Bioaccumulation mediated by water solubility leads to differences in the acute toxicity of organophosphorus insecticides to zebrafish (Danio rerio).

The use of some organophosphate insecticides is restricted or even banned in paddy fields due to their high toxicity to aquatic organisms. The aim of this study is to elucidate the main pathways and target organs of organophosphate insecticide toxicity to fish exposed via different routes by integrating histopathological and biochemical techniques. Using malathion as the model drug, when the dosage is 20-60 mg/L, the toxicity of whole body and head immersion drugs to zebrafish is much higher than that of trunk immersion drugs. A dose of 21.06-190.44 mg/kg of malathion feed was fed to adult zebrafish. Although the dosage was already high, no obvious toxicity was observed. Therefore, we believe that the drug mainly enters the fish body through the gills. When exposed to a drug solution of 20 mg/L and 60 mg/L, the fish showed significant neurological behavioral abnormalities, and the pathological damage to key organs and brain tissue was the most severe, showing obvious vacuolization and the highest residual amount (8.72-47.78 mg/L). The activity of acetylcholinesterase was the most inhibited (54.69-74.68%). Therefore, brain tissue is the key toxic target organ of malathion in fish. In addition, we compared the bioaccumulation effects of different water-soluble organophosphorus insecticides in fish and their toxic effects. We found that the higher the water solubility of organophosphorus insecticides, the lower their toxicity to fish.

Eucalyptol-loaded microcapsules combined with Cynanchum komarovii extracts provide long-term and low-risk management of Chinese wolfberry (Lycium barbarum L.).

Realizing eco-friendly, long-term, and low-risk aphid control on Lycium barbarum (medicinal cash crop) using a Cynanchum komarovii extracts and eucalyptus oil-loaded microcapsules (EOMCs) formulation compositions is viable. In this study, the aim is to optimize the composition of Cynanchum komarovii extracts and EOMCs formulation for effective control of aphids, the release of EOMCs was controlled by changing the cross-linking degree of the shell to match the aphid control characteristics of Cynanchum komarovii extracts. Four types of polyamines were used as cross-linking agents for the preparation of EOMCs by interfacial polymerization. The bioactivity, wettability, and field application efficacy of Cynanchum komarovii extracts and different EOMCs formulation compositions were evaluated. These EOMCs exhibited an encapsulation efficiency exceeding 85 %. The control efficiency of the formulation compositions of microcapsules with a moderate release rate and Cynanchum komarovii extracts on aphids remained at 62.86 %, while the control efficiency of the combination of microcapsules with the fastest and slowest rates with Cynanchum komarovii extracts was only 48.62 % and 57.11 %, respectively. The formulation compositions of Cynanchum komarovii extracts with all four types of EOMCs were found to be safe for Chinese wolfberry plants. Overall, by selecting appropriate polyamines during fabrication, the release rate can be effectively controlled to achieve sustainable and low-risk aphid control in Lycium barbarum through compounding with selected microcapsules.

Residue dissipation dynamics and dietary risk assessment of emamectin benzoate, chlorantraniliprole, chlorfenapyr, and lufenuron in cabbage.

Emamectin benzoate (EB), chlorantraniliprole (CTP), chlorfenapyr (CFP), and lufenuron (LFR) are widely used to control Spodoptera exigua on cabbage. This study is aimed at establishing a universal, sensitive, accurate, and efficient method for the determination of these pesticide residues in cabbage using QuEChERS pretreatment combined with ultra-performance liquid chromatography or gas chromatography-tandem mass spectrometry (UPLC‒MS/MS or GC‒MS/MS). The recoveries of these pesticides (containing metabolites) in cabbage detected by the optimized method ranged between 80.9% and 99.9%, with relative standard deviations (RSDs) of 0.164-12.5%. The limit of quantification (LOQ) of the four pesticides was determined to be 0.01 mg/kg. The standard curve, accuracy, precision, and LOQ of the analysis method all met the requirements of pesticide residue detection. The optimized method was used to detect the dissipation dynamics and terminal residues in 12 regions. The dissipation half-lives of CTP, CFP, and LFR were 3.35-7.01 d, 2.29-4.75 d, and 3.24-6.80 d, respectively. The terminal residues of all these pesticides were below the maximum residue limits (MRLs). The dietary risk assessment indicated that the dietary risk probabilities for EB, CTP, CFP, and LFR were all less than 1 and were within the acceptable range. This study provides a comprehensive assessment of the residues and dietary risks of EB, CTP, CFP, and LFR for the scientific use of pesticides.

A multidimensional optimization strategy of pyraclostrobin-loaded microcapsules to improve the selectivity between toxicological risk in zebrafish and efficacy in controlling rice blast.

Developing microcapsules (MCs) delivery systems can effectively mitigate toxicological risk of highly active/toxic pesticides; whereas the controlled release functions also limiting their practical effectiveness. Therefore, designing a precise regulating strategy to balance the toxicity and bioactivity of MCs is urgently needed. Here, we prepared a series of pyraclostrobin-loaded MCs with different wall materials, particle sizes, core density and shell compactness using interfacial polymerization. The results showed that the MCs released more slowly in water with increasing particle sizes and capsule compactness, and they sunk more quickly with the increasing particle sizes and core density. Additionally, MCs with slower release speed was always accompanied with lower acute toxicity levels to zebrafish. When the release dynamics slowed down to the threshold dose on demand for disease control, facilitating settlement of MCs can further reduce toxicity within spatial and temporal dimensions. The poor accumulation of MCs with larger particle sizes or dense shell in gills was closely related to their efficient detoxification. Importantly, seven of the MCs samples possessed superior selectivity between bio-performance in controlling rice blast and toxicological hazard to fish compared to commercial formulations. The results provide a comprehensive guidance for developing an efficient and safe pesticide delivery system.

Determination of the Dissipation Dynamics and Terminal Residue of Bupirimate and Its Metabolites in Cucumber by QuEChERS-Based UPLC-MS/MS.

Bupirimate is widely used as a highly active systemic fungicide. However, the frequent and heavy use of bupirimate has led to pesticide residues in crops that threaten human health and food safety. At present, there is limited research on the detection of ethirimol, which is the metabolite of bupirimate. This study established an ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method to simultaneously detect bupirimate and ethirimol residues based on QuEChERS pretreatment. The average recoveries of bupirimate and ethirimol in cucumber were between 95.2 and 98.7%, respectively, with relative standard deviations (RSDs) of 0.92-5.54% at fortified levels of 0.01, 0.1, and 5 mg L-1. The established method was used to determine the residues in field trials in 12 regions of China, and the final residues of bupirimate were all less than the maximum residue limit (MRL). Since the risk quotient (RQ) of bupirimate and ethirimol in cucumber was less than 1.3%, the dietary risk assessment indicated that bupirimate and ethirimol had a low long-term dietary risk to the general population in China. This study provides effective guidance on the proper use of bupirimate in cucumber fields and a reference for establishing the MRL of bupirimate in China.

Achieving High Efficacy and Low Safety Risk by Balancing Pesticide Deposition on Leaves and Fruits of Chinese Wolfberry (Lycium barbarum L.).

Pesticide residue has become the main technical barrier that restricts the export of Chinese wolfberry. Can we achieve high efficacy and low safety risk by balancing pesticide deposition on the leaves and fruits of Chinese wolfberry? In this research, the structural characteristics and wettability of leaves and fruits of Chinese wolfberry at different growth stages were studied. The adaxial and abaxial surfaces of leaves were hydrophobic, whereas the fruit surfaces were hydrophilic. Adding spray adjuvant could increase the retention of droplets on the leaf surfaces of Chinese wolfberry by 52.28-97.89% and reduce the retention on the fruit surfaces by 21.68-42.14%. A structural equation model analysis showed that the adhesion tension was the key factor affecting the retention of the solutions among various interface behaviors. When the concentrations of Silwet618, AEO-5, Gemini 31551, and 1227 were 2-5 times higher than their CMCs, the retention of pesticide solutions (pyraclostrobin and tylophorine) on Chinese wolfberry leaves significantly increased, and the control efficacies on aphids and powdery mildew also dramatically improved (65.90-105.15 and 41.18-133.06%, respectively). Meanwhile, the retention of pesticides on the fruit of Chinese wolfberry was reduced. This study provides new insights into increasing the utilization of pesticides in controlling pests and improving food safety.

Amphiphilicity-Driven Small Alcohols Regulate the Flexibility of Pesticide-Loaded Microcapsules for Better Foliar Adhesion and Utilization.

The foliar loss of pesticides causes serious utilization decline and environmental risk. On the basis of biomimetics, pesticide-loaded microcapsules (MCs) with spontaneous deformation on foliar micro/nanostructures, like the snail suction cup, are prepared by interfacial polymerization. By controlling the usage or types of small alcohols in the MC preparation system, the flexibility of MCs is tunable. Through the investigation of emulsions and MC structures, we discover that the migration and distribution of small alcohols driven by amphiphilicity affect the process of interfacial polymerization between polyethylene glycol and 4,4-methylenediphenyl diisocyanate. By hydrophobic modification of the polymer and competition for oil monomers of small alcohols, the thickness and compactness of shells are reduced, whereas the density of the core is increased. As a result of the regulation in structures, the flexibility of MCs is improved significantly. In particularly, the MCs-N-pentanol (0.1 mol kg-1) with the best flexibility show strong scouring resistance on varied foliar structures, sustained release property on the air/solid interface, and persistent control effect against foliar diseases. The pesticide-loaded soft MCs provide an effective way to improve pesticide foliar utilization.

The effect of abamectin application in combination with agronomic measures on the control efficacy of cucumber root-knot nematodes and the cucumber yield.

BACKGROUND: As a registered non-fumigant nematicide, abamectin has been widely used as a soil treatment against many cash crop nematode diseases. In a previous study, we found that soil adsorption hindered the stable performance of abamectin against root-knot nematodes in the field. RESULTS: In this study, an efficient and labor-saving application method of soil blending abamectin combined with rotary tillage, a common agronomic measure, was developed to improve the efficacy of abamectin against root-knot nematode disease. We revealed the role of four parameters in this application method. At an abamectin dose of 750 g a.i. ha-1 , spray water volume of 675 L ha-1 and rotation depth of 20 cm, abamectin was well distributed in the 0-20 cm soil layer at a concentration of 0.41-0.46 mg kg-1 , the efficacy against root-knot nematode disease was 72.12%, and the cucumber yield was 51.93 t ha-1 . At the same dosage, root irrigation and flood irrigation measures resulted in only 29.28% and 33.43% control, with cucumber yields of 42.96 and 44.73 t ha-1 , respectively. CONCLUSION: To control root-knot nematode disease with abamectin, a soil blending application combined with rotary tilling is superior to leaching application combined with the agronomic measure of irrigation. The former application method can improve the dispersion of abamectin in the soil, enhance the efficacy of abamectin against root-knot nematodes and maintain a stable cucumber yield. In addition, the increased labor required for application combined with agronomic measures is negligible and has excellent application prospects. © 2023 Society of Chemical Industry.

One-pot construction of epoxy resin nanocarrier delivering abamectin and its efficacy on plant root-knot nematodes.

BACKGROUND: The complex preparation process and storage instability of nanoformulations hinders their development and commercialization. In this study, nanocapsules loaded with abamectin were prepared by interfacial polymerization at room temperature and ordinary pressure using the monomers of epoxy resin (ER) and diamine. The potential mechanisms of primary amine and tertiary amine in influencing the shell strength of the nanocapsules and the dynamic stability of abamectin nanocapsules (Aba@ER) in the suspension system were systematically researched. RESULTS: The tertiary amine catalyzed the self-polymerization of epoxy resin into linear macromolecules with unstable structures. The structural stability of the diamine curing agent with a primary amine group played a key role in enhancing the structural stability of the polymers. The intramolecular structure of the nanocapsule shell formed by isophorondiamine (IPDA) crosslinked epoxy resin has multiple spatial conformations and a rigid saturated six-membered ring. Its structure was stable, and the shell strength was strong. The formulation had stable dynamic changes during storage and maintained excellent biological activity. Compared with emulsifiable concentrate (EC), Aba@ER/IPDA had superior biological activity, and the field efficacy on tomato root-knot nematode was enhanced by approximately 31.28% at 150 days after transplanting. CONCLUSION: Aba@ER/IPDA, which has excellent storage stability and simple preparation technology, can provide a nanoplatform with industrial prospects for efficient pesticide delivery. © 2023 Society of Chemical Industry.

Modification of sedimentation and bioaccumulation behavior as an efficient strategy to modulate the toxicity of pyraclostrobin to zebrafish (Danio rerio).

The behavior of pesticide particles or droplets might significantly influence their environmental risks. However, studies on the risk of different pesticide formulations in aqueous environments have rarely been reported. In this study, we prepared three types of pyraclostrobin formulations to evaluate their behavior in the aqueous environment and toxicological risks to zebrafish. The results showed that pyraclostrobin emulsifiable concentrate (EC) sank faster in water with increasing hydrophilicity and density of the solvent. The particles also sank faster with increasing particle size and particle density for suspension concentrate (SC) and microcapsules (MCs). Diverse behavior in water results in different temporal and spatial distributions of the active ingredient. EC-EGDA, SC-5 µm, CS-Large and EC-MO sink or float over time, therefore reducing the effective dose suspended in water. Lower toxicological risks of the pesticides were also observed by reducing the enrichment of pyraclostrobin in zebrafish. In addition to the direct toxicity of the active ingredient, the type of pesticide formulations and their specific compositions might also influence the integrated toxicity. The environmental behavior of pesticide formulations should also be considered for their systematic assessment of environmental risks to ensure the scientific application of pesticides in different scenarios.

Residual analysis of QoI fungicides in multiple (six) types of aquatic organisms by UPLC-MS/MS under acutely toxic conditions.

In view of the significance of food safety and the possible relationship between residual enrichment and acute toxicity for pesticides in different aquatic organisms, it is essential to establish a sensitive and reliable determination method for pesticides in different aquatic organisms to analyze the enrichment levels. Quinone outside inhibitor fungicides (QoIs) are lipophilic fungicides that pose environmental threats to aquatic organisms. Previous research has mainly focused on QoI residues in aquatic organisms under chronic toxicity, whereas less is known about how pesticide residues differ among aquatic organism under acutely toxic conditions. In the present study, the residues of QoIs in aquatic organisms (Danio rerio, Rana pipiens, Cherax quadricarinatus, Misgurnus anguillicaudatus, Corbicula fluminea, and Ampullaria gigas) were analyzed by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) coupled with a proposed QuEChERS method. The proposed method was validated in terms of linearity (coefficients of determination of 0.9980-0.9999), the limits of quantification (0.01 µg·kg-1), the relative standard deviation (0.6-4.4%), and recovery (70.12-118.15%). The results demonstrated that the proposed method fulfilled the requirements for pesticide analysis in all tested aquatic organisms. The residues of QoIs in the same aquatic organism exposed to QoI concentrations of 5 and 500 µg L-1 decreased in the order pyraoxystrobin > pyraclostrobin > triclopyricarb > picoxystrobin > azoxystrobin > fluoxastrobin. Furthermore, the acute toxicity was strongly correlated with the enrichment level of the QoIs in aquatic organisms. This study provides the first documentation of a correlation between the enrichment level of QoIs and acute toxicity in aquatic organisms, which provides a basis for the management of agrochemicals considering aquatic ecological risks.

Fungicide smoke generated by electrical heating effectively controls gray mold of Chinese chives and reduces residue risk through adequate environmental sterilization.

BACKGROUND: Labor-saving pesticide application technology is eagerly pursued in the planting system of Chinese chives. In this study, we developed a set of application approaches by turning fungicides into smoke to achieve this goal. RESULTS: The fungicides fludioxonil, fluopyram, boscalid, procymidone, and prochloraz could be vaporized into smoke at temperatures below 300 °C. The SFR (smoke formation rate) decreased with the increasing temperature. At 300 °C, the SFR of fludioxonil, fluopyram, boscalid and procymidone were all higher than 80%. At 300 °C and 600 °C, there were no significant differences in the smoke particle state of these five fungicides. However, the inhibition rate of these five fungicides against the growth of Botrytis squamosa generally decreased with the temperature. At 600 °C, only fludioxonil and boscalid had inhibition rates higher than 80%. The deposition uniformity of fungicide smoke increased with the increasing amounts of NH4 Cl. When the amount of NH4 Cl reached 80% of the total content, the smoke of fungicide was uniformly deposited throughout each glass slide. In the greenhouse experiment, the control efficacy of fungicide application by smoke was significantly better than that of spraying application, whereas its residue was much lower. CONCLUSION: It is feasible to control air-borne disease through the vaporization of fungicides into smoke by electrical heating. Smoke application would effectively inhibit the spores in the air and would not increase the humidity of the environment. These findings indicate that smoke application is a labor-saving pesticide application technology viable in production. © 2022 Society of Chemical Industry.

Ecotoxicological risk assessment of 14 pesticides and corresponding metabolites to groundwater and soil organisms using China-PEARL model and RQ approach.

Global use of pesticides brings uncertain risks to human and nontarget species via environmental matrix. Currently, various models for exposure risk assessment are developed and widely used to forecast the impact of pesticides on environmental organisms. In this study, five commonly used insecticides, seven herbicides and three fungicides were chosen to analyze the subsequent risks in groundwater in simulated scenarios using China-PEARL (Pesticide Emission Assessment at Regional and Local Scales) model. In addition, their exposure risks to soil organisms were characterized based on risk quotient (RQ) approach. The results indicated that 23.3% of the total 528 predicted environmental concentrations (PECs) of pesticides and respective metabolites in groundwater from six Chinese simulated locations with ten crops were above 10 µg L-1. Furthermore, acceptable human risks of pesticides in groundwater were observed for all simulation scenarios (RQ < 1). Based on the derived PECs in soil short-term and long-term exposure simulation scenarios, all compounds were evaluated to be with acceptable risks to soil organisms, except that imidacloprid was estimated to be with unacceptable chronic risk (RQ = 27.5) to earthworms. Overall, the present findings provide an opportunity for a more-comprehensive understanding of exposure toxicity risks of pesticides leaching into groundwater and soil.

Toxicological risks of SDHIs and QoIs to zebrafish (Danio rerio) and the corresponding poisoning mechanism.

Quinone outside inhibitor fungicides (QoIs) and succinate dehydrogenase inhibitor fungicides (SDHIs) were classified as highly or moderately toxic to nontarget aquatic organisms, which deterred their application in paddy scenario. Currently, the mechanism of toxicity regarding which factors govern their risk ranking in fish species are not fully explored. In this study, adult zebrafish were exposed to four QoIs (pyraclostrobin, trifloxystrobin, kresoxim-methyl, and azoxystrobin) and three SDHIs (isopyrazam, thifluzamide, and boscalid) to assess its acute toxicity and effects on tissue accumulation and gill injury. The results showed that the overall toxicity level was in the order of QoIs > SDHIs, whereas the order of accumulation capacity was SDHIs > QoIs. Seven mitochondrial respiratory inhibitors exposure induced serious histological damage in the gills, including aneurism, curling, telangiectasia and swelling, and caused mitochondrial dysfunction and weaker complex II and III activities. The correlation between their acute toxicities and in vitro gill cytotoxicity was significant (R = 0.868), whereas the bioaccumulation level was not markedly associated with their 96h-LC50 values in zebrafish (R = -0.686), indicating the degree of target organ (gill) injury may be the decisive factor that governs the risk grade of respiratory inhibitors in fish. Additionally, the docking positions and binding energies of fungicides with the target proteins may be responsible for their differential branchial damage. These results offer a point of reference and theoretical support for the design of fungicides and appropriate formulations with improved environmental safety that could broaden their application scenario.

One-Step Construct Responsive Lignin/Polysaccharide/Fe Nano Loading System Driven by Digestive Enzymes of Lepidopteran for Precise Delivery of Pesticides.

A strategy that relies on the differences in feeding behavior between pests and natural enemies to deliver insecticides precisely was proposed. After proving that the digestive enzymes in Lepidopteran pests can act as triggers for lignin-based controlled-release carriers, a novel multiple-enzyme-responsive lignin/polysaccharide/Fe nanocarrier was constructed by combining the electrostatic self-assembly and chelation and loaded with lambda-cyhalothrin (LC) to form a nanocapsule suspension loading system. The nanocapsules were LC@sodium lignosulfonate/chitosan/Fe (LC@SL/CS/Fe) and LC@sodium lignosulfonate/alkyl polyglycoside quaternary ammonium salt/Fe (LC@SL/APQAS/Fe). LC@SL/APQAS/Fe was more stable than LC@SL/CS/Fe because it adsorbs more Fe3+, and the half-lives of LC in LC@SL/APQAS/Fe under UV irradiation were prolonged at 4.02- and 6.03-folds than those of LC@SL/CS/Fe and LC emulsifiable concentrate (LC EC), respectively. Both LC@SL/APQAS/Fe and LC@SL/CS/Fe have responsive release functions to laccase and cellulase, and the release rate of the former was slower. The insecticidal activity of LC@SL/APQAS/Fe against Agrotis ipsilonis was similar to those of LC@SL/CS/Fe and LC EC, while the toxicity of LC@SL/APQAS/Fe to the natural enemy was 2-3 times less than those of LC@SL/CS/Fe and LC EC. Meanwhile, the organic solvent component in the nanocapsule suspension was 94% less than that in the EC preparation. Therefore, the nano loading system based on SL/APQAS/Fe is a promising nanoplatform with the advantages of high efficiency, low toxicity, and environmental friendliness.

SDH mutations confer complex cross-resistance patterns to SDHIs in Corynespora cassiicola.

Succinate dehydrogenase inhibitors (SDHIs) are one of the most frequently used fungicides in cucumber fields in China. Our previous studies indicated that the sensitivity profile of Corynespora cassiicola, the causal agent of Corynespora leaf spot, to different SDHIs varied greatly; however, the underlying mechanism remains unclear. The 50% effective concentration (EC50) values of boscalid, fluopyram, fluxapyroxad and isopyrazam in C. cassiicola collected from 2017 to 2020 shifted, with resistance frequencies of 79.83%, 78.43%, 83.19% and 49.86%, respectively. The sequence alignment of sdhB/C/D of resistant strains revealed that eight single amino acid mutations (B-H278Y/L, B-I280V, C-S73P, C-N75S, C-H134R, D-D95E and D-G109V), and three dual-mutations (B-I280V&C-S73P, B-I280V&C-N75S and C-S73P&C-N75S) conferred various SDHI resistance levels and cross-resistance profiles. The expression level of the sdhB/C/D gene and succinate dehydrogenase (SDH) activity in the mutants were significantly altered by the presence of SDHIs, compared with the wild type strain. Additionally, molecular docking results suggested that the missense mutation influenced the crystal structure of SDH and subsequently interfered with the interaction bonds and bond distances among the target protein and chemicals. In brief, amino acid mutations altered the fungicide response of target gene expression, SDH activity and the binding features of SDH-ligand complexes and subsequently conferred multiple resistance levels and complex cross-resistance patterns to SDHIs in C. cassiicola. The evaluation of C. cassiicola resistance to SDHIs provided a significant foundation for efficient chemical development and integrated CLS management strategies.

Toxicological differences of trifloxystrobin and kresoxim-methyl on zebrafish in various levels of exposure routes, organs, cells and biochemical indicators.

Trifloxystrobin (TRI) and kresoxim-methyl (KRE), as quinone outside inhibitor fungicides (QoIs), have broad applications due to their effective activity against fungi. Excessive usages of agrochemicals trigger environmental risks, such as aquatic organisms (fish). Research performed in recent years has focused on the ecotoxicology of TRI and KRE in fish containing histologic morphology, enzyme activity, protein and gene expression under chronic toxicity conditions, whereas less is known about the underlying mechanisms of toxicity and differences between TRI and KRE in fish under acute toxicity conditions. In the present study, in comparison to different exposure routes [whole-body exposure (WBE), head exposure (HE), trunk exposure (TE), and Oral administration (OA)], the external substances TRI and KRE entered the fish body mainly via gill organs and led to fish toxicity. Furthermore, gill organs and gill cells were vulnerable to TRI and KRE exposure, which indicated that the gill is a vital impaired organ. The 96 h-LC50 (sublethal concentration) value of KRE was 289.8 µg L-1 (R2 = 0.9855) with an approximate 10-fold difference in TRI toxicity. The cytotoxicity exposed to TRI was higher than that in KRE at the same concentration. The potential mechanisms of toxic differences could be various toxic effects in terms of MCIII (mitochondrial complex III) activity, ATP (Adenosine triphosphate) content, MA (mitochondrial activity), ROS (reactive oxygen species) levels, and cellular respiration. Furthermore, the disorder in MCIII activity was probably the main potential mechanisms of toxic differences. To some extent, this research provides not only new insight into the underlying toxic mechanism of TRI and KRE in fish but also a basis for the guidance of agrochemicals considering aquatic risks.

Determination of Market, Field Samples, and Dietary Risk Assessment of Chlorfenapyr and Tralopyril in 16 Crops.

The frequent and massive use of chlorfenapyr has led to pesticide residues in crops, threatening food safety and human health. However, there is limited research on the detection of tralopyril, which is the major metabolite of chlorfenapyr with high toxicity. This study aimed to develop a novel, sensitive, and highly efficient method for the determination of chlorfenapyr and tralopyril residues in 16 crops. The optimized purification procedure provided satisfactory recovery of 76.6-110%, with relative standard deviations of 1.3-11.1%. The quantification values of pesticides in crop matrixes were all 0.01 µg kg-1. The optimal method was adopted to determine the chlorfenapyr and tralopyril residues in field trials in 12 regions in China and monitor their residues in 16 agricultural products. The results of the dissipation and terminal residue experiments show that the final residue of chlorfenapyr was less than MRL (maximum residue limit) and no tralopyril was detected in the field samples. Moreover, the qualification proportion of these residues in market samples were up to 99.5%. The RQ (risk quotient) values of chlorfenapyr and chlorfenapyr with consideration of tralopyril were both apparently lower than an RQ of 100%, indicating an acceptable level. This research provides a thorough long-term dietary risk evaluation on chlorfenapyr and tralopyril and would provide reference for their scientific and safe utilization.

Effect of Curing Regime on the Mechanical Strength, Hydration, and Microstructure of Ecological Ultrahigh-Performance Concrete (EUHPC).

This paper investigates the effect of curing regimes (standard and steam curing) on the mechanical strength, hydration, and microstructure of ecological ultrahigh-performance concrete (EUHPC). The flowability, compressive strength, flexural strength, hydration, porosity, pore size distribution, and microstructure of UHPC with different contents of supplementary materials (silica fume, fly ash, and ground granulated blast furnace slag) were assessed. The test results showed that the compressive strength of EUHPC under steam curing was increased considerably compared to that under standard curing, while the flexural strength was mildly decreased. The steam curing could decrease the porosity of EUHPC, which ranged between 7% and 9% for standard curing, and between 3.5% and 5% for steam curing. The aperture of EUHPC was below 20 nm, mainly located in the range of 10 nm to 20 nm under standard curing, while it was less than 10 nm for steam curing. C-S-H gel was produced under steam curing, while unhydrated fly ash, mineral powder, and Ca(OH)2 crystal were observed in the amorphous C-S-H gel. The microstructure of EUHPC under steam curing was denser than that under standard curing, and the interfacial transition zones under both curing regimes were compact.

Simultaneous detection of ten kinds of insecticide residues in honey and pollen using UPLC-MS/MS with graphene and carbon nanotubes as adsorption and purification materials.

An analytical method of simultaneous detection of ten insecticide residues in honey and pollen was established. The samples were purified with QuEChERS approach using new adsorbents and analyzed with UPLC-MS/MS. The results showed that both of graphene and carbon nanotubes were highly efficient adsorbents for the dSPE clean up to eliminate coextractives in the samples, and graphene was superior to carbon nanotubes for the detection of pesticide residues in honey and pollen samples. The proposed method was used to detect pesticide residues in 25 honey samples and 30 pollen samples which were randomly collected from more than ten provinces in China. All honey samples contain 1-27 µg/kg of chlorpyrifos residues. Only 4% of the honey samples were detected containing acetamiprid and imidacloprid, while the other seven pesticides were not detected. Chlorpyrifos residues were found in all pollen samples (5-66 µg/kg), among which twenty percent exceeded the maximum residue limits (MRLs, 50 µg/kg, European Commission Regulation). Most of the pollen samples containing pesticide concentrations higher than MRLs were collected from rape, followed by lotus, camellia, and rose. Besides, 36.7% and 33.3% of the pollen samples had imidacloprid and flupyradifurone higher than 5 µg/kg. A total of 26.7% pollen samples were detected containing bifenthrin, while none of the other six pesticides were detected in pollen samples.