Multiresidues of pesticides in the particulate matter (PM10) emitted by rural soils of the semiarid pampas, Argentina. A potential source of air pollution.

The aim of this work was to evaluate the presence of 40 pesticides in the PM10 emitted by rural soils of the semiarid region of Argentina. Six agricultural soils for grain production under no till and with high use of pesticides (AG), 5 agricultural soils for forage and grain production under conventional tillage (AFG) and 5 unpaved rural roads (RR) were sampled. The PM10 was generated using the Easy Dust Generator and it was collected with an electrostatic precipitator. The presence of 20 herbicides, 14 insecticides and 6 fungicides was analyzed in the soil and in the PM10. More than 70% of the pesticides analyzed were detected in the soil and in the PM10. All agricultural soils and 87% of RR soils showed at least one residue of pesticides. Multiresidues of pesticides were found in the 100% of PM10 emitted by rural soils. The mean number of pesticides was higher in the PM10 (7) than in the soil (5). Some pesticides were not detected in the soils but they were detected in the PM10 (triticonazole, carbofuran, metsulfuron methyl) and vice versa. In general, the concentrations of herbicides were higher in the PM10 than in the soil, while the concentrations of insecticides and fungicides were lower in the PM10 than in the soil. These results suggest that the concentrations of pesticide in the PM10 (inhalable fraction) should be used instead the concentrations of pesticide in the soil to calculate the exposure factor to pesticides by dust inhalation. This study provides the initial evidence of the presence of multiple pesticide residues in PM10 emitted by rural soils under different land management. Also confirms that the PM10 is a potential source of air contamination with pesticides. Future studies should be driven to measure the concentrations of pesticides and their dynamics in the PM10.

Comparison of in vitro toxicity in HepG2 cells: Toxicological role of Tebuconazole-tert-butyl-hydroxy in exposure to the fungicide Tebuconazole.

Fungicides are often used prophylactically, to control fungal diseases. Although fungicides have been designed to control pests/fungi, they frequently share molecular targets with non-target species, including humans. Tebuconazole, a fungicide belonging to the class of triazoles, is widely employed, has moderate to high persistence in soil, and can be found in different environmental levels. This fungicide is metabolized to the main hydroxy-derived metabolite, Tebuconazole-tert-butyl-hydroxy (or hydroxytebuconazole). This study aims to unveil the action mechanism of Tebuconazole and the role played by its metabolite, Tebuconazole-tert-butyl-hydroxy (5-(4-Chlorophenyl)-2,2-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)-1,3-pentanediol), within the expected spectrum of toxicity. In silico and in vitro analyses (MTT assay, cell cycle evaluation, annexin/PI assay, ROS accumulation assay, and mitochondrial membrane potential determination) were performed in HepG2 cells for 24 h and 48 h. Although in silico analysis suggested that both Tebuconazole and Tebuconazole-tert-butyl-hydroxy are potentially hepatotoxic, only Tebuconazole affected the tested cell line. Reduced MTT metabolism, and decreased mitochondrial membrane potential were the main findings. In conclusion, the action mechanism of Tebuconazole may be related to mitochondrial dysfunction. However, the findings of this study pointed out that Tebuconazole-tert-butyl-hydroxy does not play an important role in Tebuconazol toxicity. The study has generated new data that will help to understand how fungicides behave in the environment.

Microstructural and physicochemical quality maintenance in green bell pepper infected with Botrytis cinerea and treated with thyme essential oil combined with carnauba wax.

Bell pepper presents rapid weight loss and is highly susceptible to gray mold caused by the fungus Botrytis cinerea. The most employed method to control this disease is the application of synthetic fungicides such as thiabendazole (TBZ); however, its continued use causes resistance in fungi as well as environmental problems. For these reasons, natural alternatives arise as a more striking option. Currently, bell pepper fruits are coated with carnauba wax (CW) to prevent weight loss and improve appearance. Moreover, CW can be used as a carrier to incorporate essential oils, and previous studies have shown that thyme essential oil (TEO) is highly effective against B. cinerea. Therefore, this study aimed to evaluate the effect of CW combined with TEO on the development of gray mold and maintenance of microestructural and postharvest quality in bell pepper stored at 13°C. The minimal inhibitory concentration of TEO was 0.5%. TEO and TBZ provoked the leakage of intracellular components. TEO and CW + TEO treatments were equally effective to inhibit the development of gray mold. On the quality parameters, firmness and weight loss were ameliorated with CW and CW + TEO treatments; whereas lightness increased in these treatments. The structural analysis showed that CW + TEO treatment maintained the cell structure reducing the apparition of deformities. The results suggest that CW + TEO treatment could be used as a natural and effective antifungal retarding the appearance of gray mold and maintaining the postharvest quality of bell pepper. PRACTICAL APPLICATION: CW and TEO are classified as generally recognized as safe (GRAS) by the US Food and Drug Administration (FDA). This combination can be employed on the bell pepper packaging system to extend shelf life and oppose gray mold developments. Bell pepper fruits are normally coated with lipid-base coatings such as CW before commercialization; therefore, TEO addition would represent a small investment without any changes on the packaging system infrastructure.

Genotoxic effects induced by iprodione and tebuconazole in meristematic cells of Allium cepa: responses dependent on concentration and exposure time.

The present work explores the genotoxicity of the fungicides iprodione (IP) and tebuconazole (TB) using the Allium cepa assay as an in vivo biological model. Both short-term and long-term exposures were studied, revealing concentration- and time-dependent cytological and genotoxic effects. IP exhibited genotoxicity over a wider concentration range (5-50 µg/ml) and required 30 h of exposure, while TB showed genotoxicity at higher concentrations (10 and 30 µg/ml) within a 4-h exposure period. The study highlights the importance of assessing potential risks associated with fungicide exposure, including handling, disposal practices, and concerns regarding food residue. Moreover, the research underscores the genotoxic effects of IP and TB on plant cells and provides valuable insights into their concentration and time-response patterns.

Association of pesticide exposure with neurobehavioral outcomes among avocado farmworkers in Mexico.

BACKGROUND AND AIM: To date, few studies have focused on the health effects of pesticide exposure among avocado farmworkers. We examined the association of exposure to insecticides, fungicides, and herbicides with cognitive and mental health outcomes among these avocado workers from Michoacan, Mexico. MATERIALS AND METHODS: We conducted a cross-sectional study of 105 avocado farmworkers between May and August 2021. We collected data on self-reported pesticide use during the 12 months prior to the baseline survey and estimated annual exposure-intensity scores (EIS) using a semi-quantitative exposure algorithm. We calculated specific gravity adjusted average concentrations of 12 insecticide, fungicide, or herbicide metabolites measured in urine samples collected during two study visits (8-10 weeks apart). We assessed participants' cognitive function and psychological distress using the NIH Toolbox Cognition Battery and the Brief Symptom Inventory 18 (BSI-18), respectively. We examined individual associations of EIS and urinary pesticide metabolites with neurobehavioral outcomes using generalized linear regression models. We also implemented Bayesian Weighted Quantile Sum (BWQS) regression to evaluate the association between a pesticide metabolite mixture and neurobehavioral outcomes. RESULTS: In individual models, after adjusting for multiple comparisons, higher concentrations of hydroxy-tebuconazole (OH-TEB, metabolite of fungicide tebuconazole) were associated with higher anxiety (IRR per two-fold increase in concentrations = 1.26, 95% CI:1.08, 1.48) and Global Severity Index (GSI) (IRR = 1.89, 95% CI:1.36, 2.75) scores, whereas higher concentrations of 3,5,6-trichloro-2-pyridinol (TCPy, metabolite of chlorpyrifos) were associated with lower GSI scores (IRR = 0.69, 95% CI: 0.56, 0.85). In BWQS analyses, we found evidence of a mixture association of urinary pesticide metabolites with higher anxiety (IRR = 1.72, 95% CrI: 1.12, 2.55), depression (IRR = 4.60, 95% CrI: 2.19, 9.43), and GSI (IRR = 1.99, 95% CrI: 1.39, 2.79) scores. OH-TEB and hydroxy-thiabendazole (metabolite of fungicide thiabendazole) combined contributed 54%, 40%, and 54% to the mixture effect in the anxiety symptoms, depression symptoms, and overall psychological distress models, respectively. CONCLUSIONS: We found that exposure to tebuconazole and thiabendazole, fungicides whose effects have been rarely studied in humans, may be associated with increased psychological distress among avocado farmworkers. We also observed that exposure to chlorpyrifos may be associated with decreased psychological distress.

Fungicides from rice cultivation (tebuconazole and azoxystrobin) alters biochemical and histological markers of hammertoad tadpoles (Boanafaber).

Tebuconazole (TBZ) and azoxystrobin (AZX) are fungicides frequently used in rice cultivation. Despite protecting crops against fungal diseases, these compounds can contaminate the natural environments close to the crops, exerting negative effects on non-target organisms, the present study aimed to characterize the contamination by fungicides of a river that flows in an area dominated by rice cultivation in the north of the state of Santa Catarina, SC, Brazil. Concentrations of TBZ and AZX found in the field were used to evaluate their negative effects on development, biochemical biomarkers and histopatology of the liver of a native tadpole species, the hammerfrog (Boana faber). Tadpoles were exposed for 16 days to the lowest (1.20 µg/L) and highest (2.60 µg/L) concentration of TBZ, lowest (0.70 µg/L) and highest (1.60 µg/L) concentration of AZX, and the mix of both fungicides at lowest and highest concentration of each found in field analyses. Exposure to the lower TBZ concentration and both concentrations of the Mix accelerated the development of tadpoles. AZX caused an increase in the activities of glutathione S-transferase (GST), carboxylesterase (CbE) and glucose-6-phosphate dehydrogenase (G6PDH) in the liver, an increase in the levels of protein carbonyls (PC) in the liver and an increase in the activity of acetylcholinesterase (AChE) in muscle of tadpoles. TBZ, on the other hand, generated an increase in GST, G6PDH, PC and histopathological severity scores in liver and in muscle AChE activity. The effects were more intense in the groups exposed to the Mix of contaminants. No treatment altered brain AChE. The data showed that the fungicides from in rice cultivation found in natural aquatic environments around the crops pose risks to the health of the animals, compromising their metabolism and development.

Occurrence of pesticide residues in indoor dust of farmworker households across Europe and Argentina.

Pesticides are widely used as plant protection products (PPPs) in farming systems to preserve crops against pests, weeds, and fungal diseases. Indoor dust can act as a chemical repository revealing occurrence of pesticides in the indoor environment at the time of sampling and the (recent) past. This in turn provides information on the exposure of humans to pesticides in their homes. In the present study, part of the Horizon 2020 funded SPRINT project, the presence of 198 pesticide residues was assessed in 128 indoor dust samples from both conventional and organic farmworker households across Europe, and in Argentina. Mixtures of pesticide residues were found in all dust samples (25-121, min-max; 75, median). Concentrations varied in a wide range (<0.01 ng/g-206 µg/g), with glyphosate and its degradation product AMPA, permethrin, cypermethrin and piperonyl butoxide found in highest levels. Regarding the type of pesticides, insecticides showed significantly higher levels than herbicides and fungicides. Indoor dust samples related to organic farms showed a significantly lower number of residues, total and individual concentrations than those related to conventional farms. Some pesticides found in indoor dust were no longer approved ones (29 %), with acute/chronic hazards to human health (32 %) and with environmental toxicity (21 %).

In vitro evaluation of the efficacy of 8-hydroxyquinoline derivatives for the control of Phaeomoniella chlamydospora, the causative agent of Petri disease in grapevines.

AIM: This study evaluates the in vitro efficacy of 8-hydroxyquinoline (8HQ) derivatives in controlling the phytopathogenic fungus Phaeomoniella chlamydospora. METHODS AND RESULTS: The in vitro tests assessed the susceptibility to the minimum inhibitory concentration (MIC), checkerboard assay, mycelial growth (MG) inhibition, and EC50 determination. Among the seven agricultural fungicides tested, tebuconazole (TEB) displayed the lowest MIC, 1.01 µg mL-1, followed by captan (CAP), thiophanate methyl (TM), and mancozeb with MICs of 4.06, 5.46, and 10.62 µg mL-1, respectively. The 8HQ derivatives used in this study were clioquinol and PH 151 (PH) with MICs of 1.09 and 2.02 µg mL-1, respectively. PH associated with TEB and CAP showed synergism and inhibited 95.8% of MG at the highest dose. TEB inhibited 100% of MG at the three highest doses, while associated with PH exhibited the lowest EC50 (0.863 + 0.0381 µg mL-1). CONCLUSIONS: We concluded that the 8HQ derivatives tested controlled effectively the P. chlamydospora in vitro. PH associated with CAP and TEB exhibited a synergistic effect. The association between PH and TM was considered indifferent. IMPACT STATEMENT: This study expands the list of active ingredients tested against P. chlamydospora, with the PH 151 and clioquinol derivatives being tested for the first time. The in vitro efficacy and synergistic action with other fungicides suggest a potential use as a grapevine wound protectant. This association makes it possible to reduce doses and increase the potency of both drugs, reducing the risk of resistance development and harm to humans and the environment.

The survival and flight capacity of commercial honeybees and endangered stingless bees are impaired by common agrochemicals.

The impact of agrochemicals on native Brazilian bees may be underestimated, since studies of non-target effects on bees have, by and large, concerned mostly the Apis mellifera L. Furthermore, bees may be exposed in the field to multiple agrochemicals through different routes, thus suggesting the necessity for more comprehensive toxicological experiments. Here, we assessed the lethal and sublethal toxicity of multiple agrochemicals (herbicide [glyphosate - Roundup®], fungicide [mancozeb], insecticide [thiamethoxam]) through distinct routes of exposure (contact or ingestion) to an endangered native Brazilian bee Melipona (Michmelia) capixaba Moure & Camargo, 1994 and to A. mellifera. Results indicate that none of the agrochemicals caused feeding repellency on the bees. Thiamethoxam caused high mortality of both species, regardless of the route of exposure or the dose used. In addition, thiametoxam altered the flight capacity of M. capixaba when exposed to the lowest dose via contact exposure. The field dose of glyphosate caused high mortality of both bee species after oral exposure as well as impaired the flight capacity of A. mellifera (ingestion exposure) and M. capixaba (contact exposure). The lower dose of glyphosate also impaired the flight of M. capixaba through either routes of exposure. Exposure of A. mellifera through contact and ingestion to both doses of mancozeb caused high mortality and significantly impaired flight capacity. Taken altogether, the results highlight the importance of testing the impact of multiple agrochemicals (i.e. not just insecticides) through different routes of exposure in order to understand more comprehensively the potential risks for Apis and non-Apis bees.

Target and non-target site mechanisms of fungicide resistance and their implications for the management of crop pathogens.

Fungicides are indispensable for high-quality crops, but the rapid emergence and evolution of fungicide resistance have become the most important issues in modern agriculture. Hence, the sustainability and profitability of agricultural production have been challenged due to the limited number of fungicide chemical classes. Resistance to site-specific fungicides has principally been linked to target and non-target site mechanisms. These mechanisms change the structure or expression level, affecting fungicide efficacy and resulting in different and varying resistance levels. This review provides background information about fungicide resistance mechanisms and their implications for developing anti-resistance strategies in plant pathogens. Here, our purpose was to review changes at the target and non-target sites of quinone outside inhibitor (QoI) fungicides, methyl-benzimidazole carbamate (MBC) fungicides, demethylation inhibitor (DMI) fungicides, and succinate dehydrogenase inhibitor (SDHI) fungicides and to evaluate if they may also be associated with a fitness cost on crop pathogen populations. The current knowledge suggests that understanding fungicide resistance mechanisms can facilitate resistance monitoring and assist in developing anti-resistance strategies and new fungicide molecules to help solve this issue. © 2023 Society of Chemical Industry.

Assessment of cellular damage with cytome assay among environmental/occupational triazole.

The use of triazole fungicides is common in Minas Gerais, Brazil. However, the risk arising from excessive and often unprotected exposure can be harmful to farmers. Therefore, we evaluated volunteers, exposed to triazole fungicides for cellular damage caused by this pesticide. In the buccal micronucleus cytome assay (BMCyt), cells were analyzed. Urinary triazoles were analyzed by the Liquid-Liquid Extraction coupled with Gas-chromatography/mass-spectrometry (LLE-GC/MS). Statistical differences were found for all cell types evaluated in residents of rural areas (n = 145). Analysis of variance showed statistical difference in kariolytic and pyknotic cells, between the groups of men and women living in rural areas, with higher incidence in the male group. Likewise, higher concentrations triazoles in urine samples in the male group were observed. Greater cellular damage suggests increases in DNA damage, chromossomal instability and cell deaths. The results showed the urgency of the public management with the implementation of measures to minimize the pesticides exposure.

Major Fusarium species and mycotoxins associated with freshly harvested maize grain in Uruguay.

Fusarium species are common fungal pathogens of maize. Fusarium graminearum and Fusarium verticillioides, among others, can cause maize ear rot, and they are also mycotoxin producers. The aims of this work were to determine the frequency and diversity of Fusarium species in Uruguayan maize kernels, evaluate the toxigenic potential of the isolates, determine toxin contamination levels on freshly harvested grain, and assess the sensitivity of main Fusarium species against fungicides. Fusarium verticillioides was the most frequent species isolated, followed by Fusarium graminearum sensu stricto. Of F. verticillioides isolates studied for fumonisin production, 72% produced fumonisin B1 and 32% fumonisin B2. Considering in vitro toxin production by F. graminearum sensu stricto isolates, deoxynivalenol was the main toxin produced, followed by zearalenone and nivalenol. Fumonisins were the most frequently found toxins on freshly harvested maize samples (98% in 2018 and 86% in 2019), and also, fumonisin B1 was the toxin with highest concentration in both years studied (4860 µg/kg in 2018 and 1453 µg/kg in 2019). Deoxynivalenol and zearalenone were also found as contaminants. Metconazole and epoxiconazole were the most effective fungicides tested on F. verticillioides isolates. Fusarium graminearum sensu stricto isolates also were more sensitive to metconazole compared to other fungicides; nevertheless, epoxiconazole was less efficient in controlling this species. This is the first study that reports Fusarium species and mycotoxin contamination levels associated with maize grain in Uruguay. Its detection is the main step to develop management strategies in order to minimize fungal infection in maize crops.

Recent drug development and treatments for fungal infections.

Fungal infections are now becoming a hazard to individuals which has paved the way for research to expand the therapeutic options available. Recent advances in drug design and compound screening have also increased the pace of the development of antifungal drugs. Although several novel potential molecules are reported, those discoveries have yet to be translated from bench to bedside. Polyenes, azoles, echinocandins, and flucytosine are among the few antifungal agents that are available for the treatment of fungal infections, but such conventional therapies show certain limitations like toxicity, drug interactions, and the development of resistance which limits the utility of existing antifungals, contributing to significant mortality and morbidity. This review article focuses on the existing therapies, the challenges associated with them, and the development of new therapies, including the ongoing and recent clinical trials, for the treatment of fungal infections. Advancements in antifungal treatment: a graphical overview of drug development, adverse effects, and future prospects.

Synthesis of bis(ylidene) cyclohexanones and their antifungal activity against selected plant pathogenic fungi.

Botrytis cinerea, Rhizoctonia solani and Hemileia vastatrix are three species of phytopathogenic fungi behind major crop losses worldwide. These have been selected as target models for testing the fungicide potential of a series of bis(ylidene) cyclohexanones. Although some compounds of this chemical class are known to have inhibitory activity against human pathogens, they have never been explored for the control of phytopathogens until now. In the present work, bis(ylidene) cyclohexanones were synthesized through simple, fast and low-cost base- or acid-catalyzed aldol condensation reaction and tested in vitro against B. cinerea, R. solani and H. vastatrix. bis(pyridylmethylene) cyclohexanones showed the highest activity against the target fungi. When tested at 200 nmol per mycelial plug against R. solani., these compounds completely inhibited the mycelial growth, and the most active bis(pyridylmethylene) cyclohexanone compound had an IC50 of 155.5 nmol plug-1. Additionally, bis(pyridylmethylene) cyclohexanones completely inhibited urediniospore germination of H. vastatrix, at 125 µmol L-1. The most active bis(pyridylmethylene) cyclohexanone had an IC50 value of 4.8 µmol L-1, which was estimated as approximately 2.6 times lower than that found for the copper oxychloride-based fungicide, used as control. Additionally, these substances had a low cytotoxicity against the mammalian Vero cell line. Finally, in silico calculations indicated that these compounds present physicochemical parameters regarded as suitable for agrochemicals. Bis(ylidene) cyclohexanones may constitute promising candidates for the development of novel antifungal agents for the control of relevant fungal diseases in agriculture.

Effect of satellite-emitted frequency sequences on Phakopsora pachyrhizi control, on soybean nutrition and yield

The obstacles in Phakopsora pachyrhizi management result especially from susceptible soybean genotypes and resistant fungal strains. The objective of the current study was to evaluate the applicability of the emission of extremely low and specific frequencies by Effatha technology in the soybean Asian rust control, nutrition, and its impact on yield. The in-vivo test followed the detached leaves method, with six treatments: frequencies 1 and 2 individually and in association; the conventional chemical treatment (fungicide azoxystrobin + benzovindiflupyr); and witnesses in presence and absence of the fungus. Frequency 1 relates to inhibition of the enzyme succinate dehydrogenase and 2 to ubiquinone oxidase. In the field, frequencies 1 and 2 associated (with the same fungicidal action of the in-vivo study); nutritional frequency; application of azoxystrobin + benzovindiflupyr + mancozeb, and control without application were evaluated. In vivo, the fungicide provided 85% control of the disease symptoms, against 65% of frequencies 1 and 2 in association, which showed a higher efficiency compared to the isolated frequencies. In the field, the rate of increase of symptoms were reduced by all treatments compared to the control. At the end of the soybean cycle, the conventional fungicide resulted in 33% severity against 56% of frequencies 1 and 2 associated, and 69.2% of the control. The emission of the frequency for increased nutrient efficiency stood out positively on yield in relation to all the other ones. The conventional application provided the highest weight of 1,000 grains, possibly a direct reflection of the better control of the disease.

Caprylic acid in Vitex mollis fruit and its inhibitory activity against a thiabendazole-resistant Colletotrichum gloeosporioides strain.

BACKGROUND: Colletotrichum gloeosporioides causes anthracnose in a large number of crops. Synthetic fungicides are employed to prevent this disease, even though their effectiveness and safety is questionable. Thus, effective and innocuous antifungal compounds are proposed as natural alternatives against anthracnose. The hexane fraction of Vitex mollis pulp (HF-VM) reduces anthracnose incidence in papaya fruit; however, the active compounds and antifungal mechanism of HF-VM are unknown. The aims of this study were to characterize the activity of HF-VM sub-fractions (sHF1 -sHF7 ) against a thiabendazole-resistant Colletotrichum gloeosporioides strain, identify the chemical components and investigate the mechanism of the most active sub-fraction. RESULTS: The sHF3 showed the highest inhibitory activity against Colletotrichum gloeosporioides with a minimal inhibitory concentration (MIC) of 0.5 mg mL-1 , whereas thiabendazole (TBZ) had a MIC value higher than 2 mg mL-1 . The gas chromatography-mass spectrometry (GC-MS) analysis showed that the compounds in sHF3 were methyl 4-decenoate, caprylic acid, and 24-methylencycloartanol. These compounds are rarely found in fruits and are reported for the first time on Vitex species. The purified 24-methylencycloartanol was inactive (MIC > 0.5 mg mL-1 ). In contrast, the commercial standard of caprylic acid presented an elevated activity (MIC = 0.125 mg mL-1 ), indicating that this compound is the main one responsible for the antifungal properties of sHF3 . Furthermore, the sHF3 inhibited the spore germination and induced membrane disruption in both the spore and mycelium of Colletotrichum gloeosporioides. CONCLUSION: Vitex mollis fruit is a novel source of antifungal caprylic acid that could be employed as a marker to prepare standardized extracts with antifungal properties. © 2022 Society of Chemical Industry.

Potential Action Mechanism and Inhibition Efficacy of Morinda citrifolia Essential Oil and Octanoic Acid against Stagonosporopsis cucurbitacearum Infestations.

The use of plant-based products has been shown to efficiently inhibit fungi-mediated diseases in agricultural crops. Here, we extracted and evaluated the composition of noni, Morinda citrifolia L., essential oil and assessed its activities against Stagonosporopsis cucurbitacearum in Cucumis melo L. Using in silico molecular approaches, potential interactions between the essential oil major components and S. cucurbitacearum tyrosine-tRNA ligase were predicted. Finally, we also measured the potential interference of plant physiology (the stomatal conductance and net photosynthesis) mediated by the application of the M. citrifolia essential oil. Chromatographic analysis revealed that octanoic acid (75.8%), hexanoic acid (12.8%), and isobutyl pent-4-enyl carbonate (3.1%) were the major essential oil compounds. Octanoic acid and noni essential oil, when used as preventive measures, reduce fungal mycelial growth at a concentration of 5 mg/mL without causing significant damage to the treated leaves, which reinforces their efficacies as preventive tools against S. cucurbitacearum. Molecular docking analyses predicted very stable interactions between the major essential oil constituents and S. cucurbitacearum tyrosine-tRNA ligase, suggesting the interference of these plant-based molecules upon enzyme activation. Octanoic acid and M. citrifolia essential oil at concentrations of 20 mg/mL decreased the stomatal conductance and net photosynthesis rate of melon plants, resulting in robust phytotoxicity. Collectively, our findings indicated that despite the phytotoxicity risks at higher concentrations, M. citrifolia essential oil and octanoic acid, have potential as alternative tools for the integrative management of S. cucurbitacearum.

Mefenoxam and pyraclostrobin: toxicity and in vitro inhibitory activity against Pythium insidiosum.

The objective of this study is to verify in vitro susceptibility of Pythium insidiosum against the agricultural fungicides mefenoxam and pyraclostrobin and evaluate the toxicity of both compounds. Twenty-one P. insidiosum isolates were tested against mefenoxam and pyraclostrobin using the broth microdilution method. Minimum inhibitory and oomicidal concentrations for both compounds were established. Additionally, scanning electron microscopy was performed on P. insidiosum hyphae treated with the sublethal concentration of each fungicide. The toxicity of the compounds was evaluated in vivo Caenorhabditis elegans model. The concentration to inhibit 100% of P. insidiosum growth ranged from 0·625 to 10 µg ml-1 for mefenoxam and from 0·019 to 5 µg ml-1 for pyraclostrobin. The SEM analysis revealed changes on the surface of the hyphae treated with the fungicides, suggesting possible damage caused by these compounds. There was no evidence of toxicity in vivo models. Mefenoxam and pyraclostrobin did not show toxicity at the doses evaluated and have inhibitory effects on the pathogenic oomycete P. insidiosum. However, further evaluations of their pharmacokinetics and toxicity in different animal species and possible pharmacological interactions are necessary to infer a possible use in the clinical management of pythiosis.

Commercial yerba mate (Ilex paraguariensis) produced in South America: Determination of dithiocarbamate residues by gas chromatography-mass spectrometry.

This work presents an easy and quick miniaturized procedure for the analysis of dithiocarbamates fungicides (DTC), by GC-MS, in yerba mate, an important product in South America. The sample amount, the volume of extracting solvent and acid solution, and the time of hot bath shaking were minimized. A clean-up procedure based on PSA, GCB and MgSO4 was studied in order to improve analytical signal and reduce GC-MS system damage. Blank yerba mate samples were spiked with thiram at equivalent CS2 concentrations of 0.1, 0.3, 0.5 and 1 mg kg-1. The validated method at least 2 times faster than the traditional method and was according to the latest European guidelines for pesticide residue analysis. Linearity, limits of detection and quantification, matrix effects, trueness and precision were assessed. Sixty-five commercialized samples from southern Brazil and Argentina were analyzed; 14% of samples presented CS2 concentration greater than LOQ (0.1 mg kg-1).

High MICs for antifungal agents in yeasts from an anthropized lagoon in South America.

The lagoons are fragile ecosystems used by several species as a refuge and breeding area, and it is also a place where certain communities practice fishing activity. With increasing urbanization around this ecosystem, pesticides used in agriculture and untreated urban wastewater are drained into the river basin, resulting in the dispersion of organic matter and antifungals used by the population and farmers. These may favor the selection of resistant pathogens directly into the environment, a concern since several fungi have emerged as pathogens in the last decades. In this study, we investigated the presence in an impacted lagoon by potentially resistant yeasts to antifungal agents. We evaluated their capacity for producing extracellular enzymes that could act as virulence factors. Water samples from the Tramandaí lagoon were analyzed for the presence of pesticides using the SPE-LC-ESI-MS/MS. Tricyclazole, carbendazim, azoxystrobin, thiabendazole, and tebuconazole were found. Twenty-eight yeast species were isolated, including the multidrug-resistant Candida haemulonii, and species with high minimal inhibitory concentrations (MICs) for clinical antifungal agents. Around 93% of the isolates had MIC values above the resistance breakpoints established for Candida species for at least two antifungal agents. And 27% had high MICs values for fluconazole, terbinafine, amphotericin B, and caspofungin. Tebuconazole MICs values were highly associated with MICs for fluconazole, terbinafine, and amphotericin B, and significant correlations between high MICs for antifungal agents and enzyme production were found. The results indicated that the lagoon is a reservoir of resistance genes and a potential source for fungal infection, highlighting the importance of the One Health approach and the integrated vision of the ecosystem when managing these environments.