that Atlantic cod can accumulate relatively high levels of CPM in liver after continuous exposure, which is then metabolized and excreted via the bile. All three exposure concentrations lead to significant inhibition of plasma cholinesterase activity, the primary target of CPM. Transcriptomics profiling pointed to effects on cholesterol and steroid biosynthesis. Metabolite profiling revealed that CPM induced responses reflecting detoxification by glutathione-S-transferase, inhibition of monoacylglycerol lipase, potential inhibition of carboxylesterase, and increased demand for ATP, followed by secondary inflammatory responses. A gradual hypoxia challenge test showed that all groups of exposed fish were less tolerant to low oxygen saturation than the controls. In conclusion, this study suggests that wild fish continuously feeding on leftover pellets near fish farms over time may be vulnerable to organophosphorus pesticides.

Enzyme immobilization on polymeric microspheres containing Schiff base for detection of organophosphate and carbamate insecticides

In this study, polymeric microsphere including Schiff base TrisPS-pyr and TrisPS-pyr-Pt(II) were obtained by condensation reaction for improve the enzymatic properties of acetylcholinesterase (AChE) and detect harmful insects. Structures of the synthesized compounds were characterized by spectroscopic methods such as FT-IR, UV–Vis, SEM-EDX, GPC. Acetylcholinesterase enzyme was immobilized to these new polymeric microspheres and their properties such as activity, reusability and storage stability were investigated. In addition, the qualitative determination of carbamate [2,3-dihydro-2,2-dimethyl-7-benzofuranol N-methylcarbamate (carbofuran), 4-methylthio-3,5-xylyl methylcarbamate (methiocarb) and S-methyl-N- (methylcarbamoyl oxy) thioacetamide (methomyl)] and organophosphate [diethyl (dimethyl thiophosphoryl) succinate (malathion), O, S-dimethyl phosphoramidothioate acetyl (acephate) and chlorpyrifos methyl] insecticides by the immobilized enzyme was performed. The reason for the selection of these pesticides is because they are widely used to combat pests of agricultural products (hazelnut, corn, sugar beet, apple and tobacco) which are grown in our region.

Insecticide resistance profiles of Anopheles gambiae s.l. in Togo and genetic mechanisms involved, during 3-year survey: is there any need for resistance management?

BackgroundMalaria, one of the world’s greatest public health challenges, is an endemic disease with stable transmission in Togo. Combating malaria requires an effective vector control. This study provides temporal data on insecticide resistance status in the major malaria vector Anopheles gambiae sensu lato (s.l.) from Togo.MethodsTwo to 5 days old females of An. gambiae s.l., originating from three localities (Baguida, Kovié, Kolokopé) were subjected to insecticide-impregnated papers during 3 years (2012, 2013, 2016) as follows: organochlorides (4% DDT), pyrethroids (0.05% deltamethrin, 0.75% permethrin, 0.05% lambdacyhalothrin), carbamates (0.4% bendiocarb and 0.1% propoxur), and organophosphates (5% malathion, 0.4% chlorpyrifos methyl, 1% fenitrothion) following the WHO standard protocol. Dead and surviving mosquitoes were stored separately in Eppendorf tubes containing silica gel for DNA extraction, species identification, and kdr and ace-1 genotyping.ResultsKnockdown times (KDT50 and KDT95) were high in An. gambiae s.l. The lowest KDTs were recorded at Baguida in 2013 for deltamethrin (KDT50 = 24.7, CI [22.4–27.12] and KDT95 = 90.78, CI [76.35–113.49]). No KDTs were recorded for DDT and in some instances for permethrin. In general, An. gambiae s.l. was resistant to most of the four classes of insecticides during the survey periods regardless of locality and year, except to chlorpyrifos methyl. In some instances, mosquitoes were fully susceptible to fenitrothion (Kolokopé: 100% and Kovié: 98.05%, CI [95.82–100.26]) and malathion (100% at both Kolokopé and Kovié) in 2013, and malathion only (Kolokopé; 100%) in 2016. Anopheles coluzzii, An. gambiae and Anopheles arabiensis were the three sibling species identified at the three localities with some hybrids at Baguida (2013), and Kovié (2012 and 2016), respectively. Anopheles gambiae was relatively dominant (61.6%). The kdr 1014F allele frequency was > 0.9 in most of the cases, except at Kolokopé (f (1014F) = 0.63, CI [0.55–0.71]) in 2013. The kdr 1014S allele frequency was below 0.02. The highest ace-1 frequencies were identified in An. gambiae at Baguida (2012: 0.52, CI [0.34–0.69] and 2013: 0.66, CI [0.46–0.86]).ConclusionThe resistance status is worrying in Togo and should be considered in future malaria vector resistance management programmes by decision-makers.

Initial Survey of Pesticide Residues in Baby’s food and The Exceedances of Maximum Residual Limit (MRLs)

Remnant or by-products of pesticides arising from the field or storage pest applications sometimes find their ways into the final food produce. They are called pesticide residues. Studies have shown the occurrence of these residues in various food produce including tea, fruits, vegetables, beverages and even baby and infants food. With about 800 pesticides permitted for use globally, residue becomes almost inevitable. For the infants, and young children, the health effects at that critical developmental phase could be severe and irreversible. This is because quantitative and qualitative differences in pesticides absorption, metabolism, detoxification and excretion relative to adults, make the children more susceptible due to much higher kg per body weight. This study assessed the pesticide residues in the common baby food and compared with international maximum residual limits. Using gas chromatography with mass spectrometric detection, five infant and baby’s food tagged A, B, C, D and E were analyzed. In all, multiple residues involving various twenty five pesticides were detected in the five food products. Fifteen of the pesticides including resmethrin (0.0002 µg/g), chlorpyrifos (0.0002 µg/g), allethrin (0.0004 µg/g), piperonyl butoxil (0.0003 µg/g), cyfluthrin (0.0001 µg/g), chlorpyrifos methyl (0.0002 µg/g), diclorovos (0.0001 µg/g), fluridane (0.0002 µg/g), fludioxonil (0.0002 µg/g and 0.0001 µg/g), lindane (0.0002 µg/g), daminozide (0.0002 µg/g), methy paraoxon (0.0001 µg/g) and DDE.p.p (0.0002 µg/g and 0.0001 µg/g) were above the WHO and USEPA maximum residual limits. The potential interaction of different mixtures for those pesticides that are below international residual limits as well as the occurrence of those at concentrations above these standards called for serious concerns, giving their critical effects on nervous, endocrine and immune systems. Further studies must be encouraged to determine the status of residue in other foods and the elimination of these residues, particularly in the infants and baby’s food.

Toward Heterogeneously Catalyzed Detoxification of Phosphotriesters: Insights from Kinetics and Theoretical Calculations

A mixed Mg2+/Al3+ oxide featuring an incipient spinel phase was employed in the catalytic decomposition of a range of phosphate triesters, including the neurotoxic biocide chlorpyrifos methyl O-analog, with estimated catalytic effects up to 104-fold. The target reaction, namely, the transesterification with 1-propanol, was conveniently chosen as a means to convert toxic organophosphorus substrates into trialkyl phosphates structurally related to a family of flame retardants. Catalytic efficiency depends upon the stereo-electronic properties of the substrate, with both leaving group ability and geometric factors displaying pivotal effects on the rate constants. To evaluate the adsorption of 1-propanol/propoxide and the phosphotriester methyl paraoxon over the MgAl2O4(100) surface, density functional theory calculations with periodic boundary conditions were performed, which showed that the most probable reactants’ conformation prior to the reaction is such that propoxide is bound to a Mg2+ center with a ju...

Terahertz biosensing with a graphene-metamaterial heterostructure platform

Terahertz (THz) radiation attracted great interest in the fields of material characterization, nondestructive security screening, clinical diagnostics, and identification of chemicals and molecules. Label-free THz sensing of trace amount of targets including biomolecules is promising because of their rich spectral fingerprint in this electromagnetic region; however, improving the sensitivity remains to be a challenge, partially due to the limitations of THz sources and detectors. The resonantly enhanced electromagnetic fields in metamaterials and metasurfaces offer a potentially viable solution, although highly complicated decoration process is still needed for biosensing on the surface of metamaterials. Here we demonstrate a simple biosensing platform by integrating a monolayer graphene on a THz metamaterial absorber cavity, where the introduction of sensing targets results in a large change of the metamaterial resonant absorption (or reflection) because of their strong interaction with graphene. We experimentally show its ultrahigh sensitivity through detecting trace amount of chlorpyrifos methyl down to 0.2 ng. Using simple decoration steps and utilizing DNA to capture thrombin, we further show the feasibility of this platform serving as a sensitive biosensor.

Fitness costs of infection with Serratia symbiotica are associated with greater susceptibility to insecticides in the pea aphid Acyrthosiphon pisum.

Aphids are agricultural pests that damage crops by direct feeding and by vectoring important plant viruses. Bacterial symbionts can influence aphid biology, e.g. by providing essential nutrients or facilitating adaptations to biotic and abiotic stress. We investigated the pea aphid (Acyrthosiphon pisum Harris) and its commonly associated secondary bacterial symbiont Serratia symbiotica to study the effect of this symbiont on host fitness and susceptibility to the insecticides imidacloprid, chlorpyrifos methyl, methomyl, cyantraniliprole and spirotetramat. There is emerging evidence that members of the genus Serratia can degrade and/or detoxify diverse insecticides. Therefore, we hypothesized that S. symbiotica may promote resistance to these artificial stress agents in aphids. Our results showed that Serratia-infected aphids were more susceptible to most of the tested insecticides than non-infected aphids. This probably reflects the severe fitness costs associated with S. symbiotica, which negatively affects development, reproduction and body weight. Our study demonstrates that S. symbiotica plays an important role in the ability of aphid hosts to tolerate insecticides. These results provide insight into the potential changes in tolerance to insecticides in the field because there is a continuous and dynamic process of symbiont acquisition and loss that may directly affect host biology. © 2018 Society of Chemical Industry.

Analysis of emergency laboratory parameters of various poisonings in tertiary care teaching hospital

Aim: India is predominantly an agricultural country; pesticides and insecticides are abundantly used during cultivation. The adult mortality rate due to mixed drug poisoning in rural south India is 0.97/1000 persons/year. Only 70%–80% of patients admitted to hospitals survive. The present study is undertaken to identifying the association of laboratory parameters with different poisoning etiologies which may help in predicting the need for ventilator support to reduce the mortality by timely entry into emergency department (ED). Materials and Methods: A prospective study on the mixed poisoning of 964 cases was done in the ED at Narayana Medical College Hospital, Nellore, Andhra Pradesh, for 8 years (from 2009 to Jan 2016). Clinical and laboratory data were recorded for all patients on admission (time 0) and 24 h later (time 24). The severity of patients graded according to the Glasgow Coma Scale (GCS) classification. Results: Among 964 patients, in the present study, the majority of the patients in the study group were males, and higher age group affected was 40–50 years. Agricultural farmers and rural residents were highly consumed pesticides. In the study, ingestion poisoning 95% had common occurrences than inhalation poisoning 5%. In severity categorization, we observed that 28.4% of patients were in mild condition, 55.6% in moderate, and 16% in severe. Mean, GCS scoring system was statistically significant between time 0 and time 24 in the survivors. Low GCS at admission was vulnerable for ventilator support. Cholinesterase activity was measured significantly depressed in the Grade 1, 2, and 3. Conclusions: The present study concludes that the need for ventilatory support in organophosphoros poisoning was significantly more in patients who consumed chlorpyrifos methyl parathion compounds, airway edema secondary to hair dye poisoning, presence of cholinergic crisis, GCS score of

Residues of pesticides and metabolites in chicken kidney, liver and muscle samples from poultry farms in Dar es Salaam and Pwani, Tanzania

The concentrations of organochlorine and organophosphorus pesticides and metabolites were investigated in chicken kidney, liver and muscle samples obtained from chickens collected from four poultry farms in Dar es Salaam and Pwani regions in Tanzania. The samples were extracted by solid dispersion using cyclohexane:ethyl acetate. The extracts were cleaned by adsorption column chromatography. The analytes were determined using gas chromatography-mass spectrometry (GC–MS). The concentrations of total DDT, total endosulfan and total HCHs in the samples ranged from 0.71 to 26, 0.3 to 7.9 and 0.02–10.4 mg/kg lipid weight (lw), respectively. The highest concentrations of aldrin, dieldrin, chlorpyrifos, fenitrothion and pirimiphos methyl were 5.5, 4.8, 9.7, 5.6 and 7.8 mg/kg lw, respectively. The highest concentrations of the contaminants were found in the kidney and liver samples. The sites in Dar es Salaam showed the highest concentrations of the compounds. Most of the concentrations were above the maximum residue limits (MRLs) indicating risks and concerns for livestock and public health.

Dietary pesticide chlorpyrifos-methyl affects arachidonic acid metabolism including phospholipid remodeling in Atlantic salmon (Salmo salar L.)

The pesticide chlorpyrifos-methyl (CLP-m) has been identified in plant ingredients intended for aquaculture feed production. To investigate systemic effects of CLP-m with emphasis on lipid metabolism, post-smolt Atlantic salmon were fed in duplicate (n=2) either diets with no CLP-m (Control) or CLP-m at different concentrations (0.1, 1.0 or 8.0mgkg−1) for a total of 67days (Low, Medium, High). Fish in all groups almost doubled their weight during the feeding trial from 262±26g (mean±SD) to 465±64g (overall mean), with no significant effects on any growth parameters. There was a significant dose-dependent inhibition of plasma cholinesterase activity (BuChE) after 67days. The CLP-m biotransformation metabolite, TCP was detected in liver and bile, with low levels of the parent compound in the organs. Spleen somatic index decreased significantly with increasing dietary CLP-m intake. Hematocrit (%) decreased linearly with increasing dietary exposure to CLP-m after 30days of exposure, but this decrease was less at 67days of exposure. A significantly reduced content of arachidonic acid (ARA 20:4n−6), accompanied by a significantly increased content of the saturated fatty acid, palmitic acid (PA 16:0), was observed in liver phospholipids (PLs) with increasing dietary content of CLP-m. Major effects were seen on the PL classes in liver which showed a significantly decreased absolute content, possibly indicating inhibition of PL remodeling pathways or other membrane perturbation effects from CLP-m exposure. In conclusion, this study shows that the pesticide CLP-m is a relatively potent toxicant in Atlantic salmon, especially affecting liver PLs and ARA metabolism.