Search Results (9)

Trichoderma afroharzianum is increasingly used in commercial bioformulations for plant disease management in Brazil, yet information about its compatibility with agricultural inputs remains scarce. This study evaluated the in vitro interactions between four Brazilian strains of T. afroharzianum and 32 inputs from different classes, including fungicides, herbicides, insecticides, and microbial products. Mycelial growth and conidial germination were analyzed to identify potential incompatibilities that could compromise the fungus’s performance in combined applications. In the first bioassay, 16 products inhibited mycelial growth by more than 67%. In the second, which simulated spray solution contact, most products (12 out of 16) did not significantly affect conidial germination (>76%). However, the bionematicide based on Bacillus amyloliquefaciens and the fungicide Picoxystrobin + Benzovindiflupyr reduced germination to below 9% and 14%, respectively. Fungicides containing Picoxystrobin + Prothioconazole and Trifloxystrobin + Tebuconazole showed strain-dependent inhibition. These results provide the first detailed assessment of the compatibility of Brazilian T. afroharzianum strains with a broad range of agricultural inputs and can support safer use of biocontrol agents in integrated and sustainable crop protection strategies. Full article

Honey bees (Apis mellifera ligustica) are essential pollinators in both ecosystems and agricultural production. However, their populations are declining due to various factors, including pesticide exposure. Despite their importance, the reproductive castes, particularly drones, remain understudied in terms of pesticide effects. To investigate the effects of azoxystrobin and picoxystrobin on honey bee drones, the drones were exposed to different concentrations of azoxystrobin and picoxystrobin for 14 days; the drone survival, body weight, nutrient content, reproductive organs, and sperm concentration were assessed. Results showed that exposure to both fungicides caused a significant reduction in drone survival rates, with survival rates decreasing progressively as the duration of exposure increased. Compared to the control group, the body weights of drones in all treatment groups were significantly lower on days 7 and 14. Nutrient analysis revealed that low concentrations of azoxystrobin and picoxystrobin increased protein levels, while free fatty acid content decreased significantly in all treatment groups. No significant changes were observed in the total carbohydrate content. Morphological examination of reproductive organs showed that the lengths of the mucus glands and seminal vesicles in drones were significantly shorter in the treatment groups compared to the control group. Furthermore, exposure to azoxystrobin and picoxystrobin resulted in a significant decline in sperm concentration in the drones. These findings indicate that azoxystrobin and picoxystrobin have adverse effects on the health and reproductive capacity of honey bee drones. The present study highlights the need to reassess the risks posed by these fungicides to pollinators, particularly given the critical role of drones in maintaining the genetic diversity and resilience of honey bee colonies. Further research is warranted to elucidate the underlying mechanisms of these effects and explore potential mitigation strategies. Full article

Cell-based test methods with a phenotypic readout are frequently used for toxicity screening. However, guidance on how to validate the hits and how to integrate this information with other data for purposes of risk assessment is missing. We present here such a procedure and exemplify it with a case study on neural crest cell (NCC)-based developmental toxicity of picoxystrobin. A library of potential environmental toxicants was screened in the UKN2 assay, which simultaneously measures migration and cytotoxicity in NCC. Several strobilurin fungicides, known as inhibitors of the mitochondrial respiratory chain complex III, emerged as specific hits. From these, picoxystrobin was chosen to exemplify a roadmap leading from cell-based testing towards toxicological predictions. Following a stringent confirmatory testing, an adverse outcome pathway was developed to provide a testable toxicity hypothesis. Mechanistic studies showed that the oxygen consumption rate was inhibited at sub-µM picoxystrobin concentrations after a 24 h pre-exposure. Migration was inhibited in the 100 nM range, under assay conditions forcing cells to rely on mitochondria. Biokinetic modeling was used to predict intracellular concentrations. Assuming an oral intake of picoxystrobin, consistent with the acceptable daily intake level, physiologically based kinetic modeling suggested that brain concentrations of 0.1–1 µM may be reached. Using this broad array of hazard and toxicokinetics data, we calculated a margin of exposure ≥ 80 between the lowest in vitro point of departure and the highest predicted tissue concentration. Thus, our study exemplifies a hit follow-up strategy and contributes to paving the way to next-generation risk assessment. Full article

Due to their multi-purpose use and, in many cases, lower requirements and financial outlays for cultivation, oats are an interesting crop. However, fungal diseases may contribute to significant declines in grain yields and quality. The aspects that may potentially influence this matter of fact include weather conditions. The aim of the study was to determine the severity of diseases caused by fungi in oat cultivation during the vegetation season. The next goal was to assess the efficacy of the selected active ingredients (a.i.) of fungicides from the chemical groups of triazoles and strobilurins in selected diseases’ control under various meteorological conditions. All of the fungicides were applied in the form of a spray treatment to reduce the severity of the diseases in the cultivation of different oat varieties. Husked and naked oat varieties were used. The health status of the oat plants was determined on the basis of a macroscopic evaluation of plants performed in accordance with the proper methodology. Field experiments were carried out under different weather conditions, which varied over the years during which the trials were conducted. Statistically significant differences were found in the reduction in infection for F and F1 leaves with D. avenae and P. coronata in comparison to the control treatment, regardless of the a.i. used. The use of a.i. tebuconazole (250 g/L), a.i. epoxiconazole (125 g/L), a.i. azoxystrobin (250 g/L) and a.i. picoxystrobin (250 g/L) enabled a reduction in the severity of oat helmintosporiosis in all years of the study for all the varieties analyzed. The efficacy was 72.4%, 74.2%, 71.5%, and 73.1%, respectively. Higher efficacy in reducing P. coronata was found in comparison with D. avenae. The obtained research results confirm the satisfactory efficacy of the above-mentioned active substances in reducing the fungi D. avenae and P. coronata. Full article

Picoxystrobin (PIC) is a fungicide extensively used for disease control in both crops and vegetables. Residues of PIC in vegetables pose a potential threat to human health due to their accumulation in the food chain. In this study, a specific PIC monoclonal antibody (mAb) was developed by introducing a carboxylic acid arm into PIC and subsequently preparing a hapten and an artificial antigen. A sensitive and rapid time-resolved fluorescence immunochromatographic assay (TRFICA) was established based on the mAb. Subsequently, using a time-resolved fluorescent microsphere (TRFM) as signal probe, mAbs and microspheres were covalently coupled. The activated pH, the mAb diluents, the mAb amount, and the probe amount were optimized. Under optimized conditions, the quantitative limits of detection (qLOD) of PIC in cucumber, green pepper, and tomato using TRFICA were established at 0.61, 0.26, and 3.44 ng/mL, respectively; the 50% inhibiting concentrations (IC₅₀) were 11.76, 5.29, and 37.68 ng/mL, respectively. The linear ranges were 1.81–76.71, 0.80–35.04, and 8.32–170.55 ng/mL, respectively. The average recovery in cucumber, green pepper, and tomato samples ranged from 79.8% to 105.0%, and the corresponding coefficients of variation (CV) were below 14.2%. In addition, 15 vegetable samples were selected and compared with the results obtained using ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). The results revealed a high degree of concordance between the proposed method and UPLC-MS/MS. In conclusion, the devised TRFICA method is a valuable tool for rapid, on-site, and highly sensitive detection of PIC residues in vegetables. Full article

The use of strobilurin fungicides in agriculture has increased steadily during the past 25 years, and although strobilurins have minimal water solubility, they regularly appear in surface waters, at times in concentrations approaching toxic levels for aquatic life. The present study examined concentrations of strobilurin fungicides in designated trout streams draining an agricultural watershed in southeastern Minnesota, USA, where fungicides may have contributed to a recent fish kill. Water samples (n = 131) were analyzed for the presence of five different strobilurin fungicides (azoxystrobin, fluoxastrobin, picoxystrobin, pyraclostrobin, trifloxystrobin). Samples were collected via grab and automated sampling during baseflow and stormflow events throughout an entire crop-growing season from sites on each of the three forks of the Whitewater River. Detection frequencies for the five strobilurins ranged from 44 to 82%. Fluoxastrobin and pyraclostrobin concentrations were above known toxic levels in 3% and 15% of total samples analyzed, respectively. The highest concentrations were detected in mid-summer (mid-June to mid-August) samples, coincident with likely strobilurin applications. Lower concentrations were present in water samples collected during the nonapplication periods in spring and fall, suggesting groundwater–stream interactions or steady leaching of fungicides from watershed soils or stream sediments. Further study is required to determine strobilurin concentrations in sediments, soils, and groundwater. Better tracking and guidance regarding strobilurin use is necessary to adequately protect aquatic life as fungicide use continues to increase. Full article

Vine tea (Ampelopsis grossedentata) is a traditional herb widely consumed in southwestern China that possesses paramount potential for human health. In 2021, the outbreak of typical leaf blight disease was observed in almost all vine tea plantations in Zhangjiajie of Hunan province, resulting in significant economic losses of vine tea production. In this study, we identified Neopestalotiopsis clavispora as the causal agent of vine tea leaf blight via its morphological characteristics and molecular identification. The sensitivity distribution of N. clavispora isolates to picoxystrobin were determined based on mycelial growth and spore germination inhibition assays. The EC₅₀ values for mycelial growth ranged from 0.0062 to 0.0658 µg/mL, with a mean of 0.0282 ± 0.0148 µg/mL. The EC₅₀ values for spore germination ranged from 0.0014 to 0.0099 µg/mL, and the mean value was 0.0048 ± 0.0022 µg/mL. Picoxystrobin increased fungal cell membrane permeability, but inhibited fungal ATP biosynthesis. Moreover, picoxystrobin exhibited good in planta control efficacy on vine tea leaves. Three picoxystrobin-resistant mutants were obtained in the current study, but no mutations were detected in the N. clavispora Cytb gene. Competitive ability assays showed that the conidium production and pathogenicity of all picoxystrobin-resistant mutants decreased as compared to their progenitors, indicating that picoxystrobin-resistant mutants suffer fitness penalty. These findings provide important evidence for picoxystrobin in vine tea leaf blight management and increase understanding of the resistance mechanism of picoxystrobin against N. clavispora. Full article

This study established a QuEChERS high-performance liquid chromatography/tandem triple-quadrupole mass spectrometry method for determining azoxystrobin, pyraclostrobin, picoxystrobin, difenoconazole, chlorantraniliprole, imidacloprid, and cyantraniliprole and its metabolite (IN-J9Z38) in litchi and longan, and applied this method to the real samples. The residues in samples were extracted with acetonitrile and purified with nano-ZrO₂, C₁₈, and PSA. The samples were then detected with multireactive ion monitoring and electrospray ionization in the positive ion mode and quantified using the external matrix-matched standard method. The results showed good linearities for the eight analytes in the range of 1–100 μg/L, with correlation coefficients (r²) of >0.99. The limit of quantification was 1–10 μg/kg, and the limit of detection was 0.3–3 μg/kg. Average recovery from litchi and longan was 81–99%, with the relative standard deviation of 3.5–8.4% at fortified concentrations of 1, 10, and 100 μg/kg. The developed method is simple, rapid, efficient, and sensitive. It allowed the rapid screening, monitoring, and confirming of the aforementioned seven pesticides and a metabolite in litchi and longan. Full article

Azoxystrobin is one of the most popular strobilurin fungicides, widely used in agricultural fields for decades.Extensive use of azoxystrobin poses a major threat to ecosystems. However, little is known about the kinetics and mechanism of azoxystrobin biodegradation. The present study reports a newly isolated bacterial strain, Ochrobactrum anthropi SH14, utilizing azoxystrobin as a sole carbon source, was isolated from contaminated soils. Strain SH14 degraded 86.3% of azoxystrobin (50 μg·mL⁻¹) in a mineral salt medium within five days. Maximum specific degradation rate (q_max), half-saturation constant (K_s), and inhibition constant (K_i) were noted as 0.6122 d⁻¹, 6.8291 μg·mL⁻¹, and 188.4680 μg·mL⁻¹, respectively.Conditions for strain SH14 based azoxystrobin degradation were optimized by response surface methodology. Optimum degradation was determined to be 30.2 °C, pH 7.9, and 1.1 × 10⁷ CFU·mL⁻¹ of inoculum. Strain SH14 degraded azoxystrobin via a novel metabolic pathway with the formation of N-(4,6-dimethoxypyrimidin-2-yl)-acetamide,2-amino-4-(4-chlorophenyl)-3-cyano-5,6-dimethyl-pyridine, and 3-quinolinecarboxylic acid,6,8-difluoro-4-hydroxy-ethyl ester as the main intermediate products, which were further transformed without any persistent accumulative product. This is the first report of azoxystrobin degradation pathway in a microorganism. Strain SH14 also degraded other strobilurin fungicides, including kresoxim-methyl (89.4%), pyraclostrobin (88.5%), trifloxystrobin (78.7%), picoxystrobin (76.6%), and fluoxastrobin (57.2%) by following first-order kinetic model. Bioaugmentation of azoxystrobin-contaminated soils with strain SH14 remarkably enhanced the degradation of azoxystrobin, and its half-life was substantially reduced by 95.7 and 65.6 days in sterile and non-sterile soils, respectively, in comparison with the controls without strain SH14. The study presents O. anthropi SH14 for enhanced biodegradation of azoxystrobin and elaborates on the metabolic pathways to eliminate its residual toxicity from the environment. Full article