Search Results (9)

Pesticides represent a significant threat to aquatic ecosystems due to their persistence and widespread use in agricultural areas, altering environments and exerting adverse effects on non-target organisms. Tebuthiuron is a phenylurea herbicide extensively used as an agrochemical to control pests and weeds in various crops, which often leads to contamination of aquatic environments. Despite its high water solubility and relatively long half-life in soil, studies on Tebuthiuron toxicity in fishes at environmental concentrations are limited. This study aimed to unravel the toxicity mechanisms of Tebuthiuron using the zebrafish model. Zebrafish embryos were exposed to Tebuthiuron (one concentration of either 0.1, 10, 1000 and 5000 µg/L) for 5 days and assessed for hatchability, heart rate, locomotor activity, oxygen reactive species, apoptosis and gene expression. There was no change in frequency of hatch, heart rate, or apoptosis. However, behavioral changes were noted, with hyperactivity in zebrafish larvae during the first light (at 10 µg/L), second light (at 10 and 1000 µg/L) and third dark (10 µg/L) periods of the Visual Motor Response assay. Biochemically, a significant depletion of basal ROS levels was observed at 1000 µg/L. At the molecular level, downregulation of oxidative stress-related genes (cat, sod1, and sod2) in larval fish was noted with exposure to 10 and 5000 µg/L Tebuthiuron, suggesting a depletion of antioxidant enzymes. In addition, some neurotoxicity-related genes were downregulated, such as acetylcholinesterase (ache), while some genes were upregulated, like microtubule-associated protein tau b (maptb) and synapsin 2 alpha (syn2a), with 5000 µg/L Tebuthiuron exposure. In conclusion, Tebuthiuron induces sublethal toxicity characterized by irregular, concentration-specific disruptions to photomotor behavior, basal ROS levels, and transcriptional markers of oxidative stress and synaptic function, even in the absence of acute morphological defects. Future research should prioritize functional assays targeting mitochondrial bioenergetics and antioxidant enzyme activities, alongside evaluations of later developmental stages, to fully elucidate the long-term ecological risks of phenylurea herbicides to non-target aquatic species. Full article

This study evaluated the individual and combined effects of different bio-inputs—traditional filter cake, filter cake composted with ash, and a microbial inoculant—on the growth and physiological performance of Mucuna pruriens cultivated in soil contaminated with the herbicide tebuthiuron. The experiment followed a completely randomized design with twelve treatments and five evaluation periods (7, 21, 35, 49, and 70 days after sowing). Morphophysiological variables such as plant height, root length, dry biomass, and chlorophyll content were assessed. The results showed that the addition of traditional filter cake promoted significant growth in tebuthiuron-contaminated soil, while, in uncontaminated conditions, both organic residues and the microbial inoculant enhanced plant development, particularly at later stages. Initial phytotoxicity was observed in treatments with organic residues (up to 67% of samples before 35 days), but these effects decreased over time. The microbial inoculant performed better in the absence of organic amendments, suggesting possible antagonistic interactions. Tebuthiuron reduced chlorophyll content by inhibiting photosystem II, but this effect was mitigated by the addition of filter cake. Overall, the findings highlight the potential of integrating Mucuna pruriens cultivation with organic residues and microbial inoculants as an effective phytomanagement strategy for tebuthiuron-affected soils. This approach provides a sustainable model for improving soil health, supporting legume-based rehabilitation, and advancing biological alternatives to conventional remediation practices. Full article

Sugarcane is a key crop for sugar, biofuels, and bioenergy, with Brazil as the world’s largest producer. Intensive cultivation demands pesticides like tebuthiuron and thiamethoxam, while fertigation with vinasse may alter their environmental behavior. Sustainable approaches, such as phytoremediation, are needed to mitigate negative impacts on soil quality. This study assessed the phytoremediation potential of Canavalia ensiformis and Mucuna pruriens in soils contaminated with tebuthiuron, thiamethoxam, and vinasse under greenhouse conditions. Experiments used a completely randomized design (five replicates, 4 × 2 factorial). Plant development impacts on the sentinel species Crotalaria juncea, and ecotoxicity via Lactuca sativa bioassays were evaluated. Tebuthiuron strongly inhibited C. ensiformis, while thiamethoxam showed mild stimulatory effects. M. pruriens maintained better growth in the presence of contaminants. Bioassays revealed greater residual toxicity in tebuthiuron treatments. Overall, M. pruriens demonstrated superior biomass production and capacity to lessen soil toxicity, underscoring its potential as a sustainable tool for phytoremediation of pesticide-impacted soils. Full article

Herbicides are important for weed control but can severely impact ecosystems, causing soil and water contamination, biodiversity loss, and harm to non-target organisms. Tebuthiuron, widely used in sugarcane cultivation, is highly soluble and persistent, posing significant environmental risks. Microbial inoculation has emerged as a sustainable strategy to mitigate such damage. This study investigated the phytoremediation potential of Mucuna pruriens and Canavalia ensiformis in tebuthiuron-contaminated soils, enhanced by fungal and bacterial inoculants. Crotalaria juncea served as a bioindicator plant, and Lactuca sativa was used in ecotoxicological bioassays. During a 140-day greenhouse experiment from September 2021 to March 2022, M. pruriens showed faster growth than C. ensiformis in uncontaminated soils but was more affected by tebuthiuron. Bacterial inoculants improved M. pruriens growth under stress, while fungal inoculants mitigated tebuthiuron’s effects on C. ensiformis. C. juncea exhibited high sensitivity to tebuthiuron but grew beyond 100 cm with bacterial inoculants. Ecotoxicological assays showed that bacterial bioaugmentation significantly reduced soil toxicity. Natural attenuation further decreased tebuthiuron toxicity, and prior cultivation of M. pruriens enhanced soil detoxification. This integrated approach combining phytoremediation and bioaugmentation offers a sustainable method to degrade tebuthiuron, foster safer agriculture, and reduce environmental and health risks. Full article

Pimelea trichostachya Lindl. is a native Australian forb responsible for livestock poisoning and reducing the productivity and sustainability of grazing enterprises. This study was conducted as a pot trial under controlled conditions to investigate an effective chemical management strategy for P. trichostachya, a method that did not leave standing dead plant material, as such material can also be toxic to grazing cattle. Three herbicides, including one pre-emergence (tebuthiuron) and two post-emergence herbicides (2,4-D and metsulfuron-methyl), were tested in pot trials for their efficacy on P. trichostachya. Results showed that tebuthiuron applied as either a granular (10% active ingredient, a.i.) or pelleted (20% a.i.) form efficiently reduced the emergence of P. trichostachya seedlings. Although some seedlings emerged, they perished within 7 days post treatment, leaving no residual plant matter. Testing now needs to be undertaken under field conditions to validate the findings within vegetation communities where potential non-target impacts need to be accounted for as well. The post-emergence application of 2,4-D and metsulfuron-methyl demonstrated that the highest efficacy and reduced application rates were achieved by treating earlier growth stages (i.e., seedlings) of P. trichostachya plants. In addition, the amount of toxic dead plant material was minimized due to the faster degradation of these small plants. These findings offer practical, cost-effective solutions for sustaining grazing lands from P. trichostachya challenges. Full article

Tebuthiuron is a selective herbicide for woody species and is commonly manufactured and sold as a granular formulation. This project investigated the use of infrared spectroscopy for the quality analysis of tebuthiuron granules, specifically the prediction of moisture content and tebuthiuron content. A comparison of different methods showed that near-infrared spectroscopy showed better results than mid-infrared spectroscopy, while a handheld NIR instrument (MicroNIR) showed slightly improved results over a benchtop NIR instrument (Antaris II FT-NIR Analyzer). The best-performing models gave an R²_CV of 0.92 and RMSECV of 0.83% w/w for moisture content, and R²_CV of 0.50 and RMSECV of 7.5 mg/g for tebuthiuron content. This analytical technique could be used to optimise the manufacturing process and reduce the costs of post-manufacturing quality assurance. Full article

While there are many high profile Opuntioid cactus species invading rangeland environments in Australia, Cereus uruguayanus Ritt. ex Kiesl. has also naturalised and formed large and dense infestations at several locations. With no herbicides registered for control of C. uruguayanus in Australia, the primary aim of this study was to identify effective herbicides to control it using a range of techniques. This involved a large screening trial of twelve herbicides and four techniques, followed by a rate refinement trial for cut stump applications and another to test residual herbicides. Despite most treatments (except monosodium methylarsonate (MSMA)) taking a long time to kill plants, at least one effective herbicide was identified for basal bark (triclopyr/picloram), cut stump (aminopyralid/metsulfuron-methyl, glyphosate, metsulfuron-methyl, triclopyr/picloram, triclopyr/picloram/aminopyralid), stem injection (glyphosate, MSMA, triclopyr/picloram/aminopyralid) and foliar applications (aminopyralid/metsulfuron-methyl, MSMA, triclopyr, triclopyr/picloram/aminopyralid) due to their ability to kill both small and large plants. Ground application of residual herbicides was less conclusive with neither hexazinone nor tebuthiuron causing adequate mortality at the rates applied. This study has identified effective herbicides for the control of C. uruguayanus using several techniques, but further research is needed to refine herbicide rates and develop integrated management strategies for a range of situations and infestation sizes and densities. Full article

Non-native plant species have become serious pests in Hawaii’s delicate island ecosystems. It is necessary to control invasive plants. The herbicides hexazinone and tebuthiuron were evaluated for defoliation efficacy to control several major invasive plants and for non-target effects on native plants at Site I in a rainforest at 1200 m elevation and Site II in a mesic area at 640 m elevation on the island of Kauai, Hawaii. The invasive weed species in the sites included daisy fleabane (Erigeron karvinskianus DC.), faya tree (Myrica faya Ait.), strawberry guava (Psidium cattleyanum Sabine), banana passion fruit (Passiflora mollissima Bailey), vaseygrass (Paspalum urvillei Steud.), and highbush blackberry (Rubus argutus Link. 1822). Native plants included ohia lehua (Metrosideros polymorpha Gaudich.), naupaka (Scaevola cerasifolia Labill.), pilo (Hedyotis mannii), hona (Urera glabra (Hook. & Arn.)), aalii (Dodonaea viscosa Jacq.), and amau (Sadleria sp.). The results showed that broadcast applications of hexazinone granules and tebuthiuron pellets were effective on some of those invasive species. Herbicidal tolerance varied among the native species. For example, D. viscosa showed high tolerance to hexazinone. S. cerasifolia was susceptible to hexazinone, but not to tebuthiuron. The inconsistent defoliation of Sadleria sp. occurred among different applications rates of the two herbicides. M. polymorpha, particularly when it was small, could tolerate hexazinone and tebuthiuron. U. glabra was severely injured by the two herbicides. H. mannii was moderately tolerant to hexazinone, but fairly sensitive to tebuthiuron. The invasive loblolly pine (Pinus taeda L.) was highly tolerant to hexazinone, but was very sensitive to tebuthiuron. M. faya was very sensitive to hexazinone, but very tolerant to tebuthiuron. P. cattleyanum was sensitive to both herbicides. Six and nine months after hexazinone and tebuthiuron treatment, respectively, native plants were transplanted into the Sites to observe injury from residual herbicides. Approximately less than 10% mortality was observed for the out-planted native species three months after planting (MAP), indicating that the native species showed less injury in the early period of transplant. The mortality of the three endangered species Kauai hau kuahiwi (Hibiscadelphis distans), Kauai delissea (Delissea rhytidosperma H.Mann) and kawawaenohu (Alsinidendron lynchnoides), however, increased as the MAP increased. Overall, broadcast treatments of hexazinone and tebuthiuron at rates higher than 1 kg active ingredient per hectare would be problematic. The dissipation half-life values of hexazinone and tebuthiuron in the 1–15 cm layer of soils at the two sites were approximately 7 days and greater than 180 days, respectively. Full article

The extraction of powdered nutraceuticals is challenging due to the low water content and high concentration of matrix components that can lead to significant matrix effects in liquid chromatography-positive ion electrospray ionization-tandem mass spectrometry (LC-ESI⁺-MS/MS). In this study we assess the feasibility of using pressurized solvent extraction with ethyl acetate to reduce the co-extraction of polar matrix components. Pigment attributed to chlorophyll was removed with in-cell clean-up utilizing Anasorb 747, Florisil^®, and C18. Visible inspection of the extracts showed that pigment was removed from matcha, a powdered green tea sample. Pressurized solvent extraction with in-cell clean-up can be utilized to remove pigments from powdered samples such as nutraceuticals. Average matrix effect of the 32 target analytes that observed mass spectrometric signal suppression or soft MS signal enhancement was −41 ± 19% with the majority of analytes having a protonated molecular ion with m/z of 250 to 412. As generally moderate signal suppression was observed for conazole fungicides and structurally related compounds analyzed by LC-ESI⁺-MS/MS, it is recommended that matrix matched or standard addition calibration is used for quantitation. Catachins, other polyphenols, and caffeine are expected to contribute to the matrix effects observed in LC-ESI⁺-MS/MS. Diniconazole, fenbuconazole, and tebufenozide were the only target analytes with severe MS signal enhancement. Low levels (0.002–0.004 mg/kg) of prothioconazole-desthio and flusilazole were detected, along with trace levels of tebuthiuron in matcha. Full article