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Contamination with pesticides has inflicted substantial harm on human health; therefore, developing rapid, ultra-sensitive, and non-labelling simultaneous detection methods for multiple pesticides is necessary. In this study, we demonstrated that α-hemolysin (α-HL) nanopore sensor can detect and discriminate organophosphorus pesticides of phoxim and omethoate in a single nanopore without requiring labels of the probes or purification of the pesticides in real samples. Aptamers specifically recognise and bind pesticides to obtain pesticide-aptamer complexes that produce characteristic current signals while passing through the nanopore. Phoxim and omethoate were accurately distinguished by a portable instrument within minutes, and their detection sensitivity was up to the femtomole level, whether detected alone or simultaneously. The detection limits of phoxim and omethoate were 8.13 × 10−16 M and 4.16 × 10−15 M. The recoveries of phoxim and omethoate from pear, tomato, and cucumber samples were 82.0–107.0 % and 81.9–118.3 % respectively, with coefficient of variable below 8.0 %. • The α-hemolysin nanopore sensor can detect and discriminate phoxim and omethoate in real samples. • The sensor enables simultaneously detection of phoxim and omethoate within minutes. • The detection limit of the sensor is up to the femtomole level. • The sensor is as reliable and accurate as UHPLC-MS/MS. [ABSTRACT FROM AUTHOR]

Phoxim, extensively utilized in agriculture as an organothiophosphate insecticide, has the potential to cause neurotoxicity and pose human health hazards. In this study, an electrochemical enzyme biosensor based on Ti 3 C 2 MXene/MoS 2 @AuNPs/AChE was constructed for the sensitive detection of phoxim. The two-dimensional multilayer structure of Ti 3 C 2 MXene provides a robust framework for MoS 2 , leading to an expansion of the specific surface area and effectively preventing re-stacking of Ti 3 C 2 MXene. Additionally, the synergistic effect of self-reduced grown AuNPs with MoS 2 further improves the electrical conductivity of the composites, while the robust framework provides a favorable microenvironment for immobilization of enzyme molecules. Ti 3 C 2 MXene/MoS 2 @AuNPs electrochemical enzyme sensor showed a significant response to phoxim in the range of 1 × 10−13 M to 1 × 10−7 M with a detection limit of 5.29 × 10−15 M. Moreover, the sensor demonstrated excellent repeatability, reproducibility, and stability, thereby showing its promising potential for real sample detection. • AuNPs was assembled onto Ti 3 C 2 MXene/MoS 2 substrates by self-reduction for sensitive detection of phoxim in fruit. • The electrochemical biosensor had a wide linear range of phoxim detection with a LOD of 5.29 × 10−15 M. • The electrochemical biosensor has good stability, selectivity and reproducibility. [ABSTRACT FROM AUTHOR]

Nanopolystyrene (NP) and phoxim (PHO) are pervasive environmental contaminants that pose a significant threat to the health of aquatic organisms, prompting widespread concern among researchers and the public alike. The hepatopancreas play important roles in the Chinese mitten crab (Eriocheir sinensis), such as digestion, absorption and detoxification. This study assessed the hepatopancreatic toxicity caused by the exposure of Eriocheir sinensis to environmentally relevant concentrations of NP and/or PHO. After a 21-day exposure period, NP (1.0 × 1010 particles/L) and PHO (24 μg/L) exposure resulted in reduced number of blister-like, resorptive, and fibrillar cells and an elevation in lipid droplets within the hepatopancreas compared to the control group. Furthermore, trypsin and lipase activity decreased, amylase activity increased, and a significantly decrease in the expression of digestion-related genes, including CHT , CarL , and CarB , suggested impairment in both digestive and metabolic functions. The marked upregulation of key genes, including PPARγ , GYK , PEPCK , and SCD , as well as key metabolites such as 4-methylzymosterol-carboxylate, zymosterone, lathosterol, 7-dehydro-desmosterol, vitamin D2, 24-methylene-cycloartanol, 5-dehydroepisterol, and sitosterol in the lipid metabolic pathway, showed that the peroxisome proliferator-activated receptor (PPAR) and steroid biosynthesis signaling pathways were highly affected by exposure to NP and/or PHO. These findings indicated that exposure to NP and/or PHO might adversely affect the hepatopancreatic physiological homeostasis in E. sinensis by causing tissue damage and interfering with digestive and metabolic functions. Our results provide ecotoxicological insights into the effects of nanopolystyrene and/or phoxim exposure on the digestive function of Eriocheir sinensis. [Display omitted] • Nanopolystyrene and/or phoxim exposure caused tissue damage. • Nanopolystyrene and/or phoxim exposure affects digestive function. • Nanopolystyrene and/or phoxim might disrupt hepatopancreatic energy metabolism. [ABSTRACT FROM AUTHOR]

• This work provides a novel plasma activated water strategy for reduction of pesticide. • The acidic environment and oxidation capacity are beneficial to the phoxim reduction. • Plasma activated water treatment will not significantly affect the quality of grapes. • One possible degradation pathway of phoxim is proposed. • The strategy provides a potential possibility for large-scale industrial production. In this study, we propose a novel strategy, plasma activated water (PAW) to reduce pesticide residues on agricultural products. To validate its feasibility and effectiveness, we employee high-performance liquid chromatography (HPLC) to detect phoxim on grapes. HPLC results suggest that the reduction of phoxim on grapes achieve 73.60% after treated 10 min by PAW prepared 30 min, and the concentration of phoxim decreased significantly (p < 0.05) with the preparation time of PAW. Furthermore, HPLC-MS analysis shows that the reduction effect of phoxim by PAW is dominated by the degradation of phoxim. Combined with analyzing the physicochemical properties of PAW, one possible degradation pathway is proposed under the present experimental conditions, mediated by reactive oxygen and nitrogen species. The acidic environment (pH < 3) and high oxidation capacity (ORP > 500 mV) are suggested to be a benefit to the reduction of phoxim. Besides, the experimental results regarding color, firmness, sugar, vitamin C, and superoxide dismutase of grapes demonstrate that the PAW treatment will not significantly affect the quality of grapes. In conclusion, phoxim pesticide residues on grapes could be effectively reduced by the PAW strategy and without a significant (p < 0.05) effect on grapes quality. [ABSTRACT FROM AUTHOR]

• A novel MIP/perovskite CsPbBr 3 QDs fluorescence sensor for phoxim detection. • A siloxane functional monomer with two kinds of functional groups has been synthesized. • The MIP/QDs were synthesized by slowly hydrolyzing the organosilicon monomers in situ. • The QDs were encapsulated in an imprinted silica matrix, which improved the stability of the QDs. In spite of the high-brightness of perovskite quantum dots (QDs), their instability and sensitive to oxygen and moisture are still major challenges that obstruct their analytical applications. This work demonstrates the fabrication and application of perovskite CsPbBr 3 QDs embedded in a molecularly imprinted polymer (MIP) for specific and sensitive detection of phoxim in real samples. CsPbBr3 QDs were obtained via a simple and convenient hot injection method. Based on the chemical structure of phoxim, we designed and synthesized a siloxane functional monomer with multiple functional groups to allow various types of interactions with phoxim. Next, the MIP/QDs composites were synthesized by slowly hydrolyzing the organosilicon monomers in situ. The obtained MIP/QDs composites possessed excellent selectivity for phoxim, and the imprinting factor of the optimized MIP/QDs was 3.27. Compared with previous studies regarding the detection of organophosphorus pesticides, the MIP/QDs fluorescence sensor exhibited high sensitivity and specificity. Under optimal conditions, the fluorescence quenching of the MIP/QDs had a good linear correlation for phoxim in the concentration range of 5–100 ng/mL, and with a limit of detection of 1.45 ng/mL. Finally, the method was used for the detection of phoxim in potato and soil samples, achieving recoveries of 86.8–98.2%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recombinant protein SlGSTD3 and SlGSTD4 in S. litura could metabolize phoxim and chlorpyrifos. • Recombinant vector SlGSTD3 and SlGSTD4 in S. litura both showed antioxidant activity to CHP. • The 3D structure of SlGSTD3 and SlGSTD4 in S. litura could bind to phoxim and chlorpyrifos. Glutathione S -transferases (GSTs) is one of the main detoxification enzyme systems in insects and play important roles in insecticide resistance by direct metabolism, sequestration and antioxidant activity. Several GSTs genes in Spodoptera litura , a polyphagous agricultural pest, have been demonstrated to be overexpressed and involved in organophosphates and pyrethroids resistance. Previous studies have indicated the significant overexpression of two delta class GSTs genes (SlGSTd3 and SlGSTd4) in organophosphates and pyrethroids resistant populations. Here, they were heterologous expressed, and their metabolism activity and antioxidant activity were determined. Results indicated that the recombinant protein SlGSTD3 and SlGSTD4 both showed metabolism activity to phoxim and chlorpyrifos, but not to fenvalerate, cyhalothrin or beta cypermethrin. The metabolism activity of SlGSTD3 to phoxim and chlorpyrifos is higher than that of SlGSTD4. The recombinant vector of SlGSTD3 and SlGSTD4 both showed antioxidant activity after exposure to cumene hydroperoxide. Further modeling and docking analysis indicated that the 3D structure of SlGSTD3 and SlGSTD4 were well shaped for phoxim and chlorpyrifos, and the binding affinity for phoxim was stronger than that of chlorpyrifos. Our work provides evidence that SlGSTd3 and SlGSTd4 both play roles in phoxim and chlorpyrifos resistance in S. litura. [ABSTRACT FROM AUTHOR]

Abstract: Silk gland is a major organ of Bombyx mori for the synthesis and secretion of silk protein. Phoxim exposure can be toxic to B. mori and causes a decrease of fibroin synthesis, finally affecting the silk production in industry. To study the mechanism of metabolism and detoxification of silk gland under phoxim exposure, we measured the residual quantity of phoxim in silk gland and hemolymph after phoxim exposure, and the detoxifying enzymes-related genes and enzyme activity were also investigated. Results indicated that the residual amount of phoxim existed up to 24 h in silk gland compared with that in hemolymph, suggesting that phoxim can accumulate in the silk glands within a certain time course. The transcriptional levels of PI3K/Akt genes, including Akt, Tor1, p70s6k and 4e-bp , were up-regulated by 6.919, 1.358, 10.766 and 7.708-fold, respectively. The expression of two downstream genes ( CncC and Keap1 ) was up-regulated by 1.939 and 3.373-fold, respectively. In addition, the transcriptional levels of detoxification-related genes including CYP6AB, CYP3 06A , CarE2, GST1 and GSTd1 were up-regulated by 1.731, 1.221, 1.366, 1.376 and 6.591-fold, respectively. The enzymatic activity of CYP450, CarE and GST were increased over time. These results provided possible insights into the injury of silk gland and the transcriptional response to detoxifying enzymes-related genes in silkworm after phoxim exposure. [ABSTRACT FROM AUTHOR]

In this work, Lycii Fructus as raw materials for green synthesis of fluorescent carbon dots (CDs) reduce AgNO 3 . The CDs-AgNPs were synthesized by one-step method. CDs were applied to stabilize AgNPs due to abundant functional groups on the surface of CDs. In presence of phoxim, the dispersed CDs-AgNPs get aggregated and the absorption peak with red shift from 400 nm to 525 nm, resulting in the color changed from yellow to red. Under optimized conditions, the absorbance ratio at A 525 nm /A 400 nm was related linearly to the concentrations of phoxim in the range of 0.1–100 μM. The detection limit was calculated to 0.04 μM, which is lower than maximum residue limits of phoxim in samples in China. The colorimetric sensor was successfully utilized to monitoring phoxim in environmental and fruit samples with good recoveries ranges from 87% to 110.0%. These results showed the sensor had a promising application prospect in real samples. [ABSTRACT FROM AUTHOR]

Folate metabolism pathway is mainly associated with syntheses of nucleic acids and proteins as well as DNA methylation and repair. Cytoplasmic C 1 tetrahydrofolate (C 1 -THF) synthase is a central enzyme in folate metabolism and plays an important role in C 1 -THF conversion. The full-length sequence of silkworm ( Bombyx mori ) cytoplasmic C 1 -THF synthase ( Bm C 1 -THF synthase) gene including an open reading frame (ORF) of 932 amino acid residues was cloned. Phylogenetic analysis indicated that Bm C 1 -THF synthase shares 84% and 81% identity with C 1 -THF synthase of Papilio Xuthus and Danaus plexippus , respectively. Conserved sequence analysis showed that the 330 to 710 amino acid residues of Bm C 1 -THF synthase were highly conserved among various organisms. Recombinant Bm C 1 -THF synthase protein with a molecular weight of about 105.5 kDa was expressed in E. coli cells and identified using SDS-PAGE and western blot analysis. The expression of Bm C 1 -THF synthase gene in eight silkworm tissues revealed that Bm C 1 -THF synthase gene is widely expressed in various tissues of silkworm and highly expressed in the fat body. The expression characteristics of Bm C 1 -THF synthase gene in response to oxidative stress were conducted under phoxim and high temperature (30 °C) exposure. The results showed that the transcriptional level of Bm C 1 -THF synthase gene was upregulated by 3.435-fold and 6.845-fold after phoxim and high temperature (30 °C) exposure, respectively, indicating that Bm C 1 -THF synthase gene may play a significant role in response of silkworm to oxidative stresses. [ABSTRACT FROM AUTHOR]

To control and on-site evaluate the contamination of organophosphorus pesticides, one direct sensing approach based on spontaneous fluorescence resonance energy transfer (FRET) was developed in this study. The luminescent metal-organic frameworks (LMOFs), a novel achievement of MOFs, could provide adjustable adsorption capacity and fluorescence index to scientific analysis was first employed to evaluate phoxim molecules in vegetables and fruits. Through the π-π recognition and FRET sensing between phoxim molecules and skeleton of Nu-1000 LMOFs probes, an ultra-low detection limit of 1.65 pg/L in the range of 5×10−7 to 5×10−3 mg/mL (R 2=0.998) was achieved in the presence of phoxim. Such simple and accurate LMOFs- FRET-based sensing strategy could offer valuable reference for developing sensitive FRET sensors and/or on-site evaluation approaches in the areas of food quality control and food safety. • Nu-1000 luminescent metal-organic frameworks (LMOFs) probes can directly responsive to phoxim without aptamers or enzymes and be able to differentiate from other structurally similar organophosphorus pesticides. • The π - π interaction between organic ligands and phoxim improves sensitivity, which is beneficial for the occurrence of fluorescence resonance energy transfer (FRET). The detection limit is as low as 1.65 pg/L. • A systematic and detailed calculation of FERT was conducted. • Such simple and accurate LMOFs-FRET-based sensing strategy could offer valuable reference for developing sensitive sensors and/or on-site evaluation approaches in the areas of food quality control and food safety. [ABSTRACT FROM AUTHOR]

Insect fat body is an important intermediate metabolic organ that plays an important role in protein metabolism and detoxification. In order to study the effects of TiO 2 NPs and phoxim on fat body protein synthesis through MAPK and PI3K/Akt signaling pathways in silkworms, we determined the effects of TiO 2 NPs and phoxim, alone and in combination, on fat body protein content of silkworms, analyzed the gene expression profile of the fat body, and verified the expression of characteristic genes. We found that TiO 2 NPs and phoxim alone increased the total protein content of the fat body, and up-regulated MAPK and PI3K/Akt signaling pathway genes. TiO 2 NPs up-regulated the expression of two growth and development-related genes- insulin-like peptide and neuropeptide receptor B -by 5.17 and 3.89-fold, respectively. Phoxim up-regulated the expression of detoxification genes -P450 , GST , and CarE2 . Pretreatment with TiO 2 NPs could reduce phoxim-increased total protein content and up-regulated MAPK and PI3K/Akt signaling pathway genes and detoxification genes; the activities of detoxification enzymes were consistent with the gene expression pattern. Our results showed that MAPK and PI3K/Akt signaling pathways both regulate fat body protein synthesis in silkworms, but the target proteins induced to express were different under different inducing factors. Our finding may provide a reference for investigating the mechanism of protein synthesis regulation through MAPK and PI3K/Akt signaling pathways. [ABSTRACT FROM AUTHOR]

Instead of individual ones, pesticides are usually detected in water environment as mixtures of contaminants. Laboratory tests were conducted in order to investigate the effects of individual and joint pesticides (phoxim, atrazine, chlorpyrifos, butachlor and λ-cyhalothrin) on zebrafish ( Denio rerio ). Results from 96-h semi-static toxicity test indicated that λ-cyhalothrin had the greatest toxicity to the three life stages (embryonic, larval and juvenile stages) of D. rerio with LC 50 values ranging from 0.0031 (0.0017–0.0042) to 0.38 (0.21–0.53) mg a.i. L −1 , followed by butachlor and chlorpyrifos with LC 50 values ranging from 0.45 (0.31–0.59) to 1.93 (1.37–3.55) and from 0.28 (0.13–0.38) to 13.03 (7.54–19.71) mg a.i. L −1 , respectively. In contrast, atrazine showed the least toxicity with LC 50 values ranging from 6.09 (3.34–8.35) to 34.19 (24.42–51.9) mg a.i. L −1 . The larval stage of D. rerio was a vulnerable period to most of the selected pesticides in the multiple life stages tested. Pesticide mixtures containing phoxim and λ-cyhalothrin exerted synergistic effects on the larvae of D. rerio . Moreover, the binary mixture of phoxim-atrazine also displayed synergistic response to zebrafish. It has been assumed that most chemicals are additive in toxicity. Therefore, it is crucial to clarify the synergistic interaction for pesticide regulators and environment managers. In the present study, our data provided a clear picture on ecological risk of these pesticide mixtures to aquatic organisms. Moreover, joint effects play a more important role than individual ones, which require more attention when defining standard for water environment quality and risk assessment protocols. [ABSTRACT FROM AUTHOR]

Bradysia odoriphaga Yang and Zhang (the chive gnat) is the major insect pest affecting Chinese chives ( Allium tuberosum Rottl. ex Spreng.) in Northern China. Only three insecticide products are registered for its control. In the present study, we compared the persistence and distribution of thiamethoxam and phoxim in soil and determined their long-acting control effects against B. odoriphaga and two other secondary pests, Thrips alliorum Priesner and the Asiatic onion leaf miner Acrolepia alliella Semenov and Kuznetsov (Lepidoptera: Acrolepiidae), after a single soil application using the directional spray-washing method during the early Chinese chive root-rearing period. Under the same applied dosage, the rhizosphere soil at a depth of 4.0–10.0 cm had concentrations of thiamethoxam and phoxim ranging from 2.21 to 7.44 mg/kg and 0.09–0.44 mg/kg, respectively, at the 7th day after application. The half-lives of thiamethoxam and phoxim in the soil were 27.5 and 6.7 days, respectively. Thiamethoxam persisted for 210 days, whereas phoxim only persisted for 45 days in the soil and plants. In addition, thiamethoxam applied at 6.0 kg a.i./ha maintained a low population density of B. odoriphaga, T. alliorum and A. alliella for nine months longer than phoxim. In conclusion, thiamethoxam may help farmers more effectively manage B. odoriphaga and other secondary pests on Chinese chive and reduce the costs of insecticide use while sustaining protection. [ABSTRACT FROM AUTHOR]

Silkworm ( Bombyx mori ) is an important economic insect. Each year, poisoning caused by phoxim pesticide leads to huge economic losses in sericulture in China. Silkworm midgut is the major organ for food digestion and nutrient absorption. In this study, we found that the activity and expression of nutrition metabolism-related enzymes were dysregulated in midgut by phoxim exposure. DGE analysis revealed that 40 nutrition metabolism-related genes were differentially expressed. qRT-PCR results indicated that the expression levels of insulin/insulin growth factor signaling (IIS) pathway genes Akt, PI3K, PI3K60, PI3K110, IRS and PDK were reduced, whereas PTEN’s expression was significantly increased in the midgut at 24 h after phoxim treatment. However, the transcription levels of Akt, PI3K60, PI3K110, IRS, InR and PDK were elevated and reached the peaks at 48 h, which were 1.48-, 1.35-, 1.21-, 2.24-, 2.89-, and 1.44-fold of those of the control, respectively. At 72 h, the transcription of these genes was reduced. Akt phosphorylation level was increasing along with the growth of silkworms in the control group. However, phoxim treatment led to increased Akt phosphorylation that surged at 24 h but gradually decreased at 48 h and 72 h. The results indicated that phoxim dysregulated the expression of IIS pathway genes and induced abnormal nutrient metabolism in silkworm midgut, which may be the reason of the slow growth of silkworms. [ABSTRACT FROM AUTHOR]

Phoxim (emulsifiable concentrate (EC) and granules (G)) has been widely used in bamboo forests. The persistence and magnitude of phoxim residues in the crop and soil must be investigated to ensure human and environmental safety. The environmental behaviors of the two formulations were investigated in a bamboo forest under soil surface mulching conditions (CP) and non-covered cultivation conditions (NCP). The half-lives of phoxim in soil under the two conditions in soil were 4.1–6.2 days (EC) and 31.5–49.5 days (G), respectively. Phoxim in EC could be leached from the topsoil into the subsoil. A minimized leaching effect was observed for G under NCP. Inversely, an enhanced leaching effect was observed for G under CP. The G formulation resulted in more parent compound (in bamboo shoots) and metabolite (in soil) residues of phoxim than in the case of EC, especially under CP conditions. In addition, the intensity and duration of the formulation effect on soil pH adjustment from G were more obvious than that from EC. Results showed that the environmental behaviors (distribution, degradation, residue) of phoxim in the bamboo forest were significantly influenced by the type of formulation. The prolongation effect from phoxim G might cause persistence and long-term environmental risk. However, bamboo shoot consumption could be considered relatively safe after applying the recommended dose of the two phoxim formulations. [ABSTRACT FROM AUTHOR]

Poly(3-methylthiophene)/nitrogen doped graphene modified glassy carbon electrode (P3MT/NGE/GCE) was prepared through simple drop-casting of NGE, followed by the electrodeposition of P3MT film for sensitive electrochemical determination of trace amounts of pesticide phoxim. The morphology and structure of P3MT/NGE/GCE were characterized by scanning electron microscopy; the electrochemical behavior of P3MT/NGE/GCE was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and chronocoulometry. The preparation conditions of modified electrode, the dropping amount of NGE and polymerization laps of P3MT, were optimized. Under the optimized conditions, the reduction peak current of cyclic voltammetric curve varied linearly with the concentration of phoxim over the two linear ranges of 0.02–0.2 μM and 0.2–2.0 μM, and the low detection limit was 6.4 nM according to lower linear range (S/N = 3). The sensor also exhibited excellent selectivity to phoxim over a wide range of possible interferents including ions, biomolecules, common environment pollutants and widely-used organophosphate pesticides. Moreover, the satisfactory practical feasibility of the sensor was evaluated by the environmental phoxim measurements. [ABSTRACT FROM AUTHOR]

• DTNS-based ratiometric immunosensor is brought for vegetables phoxim detection. • Three-dimensional DTNS is self-assembled with flexibly-designed ssDNA sequences. • DTNS-based functionalization is certified as a better MB carrier than other rivals. • Active m-Ab is vertically and evenly bonded on DTNS vertex, improving phoxim signal. • This method is confidently proven with real-analysis and certified HPLC. A ratiometric electrochemical immunosensor, based on DNA tetrahedron nanostructure (DTNS), is introduced for vegetable phoxim determination. DTNS spontaneously adheres onto gold-nanoparticle-modified electrode and forms stable three-dimensional structure, providing plenty of binding sites to the built-in reference, methylene blue (MB). Monoclonal antibody (m-Ab) is vertically linked onto DTNS vertex, selectively responses antigenic phoxim, and promotes the target signal of I PHO. Thus, a ratiometric indicator, I PHO / I MB , is sensibly established with the target signal (I PHO) and the reference signal (I MB). Modifications, mechanisms and advances of the proposed method are subsequently examined with morphological methods and electrochemical experiments. This method brings considerable advances in analytical behaviors. The ratiometric signal presents better performance than solo system in repeatability and long-time stability. As-fabricated sensor presents wide dynamic range as 0.1∼30 μg/L, and limit of detection is well defined as 0.003 μg/L (S/N = 3). Finally, this method is verified with real-vegetable-sample analysis, certified HPLC and recovery test. [ABSTRACT FROM AUTHOR]

Abstract: Organobentonite, prepared by employing dodecyl trimethyl ammonium chloride (DTMAC) and hexadecyl trimethyl ammonium chloride (HTMAC) as modifying agents, was used as carrier of phoxim to obtain controlled release granule. The structure of organobentonite was investigated by XRD, and utilized to reveal the effects on the sorption and release of phoxim. The results indicated that organobentonite was an excellent sorbent towards phoxim and greatly reduced the release of phoxim. It was found that the sorbed quaternary ammonium aggregates together to form organic phase in bentonite interlayer to accommodate the pesticide molecules. The average loading percentages for organobentonite modified with DTMAC and HTMAC at the loading level of 50, 100 and 150% of the clay's cation exchange capacity were 70.8, 75.3, 71.0% and 91.8, 93.9, 90.3%, and the time taken for 50% of phoxim to be release, T 50, for the CRF based on the organobentonites was 3.7, 11.8, 10.7 times and 3.4, 10.4, 8.2 times of the value for the formulation without organobentonite, respectively. An enhancement of the release of phoxim could be achieved by increasing the carbon chain of quaternary ammonium. The results also showed that an increase of quaternary ammonium loading via electrostatic interaction significantly slowed down the release of phoxim, whereas that via hydrophobic interaction showed little effect. The results suggested the feasibility of regulating the release of phoxim via controlling the structure of organobentonite. [Copyright &y& Elsevier]

Abstract: This paper has established a simple method to detect directly phoxim in water. In the light of two-dimensional correlation analysis, the band of wavenumber for near-infrared spectroscopy of the model is between 5364.8 and 7552.9cm−1, the rate of accuracy for partial least squares discriminant analysis to calibration set (n =149) is 100%, prediction set (n =75) is 93.3% and the overall rate of accuracy for all the samples is 97.8% under the limit of detection 1μgml−1 owing to the spectra preprocessing by standard normal variate transformation and multiplicative scatter correction. It is made clear that this method (two-dimensional correlation analysis combined with partial least squares discriminant analysis) is effective to detect directly phoxim in water. [Copyright &y& Elsevier]

Abstract: Diamondback moth Plutella xylostella (L.) is a cosmopolitan pest of crucifers and it is particularly notorious for its resistance to commonly used insecticides. To provide a basis for future resistance management strategies, this study evaluated the resistance status of this pest to five insecticides, namely abamectin, β-cypermethrin, fipronil, monosultap and phoxim, in South China from 1999 to 2009 with 4–6 populations tested each year. Laboratory bioassays using a standard leaf-dip method were conducted on 3rd instar larvae which were the progeny of field collected insects. LC50 values were estimated by probit analysis and resistance factors were calculated by comparing the field populations with a fully insecticide-susceptible lab population. The results showed that the diamondback moth populations generally had low resistance to abamectin from 1999 to 2005, but that resistance increased significantly during 2007–2009 with resistance factors as high as 122.4. Resistance factors for β-cypermethrin in 35 populations tested were high to very high in all 10 years with values ranging from 32.2 to 683.6. Resistance to fipronil had a progressive increase and increased markedly from 2007 to 2009 with one resistance factor of 56.1. Resistance to monosultap was low in 2004, but increased progressively from 2007 to 2009 with one resistance factor of 129.1. Resistance to phoxim was low to moderate from 2004 to 2008, but was moderate and high in 2009 with resistance factors ranging from 58.7 to 129.1. These results indicate that resistance of diamondback moth populations to most commonly used insecticides in South China has increased and is now generally high. [Copyright &y& Elsevier]

Abstract: The principal objective of this study was to develop an appropriate, sensitive, and selective method for the simultaneous quantitative determination of phoxim and its photo-transformation product, O,O-diethyl α-cyanobenzylideneamino-thiophosphonate (DCTP) in both chicken and quail eggs. Eggs (1g) were blended with anhydrous magnesium sulfate (1g) for sample pretreatment and extracted with acetonitrile. The extracts were then further purified with SPE silica gel tubes deactivated with trimethylamine. Residues were analyzed via a reversed phase-liquid chromatography–tandem mass spectrometry (RP-LC–MS/MS) in positive-ion electrospray ionization (ESI) mode. Tebufenozide was utilized as an internal standard for the quantification of phoxim and its metabolite residues. The identification and quantification of analytes were based on ion transitions monitored by multiple reaction monitoring (MRM). LC–MS/MS analysis was performed from 0.02 to 1mgkg−1 and correlation coefficients (r 2 ) ranging from 0.998 to 0.999 were obtained for both analytes in blank egg extracts. The relative standard deviations (RSDs) of intra- and inter-day variations ranged from 2.1% to 6.7% and from 2.8% to 6.4% for phoxim and DCTP in chicken and quail eggs. At all levels of fortification (0.02, 0.05, and 0.125mgkg−1), the recoveries fell within a range of 81.3% to 93.6% for phoxim and 83.3% to 90.1% for DCTP. The matrix effect was <2%, due to the partial dilution of the sample. Decision limits (CCα) and detection capabilities (CCβ) were in the range of 0.0005–0.0044 and 0.0054–0.0224mgkg−1, respectively. The method was evaluated further by analyzing real samples purchased from markets. All chicken and quail egg samples were free from residues of the target compounds. [Copyright &y& Elsevier]

Abstract: A new sensitive and stable amperometric biosensor for the detection of methyl paraoxon, carbofuran and phoxim had been developed based on immobilization of acetylcholinasterase (AChE) on gold nanoparticles (AuNPs) and silk fibroin (SF) modified platinum electrode. The SF provided a biocompatible microenvironment around the enzyme molecule to stabilize its biological activity and effectively prevented it from leaking out of platinum electrode surface. In the presence of acetylthiocholine chloride (ATCl) as a substrate, AuNPs promoted electron transfer reaction at a lower potential and catalyzed the electrochemical oxidation of thiocholine (TCh), thus increasing detection sensitivity. The influences of pH, enzyme loading, temperature and inhibition time on the response of the fabricated biosensor were investigated. Under optimum conditions, the inhibition percentages of methyl paraoxon, carbofuran and phoxim were proportional to their concentrations in the range of 6×10−11–5×10−8 M, 2×10−10–1×10−7 M and 5×10−9–2×10−7 M, respectively. The detection limits were found to be 2×10−11 M for methyl paraoxon, 1×10−10 M for carbofuran and 2×10−9 M for phoxim. Moreover, the fabricated biosensor had good reproducibility and acceptable stability. The biosensor is a promising new tool for pesticide analysis. [Copyright &y& Elsevier]

In this work, we reported the first use of a novel fluorescent probe for phoxim detection based on yellowish-green emissive carbon quantum dots (CQDs). By facile one-pot hydrothermal treatment of citric acid and p-phenylenediamine, the CQDs with yellowish-green luminescence were synthesized. The sensing mechanism is based on the quenching effect of phoxim on the fluorescence emission of CQDs by inner filter effect (IFE). The CQDs showed a good sensitivity and selectivity to phoxim detection and dual good linear relationships were provided in the concentration ranges of 1–10 μM and 10–98 μM, associated with the limit of detection of 0.09 μM. The proposed assay has been allowed to detect phoxim in real samples with satisfying recoveries ranging from 93 to 105.9%. Furthermore, due to the low cytotoxicity and excellent biocompatibility, the as-prepared CQDs was successfully used for cell imaging, demonstrating the considerable potential applications of such CQDs in biological field. [Display omitted] • A novel sensing platform based on yellowish-green emitting CQDs was developed. • The proposed method exhibited high selectivity and sensitivity towards phoxim. • The new analytical method was feasible for phoxim determination in real samples. • The as-prepared CQDs was successfully used for cell imaging. [ABSTRACT FROM AUTHOR]

Abstract: Field populations of Helicoverpa assulta (Guenée) (Lepidoptera: Noctuidae) from the main tobacco-growing regions of China were investigated for their resistance to the conventional insecticidal chemicals fenvalerate (pyrethroid), phoxim (organophosphate), and methomyl (carbamate) during 2004–2005 using a micro-topical method under laboratory conditions. The studied strains exhibited an increased resistance to fenvalerate by 5.83–17,622-fold compared to the control strain. The highest levels of resistance to fenvalerate were 1042–17,622-fold and observed for 12 out of the 25 studied strains. Four strains showed a resistance level increased by 189–823-fold and 5 strains showed very low resistance to fenvalerate (<10). Substantial resistance to phoxim was observed only in one strain (50.8-fold), which was collected from Anhui in East China (AH1). Significant resistance to methomyl was detected in two strains with increases of 37.1- and 31.6-fold, respectively. These were collected from Anhui (AH1) and Yunnan (YN1) in East China and Southwest China. The impacts of H. assulta resistance to these insecticides on its management in China are discussed. [Copyright &y& Elsevier]

Abstract: This paper described a new approach for the determination of organophosphorus pesticides by temperature-controlled ionic liquid dispersive liquid-phase microextraction prior to high-performance liquid chromatography with ultraviolet detection. Methylparathion and phoxim, two of the typical organophosphorus pesticides, were used as the model analytes for the investigation of the development and application of the new microextraction method. 1-Hexyl-3-methylimidazolium hexafluorophosphate [C6MIM][PF6] was used as the extraction solvent and the factors affecting the extraction efficiency such as the volume of [C6MIM][PF6], pH of working solutions, extraction time, centrifuging time, dissoluble temperature and salt effect were optimized. Under the optimal extraction conditions, methylparathion and phoxim exhibited good linear relationship in the concentration range of 1–100ngmL−1. The detection limits were 0.17ngmL−1 and 0.29ngmL−1, respectively. Precisions of proposed method (RSDs, n =6) were 2.5% and 2.7%, respectively. This proposed method was successfully applied in the analysis of four real environmental water samples and good spiked recoveries over the range of 88.2–103.6% were obtained. These results indicated that temperature-controlled ionic liquid dispersive liquid-phase microextraction had excellent application prospect in environmental field. [Copyright &y& Elsevier]

Abstract: The plant cell/microbe coincubation assay was used to analyze organophosphorus insecticide activation. Salmonella typhimurium strains TA98 and TA100 were exposed to several concentrations of the pesticides phoxim and azinphos methyl with and without TX1 cell line of Nicotiana tabacum activation. When the bacterial strains were treated directly with phoxim, mutagenic activity increased significantly. In contrast, no mutagenic activity was detected with plant activation. Azinphos methyl inhibited the growth of Salmonella strains without plant activation. The coincubation with N. tabacum increased mutagenic activity significantly. These findings and those obtained in animals demonstrated that azinphos-methyl was an indirect mutagen or pro-mutagen activated by the plant metabolism. [Copyright &y& Elsevier]

Abstract: Field populations of Spodoptera litura from Pakistan were evaluated for their resistance to conventional insecticidal chemistries viz. organochlorine (endosulfan), organophosphates (chlorpyrifos, phoxim, quinalphos, profenofos), carbamates (methomyl, thiodicarb) and pyrethroids (bifenthrin, cyfluthrin) during 1997–2005 using a leaf-dip bioassay method. Generally, resistance levels were very low to low to endosulfan, chlorpyrifos, phoxim, quinalphos, profenofos, bifenthrin and thiodicarb, and moderate to high to methomyl and cyfluthrin. Correlation analysis indicated that insecticides belonging to the same class such as organophosphate, carbamate or pyrethroid exhibited a positive cross-resistance in S. litura. Positive correlation was also found between endosulfan and carbamates. Except methomyl and bifenthrin, which were negatively correlated, there was no cross-resistance between organophosphate or carbamate or pyrethroid insecticides in the resistant populations of S. litura. Integrated pest management tactics aimed at reducing pesticidal applications, rotating chemistries of diverse modes of action and conserving natural enemies are recommended. [Copyright &y& Elsevier]

Abstract: A sensitive and selective enzymatic kinetic method for the simultaneous determination of mixtures of carbaryl and phoxim pesticides was researched and developed. It was based on the inhibitory effect of the pesticides on acetylcholinesterase (AChE), and the use of 5,5′-dithiobis(2-nitrobenzoic) acid (DTNB) as a chromogenic reagent for the thiocholine iodide (TChI) released from the acetylthiocholine iodide (ATChI) substrate. The DTNB-thiocholine reaction was investigated by a spectrophotometric-kinetic approach. The complex rate equation for the formation of the chromogenic product, P, was solved under certain experimental conditions, which enabled the absorbance (A P, at λ max =412nm) from the mixtures of the two pesticide inhibitors to be directly related to their concentrations provided the absorbance additivity was followed. The spectra were measured for mixtures of carbaryl and phoxim at different concentrations, and at t =904s, T =35°C, pH=7.5, c ATChI =0.14, and c AChE =0.10mgmL−1. The detection limits of the enzymatic kinetic spectrophotometric procedures for the determination of the carbaryl and phoxim were 4.7 and 0.59μgL−1, respectively. Calibration models for chemometrics methods, such as principal component regression (PCR), partial least squares (PLS) and radial basis function-artificial neural network (RBF-ANN) were constructed and verified with synthetic samples of the mixtures of the two pesticides. The best performing model was based on the RBF-ANN method yielding at approximately 10ppb analyte concentrations, %RPET (carbaryl=5.2; phoxim=6.5), %Recovery (approx.105%) and %RPET (6.5). Various spiked town-water samples produced recoveries in the range of 98.8–103% for each pesticide. [Copyright &y& Elsevier]

Abstract: The poultry red mite Dermanyssus gallinae is the most important ectoparasite of poultry in several European countries. Phoxim is a well-known antiparasitic agent in wide use. Initial studies indicated that this compound could successfully be applied to eliminate D. gallinae in egg-laying birds and in henhouses by treating the cages and the equipment with it. In order to investigate whether phoxim residues are present in eggs from laying hens, we developed a selective and sensitive high-performance liquid chromatography method employing a simple water/acetonitrile gradient system. The amount of phoxim was determined by UV detection at 281nm, and the presence of the residue was confirmed by diode array detection. The eggs were homogenized for sample pretreatment and extracted with acetonitrile and partitioned with n-hexane. The acetonitrile extract was further purified with silica gel column chromatography. Recovery rates (performed at the 5–120μgkg−1 level) were in the range of 86.0–92.1% with relative standard deviations between 3.1% and 16.3%. Based on a signal to noise ratio of 3, the limit of detection of the assay was approximately 2μgkg−1. The day-to-day variation in the concentration of phoxim in four contaminated eggs (5.7–51.6μgkg−1) was generally less than 20%. The decision limit (CCα) and the detection capability (CCβ) were 62.0 and 68.7μgkg−1, respectively. The applicability of the method was demonstrated in eggs from three clinical trials and from a field study. In these investigations, all animals were kept in conventional battery cages. No sample was found containing more than the maximum residue level of 60μgkg−1 for phoxim in eggs as given in Annex I of Council Regulation (EEC) No. 2377/90. [Copyright &y& Elsevier]

Abstract: A new method, which involves liquid-phase microextraction (LPME) followed by high performance liquid chromatography (HPLC) with diode array detector (DAD), was developed to determine phoxim in water sample. Experimental parameters affecting the extraction efficiency, such as extraction solvent, solvent volume, agitation speed of the sample and extraction time were investigated. Under the optimal extraction conditions, phoxim was found to yield a good linear calibration curve in the concentration range from 0.01 to 5 μg mL−1. The limit of detection (LOD) is 10 ng mL−1, and relative standard deviation (RSD) at the 100 ng mL−1 levels is 8.4%. Lake water and tap water samples were successfully analyzed using the proposed method. [Copyright &y& Elsevier]

Phoxim is a widely used organophosphorus pesticide in agriculture. People are paying more and more attention to its toxicity. At present, there is no appropriate way to solve the phoxim poisoning of silkworm, which severely affected the development of sericulture. Fe2+, Cu2+, Rb+ exerted their biological effects through various forms in vivo. To evaluate the effect of Fe2+/Cu2+/Rb+ on phoxim poisoning in silkworm, Bombyx mori were treated with fresh mulberry leaves soaked in 2.5 mg/L phoxim for 2 min with 50 mg/L FeCl 2 , 150 mg/L CuCl 2 , or 0.5 mg/L RbCl from 5 days of the fifth-instar silkworm. Fe2+, Cu2+, and Rb+ pretreatments significantly inhibited the phoxim-induced reduction of survival rate and alleviated the phoxim-induced poisoning symptoms. The protective effects of Fe2+, Cu2+, and Rb+ on phoxim poisoning might be due to their enhancement of superoxide dismutase (SOD), catalase (CAT), and carboxylesterase (CarE) in the hemolymph and fat body of silkworm. This enhancement might reduce reactive oxygen species (ROS) accumulation and oxidative stress (OS) caused by phoxim poisoning. Thereby it reduced the damage to silkworm tissues and cells. These results showed that Fe2+, Cu2+, and Rb+ treatments protected the silkworm from phoxim poisoning by directly enhancing the activity of SOD, CAT, and CarE enzymes and reducing oxidative stress, but not dependent on the high expression of CYP genes. The use of Fe2+, Cu2+, and Rb+ to enhance the activity of SOD, CAT, and CarE enzymes may be an underlying effective way to solve phoxim poisoning in the silkworm industry. [ABSTRACT FROM AUTHOR]

Phoxim, is a common pollutant present in the environment and food chains, which exhibits irreversible neurotoxicity and poses a grave threat to food security. Herein, a novel 8-hydroxyquinoline-pillar[5]arene was synthesized and applied in a fluorometric chemosensor to detect phoxim. The fluorometric chemosensor shows great selectivity/sensitivity to phoxim, which is due to the formation of inclusion complex between 8-hydroxyquinoline-pillar[5]arene host and phoxim guest. Besides, the presence of other common pesticides did not disturb the responsivity of this chemosensor. This work provided a reliable and rapid method for detecting the pesticide residue. 1. A novel 8-hydroxyquinoline-pillar[5]arene (8-HQPA) fluorometric chemosensor was designed and synthesized. 2. 8-HQPA chemosensor exhibits great selectivity/sensitivity to detect phoxim based on host-guest interactions. 3. The LODs for detecting phoxim could reach to 0.2 μM. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we use mid-infrared spectroscopy to detect illicit fipronil in phoxim granules by partial least discrimination analysis (PLS-DA). The classification accuracy (CA) of the calibration set and prediction set are both 100.0% with the additive level of fipronil ranges from 0.1% to 5.0%. The results indicate that MIR coupled with chemometric method has the potential in detecting illicit pesticide addition and the proposed method provides a new idea on pesticide quality control. [Copyright &y& Elsevier]

• Both AlepPBPs display high bindings to an organophosphorus insecticide phoxim. • Computational simulations and binding assays were used to reveal the interactions between AlepPBPs and phoxim. • Residues F15, F39, and I97 of AlepPBP2, F14 and I134 of AlepPBP3 may involve in the binding process of phoxim. • The obtained results will help to develop novel insecticides with better insecticidal effect using a CADD approach. Athetis lepigone is one of the most severe polyphagous pests, and it has developed resistance to different chemical insecticides. Insects primarily rely on the olfactory system to recognize various environmental chemicals, including xenobiotics such as insecticides. Here, we expressed two A. lepigone pheromone-binding proteins (AlepPBP2 and AlepPBP3), and observed they had higher binding affinities to phoxim than other insecticides, with Ki was 3.30 ± 0.38 μM and 3.27 ± 0.10 μM, respectively. Molecular dynamics simulation, binding mode analysis, and computational alanine scanning showed that six residues (Phe15, Phe39, Ile55, Leu65, Ile97, and Phe122) of AlepPBP2 and three residues (Phe12, Ile52, and Ile134) of AlepPBP3 maybe as potential residues that can change protein ability to bind an organophosphorus insecticide phoxim. Then, we used site-directed mutagenesis assay to mutate these residues into alanine, respectively. Subsequently, the binding assays displayed that Phe15, Phe39, and Ile97 of AlepPBP2, Phe12 and Ile134 of AlepPBP3 caused a significant decrease of AlepPBPs binding ability to phoxim, suggesting they should play crucial roles in the AlepPBPs/phoxim interactions. Our findings could further advance in using PBPs as unique targets to design and develop precise and environmentally-friendly pest control agents with high insecticidal potential using a computer-aided drug design (CADD) approach. [ABSTRACT FROM AUTHOR]

Phoxim, a broad-spectrum organophosphate pesticide, is widely used in agriculture to control insect pests in vegetable crops as well as in farm mammals. However, the indiscriminate use of phoxim has increased its release into the environment, leading to the contamination of plant-based foods such as vegetables. In this study, we investigated the effect of Trichoderma asperellum (TM, an opportunistic fungus) on phoxim residue in tomato roots and explored the mechanisms of phoxim metabolism through analysis of detoxification enzymes and gene expression. Degradation kinetics of phoxim showed that TM inoculation rapidly and significantly reduced phoxim residues in tomato roots. Phoxim concentrations at 5d, 10d and 15d post treatment were 75.12, 65.71 and 77.45% lower in TM + phoxim than only phoxim treatment, respectively. The TM inoculation significantly increased the glutathione (GSH) content, the activity of glutathione S -transferase (GST) and the transcript levels of GSH, GST1, GST2 and GST3 in phoxim-treated roots. In addition, the activity of peroxidase and polyphenol peroxidase involved in the xenobiotic conversion also increased in TM + phoxim treatment. The expression of detoxification genes, such as CYP724B2 , GR , ABC2 and GPX increased by 3.82, 3.08, 7.89 and 2.46 fold, respectively in TM + phoxim compared with only phoxim. Similarly, the content of ascorbate (AsA) and the ratio of AsA to dehydroascorbate increased by 45.16% and 57.34%, respectively in TM + phoxim-treated roots. Our results suggest that TM stimulates plant detoxification potential in all three phases (conversion, conjugation and sequestration) of xenobiotc metabolism, leading to a reduced phoxim residue in tomato roots. Image 1 • Trichoderma (TM) rapidly and significantly reduced phoxim residues in tomato roots. • Secondary metabolism-related enzymes activity was induced by TM. • TM inoculation enhanced glutathione content and GST activity. • TM upregulated the expression of detoxification genes (GSH1, GSTs, GR , ABC2, GPX). • TM promoted the phoxim metabolism by improving plant detoxification potential. [ABSTRACT FROM AUTHOR]

Meteorus pulchricornis (Wesmael) (Hymenoptera: Braconidae) is a preponderant endoparasitoid wasp, attacking the larvae of many lepidopteran pests. We present the first body transcriptome dataset for M. pulchricornis. In total, 50,781,796 clean reads were obtained and 33,144 unigenes were assembled; 15,458 unigenes showed a significant similarity (E value < 10−5) to known proteins in the NCBI non-redundant protein database. Gene ontology and cluster of orthologous group analyses were performed to classify the functions of genes. To better understand the role of glutathione-S-transferases (GSTs) in detoxification mechanism in M. pulchricornis , we identified seventeen GST genes (MpulGSTs) from the body transcriptome. Among these, fifteen MpulGSTs belonged to cytosolic GSTs and the other two belonged to microsomal classes. The cytosolic GSTs were classified into four different clades: four in delta, three in omega, seven in sigma, and one in zeta. The expression levels of these MpulGSTs after exposure to sub-lethal concentrations of phoxim and cypermethrin were determined using real-time quantitative polymerase chain reaction: seven MpulGSTs (MpulGSTD3 , MpulGSTS1 , MpulGSTS2 , MpulGSTS4 , MpulGSTS6 MpulGSTO3 , and MpulGSTmic1) and 11 MpulGSTs (MpulGSTD1 , MpulGSTD2 , MpulGSTD3 , MpulGSTO2 , MpulGSTS1 , MpulGSTS2 , MpulGSTS3 , MpulGSTS4 , MpulGSTS5 , MpulGSTS7 , and MpulGSTmic1) were highly expressed, respectively. These results suggested that GST genes may play a pivotal role in detoxification process in M. pulchricornis. Our findings would provide a theoretical base for elucidating insecticide susceptibility and should promote functional research on specific GST genes in parasitoid wasps. Unlabelled Image • Large scale identification of detoxification enzyme genes in parasitoids was performed by using transcriptome sequencing. • A total of 17 glutathione-S-transferase genes were identified from the transcriptome dataset in Meteorus pulchricornis. • 15 MpulGSTs can be classified into delta-, omega-, sigma- and zeta- clades, and two MpulGSTs were microsomal type. • Seven and eleven MpulGSTs were highly expressed after exposure to sublethal doses of phoxim and cypermethrin, respectively. • These results suggested that GST genes may play a pivotal role in detoxification process in M. pulchricornis. [ABSTRACT FROM AUTHOR]