Acute exposure to fungicide fluazinam induces cell death in the midgut, oxidative stress and alters behavior of the stingless bee Partamona helleri (Hymenoptera: Apidae).

Stingless bees (Hymenoptera: Meliponini) are pollinators of both cultivated and wild crop plants in the Neotropical region. However, they are susceptible to pesticide exposure during foraging activities. The fungicide fluazinam is commonly applied in bean and sunflower cultivation during the flowering period, posing a potential risk to the stingless bee Partamona helleri, which serves as a pollinator for these crops. In this study, we investigated the impact of acute oral exposure (24 h) fluazinam on the survival, morphology and cell death signaling pathways in the midgut, oxidative stress and behavior of P. helleri worker bees. Worker bees were exposed for 24 h to fluazinam (field concentrations 0.5, 1.5 and 2.5 mg a.i. mL-1), diluted in 50 % honey aqueous solution. After oral exposure, fluazinam did not harm the survival of worker bees. However, sublethal effects were revealed using the highest concentration of fluazinam (2.5 mg a.i. mL-1), particularly a reduction in food consumption, damage in the midgut epithelium, characterized by degeneration of the brush border, an increase in the number and size of cytoplasm vacuoles, condensation of nuclear chromatin, and an increase in the release of cell fragments into the gut lumen. Bees exposed to fluazinam exhibited an increase in cells undergoing autophagy and apoptosis, indicating cell death in the midgut epithelium. Furthermore, the fungicide induced oxidative stress as evidenced by an increase in total antioxidant and catalase enzyme activities, along with a decrease in glutathione S-transferase activity. And finally, fluazinam altered the walking behavior of bees, which could potentially impede their foraging activities. In conclusion, our findings indicate that fluazinam at field concentrations is not lethal for workers P. helleri. Nevertheless, it has side effects on midgut integrity, oxidative stress and worker bee behavior, pointing to potential risks for this pollinator.

Application of ultra-low-volume spray for the control of vegetable disease in greenhouse: Investigation of formulation performance and potential dermal exposure.

BACKGROUND: The use of pesticides in greenhouse vegetable cultivation is necessary and significant. However, traditional pesticide application methods such as the use of backpack sprayers with water-diluted pesticides have certain drawbacks, e.g., uneven distribution, high labor intensity, and safety risks. RESULTS: In this work, fluazinam ultra-low-volume liquids (Flu-ULVs) were prepared using oily solvents as carriers. The effects of different oils on the physical properties of the preparations were investigated. The Flu-ULV can be sprayed directly using a hand-held ultra-low-volume (ULV) sprayer without dilution with water. Compared with commercial water-based suspension concentrates of fluazinam, the Flu-ULV samples showed better wetting of tomato leaves, better atomization, and more uniform droplet distribution. At a dosage of 300 mL/ha, the coverage rate of tomato leaves ranged from 32.47% to 79.3%, with a droplet deposition density of 556 to 2017 droplets/cm2. Application of Flu-ULVs provided 70.86% control efficacy against gray mold in tomatoes, which was higher than those achieved with reference products. Dermal exposure to Flu-ULVs was also evaluated in greenhouse experiments. The coverage rates for all parts of the operator's body ranged from 0.02% to 0.07%, with deposition volumes of 2.23 to 12.26 µg/cm2. CONCLUSION: Ground ULV spraying of fluazinam was proved to be an effective and safe management option for the control of tomato gray mold in greenhouses. This study laid a foundation for the use of ultra-low volume spray to control vegetable diseases in greenhouse, especially those induced by high humidity environment. © 2024 Society of Chemical Industry.

Fabrication of Enzyme-Responsive Prodrug Self-Assembly Based on Fluazinam for Reducing Toxicity to Aquatic Organisms.

Prodrug-based nanodrug delivery systems were drug formulations by covalently conjugating drugs with inversely polar groups via a cleavable bond to self-assemble into nanoparticles for efficient drug delivery. To improve the utilization efficiency of fluazinam (FZN), enzyme-responsive prodrugs were prepared by conjugating FZN with different alkyl aliphatic acids through a nucleophilic substitution reaction and subsequently self-assembled into nanoparticles (FZNP NPs) without using any harmful adjuvant. The obtained FZNP NPs exhibited excellent efficacies against Sclerotinia sclerotiorum as a result of improved physicochemical properties, including low surface tension, high retention, and enhanced photostability. The LC50 values of FZNP NPs toward zebrafish were 3-8 times that of FZN, which illustrated that the FZNP NPs reduced the detriments of FZN to the aquatic organisms while retaining good biological activity. Therefore, prodrug self-assembly technology would offer a potential method for improving the utilization efficiency of pesticides and lowering the risks to the ecological environment.

The transient character of mitochondrial uncoupling by the popular fungicide fluazinam is specific for liver.

The popular fungicide fluazinam is known to exhibit an unusual cyclic pattern of the protonophoric uncoupling activity in isolated rat liver mitochondria (RLM), with membrane deenergization followed by spontaneous recoupling in the minute scale, which is associated with glutathione conjugation of fluazinam catalyzed by glutathione-S-transferase (GST). Here, we compare the fluazinam effect on RLM with that on rat kidney (RKM) and heart (RHM) mitochondria by monitoring three bioenergetic parameters: oxygen consumption rate, mitochondrial membrane potential and reduction of nucleotides. Only in RLM, the uncoupling activity of fluazinam was transient, i.e. disappeared in a few minutes, whereas in RKM and RHM it was stable in this time scale. We attribute this difference to the increased activity of mitochondrial GST in liver. We report data on the detection of glutathione-fluazinam conjugates by mass-spectrometry, thin layer chromatography and capillary electrophoresis after incubation of fluazinam with RLM but not with RKM, which supports the assumption of the tissue specificity of the conjugation.

Residues and dietary risk assessment of fluazinam in root mustard after field experiments.

The residue levels of fluazinam in root mustard were investigated by using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique with ultra-performance liquid chromatography tandem mass spectrometry. Samples of leaf and root mustard were analyzed. The recoveries of fluazinam were 85.2-110.8% for leaf mustard with the coefficient of variation of 1.0-7.2%, and 88.8-93.3% for root mustard with the coefficient of variation of 1.9-12.4%. The suspension concentrate formulation of fluazinam was applied on root mustard at 262.5 g a.i. ha-1 in accordance with good agricultural practice (GAP), respectively. After the final application, the root mustard samples were collected at 3, 7, and 14 days. Fluazinam residues in root mustard were less than 0.01-0.493 mg kg-1. The dietary risk of fluazinam was predicted by comparing intake amounts with the toxicological data, namely acceptable daily intake (ADI) and acute reference dose (ARfD). The risk quotient (RQ) was 72.2-74.3%, for ordinary consumers, which showed negligible risk. According to the maximum residue limit (MRL) and dietary risk assessment, it is suggested that the pre-harvest interval (PHI) of 3 days; meanwhile, the MRL of 2 mg kg-1 was suggested for fluazinam in root mustard, which indicates that the dietary risk of fluazinam 500 g L-1 suspension concentrate (SC) with the recommended usage on root mustard is negligible. This study provided basic data on the use and safety of fluazinam in root mustard to help the Chinese government formulate a maximum residue level for fluazinam in root mustard.

Effects of fungicides on the ultrastructure of the hypopharyngeal glands and the strength of the hives of Apis mellifera Linnaeus, 1758 (Hymenoptera: Apidae).

Several crops of agronomic interest depend on bees' pollination, and Apis mellifera L (Hymanoptera: Apidae) is the most studied direct pollinator. Nevertheless, the use of pesticides in agricultural environments is common, including fungicides. Studies that seek to evaluate the effects of fungicides on the hypopharyngeal glands of bees, the site of royal jelly synthesis, are lacking. Thus, this work aimed to evaluate the effect of field doses of fungicides (Captan SC® and Zignal®), alone or in mixture, on the hypopharyngeal glands and their subsequent effect on the strength of hives. The evaluations were carried out under field conditions in three hives per treatment. For a period of one month, bee hives received feed containing sugar syrup, pollen and 1.2 mL of Zignal® and 3 mL of Captan SC® in the isolated treatments and 4.2 mL in the mixture. The action of fungicides on the hypopharyngeal glands was determined by transmission electron microscopy analysis in bees 7 and 15 days old, collected in the hives one month after exposure to fungicides. The strength of the hives was evaluated for six months based on the number of frames with adult bees, open and closed brood, and stored food. The results indicate that fungicides promote early degeneration of the rough endoplasmic reticulum and morphological and structural changes in mitochondria. In addition, a reduction in adult population, open and closed breeding and food stock was observed. More pronounced damage occurred when bees were exposed to the mixture of fungicides. Overall, it can be concluded that the presence of fungicides in bee diets promotes harm accentuated over time and compromises the survival of hives. It will be worth estimating the fungicide effects of the queen development and on the colony heath.

Activity and cell toxicology of fluazinam on Fusarium graminearum.

Fusarium graminearum is an important plant pathogen and the causal agent of Fusarium head blight (FHB). At present, the principal method of controlling FHB is through fungicides. Fluazinam is an agent with strong broad-spectrum antifungal activity and has been used to control many diseases. However, there are no reported uses of fluazinam for controlling FHB. This study reports the activity and cell toxicology mechanisms of fluazinam on the filamentous fungus F. graminearum and its effect on fungal growth and development. The activity of fluazinam was tested for 95 wild-type field strains of F. graminearum. The EC50 values (the 50% effective concentration) of fluazinam for inhibition of mycelial growth and spore germination ranged from 0.037 µg/ml to 0.179 µg/ml and from 0.039 µg/ml to 0.506 µg/ml, respectively. The fluazinam sensitivity of these strains varied in 4.9 and 13.0 folds, implying that the target of the fungicide remained unchanged. After treatment with 0.3 µg/ml (≈EC90) fluazinam, the production of conidia was reduced, and the cell wall and cell membrane had shrunked; the cell nucleus and septum morphology, cell membrane permeability, and sexual development were not affected. When treated with 0.1 µg/ml (≈EC50) or 0.3 µg/ml fluazinam, the mycelial respiration and deoxynivalenol (DON) synthesis of F. graminearum were decreased. Confocal images showed that the formation of toxisomes was disturbed after fluazinam treatment, suggesting that fluazinam reduces DON synthesis by inhibiting toxisome formation. Infection of wheat coleoptiles revealed that fluazinam had a strong protective activity against F. graminearum. At 250 µg/ml fluazinam the control efficacy of protective treatments reached 100% and controlled strains resistant to carbendazim. These results contribute to the understanding of the mode of action of fluazinam and its application.

Managing White Mold on Common Bean with Type III Growth Habit by Integrating Partial Resistance, Plant Density, and Fungicide.

The combination of plant density, fungicide, and levels of genotype resistance to white mold (WM) has not been studied for its effect on performance of common bean with type III growth habit under WM pressure. We established four sprinkler-irrigated trials in the fall to winter season in Brazil, combining density (8, 14, 20, or 26 plants/m2), genotype (susceptible or partially resistant to WM), and fungicide to manage WM (two fluazinam applications or without fluazinam) at 0.5 m row spacing in fields infested with sclerotia. One trial was established in a warm region, aiming to obtain low WM pressure. For three trials, the linear mixed model was used. WM pressure in the trials ranged from low to high. Genotype × density × fungicide and genotype × density interactions were not significant for incidence, severity, and yield for all trials. In the three trials, severity was 29% lower at eight than at 26 plants/m2, and yield at 14 plants/m2 (3,294 kg/ha) was 14% higher than yield at eight plants/m2 (P = 0.035) where fluazinam was applied. However, without fluazinam, density did not affect yield. In conclusion, choices of plant density for type III bean cultivars do not need to take into account their resistance levels to WM in the fall to winter season. However, fungicide treatment to manage WM affects the choice of density, with 8 to 12 plants/m2 recommended if fungicide is not an option to manage WM (as in organic systems), and 10 to 14 plants/m2 recommended if fungicide applications are likely.

Biochemical compounds and stress markers in lettuce upon exposure to pathogenic Botrytis cinerea and fungicides inhibiting oxidative phosphorylation.

MAIN CONCLUSION: Botrytis cinerea and fungicides interacted and influenced selected biochemical compounds. DPPH and glutathione are the first line of defence against biotic/abiotic stress. Plant metabolites are correlated with fungicides level during dissipation. Botrytis cinerea is an etiological agent of gray mould in leafy vegetables and is combated by fungicides. Fluazinam and azoxystrobin are commonly used fungicides, which inhibit oxidative phosphorylation in fungi. In this study, lettuce was (i) inoculated with B. cinerea; (ii) sprayed with azoxystrobin or fluazinam; (iii) inoculated with B. cinerea and sprayed with fungicides. This investigation confirmed that B. cinerea and fungicides affected lettuce's biochemistry and stress status. B. cinerea influenced the behaviour of fungicides reflected by shortened dissipation of azoxystrobin compared to non-inoculated plants, while prolonged degradation of fluazinam. Stress caused by B. cinerea combined with fungicides reduced level of chlorophylls (53.46%) and carotenoids (75.42%), whereas increased phenolic compounds (81%), ascorbate concentrations (32.4%), and catalase activity (116.1%). Abiotic stress caused by fungicides contributed most to the induction of carotenoids (107.68 µg g-1 on dissipation day 3-1). Diphenyl picrylhydrazyl (DPPH) radical scavenging activity and glutathione concentration peaked from the first hour of fungicides dissipation. For the first time correlation between the status of plant metabolites and fungicides during their dissipation was observed. These results indicate that non-enzymatic antioxidants could be the first-line compounds against stress factors, whereas ascorbate and antioxidant enzymes tend to mitigate stress only secondarily. The findings of this study help better understand plant biochemistry under biotic/abiotic stress conditions.

Repeated exposure of fluazinam fungicides affects gene expression profiles yet carries no costs on a nontarget pest.

Fungicides are used to control pathogenic fungi of crop species, but they have also been shown to alter behavioral, life history and fitness related traits of nontarget insects. Here, we tested the fungicide effects on feeding behavior, survival and physiology of the nontarget pest insect, the Colorado potato beetle (CPB) (Leptinotarsa decemlineata). Feeding behavior was studied by a choice test of adult beetles, which were allowed to choose between a control and a fungicide (fluazinam) treated potato leaf. Larval survival was recorded after 24 and 72 h exposure to control and fungicide-treated leaves with 2 different concentrations. The adults did not show fungicide avoidance behavior. Similarly, survival of the larvae was not affected by the exposure to fungicides. Finally, to understand the effects of fungicides at the physiological level (gene expression), we tested whether the larval exposure to fungicide alter the expression of 5 metabolic pathway and stress associated genes. Highest concentration and 72-h exposure caused upregulation of 1 cytochrome P450 (CYP9Z14v2) and 1 insecticide resistance gene (Ldace1), whereas metabolic detoxification gene (Ugt1) was downregulated. At 24-h exposure, highest concentration caused downregulation of another common detoxification gene (Gs), while both exposure times to lowest concentration caused upregulation of the Hsp70 stress tolerance gene. Despite these overall effects, there was a considerable amount of variation among different families in the gene expression levels. Even though the behavioral effects of the fungicide treatments were minor, the expression level differences of the studied genes indicate changes on the metabolic detoxifications and stress-related pathways.

Fungicide Sensitivity of Colletotrichum Species Causing Bitter Rot of Apple in the Mid-Atlantic U.S.A.

Apple growers in the Mid-Atlantic region of the U.S.A. have reported increased losses to bitter rot of apple. We tested the hypothesis that this increase is because the Colletotrichum population has developed resistance to commonly used single-mode-of-action (single-MoA) fungicides. We screened 220 Colletotrichum isolates obtained from 38 apple orchards in the Mid-Atlantic region for resistance to 11 fungicides in Fungicide Resistance Action Committee (FRAC) groups 1, 7, 9, 11, 12, and 29. Eleven (5%) of these isolates were resistant to FRAC group 1 with confirmed ß-tubulin E198A mutations, and two (<1%) were also resistant to FRAC group 11 with confirmed cytochrome-b G143A mutations. Such low frequencies of resistant isolates indicate that fungicide resistance is unlikely to be the cause of any regional increase in bitter rot. A subsample of isolates was subsequently tested in vitro for sensitivity to every single-MoA fungicide registered for apple in the Mid-Atlantic U.S.A. (22 fungicides; FRAC groups 1, 3, 7, 9, 11, 12, and 29), and 13 fungicides were tested in field trials. These fungicides varied widely in efficacy both within and between FRAC groups. Comparisons of results from our in vitro tests with results from our field trials and other field trials conducted across the eastern U.S.A. suggested that EC25 values (concentrations that reduce growth by 25%) are better predictors of fungicide efficacy in normal field conditions than EC50 values. We present these results as a guideline for choosing single-MoA fungicides for bitter rot control in the Mid-Atlantic U.S.A.

Efficacy of Potential Control Agents Against Rosellinia necatrix and Their Physiological Impact on Avocado.

Rosellinia necatrix is the causal agent of white root rot (WRR), a fatal disease affecting many woody plants, including avocado (Persea americana). As with other root diseases, an integrated approach is required to control WRR. No fully effective control methods are available, and no chemical or biological agents against R. necatrix have been registered for use on avocado in South Africa. Fluazinam has shown promising results in the greenhouse and field in other countries, including Spain. The current study aimed to investigate the potential of a fumigant, chloropicrin, and biological control agents (B-Rus, Beta-Bak, Mity-Gro, and Trichoderma) against R. necatrix both in vitro and in vivo as compared with fluazinam. In a greenhouse trial, results showed that Trichoderma and B-Rus were as effective as fluazinam at inhibiting R. necatrix in vitro and suppressed WRR symptoms when applied before inoculation with R. necatrix. In contrast, Mity-Gro and Beta-Bak failed to inhibit the pathogen in vitro and in the greenhouse trial, despite application of the products to plants before R. necatrix infection. Fluazinam suppressed WRR symptoms in plants when applied at the early stages of infection, whereas chloropicrin rendered the pathogen nonviable when used as a preplant treatment. Plants treated with Trichoderma, B-Rus, and fluazinam sustained dry mass production and net CO2 assimilation by maintaining the green leaf tissues despite being infected with the pathogen. This study has important implications for the integrated management of WRR.

Comparative Transcriptome Analysis Reveals the Mechanism Related to Fluazinam Stress of Panonychus citri (Acarina: Tetranychidae).

The use of a large number of chemical acaricides to control these pest mites has led to an increasing problem of pesticide resistance, which has always been the difficulty in integrated pest management (IPM). Fluazinam has a good control effect on Panonychus citri, the serious pest on citrus; however, we only know the mechanism of action of fluazinam as a fungicide and its mechanism of action on mites remains unclear. Through analysis using Illumina high-throughput transcriptomic sequencing and differential expression genes in P. citri treated with fluazinam, 59 cytochrome P450 genes, 23 glutathione s-transferase genes, five carboxylate esterase genes, 11 superoxide dismutase genes and 15 catalase genes were identified. The Gene Ontology enrichment and the enrichment of KEGG results showed that the treatment were enrichment for redox enzyme pathways. Evaluating the efficacy of fluazinam, and analyzing the transcriptome data of P. citri under fluazinam stress, potentially provide a new agent for prevention and control of P. citri, and also preliminary research results for exploring the mechanism of action of fluazinam on P. citri. Given the up-regulated expression levels of genes for Mn-superoxide dismutase and catalase, we speculate that they play an important role in fluazinam-stress action on P. citri.

Pharmacological Characteristics and Efficacy of Fluazinam Against Corynespora cassiicola, Causing Cucumber Target Spot in Greenhouses.

Cucumber target spot, caused by Corynespora cassiicola, is a devastating fungal disease in greenhouses in China. Lack of resistant cultivars and unscientific use of fungicides aggravated the difficulty to manage this disease. In recent years, resistance of C. cassiicola to benzimidazoles, quinone outside inhibitors, and succinate dehydrogenase inhibitors has occurred in China. Here, we tested the fluazinam sensitivity distribution of 79 C. cassiicola isolates from different provinces in China based on mycelial growth inhibition. The EC50 values of fluazinam ranged from 0.1002 to 0.3129 µg/ml with a mean of 0.2136 ± 0.0495 µg/ml, and the sensitivity frequency was normally distributed (P = 0.2083, Shapiro-Wilk test). Meanwhile, the EC50 values for spore germination inhibition ranged from 0.0992 to 0.2278 µg/ml with a mean of 0.1499 ± 0.0504 µg/ml. This indicated that fluazinam exhibited an excellent in vitro fungicidal activity on both mycelial growth and spore germination. In addition, fluazinam also exhibited a good in planta control efficacy on detached cucumber leaves in the protective and curative assays. Moreover, the biological and physiological characteristics of C. cassiicola as affected by fluazinam were determined. Fluazinam not only significantly inhibited respiration and adenosine triphosphate production but also caused the increase of cell membrane permeability and the dysfunctions of cellular homeostasis. Interestingly, we found that fluazinam especially damaged vacuole structures, causing the redistribution of vacuole substances. Taken together, our findings provide not only essential references for resistance management of C. cassiicola but also interesting insights for further revealing the action mode of fluazinam against plant pathogens.

Acute toxicity of fluazinam to aquatic organisms and its bioaccumulation in Brachydanio rerio.

Fluazinam (FZN) is a dinitroaniline fungicide. To evaluate the environmental risk of FZN in aquatic environments and ascertain the potential danger to typical aquatic organisms in China, the acute toxicity of FZN to representative aquatic organisms, including Brachydanio rerio, Chlorella vulgaris Beij., Daphnia magna Straus, and Xenopus laevis, was measured, and its bioaccumulation properties in Brachydanio rerio were further investigated. The results showed that the acute toxicity of FZN to Brachydanio rerio and Xenopus laevis is extremely high, and the bioaccumulation factor BCF8d of FZN in Brachydanio rerio ranges between 2287 and 3570, implying that it has high bioaccumulation properties. FZN poses a strong environmental risk for aquatic organisms and possesses great bioaccumulation properties, which may cause pollution to aquatic environments.

MoS2 QDs-Based sensor for measurement of fluazinam with triple signal output.

In this study, direct detection of fluazinam was realized using a fluorescent sensor using disulfide quantum dots (MoS2 QDs) via inner filter effect (IFE). The maximum excitation of as-prepared MoS2 QDs presented a complementary spectral-overlap with the maximum absorption of fluazinam. Thus the occurrence of inner filter effect led to the significant fluorescence quenching of MoS2 QDs. Additionally, fluorescent quenching efficiency of MoS2 QDs could be enhanced by the effects of π-π stacking, hydrogen bond and electrostatic interaction between fluazinam and MoS2 QDs, and these non-chemical bond responses also promoted the selectivity for fluazinam detection. Under the optimum conditions, the IFE-based fluorescent sensor exhibited a relative wide linear range from 50 nM to 25 µM with the LOD of 2.53 nM (S/N = 3). In addition, a paper-based sensor was established by cross-linking the MoS2 QDs into cellulose membrane for naked-eyed detection and digital analysis of fluazinam. The paper-based sensor presented a liner range from 10 µM to 800 µM for fluazinam detection with the LOD of 2.26 µM. Additionally, the acceptable recoveries were obtained for fluazinam detection in the spiked samples of tomato, potato and cucumber, indicating that the proposed method provided an effective sensing platform for real applications of fluazinam detection in food safety.

The phyto-impact of fluazinam fungicide on cellular structure, agro-physiological, and yield traits of pepper and eggplant crops.

Fluazinam is a widely used fungicide; most of the available information associated with its impact predominately on birds, invertebrates, mammals, and algae and scarce works studied its impact on crop plants. A two years-field experiments were conducted to study the response of pepper and eggplant to fluazinam at 0, 1, 2, and 3 times of the fluazinam-recommended dose (0, 0.5, 1, and 1.5 mL/L). The results revealed that fluazinam did not cause toxic effect on the tested plants except for temporary decline of shoot weights and lengths after 3 days of fluazinam application. However, fluazinam improved the physiological status of leaves via promoting metabolites, antioxidants, better membrane integrity, and adjustment of the redox status of fluazinam-sprayed plants. The ultrastructure changes of fluazinam-treated leaves associated with increment of chloroplasts' starch granules, giant nucleus, and elevated number of mitochondria. After 35 days of treatments, plant length of fungicide-treated plants was found to be higher than control and flowering time showed significant earliness. Furthermore, the yield traits were increased significantly in response to fluazinam. Our findings suggested that fluazinam-treated plants could initiate an early defense mechanism to mitigate the permanent growth retardation. This study could serve as a matrix for further studies to seek elucidation of plants' response to other doses of fluazinam. Graphical abstract .

Dissipation of fluazinam in citrus groves and a risk assessment for its dietary intake.

BACKGROUND: Citrus is one of the most important fruit crops worldwide. Fluazinam is a fungicide that is used to control fungal diseases, and its dissipation and residue in citrus fruits should be studied. RESULTS: A Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) procedure combined with gas chromatography with an electron capture detector (GC-ECD) has been developed. The fortified recoveries ranged from 82.1% to 105.9%, with relative standard deviations (RSDs) of less than 5.7%. Fluazinam dissipated relatively quickly following first-order kinetics, with a half-life of 8.5-9.5 days. The experiments on the terminal residue of fluazinam in citrus were conducted at six locations in China, and the risk quotient (RQ) method was applied to citrus fruits for dietary exposure risk assessment based on the terminal residue test. The RQs of fluazinam at three preharvest intervals (PHIs) (21, 28, and 35 days) were all less than 100%, which is an acceptable level for human consumption. The present study provides a reference for the establishment of maximum residue limit (MRL) for fluazinam in citrus. CONCLUSIONS: The dissipation and residues of fluazinam in citrus were monitored. The half-life of less than 10 days showed that fluazinam could degrade relatively easily in citrus. The risk assessment also indicated the intake safety of fluazinam in citrus. © 2019 Society of Chemical Industry.

Controlled-release of fluazinam from biodegradable PLGA-based microspheres.

Pesticides are biological or chemical substances used to manage pests and diseases. Encapsulation of pesticides in biodegradable carriers creates a slow-release system that can improve water dispersibility and prolong residual activity. We prepared two kinds of poly (lactic-co-glycolic acid)(PLGA) nanoparticles (NPs) with polyvinyl alcohol (PVA) and sodium dodecyl sulfate (SDS) surfactants. These were used to encapsulate the fungicide fluazinam (Flu) against Rhizoctonia solani using the Shirasu Porous Glass (SPG) membrane emulsification method. Both nanoparticles had uniform spherical shapes with average diameters of 314.13 nm (SDS) and 612.80 nm (PVA). The slow-release microspheres had excellent sustained-release properties, resistance to UV degradation, storage stability, leaf surface coverage and antifungal efficacy compared to the commercial formulation.

Interaction of Potent Mitochondrial Uncouplers with Thiol-Containing Antioxidants.

It is generally considered that reactive oxygen species (ROS) are involved in the development of numerous pathologies. The level of ROS can be altered via the uncoupling of oxidative phosphorylation by using protonophores causing mitochondrial membrane depolarization. Here, we report that the uncoupling activity of potent protonophores, such as carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP), carbonyl cyanide 3-chlorophenylhydrazone (CCCP), and fluazinam, can be abrogated by the addition of thiol-containing antioxidants to isolated mitochondria. In particular, N-acetylcysteine, glutathione, cysteine, and dithiothreitol removed both a decrease in the mitochondrial membrane potential and an increase in the respiration rate that is caused by FCCP. The thiols also reduced the electrical current that is induced by FCCP and CCCP across planar bilayer lipid membranes. Thus, when speculating on the mechanistic roles of ROS level modulation by mitochondrial uncoupling based on the antioxidant reversing certain FCCP and CCCP effects on cellular processes, one should take into account the ability of these protonophoric uncouplers to directly interact with the thiol-containing antioxidants.