Glyphosate in northern ecosystems

Chemical Modification of Acrylonitrile-Divinylbenzene Polymer Supports with Aminophosphonate Groups and Their Antibacterial Activity Testing

Bacterial contamination is a major public health concern on a global scale. Treatment resistance in bacterial infections is becoming a significant problem that requires solutions. We were interested in obtaining new polymeric functionalized compounds with antibacterial properties. Three components (polymeric amine, aldehyde, and phosphite) were used in the paper in a modified "one-pot" Kabachnik-Fields reaction, in tetrahydrofuran at 60 °C, to create the N-C-P skeleton in aminophosphonate groups. Two copolymers were thus prepared starting from an acrylonitriledivinylbenzene (AN-15%DVB) copolymer containing pendant primary amine groups modified by grafting aminophosphonate groups, i.e., aminobenzylphosphonate (Bz-DVB-AN) and aminoethylphosphonate (Et-DVB-AN). The two copolymers were characterized by FT-IR spectroscopy, SEM-EDX, TGA, and antibacterial properties. It was shown that the novel products have antibacterial qualities against S. aureus and E. coli bacteria. The sample with the strongest antibacterial activity was Et-DVB-AN. We assessed how well the Weibull model and the first-order kinetic model represent the inactivation of microbial cells in our samples. The main advantage of the new antibacterial agents developed in this work is their easy recovery, which helps to avoid environmental contamination.

Fabrication of a novel bifunctional magnetic nanocomposite for colorimetric detection and removal of glyphosate

Overuse of glyphosate, the most widespread herbicide used in agricultural areas around the world, causes it to accumulate in soil and water, posing a serious threat to the agricultural environment, crop growth and food safety. It is of vital significance to develop effective strategies to achieve rapid monitoring and management of glyphosate. However, previously documented methods have rarely been applied to simultaneously detect and remove glyphosate in water environments. Here, we have created a novel magnetic nanocomposite Iron-oxide/polydopamine/graphene-oxide/copper-oxide (Fe3O4/PDA/GO/CuO) that integrated the dual functions of detection and removal, enabling the colorimetric detection and adsorption of glyphosate. As a colorimetric probe, Fe3O4/PDA/GO/CuO exhibited excellent sensing performance with broad detection range (0.05-1 mg/L and 5-110 mg/L), low detection limit (0.028 mg/L), and good selectivity. Simultaneously, it realized a rapid and sensitive visual analysis of glyphosate on the test strips by RGB color. As an adsorbent, Fe3O4/PDA/GO/CuO obtained effective adsorption and rapid separation of glyphosate in water solution. Moreover, as an attempt, we explored the potential of Fe3O4/PDA/GO/CuO for crop remediation by removing glyphosate-contaminated water. This work opens up a new idea for the integrated strategy of glyphosate detection and removal in water environments and also demonstrates its enormous potential for rapid monitoring and management of herbicide.

The systemic herbicide glyphosate affects the sporulation dynamics of Rhizophagus species more severely than mechanical defoliation or the contact herbicide diquat

Arbuscular mycorrhizal fungi (AMF) are totally dependent on a suitable host plant for their carbon resources. Here, we investigated under in vitro conditions, the impact of defoliation practices, i.e., mechanical defoliation or chemical defoliation with a contact herbicide (Reglone®, containing the active ingredient diquat) or systemic herbicide (RoundUp®, containing the active ingredient glyphosate), on the dynamics of spore production of Rhizophagus irregularis and Rhizophagus intraradices associated with Solanum tuberosum and/or Medicago truncatula. Glyphosate affected the spore production rate more rapidly and severely than diquat or mechanical defoliation. We hypothesize that this effect was related to disruption of the C metabolism in the whole plant combined with a possible direct effect of glyphosate on the fungus within the roots and/or perhaps in soil via the release of this active ingredient from decaying roots. No glyphosate could be detected in the roots due to technical constraints, while its release from the roots in the medium corresponded to 0.11% of the active ingredient applied to the leaves. The three defoliation practices strongly affected root colonization, compared to the non-defoliated plants. However, the amount of glyphosate released into the medium did not affect spore germination and germ tube growth. These results suggest that the effects of defoliation on the dynamics of spore production are mainly indirect via an impact on the plant, and that the effect is faster and more marked with the glyphosate-formulation, possibly via a direct effect on the fungus in the roots and more unlikely on spore germination.

Enhanced capacity of a leaf beetle to combat dual stress from entomopathogens and herbicides mediated by associated microbiota

Herbicides have demonstrated their impact on insect fitness by affecting their associated microbiota or altering the virulence of entomopathogenic fungi toward insects. However, limited research has explored the implications of herbicide stress on the intricate tripartite interaction among insects, associated bacterial communities, and entomopathogens. In this study, we initially demonstrated that associated bacteria confer a leaf beetle, Plagiodera versicolora, with the capability to resist the entomopathogenic fungus Aspergillus nomius infection, a capability sustained even under herbicide glyphosate stress. Further analysis of the associated microbiota revealed a significant alteration in abundance and composition due to glyphosate treatment. The dominant bacterium, post A. nomius infection or following a combination of glyphosate treatments, exhibited strong suppressive effects on fungal growth. Additionally, glyphosate markedly inhibited the pathogenic associated bacterium Pseudomonas though it inhibited P. versicolora's immunity, ultimately enhancing the beetle's tolerance to A. nomius. In summary, our findings suggest that the leaf beetle's associated microbiota bestow an augmented resilience against the dual stressors of both the entomopathogen and glyphosate. These results provide insight into the effects of herbicide residues on interactions among insects, associated bacteria, and entomopathogenic fungi, holding significant implications for pest control and ecosystem assessment.

Plant metabolic responses to soil herbicide residues differ under herbivory in two woodland strawberry genotypes

The use of glyphosate-based herbicides (GBHs) to control weeds has increased exponentially in recent decades, and their residues and degradation products have been found in soils across the globe. GBH residues in soil have been shown to affect plant physiology and specialised metabolite biosynthesis, which, in turn, may impact plant resistance to biotic stressors. In a greenhouse study, we investigated the interactive effects between soil GBH residues and herbivory on the performance, phytohormone concentrations, phenolic compound concentrations and volatile organic compound (VOC) emissions of two woodland strawberry (Fragaria vesca) genotypes, which were classified as herbivore resistant and herbivore susceptible. Plants were subjected to herbivory by strawberry leaf beetle (Galerucella tenella) larvae, and to GBH residues by growing in soil collected from a field site with GBH treatments twice a year over the past eight years. Soil GBH residues reduced the belowground biomass of the susceptible genotype and the aboveground biomass of both woodland strawberry genotypes. Herbivory increased the belowground biomass of the resistant genotype and the root-shoot ratio of both genotypes. At the metabolite level, herbivory induced the emission of several VOCs. Jasmonic acid, abscisic acid and auxin concentrations were induced by herbivory, in contrast to salicylic acid, which was only induced by herbivory in combination with soil GBH residues in the resistant genotype. The concentrations of phenolic compounds were higher in the resistant genotype compared to the susceptible genotype and were induced by soil GBH residues in the resistant genotype. Our results indicate that soil GBH residues can differentially affect plant performance, phytohormone concentrations and phenolic compound concentrations under herbivore attack, in a genotype-dependent manner. Soil GBH altered plant responses to herbivory, which may impact plant resistance traits and species interactions. With ongoing agrochemical pollution, we need to consider plant cultivars with better resistance to polluted soils while maintaining plant resilience under challenging environmental conditions.

Persistence and pathway of glyphosate degradation in the coastal wetland soil of central Delaware

Glyphosate is a globally dominant herbicide. Here, we studied the degradation and microbial response to glyphosate application in a wetland soil in central Delaware for controlling invasive species (Phragmites australis). We applied a two-step solid-phase extraction method using molecularly imprinted polymers designed for the separation and enrichment of glyphosate and aminomethylphosphonic acid (AMPA) from soils before their analysis by ultra-high-performance liquid chromatography (UHPLC) and Q Exactive Orbitrap mass spectrometry methods. Our results showed that approximately 90 % of glyphosate degraded over 100 d after application, with AMPA being a minor (<10 %) product. Analysis of glyphosate-specific microbial genes to identify microbial response and function revealed that the expression of the phnJ gene, which codes C-P lyase enzyme, was consistently dominant over the gox gene, which codes glyphosate oxidoreductase enzyme, after glyphosate application. Both gene and concentration data independently suggested that C-P bond cleavage-which forms sarcosine or glycine-was the dominant degradation pathway. This is significant because AMPA, a more toxic product, is reported to be the preferred pathway of glyphosate degradation in other soil and natural environments. The degradation through a safer pathway is encouraging for minimizing the detrimental impacts of glyphosate on the environment.

Hormetic dose response induced by sublethal-dose sulfoxaflor leads to reproductive stimulation of Aphis gossypii

Aphis gossypii Glover is one of the most agriculturally important phloem-feeding economic pests, causing tremendous loss in crop yield annually. The hormesis is an important cause of A. gossypii resistance formation, population resurgence, and re-outbreak. However, whether the hormesises induced by different insecticides interact mutually remain largely unclear. In the study, four-generation A. gossypii experiment found that the 24-h sublethal-dose (LC20) sulfoxaflor treatment on G0 significantly increased the net reproductive rate (R0) and fecundity of G1 and G2 generation A. gossypii, but it did not significantly affect the fecundity of G3 and G4 individuals. Transcriptomic analyses revealed that the insecticide-induced significant up-regulation of pathways ribosome, energy metabolism, and the DNA replication and reparation might be responsible for the enhancement of fecundity in G1 and G2 A. gossypii. Notably, G0 exposure to LC20 sulfoxaflor followed by G1 exposure to LC30 deltamethrin resulted in a stronger reproductive stimulation than sulfoxaflor or deltamethrin exposure alone. Our findings provide valuable reference for optimizing sulfoxaflor application in integrated pest management strategies.

Biomimetic laser-induced graphene fern leaf and enzymatic biosensor for pesticide spray collection and monitoring

Monitoring of pesticide concentration distribution across farm fields is crucial to ensure precise and efficient application while preventing overuse or untreated areas. Inspired by nature's wettability patterns, we developed a biomimetic fern leaf pesticide collection patch using laser-induced graphene (LIG) alongside an external electrochemical LIG biosensor. This "collect-and-sense" system allows for rapid pesticide spray monitoring in the farm field. The LIG is synthesized and patterned on polyimide through a high-throughput gantry-based CO2 laser process, making it amenable to scalable manufacturing. The resulting LIG-based leaf exhibits a remarkable water collection capacity, harvesting spray mist/fog at a rate approximately 11 times greater than a natural ostrich fern leaf when the collection is normalized to surface area. The developed three-electrode LIG pesticide biosensor, featuring a working electrode functionalized with electrodeposited platinum nanoparticles (PtNPs) and the enzyme glycine oxidase, displayed a linear range of 10-260 μM, a detection limit of 1.15 μM, and a sensitivity of 5.64 nA μM-1 for the widely used herbicide glyphosate. Also, a portable potentiostat with a user-friendly interface was developed for remote operation, achieving an accuracy of up to 97%, when compared to a standard commercial benchtop potentiostat. The LIG "collect-and-sense" system can consistently collect and monitor glyphosate spray after 24-48 hours of spraying, a time that corresponds to the restricted-entry interval required to enter most farm fields after pesticide spraying. Hence, this innovative "collect-and-sense" system not only advances precision agriculture by enabling monitoring and mapping of pesticide distribution but also holds the potential to significantly reduce environmental impact, enhance crop management practices, and contribute to the sustainable and efficient use of agrochemicals in modern agriculture.

Associations between Glyphosate Exposure and Glycemic Disorders: A Focus on the Modifying Effect of Sex Hormones

Widespread glyphosate contamination in the environment and its endocrine-disrupting potential are concerning. However, evidence of glyphosate's effects on glycemic health is limited. To examine the association between glyphosate and glucose homeostasis in the general US population, a total of 3038 individuals were enrolled from the 2013-2016 cycles of the National Health and Nutrition Examination Survey (NHANES). Survey-weighted linear regression and restricted cubic spline curves were used to detect the associations between glyphosate and glycemic disorders. The effects of interactions between sex hormones and glyphosate on glycemic outcomes were evaluated. The results showed that glyphosate was significantly linked to increased glycated hemoglobin A1c (HbA1c) levels (β = 0.01; 95%CI, 0.01 to 0.02; p = 0.001) and the compromised homeostatic model assessment of beta-cell function (HOMA-beta) scores (β = -0.09; 95%CI, -0.17 to -0.01; p = 0.024). More importantly, these "glyphosate-glycemic disorder" associations were significantly modified by sex hormone-binding globulin (SHBG; P for interaction < 0.05), with more pronounced relationships being identified in individuals with low SHBG levels. Our findings indicate that glyphosate is correlated with glucose dyshomeostasis. Individuals with low SHBG levels exhibited susceptibility to glyphosate-related glycemic toxicity; therefore, it might be prudent to determine glycemic health in those subjects with glyphosate exposure.

Connectivity mediates the spatial ecological impacts of a glyphosate-based herbicide in experimental metaecosystems

Metacommunity ecology has shown that connectivity is important for the persistence of a species locally and across connected ecosystems, however we do not know if ecological effects in freshwater ecosystems exposed to biocides leaking from agriculture depend on metaecosystem connectivity. We experimentally replicated metaecosystems in the laboratory using gradostats as a model system. We tested the effects of connectivity, in terms of node distance from the pollutant-source, flow rate, and a glyphosate-based herbicide, on phytoplankton productivity, diversity and stability. Gradostats were composed of interconnected equally spaced nodes where resources and phytoplankton move directionally along a gradient of increasing distance from the source of the polluting herbicide. We hypothesised that ecological effects would be stronger in the node situated closer to the point of herbicide input, but that flow would suppress phytoplankton populations in distant nodes. Overall, RoundUp impacted phytoplankton productivity and stability by reducing algal biomass and abundances. This occurred especially in the node closest to the diluted herbicide point-source and under high flow, where species abundances were heavily suppressed by the effects of the rapidly flowing herbicide. At low flow on the other hand, distant nodes where buffered from the effects of the slow-moving herbicide. No differences in beta and gamma diversity among replicate metaecosystems was found; however, a significant loss of alpha diversity in all metaecosystems occurred through time until the end of the experiment. Together, these results point to the importance of considering aquatic connectivity in management plans for monitoring and mitigating unintended ecological consequences of agrochemical runoff.

Unraveling the atomic mechanisms underlying glyphosate insensitivity in EPSPS: implications of distal mutations

5-enolpyruvyl shikimate-3-phosphate synthase (EPSPS), as an indispensable enzyme in the shikimate pathway, is the specific target of grasser killer glyphosate (GPJ). GPJ is a competitive inhibitor of phosphoenolpyruvate (PEP), which is the natural substrate of EPSPS. A novel Ls-EPSPS gene variant discovered from Liliaceae, named ELs-EPSPS, includes five distal mutations, E112V, D142N, T351S, D425G, and R496G, endowing high GPJ insensitivity. However, the implicit molecular mechanism of the enhanced tolerance/insensitivity of GPJ in ELs-EPSPS is not fully understood. Herein, we try to interpret the hidden molecular mechanism using computational methods. Computational results reveal the enhanced flexibility of apo EPSPS upon mutations. The enhanced affinity of the initial binding substrate shikimate-3-phosphate (S3P), and the higher probability of second ligands PEP/GPJ entering the pocket are observed in the ELs-EPSPS-S3P system. Docking and MD results further confirmed the decreased GPJ-induced EPSPS inhibition upon mutations. And, the alterations of K98 and R179 side-chain orientations upon mutations are detrimental to GPJ binding at the active site. Additionally, the oscillation of side chain K98, in charge of PEP location, improves the proximity effect for substrates in the dual-substrate systems upon mutations. Our results clarify that the enhanced GPJ tolerance of EPSPS is achieved from decreased competitive inhibition of GPJ at the atomic perspective, and this finding further contributes to the cultivation of EPSPS genes with higher GPJ tolerance/insensitivity and a mighty renovation for developing glyphosate-resistant crops.Communicated by Ramaswamy H. Sarma.

Glyphosate Disorders Soil Enchytraeid Gut Microbiota and Increases Its Antibiotic Resistance Risk

Pesticides promote the stable development of intensive global agriculture. Nevertheless, their residues in the soil can cause ecological and human health risks. Glyphosate is a popular herbicide and is generally thought to be ecologically safe and nontoxic, but this conclusion has been questioned. Herein, we investigated the interaction among soil fauna (Enchytraeus crypticus) exposed to glyphosate and found that glyphosate induced oxidative stress and detoxification responses in E. crypticus and disturbed their lipid metabolism and digestive systems. We further demonstrated that glyphosate disordered the gut microbiota of E. crypticus and increased the abundance of resistance determinants with significant human health risks. Empirical tests and structural equation models were then used to confirm that glyphosate could cause E. crypticus to generate reactive oxygen species, indirectly interfering with their gut microbiota. Our study provides important implications for deciphering the mechanisms of the ecotoxicity of pesticides under the challenge of worldwide pesticide contamination.

Metagenomics reveals the effects of glyphosate on soil microbial communities and functional profiles of C and P cycling in the competitive vegetation control process of Chinese fir plantation

Although considerable efforts have been devoted to investigate the behavior of glyphosate on microbiome in various environment, knowledge about the soil microbial community and functional profile in weeds control process of the Chinese fir plantation are limited. In this study, shotgun metagenomic sequencing was used to determine the abundance and diversity of microbial communities and functional genes after foliar application of glyphosate for 1, 2, 3 and 4 months in a Chinese fir plantation. The results showed that glyphosate increased the copy numbers (qPCR) of 16S rRNA gene for 16.9%, improved the bacterial diversity (Shannon index) and complexity of bacterial co-occurrence network, and changed the abundances of some bacterial and fungal taxa, but had no effects on ITS gene copy numbers, fungal Shannon index, and bacterial and fungal communities (PCoA). Glyphosate application significantly decreased the amount of microbial function potentials involved in organic P mineralization for 10.7%, chitin degradation for 13.1%, and CAZy gene families with an exception of PL for 11.5% at the first month, while did not affect the profile of microbial genes response to P and C cycling in longer term. In addition, glyphosate reduced the contents of soil TOC, DOC and NH4+-H for 17.6%, 52.3% and 44.6% respectively, and decreased the starch, soluble sugar, Zn and Fe of Chinese fir leaves for 20.6%, 19.8%, 32.8% and 48.4% respectively. Mantle test, Spearman's correlation, and PLS-PM model revealed the connections among soil properties, tree nutrients, bacterial and fungal communities, and microbial function potentials were influenced by glyphosate. While our findings need to be validated in other filed and mechanistic studies, they may indicate that the foliar application of glyphosate has a potential effect on Chinese fir seedlings, and this effect may contribute to the changes of the bacterial community and soil properties including AN, DON and NH4+-H.

Glyphosate in the environment: interactions and fate in complex soil and water settings, and (phyto) remediation strategies

Glyphosate (Gly) and its formulations are broad-spectrum herbicides globally used for pre- and post-emergent weed control. Glyphosate has been applied to terrestrial and aquatic ecosystems. Critics have claimed that Gly-treated plants have altered mineral nutrition and increased susceptibility to plant pathogens because of Gly ability to chelate divalent metal cations. Still, the complete resistance of Gly indicates that chelation of metal cations does not play a role in herbicidal efficacy or have a substantial impact on mineral nutrition. Due to its extensive and inadequate use, this herbicide has been frequently detected in soil (2 mg kg-1, European Union) and in stream water (328 µg L-1, USA), mostly in surface (7.6 µg L-1, USA) and groundwater (2.5 µg L-1, Denmark). International Agency for Research on Cancer (IARC) already classified Gly as a category 2 A carcinogen in 2016. Therefore, it is necessary to find the best degradation techniques to remediate soil and aquatic environments polluted with Gly. This review elucidates the effects of Gly on humans, soil microbiota, plants, algae, and water. This review develops deeper insight toward the advances in Gly biodegradation using microbial communities. This review provides a thorough understanding of Gly interaction with mineral elements and its limitations by interfering with the plants biochemical and morphological attributes.

How Benthic Sediment Microbial Communities Respond to Glyphosate and Its Metabolite: a Microcosm Experiment

Glyphosate is the most commonly used agricultural herbicide in the world. In aquatic ecosystems, glyphosate often adsorbs to benthic substrates or is metabolized and degraded by microorganisms. The effects of glyphosate on microbial communities vary widely as microorganisms respond differently to exposure. To help understand the impacts of glyphosate on the sediment microbiome, we conducted a microcosm experiment examining the responses of benthic sediment microbial communities to herbicide treatments. Sediments from a prairie pothole wetland were collected, and 16S rRNA gene sequencing was used to analyze community composition 2-h and 14-days after a single treatment of low (0.07 ppm), medium (0.7 ppm), or high (7 ppm) glyphosate, aminomethylphosphonic acid (glyphosate metabolite), or a glyphosate-based commercial formula. We found no significant differences in microbial community composition across treatments, concentration levels, or day of sampling. These findings suggest that microbial species in the Prairie Pothole Region of North America may be tolerant to glyphosate exposure.

Glyphosate and environmental toxicity with "One Health" approach, a review

The herbicide Glyphosate (GLY), or N-(phosphonomethyl) glycine was synthesized in 1950 and applied to control weeds in agricultural production. For a long time, it was believed that it was an inert compound, but many studies have instead demonstrated over the years the dangers of GLY to the ecosystem and human health. Among the best-known effects, it is known that GLY interferes with the metabolic pathways of plants and the main groups of microorganisms, negatively influencing their growth. GLY interferes with the metabolic pathways of plants and major groups of microorganisms negatively affecting their growth. The extensive GLY application on fields results in a "slow death" of plants through the minor resistance to root pathogens and in increasing pollution of freshwaters and soils. Unfortunately, however, unlike the old beliefs, GLY can reach non-target destinations, in this regard, ecological studies and environmental epidemiology are of significant interest. In this review, we focus on the effects of acute and chronic exposure to GLY on the health of plants, animals, and humans from a One Health perspective. GLY has been linked to neurological and endocrine issues in both humans and animals, and behavioral modification on specific bioindicators, but the knowledge about the ratio cause-and-effect still needs to be better understood and elucidated. Environmental GLY residues analysis and policy acts will both require new criteria to protect environmental and human health.

Biomarkers of pollution by glyphosate in the lichens, Parmotrema tinctorium and Usnea barbata

Glyphosate is a herbicide commonly used in agriculture for weed control. Current agricultural production demands vast amounts of this product, which are applied by ground or aerial spraying. The concomitant aerial currents promote glyphosate drift to vegetated or urban areas. In this context, we hypothesized that the lichens, Parmotrema tinctorum and Usnea barbata, could be sensitive to the action of glyphosate and therefore be used to bio-indicate the presence of this herbicide in areas affected by drift. Since living organisms respond in different ways to the action of herbicides, our interest was also to indicate biological markers responsive to the action of glyphosate, through concentrations and exposure times of the thallus, besides identifying the most sensitive species. We evaluated the effect of different concentrations (0.0, 4.8, 9.6, and 19.2 mg L-1) and exposure times (24, 48, and 72 hours) to glyphosate on the morphoanatomy, photobiont vitality, photosynthetic efficiency, and oxidative metabolism of the thalli. We found that the lichens, P. tinctorum and U. barbata, respond to glyphosate stress, with prospects for use in the biomonitoring of pollutant dispersal from plantation areas. When using P. tinctorum as a bioindicator, lichen morphoanatomy, photobiont vitality, and photosynthetic pigment concentration were efficient biomarkers for the effect of concentration and exposure time. For U. barbata, the lichenic morphoanatomy and the activity of SOD and APX enzymes were essential tools to indicate the herbicide action. Parmotrema tinctotum, however, was characterized as more sensitive in bio-indicating the presence of this herbicide to diagnose the air quality in urban areas or vegetation sectors adjacent to agricultural environments.

Exposure to Low Concentrations of AMPA Influences Morphology and Decreases Survival During Larval Development in a Widespread Amphibian Species

Glyphosate's primary metabolite, AMPA (aminomethylphosphonic acid), is one of the most widely detected anthropogenic substance in surface waters worldwide. However, ecotoxicological studies on the potential effects of this metabolite at environmental concentrations on wildlife are scarce. Yet, due to its chemical properties, AMPA is likely to affect non-target species. In this study, we investigated sublethal effects of environmental concentrations of AMPA on the larval development of a widespread amphibian species, the spined toad Bufo spinosus. We performed a factorial experiment to study the effect of concentration and the timing of exposure (during embryonic development, larval development or both) to AMPA on the morphology, rate of development and survival of tadpoles. AMPA and timing of exposure interactively affected tadpole size (individuals exposed to AMPA after hatching were transitorily smaller, while individuals exposed to AMPA before hatching were longer), but not duration of development. Most of these effects were linked to exposure during embryonic development. Such effects in individuals exposed during embryonic development solely were long-lasting and persisted until the latest larval stages. Finally, we found that exposure to AMPA after hatching (during the larval stage) increased mortality. Exposure to low environmental concentrations of AMPA could have long-lasting consequences on fitness and population persistence. These findings are especially important to take into account at a time when multiple threats can interact to affect wildlife.

Hazardous impacts of glyphosate on human and environment health: Occurrence and detection in food

With the ever-increasing human population, farming lands are decreasing every year, therefore, for effective crop management; agricultural scientists are continually developing new strategies. However, small plants and herbs always impart a much loss in the yields of the crop and farmers are using tons of herbicides to eradicate that problem. Across the world, several herbicides are available in the market for effective crop management, however, scientists observed various environmental and health effects of the herbicides. Over the past 40 years, the herbicide glyphosate has been used extensively with the assumption of negligible effects on the environment and human health. However, in recent years, concerns have increased globally about the potential direct and indirect effects on human health due to the excessive use of glyphosate. As well, the toxicity on ecosystems and the possible effects on all living creatures have long been at the center of a complex discrepancy about the authorization for its use. The World Health Organization also further classified glyphosate as a carcinogenic toxic component and it was banned in 2017 due to numerous life-threatening side effects on human health. In the present era, the residues of banned glyphosate are more prevalent in agricultural and environmental samples which are directly affecting human health. Various reports revealed the detailed extraction process of glyphosate from different categories of the food matrix. Therefore, in the present review, to reveal the importance of glyphosate monitoring in the food matrix, we discussed the environmental and health effects of glyphosate with acute toxicity levels. Also, the effect of glyphosate on aquatic life is discussed in detail and various detection methods such as fluorescence, chromatography, and colorimetric techniques from different food samples with a limit of detection values are revealed. Overall, this review will give an in-depth insight into the various toxicological aspects and detection of glyphosate from food matrix using various advanced analytical techniques.

Herbicide residues in soil decrease microbe-mediated plant protection

The residues of glyphosate are found to remain in soils longer than previously reported, affecting rhizosphere microbes. This may adversely affect crop and other non-target plants because the plant's resilience and resistance largely rely on plant-associated microbes. Ubiquitous glyphosate residues in soil and how they impact mutualistic microbes inhabiting the aboveground plant parts are largely unexplored. We studied the effects of herbicide residues in soil on Epichloë sp., which are common endophytic symbionts inhabiting aerial parts of cool-season grasses. In this symbiosis, the obligate symbiont subsists entirely on its host plant, and in exchange, it provides alkaloids conferring resistance to herbivores for the host grass that invests little in its own chemical defence. We first show decreased growth of Epichloë endophytes in vitro when directly exposed to two concentrations of glyphosate or glyphosate-based herbicides. Second, we provide evidence for a reduction of Epichloë-derived, insect-toxic loline alkaloids in endophyte-symbiotic meadow fescue (F. pratensis) plants growing in soil with a glyphosate history. Plants were grown for 2 years in an open field site, and natural herbivore infestation was correlated with the glyphosate-mediated reduction of loline alkaloid concentrations. Our findings indicate that herbicides residing in soil not only affect rhizosphere microbiota but also aerial plant endophyte functionality, which emphasizes the destructive effects of glyphosate on plant symbiotic microbes, here with cascading effects on plant-pest insect interactions.

The effects of glyphosate, pure or in herbicide formulation, on bumble bees and their gut microbial communities

The widespread use of glyphosate-based formulations to eliminate unwanted vegetation has increased concerns regarding their effects on non-target organisms, such as honey bees and their gut microbial communities. These effects have been associated with both glyphosate and co-formulants, but it is still unknown whether they translate to other bee species. In this study, we tested whether glyphosate, pure or in herbicide formulation, can affect the gut microbiota and survival rates of the eastern bumble bee, Bombus impatiens. We performed mark-recapture experiments with bumble bee workers from four different commercial colonies, which were exposed to field relevant concentrations of glyphosate or a glyphosate-based formulation (0.01 mM to 1 mM). After a 5-day period of exposure, we returned the bees to their original colonies, and they were sampled at days 0, 3 and 7 post-exposure to investigate changes in microbial community and microbiota resilience by 16S rRNA amplicon sequencing and quantitative PCR. We found that exposure to glyphosate, pure or in herbicide formulation, reduced the relative abundance of a beneficial bee gut bacterium, Snodgrassella, in bees from two of four colonies when compared to control bees at day 0 post-exposure, but this reduction became non-significant at days 3 and 7 post-exposure, suggesting microbiota resilience. We did not find significant changes in total bacteria between control and exposed bees. Moreover, we observed an overall trend in decreased survival rates in bumble bees exposed to 1 mM herbicide formulation during the 7-day post-exposure period, suggesting a potential negative effect of this formulation on bumble bees.

Directed evolution of glyphosate oxidase and a chemiluminescence system for glyphosate detection: A comprehensive practical laboratory experiment on biotechnology

This article describes a comprehensive practical laboratory method for developing an enzyme to more easily measure glyphosate levels in solution. Through this article, undergraduate students of biology majors can conduct research experiments in critical fields by utilizing various techniques, such as chemiluminescence (CL) biosensors with engineered enzymes and are guided in molecular biology laboratories. A glyphosate oxidase mutant library was constructed by DNA shuffling, and a glyphosate oxidase variant with increased glyphosate degradation activity was selected by using a high-throughput screening assay. Following protein overexpression in Escherichia coli (DE3) and purification by affinity chromatography, the glyphosate oxidase variant protein combined with luminol-H₂ O₂ reaction was constructed as a new CL biosensor for detecting glyphosate in soils.

The effects of short-term glyphosate-based herbicide exposure on insect gene expression profiles

Glyphosate-based herbicides (GBHs) are the most frequently used herbicides worldwide. The use of GBHs is intended to tackle weeds, but GBHs have been shown to affect the life-history traits and antioxidant defense system of invertebrates found in agroecosystems. Thus far, the effects of GBHs on detoxification pathways among invertebrates have not been sufficiently investigated. We performed two different experiments-1) the direct pure glyphosate and GBH treatment, and 2) the indirect GBH experiment via food-to examine the possible effects of environmentally relevant GBH levels on the survival of the Colorado potato beetle (Leptinotarsa decemlineata) and the expression profiles of their detoxification genes. As candidate genes, we selected four cytochrome P450 (CYP), three glutathione-S-transferase (GST), and two acetylcholinesterase (AChE) genes that are known to be related to metabolic or target-site resistances in insects. We showed that environmentally relevant levels of pure glyphosate and GBH increased the probability for higher mortality in the Colorado potato beetle larvae in the direct experiment, but not in the indirect experiment. The GBHs or glyphosate did not affect the expression profiles of the studied CYP, GST, or AChE genes; however, we found a large family-level variation in expression profiles in both the direct and indirect treatment experiments. These results suggest that the genes selected for this study may not be the ones expressed in response to glyphosate or GBHs. It is also possible that the relatively short exposure time did not affect gene expression profiles, or the response may have already occurred at a shorter exposure time. Our results show that glyphosate products may affect the survival of the herbivorous insect already at lower levels, depending on their sensitivity to pesticides.

A Roundup herbicide causes high mortality and impairs development of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae)

Glyphosate has and is being used extensively in herbicide formulations worldwide. Thus, glyphosate-based herbicides (GBH) substantially add to the environmental load of pesticides and warrant a strict risk assessment. Ecotoxicological testing of herbicides focuses on non-target plants and higher animals while direct effects on arthropods are only cursory tested on the premise of contact exposure. However, oral exposure, as we show in our case, can be highly relevant for systemic pesticides, such as GBH. Specifically, in crop systems including genetically modified crops that are tolerant to GBH, these herbicides and their breakdown products are present both internally and externally of the crop plants and, therefore, are ingested by the crop-associated arthropod fauna. We tested the effects of oral uptake of the Roundup formulation WeatherMax on larvae of the lacewing Chrysoperla carnea, a model organism in ecotoxicity testing programs. Long-term oral exposure of C. carnea larvae throughout its juvenile life stages was tested with concentrations ranging from 0.001 to 1 % dilution, thus, lower than the 1.67 % recommended for field applications. Inhibition of metamorphosis was observable at 0.1 % but at a concentration of 0.5 %, GBH significantly impaired cocoon formation and led to massive lethal malformations. At GBH concentration of 1 % half of the individuals remained permanent larvae and no adult hatched alive. The effects observed followed a clear dose-response relationship. The hazard caused by direct insecticidal action of GHB after oral uptake is highly relevant for the environmental safety and reveals a gap in regulatory risk assessments that should urgently be addressed, specifically in light of the on-going insect decline.

Glyphosate Toxicity: In Vivo, In Vitro, and Epidemiological Evidence

Glyphosate is the most applied agricultural chemical worldwide and has become nearly ubiquitous throughout the environment. Glyphosate is an effective herbicide because it disrupts the shikimate pathway, which is responsible for the synthesis of essential amino acids in plants and microorganisms. Given that there is no known target for glyphosate in higher animals, its toxicity to humans and other animals is heavily debated, especially after the 2015 IARC ruling that glyphosate is carcinogenic. Today, a growing body of literature shows in vitro, in vivo, and epidemiological evidence for the toxicity of glyphosate across animal species. With the application of glyphosate increasing globally, it is important to discuss these reports to enable a broader conversation on glyphosate toxicity and its impact on human and environmental health. Here, we summarize the recent glyphosate literature and discuss its implications.

The effects of glyphosate exposure on gene transcription and immune function of the silkworm, Bombyx mori

Glyphosate is a widely used herbicide and crop desiccant. However, whether its extensive use has any effect on the species diversity of nontarget organisms is still unclear. In this study, we used the silkworm, Bombyx mori, as the research subject, and performed RNA sequencing to analyze the transcriptional profile of silkworm midgut after exposure to glyphosate at 2975.20 mg/L (a concentration commonly used at mulberry fields). A total of 125 significantly differentially expressed genes (DEGs) were detected in the midgut of glyphosate-exposed silkworm (q < 0.05), of which 53 were upregulated and 72 were downregulated. Gene ontology enrichment analysis showed that the DEGs were mainly enriched in biological process, cellular component, and molecular function. Kyoto encyclopedia of genes and genomes analysis showed that the differential genes were mainly related to oxidative stress, nutrient metabolism, and immune defense pathways, including oxidative stress-related Cat and Jafrac1, nutrient metabolism-related Fatp and Scpx, and immune-related CYP6AN2, UGT40B4, CTL11, serpin-2, and so forth. Experimental verification showed that glyphosate exposure led to a 4.35-fold increase in the mortality of silkworm after Beauveria bassiana infection, which might be caused by the decreased PO (phenoloxidase) activity and impaired immunity. These results provide evidence for the potential effects of residue glyphosate on the physiological functions of silkworm, and also provide a reference for the biosafety evaluation of glyphosate.

Glyphosate-based herbicide use affects individual microbial taxa in strawberry endosphere but not the microbial community composition

AIMS

In a field study, the effects of treatments of glyphosate-based herbicides (GBHs) in soil, alone and in combination with phosphate fertilizer, were examined on the performance and endophytic microbiota of garden strawberry.

METHODS AND RESULTS

The root and leaf endophytic microbiota of garden strawberries grown in GBH-treated and untreated soil, with and without phosphate fertilizer, were analyzed. Next, bioinformatics analysis on the type of 5-enolpyruvylshikimate-3-phosphate synthase enzyme was conducted to assess the potential sensitivity of strawberry-associated bacteria and fungi to glyphosate, and to compare the results with field observations. GBH treatments altered the abundance and/or frequency of several operational taxonomic units (OTUs), especially those of root-associated fungi and bacteria. These changes were partly related to their sensitivity to glyphosate. Still, GBH treatments did not shape the overall community structure of strawberry microbiota or affect plant performance. Phosphate fertilizer increased the abundance of both glyphosate-resistant and glyphosate-sensitive bacterial OTUs, regardless of the GBH treatments.

CONCLUSIONS

These findings demonstrate that although the overall community structure of strawberry endophytic microbes is not affected by GBH use, some individual taxa are.

Distinct response patterns of plants and soil microorganisms to agronomic practices and seasonal variation in a floodplain ecosystem

Introduction

Climate change and anthropogenic activities are the greatest threats to floodplain ecosystems. A growing body of literature shows that floodplain ecosystems have experienced increased chemical fertilizer and pesticide loads, which will disturb the above and belowground ecosystems. However, we lack knowledge regarding the effects of such human activities on the vegetation and soil microbiomes in these ecosystems.

Methods

In the present study, plant functional traits and Illumina Mi-Seq sequencing were to assess the impact of nitrogen fertilizer and glyphosate addition on the structure and function of the vegetation and soil microbiomes (bacteria, fungi, and protists) in a floodplain ecosystem, and to assess the influence of seasonal variation.

Results

We identified distinct response mechanisms of plant and microbial communities to the addition of nitrogen fertilizer and glyphosate, and seasonal variation. Nitrogen fertilizer and glyphosate significantly affected plant diversity, aboveground and underground biomass, and C and N content and significantly changed the leaf area and plant stature of dominant plants. However, the addition of nitrogen fertilizer and glyphosate did not significantly affect the diversity and structure of bacterial, fungal, and protist communities. The application of nitrogen fertilizer could improve the negative effects of glyphosate on the functional traits of plant communities. The seasonal variation of floodplain has significantly changed the soil's physical, chemical, and biological properties. Our results showed that compared with that in summer, the soil ecosystem multifunctionality of the floodplain ecosystem in autumn was significantly lower. Seasonal variation had a significant effect on plant diversity and functional traits. Moreover, seasonal variation significantly affected the community compositions, diversity, and structure of bacteria, fungi, and protists. Seasonal variation had a stronger impact on fungal community assembly than on that of bacteria and protists. In summer, the assembly of the fungal community was dominated by a deterministic process, while in autumn, it is dominated by a stochastic process. In addition, the negative association among bacteria, fungi, and protists has been strengthened in autumn and formed a more robust network to cope with external changes.

Discussion

These results extended our understanding of the ecological patterns of soil microbiomes in floodplain ecosystems and provided support for enhancing the ecological barrier function and the service potential of floodplain ecosystems.

Field-realistic acute exposure to glyphosate-based herbicide impairs fine-color discrimination in bumblebees

Pollinator decline is a grave challenge worldwide. One of the main culprits for this decline is the widespread use of, and pollinators' chronic exposure to, agrochemicals. Here, we examined the effect of a field-realistic dose of the world's most commonly used pesticide, glyphosate-based herbicide (GBH), on bumblebee cognition. We experimentally tested bumblebee (Bombus terrestris) color and scent discrimination using acute GBH exposure, approximating a field-realistic dose from a day's foraging in a patch recently sprayed with GBH. In a 10-color discrimination experiment with five learning bouts, GBH treated bumblebees' learning rate fell to zero by third learning bout, whereas the control bees increased their performance in the last two bouts. In the memory test, the GBH treated bumblebees performed to near chance level, indicating that they had lost everything they had learned during the learning bouts, while the control bees were performing close to the level in their last learning bout. However, GBH did not affect bees' learning in a 2-color or 10-odor discrimination experiment, which suggests that the impact is limited to fine color learning and does not necessarily generalize to less specific tasks or other modalities. These results indicate that the widely used pesticide damages bumblebees' fine-color discrimination, which is essential to the pollinator's individual success and to colony fitness in complex foraging environments. Hence, our study suggests that acute sublethal exposure to GBH poses a greater threat to pollination-based ecosystem services than previously thought, and that tests for learning and memory should be integrated into pesticide risk assessment.

Ecosystem consequences of herbicides: the role of microbiome

Non-target organisms are globally exposed to herbicides. While many herbicides - for example, glyphosate - were initially considered safe, increasing evidence demonstrates that they have profound effects on ecosystem functions via altered microbial communities. We provide a comprehensive framework on how herbicide residues may modulate ecosystem-level outcomes via alteration of microbiomes. The changes in soil microbiome are likely to influence key nutrient cycling and plant-soil processes. Herbicide-altered microbiome affects plant and animal performance and can influence trophic interactions such as herbivory and pollination. These changes are expected to lead to ecosystem and even evolutionary consequences for both microbes and hosts. Tackling the threats caused by agrochemicals to ecosystem functions and services requires tools and solutions based on a comprehensive understanding of microbe-mediated risks.

Root biomass and cumulative yield increase with mowing height in Festuca pratensis irrespective of Epichloë symbiosis

Increasing agricultural soil carbon sequestration without compromising the productivity of the land is a key challenge in global climate change mitigation. The carbon mitigation potential of grass-based agriculture is particularly high because grasslands represent 70% of the world's agricultural area. The root systems of grasses transfer large amounts of carbon to below-ground storage, and the carbon allocation to the roots is dependent on the grasses' photosynthesizing shoot biomass. In a common-garden experiment, Festuca pratensis was used as a model species to study how mowing and weed control practices of perennial cool-season fodder grasses affect total yield and root biomass. Additionally, grass-associated Epichloë endophytes and soil residual glyphosate were tested for their effect on the total yield and root biomass alone or in interaction with mowing. The results demonstrate that elevating the cutting height increases both cumulative yield and root biomass in F. pratensis. Endophyte symbiosis increased the total yield, while glyphosate-based herbicide residues in the soil decreased the root biomass, which indicates a reduction of soil bound carbon sequestration. The findings demonstrate that carbon sequestration and yield quantities on farmed grasslands may significantly be improved by optimizing strategies for the use of plant protection products and adjustment of mowing intensity.

Legacy of agrochemicals in the circular food economy: Glyphosate-based herbicides introduced via manure fertilizer affect the yield and biochemistry of perennial crop plants during the following year

Conventional agricultural practices favoring the use of glyphosate-based herbicides (GBHs) increase the risk of GBH residues ending up in animal feed, feces, and, eventually, manure. The use of poultry manure as organic fertilizer in the circular food economy increases the unintentional introduction of GBH residues into horticultural and agricultural systems, with reportedly negative effects on the growth and reproduction of crop plants. To understand the potential lasting effects of exposure to GBH residues via organic manure fertilizers, we studied strawberry (Fragaria x vescana) plant performance, yield quantity, biochemistry, folivory, phytochemistry, and soil elemental composition the year after exposure to GBH. Although plants exposed to GBH residues via manure fertilizer were, on average, 23% smaller in the year of exposure, they were able to compensate for their growth during the following growing season. Interestingly, GBH residue exposure in the previous growing season led to a trend in altered plant size preferences of folivores during the following growing season. Furthermore, the plants that had been exposed to GBH residues in the previous growing season produced 20% heavier fruits with an altered composition of phenolic compounds compared to non-exposed plants. Our results indicate that GBHs introduced via manure fertilizer following circular economy practices in one year can have effects on perennial crop plants in the following year, although GBH residues in soil have largely vanished.

Glyphosate residues in soil can modify plant resistance to herbivores through changes in leaf quality

Glyphosate is the most widely used non-selective herbicide in the world. Glyphosate residues in soil can affect plant quality by modifying plant physiology, hormonal pathways and traits, with potential consequences for plants' interactions with herbivores. We explored these indirect effects in the context of plant-herbivore interactions in a perennial, nitrogen-fixing herb. We quantified leaf herbivory for glyphosate-exposed and control plants grown in phosphorus-fertilized and non-fertilized soils, and assessed the impacts of glyphosate treatment on traits related to plant resistance against herbivores (leaf trichome density, leaf mass per area) and performance (aboveground biomass, root:shoot ratio, nodule number, nodule activity). Moreover, we conducted a laboratory feeding experiment to compare the palatability of leaves from glyphosate-exposed and control plants to a generalist mollusc herbivore. Herbivore damage and intensity in situ increased during the growing season regardless of glyphosate or phosphorus treatment. Glyphosate treatment reduced leaf trichome density but had no effect on the other plant traits considered. Herbivore damage was negatively associated with leaf trichome density. The feeding experiment revealed no difference in the feeding probability of mollusc herbivores between glyphosate-exposed and control plants. However, there was an interaction between glyphosate treatment and initial leaf area for leaf consumption by herbivores: leaf consumption increased with increasing leaf area in both groups, but at a lower rate for glyphosate-exposed plants than for control plants. Our results show that glyphosate residues in soil have the potential to indirectly affect aboveground herbivores through changes in leaf quality, which may have mixed consequences for folivore damage.

Enzymatic Laser-Induced Graphene Biosensor for Electrochemical Sensing of the Herbicide Glyphosate

Glyphosate is a globally applied herbicide yet it has been relatively undetectable in-field samples outside of gold-standard techniques. Its presumed nontoxicity toward humans has been contested by the International Agency for Research on Cancer, while it has been detected in farmers' urine, surface waters and crop residues. Rapid, on-site detection of glyphosate is hindered by lack of field-deployable and easy-to-use sensors that circumvent sample transportation to limited laboratories that possess the equipment needed for detection. Herein, the flavoenzyme, glycine oxidase, immobilized on platinum-decorated laser-induced graphene (LIG) is used for selective detection of glyphosate as it is a substrate for GlyOx. The LIG platform provides a scaffold for enzyme attachment while maintaining the electronic and surface properties of graphene. The sensor exhibits a linear range of 10-260 µ m, detection limit of 3.03 µ m, and sensitivity of 0.991 nA µ m -1. The sensor shows minimal interference from the commonly used herbicides and insecticides: atrazine, 2,4-dichlorophenoxyacetic acid, dicamba, parathion-methyl, paraoxon-methyl, malathion, chlorpyrifos, thiamethoxam, clothianidin, and imidacloprid. Sensor function is further tested in complex river water and crop residue fluids, which validate this platform as a scalable, direct-write, and selective method of glyphosate detection for herbicide mapping and food analysis.

Effect of Glyphosate and Carbaryl Applications on Okra (Abelmoschus esculentus) Biomass and Arbuscular Mycorrhizal Fungi (AMF) Root Colonization in Organic Soil

Pesticide application in horticultural crops has recently multiplied to increase crop yields and boost economic return. Consequently, the effects of pesticides on soil organisms and plant symbionts is an evolving subject of research. In this short-term study, we evaluated the effects of glyphosate (herbicide) and carbaryl (insecticide) on okra biomass and AMF root colonization in both shade house and field settings. An additional treatment, the combination of glyphosate and carbaryl, was applied in the field trial. Soil and root samples were collected three times during the experiment: 30 days after planting (before first spray, or T0), 45 days after planting (before second spray, or T1), and at full maturity (at 66 days after planting, or T2). Our results indicate that glyphosate and combined treatments were most effective in controlling weeds and produced almost 40% higher okra biomass than the control. There was a ~40% increase in AMF root colonization in glyphosate-treated plots from T0 to T1. This result was likely due to high initial soil P content, high soil temperature, and low rainfall, which aided in the rapid degradation of glyphosate in the soil. However, at T2 (second spray), high rainfall and the presence of excess glyphosate resulted in a 15% reduction in AMF root colonization when compared to T1. We found carbaryl had little to negligible effect on AMF root colonization.

Metabolic stability of glyphosate and its environmental metabolite (aminomethylphosphonic acid) in the ruminal content of cattle

Glyphosate (GLY) is one of the most commonly used herbicides worldwide. Both GLY and aminomethylphosphonic acid (AMPA), its main degradation product, may be present in feedstuffs offered to dairy cows. Although the major proportions of ingested GLY and AMPA are eliminated with faeces, a potential degradation of GLY to AMPA in the rumen of dairy cows has been suggested. Considering that the rumen plays a central role in the pre-systemic metabolism of xenobiotics, this research aimed to investigate whether or not GLY and AMPA are metabolised in the ruminal environment of cattle. The distribution of both compounds between the fluid and solid phases of the ruminal content (RC) was also evaluated. RC from 3 steers were collected in an abattoir. Aliquots were incubated (3-6 h) in anaerobiosis with GLY (15 µg/mL) and AMPA (1.5 µg/mL). Metabolic viability of RC was assessed by the measurement of the sulpho-reduction of the anthelmintic derivative albendazole sulphoxide (ABZSO) into albendazole (ABZ) in the absence (controls) or in presence of GLY and AMPA. Incubations of boiled (inactive) RC were used as controls. Samples were analysed by HLPC with fluorescence detection. Neither GLY nor AMPA were metabolised in metabolically active RC from cattle. Both compounds were predominantly found in the fluid phase compared to the solid (particulate) matter of RC. Neither GLY nor AMPA had a negative effect on the metabolic production of ABZ. A high metabolic stability of both compounds within the ruminal environment would be expected in vivo. Their presence in high proportion in the fluid phase of the ruminal content may give rise to a rapid flow of both GLY and AMPA to the posterior gastrointestinal tract. Negative effects on the ruminal biotransformation of therapeutically used drugs would not be expected when the herbicide and its degradation product are consumed with food.

Advances in organophosphorus pesticides pollution: Current status and challenges in ecotoxicological, sustainable agriculture, and degradation strategies

Organophosphorus pesticides (OPPs) are one of the most widely used types of pesticide that play an important role in the production process due to their effects on preventing pathogen infection and increasing yield. However, in the early development and application of OPPs, their toxicological effects and the issue of environmental pollution were not considered. With the long-term overuse of OPPs, their hazards to the ecological environment (including soil and water) and animal health have attracted increasing attention. Therefore, this review first clarified the classification, characteristics, applications of various OPPs, and the government's restriction requirements on various OPPs. Second, the toxicological effects and metabolic mechanisms of OPPs and their metabolites were introduced in organisms. Finally, the existing methods of degrading OPPs were summarized, and the challenges and further addressing strategy of OPPs in the sustainable development of agriculture, the environment, and ecology were prospected. However, methods to solve the environmental and ecological problems caused by OPPs from the three aspects of use source, use process, and degradation methods were proposed, which provided a theoretical basis for addressing the stability of the ecological environment and improving the structure of the pesticide industry in the future.

A Glyphosate-Based Herbicide in Soil Differentially Affects Hormonal Homeostasis and Performance of Non-target Crop Plants

Glyphosate is the most widely used herbicide with a yearly increase in global application. Recent studies report glyphosate residues from diverse habitats globally where the effect on non-target plants are still to be explored. Glyphosate disrupts the shikimate pathway which is the basis for several plant metabolites. The central role of phytohormones in regulating plant growth and responses to abiotic and biotic environment has been ignored in studies examining the effects of glyphosate residues on plant performance and trophic interactions. We studied interactive effects of glyphosate-based herbicide (GBH) residues and phosphate fertilizer in soil on the content of main phytohormones, their precursors and metabolites, as well as on plant performance and herbivore damage, in three plant species, oat (Avena sativa), potato (Solanum tuberosum), and strawberry (Fragaria x ananassa). Plant hormonal responses to GBH residues were highly species-specific. Potato responded to GBH soil treatment with an increase in stress-related phytohormones abscisic acid (ABA), indole-3-acetic acid (IAA), and jasmonic acid (JA) but a decrease in cytokinin (CK) ribosides and cytokinin-O-glycosides. GBH residues in combination with phosphate in soil increased aboveground biomass of potato plants and the concentration of the auxin phenylacetic acid (PAA) but decreased phaseic acid and cytokinin ribosides (CKR) and O-glycosides. Chorismate-derived compounds [IAA, PAA and benzoic acid (BzA)] as well as herbivore damage decreased in oat, when growing in GBH-treated soil but concentrations of the cytokinin dihydrozeatin (DZ) and CKR increased. In strawberry plants, phosphate treatment was associated with an elevation of auxin (IAA) and the CK trans-zeatin (tZ), while decreasing concentrations of the auxin PAA and CK DZ was observed in the case of GBH treatment. Our results demonstrate that ubiquitous herbicide residues have multifaceted consequences by modulating the hormonal equilibrium of plants, which can have cascading effects on trophic interactions.

Oxidative Stress and Metabolism: A Mechanistic Insight for Glyphosate Toxicology

Glyphosate (GLYP) is a widely used pesticide; it is considered to be a safe herbicide for animals and humans because it targets 5-enolpyruvylshikimate-3-phosphate synthase. However, there has been increasing evidence that GLYP causes varying degrees of toxicity. Moreover, oxidative stress and metabolism are highly correlated with toxicity. This review provides a comprehensive introduction to the toxicity of GLYP and, for the first time, systematically summarizes the toxicity mechanism of GLYP from the perspective of oxidative stress, including GLYP-mediated oxidative damage, changes in antioxidant status, altered signaling pathways, and the regulation of oxidative stress by exogenous substances. In addition, the metabolism of GLYP is discussed, including metabolites,metabolic pathways, metabolic enzymes, and the toxicity of metabolites. This review provides new ideas for the toxicity mechanism of GLYP and proposes effective strategies for reducing its toxicity.

New Methods for Testing/Determining the Environmental Exposure to Glyphosate in Sunflower (Helianthus annuus L.) Plants

Glyphosate is still the subject of much debate, as several studies report its effects on the environment. Sunflower (GK Milia CL) was set up as an experimental plant and treated with glyphosate concentrations of 500 ppm and 1000 ppm in two treatments. Glyphosate was found to be absorbed from the soil into the plant organism through the roots, which was also detectable in the leaf and root. Glyphosate was also significantly detected in the plant 5 weeks after treatment and in plants that did not receive glyphosate treatment directly, so it could be taken up through the soil. Based on the morphological results, treatment with higher concentrations (1000 ppm) of glyphosate increased the dried mass and resulted in shorter, thicker roots. Histological results also showed that basal and transporter tissue distortions were observed in the glyphosate-treated plants compared to the control group. Cells were distorted with increasing concentration, vacuoles formed, and the cell wall was weakened in both the leaf-treated and inter-row-treated groups. In the future, it will be worth exploring alternative agricultural technologies that can reduce the risk of glyphosate while increasing economic outcomes. This may make the use of glyphosate more environmentally conscious.

Aminomethylphosphonic acid (AMPA) alters oxidative status during embryonic development in an amphibian species

Glyphosate's primary metabolite (aminomethylphosphonic acid, AMPA) is known to alter embryonic development at environmentally relevant concentrations in amphibians. However, we have limited understanding of the physiological mechanisms through which AMPA affects organisms. In this study, we tested whether alteration of the oxidative status is one mechanism through which AMPA affects organism performance. To this end, we analysed several oxidative status markers in hatchling tadpoles that were exposed to sublethal concentrations of AMPA during embryonic development (~16 days). We compared the influence of environmentally relevant concentrations of AMPA (from 0.07 to 3.57 μg l^-1) on the relation between developmental traits (i.e, embryonic development duration, embryonic mortality and hatchling size) and oxidative status markers known to alter homeostasis when unbalanced (superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), thiols and ratios thereof). We included measures of telomere length as an indicator of physiological state. We found that AMPA concentrations induce non-monotonic effects on some oxidative status markers with hatchlings displaying elevated antioxidant responses (elevated thiols and unbalanced SOD/(GPx + CAT) ratio). The lack of effect of AMPA on the relation between developmental traits, oxidative status and telomere length suggests that selective mortality of embryos susceptible to oxidative stress may have occurred prior to hatching in individuals less resistant to AMPA which display lower hatching success. Future studies are required to disentangle whether oxidative unbalance is a cause or a consequence of AMPA exposition. This study highlights the need to investigate effects of the metabolites of contaminants at environmental concentrations to comprehensively assess impacts of anthropogenic contamination on wildlife.

A comprehensive experimental assessment of glyphosate ecological impacts in riparian forest restoration

Competition with invasive grasses is one of the most important drivers of tree planting failures, especially in tropical forests. A widely disseminated weeding approach has been glyphosate spraying, the most used herbicide globally in forestry and ecosystem restoration. However, glyphosate use in restoration is highly controversial and requires further studies to elucidate its effects on restoration processes and the environment. We evaluated the use of glyphosate in riparian forest restoration and its impacts on tree planting costs, weed control efficiency, planted seedling performance, herbaceous and woody species regeneration, soil bacteria, and environmental contamination, using mowing treatments as a reference and based on a controlled experiment established in the Brazilian Atlantic Forest. Glyphosate spraying reduced by one-half and one-third the accumulated aboveground biomass of, respectively, weeds in general and of the invasive grass Urochloa decumbens compared to mowing treatments, and it reduced the cost by half. The performance of planted tree seedlings was markedly favored by glyphosate spraying compared to mowing treatments, as expressed by improved seedling height (~twice higher), crown area (~5× higher), and basal area (~5× higher); the regeneration of both native woody and ruderal herbaceous plants were also enhanced. Neither glyphosate nor its metabolite Aminomethylphosphonic acid (AMPA) residues were detected in either water runoff or soil samples, but they were found at relatively high concentrations in the runoff sediments (from 1.32 to 24.75 mg/kg for glyphosate and from 1.75 to 76.13 mg/kg for AMPA). Soil bacteria communities differed before and after glyphosate spraying in comparison to mowing plots (without glyphosate). Glyphosate spraying was far more cost effective than mowing for controlling U. decumbens and greatly improved the performance of planted tree seedlings and natural regeneration, while not leaving residues in soil and water. However, the changes in the structure of bacterial communities and high concentration of glyphosate and AMPA residues in runoff sediments highlight the need for caution when using this herbicide in riparian buffers. We present alternatives for reducing glyphosate use and minimizing its risks in tree planting initiatives.

Reproductive toxicological changes in avian embryos due to a pesticide and an environmental contaminant

Single and simultaneous toxic effects of glyphosate (Amega Up, 360 g L-1, 4%) and copper sulphate (0.01%) were studied in avian embryos treated either with injection directly into the air chamber or by immersion application for 30 min on day 0 of incubation. Alterations of the chicken embryos were evaluated during necropsy performed on day 19 of incubation, together with mortality, body weight and the type of developmental abnormalities. Based on the results, the injection application appeared to be more toxic than the immersion method, as it induced increased mortality and reduced the average body weight, and resulted in a higher incidence of congenital anomalies. Supposedly, a toxicodynamic interaction occurs between copper sulphate and glyphosate, which may reduce the vitality of embryos and thus decrease the number of offspring in wild birds.

The Tripartite Rhizobacteria-AM Fungal-Host Plant Relationship in Winter Wheat: Impact of Multi-Species Inoculation, Tillage Regime and Naturally Occurring Rhizobacteria Species

Soils and plant root rhizospheres have diverse microorganism profiles. Components of this naturally occurring microbiome, arbuscular mycorrhizal (AM) fungi and plant growth promoting rhizobacteria (PGPR), may be beneficial to plant growth. Supplementary application to host plants of AM fungi and PGPR either as single species or multiple species inoculants has the potential to enhance this symbiotic relationship further. Single species interactions have been described; the nature of multi-species tripartite relationships between AM fungi, PGPR and the host plant require further scrutiny. The impact of select Bacilli spp. rhizobacteria and the AM fungus Rhizophagus intraradices as both single and combined inoculations (PGPR[i] and AMF[i]) within field extracted arable soils of two tillage treatments, conventional soil inversion (CT) and zero tillage (ZT) at winter wheat growth stages GS30 and GS39 have been conducted. The naturally occurring soil borne species (PGPR[s] and AMF[s]) have been determined by qPCR analysis. Significant differences (p < 0.05) were evident between inocula treatments and the method of seedbed preparation. A positive impact on wheat plant growth was noted for B. amyloliquefaciens applied as both a single inoculant (PGPR[i]) and in combination with R. intraradices (PGPR[i] + AMF[i]); however, the two treatments did not differ significantly from each other. The findings are discussed in the context of the inocula applied and the naturally occurring soil borne PGPR[s] present in the field extracted soil under each method of tillage.

Adaptation of bacteria to glyphosate: a microevolutionary perspective of the enzyme 5-enolpyruvylshikimate-3-phosphate synthase

Glyphosate is the leading herbicide worldwide, but it also affects prokaryotes because it targets the central enzyme (5-enolpyruvylshikimate-3-phosphate, EPSP) of the shikimate pathway in the synthesis of the three essential aromatic amino acids in bacteria, fungi and plants. Our results reveal that bacteria may easily become resistant to glyphosate through changes in the 5-enolpyruvylshikimate-3-phosphate synthase active site. This indicates the importance of examining how glyphosate affects microbe-mediated ecosystem functions and human microbiomes.

Classification of the glyphosate target enzyme (5-enolpyruvylshikimate-3-phosphate synthase) for assessing sensitivity of organisms to the herbicide

Glyphosate is the most common broad-spectrum herbicide. It targets the key enzyme of the shikimate pathway, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), which synthesizes three essential aromatic amino acids (phenylalanine, tyrosine and tryptophan) in plants. Because the shikimate pathway is also found in many prokaryotes and fungi, the widespread use of glyphosate may have unsuspected impacts on the diversity and composition of microbial communities, including the human gut microbiome. Here, we introduce the first bioinformatics method to assess the potential sensitivity of organisms to glyphosate based on the type of EPSPS enzyme. We have precomputed a dataset of EPSPS sequences from thousands of species that will be an invaluable resource to advancing the research field. This novel methodology can classify sequences from nearly 90% of eukaryotes and >80% of prokaryotes. A conservative estimate from our results shows that 54% of species in the core human gut microbiome are sensitive to glyphosate.

Glyphosate-Modulated Biosynthesis Driving Plant Defense and Species Interactions

Glyphosate has become the best-selling herbicide used in agriculture, horticulture, silviculture, and urban environments. It disrupts the shikimate metabolic pathway and thereby blocks the production of aromatic amino acids, which are the basis for several plant metabolites. Glyphosate residues are reported in soils from diverse environments, but the effects on plant physiology and consequences for species interactions are largely unknown. Here, we emphasize the complexity of these physiological processes, and argue that glyphosate residues modulate biosynthetic pathways, individually or interactively, which may affect interactions between plants and heterotrophic organisms. In this way, glyphosate residues can substantially interfere with plant resistance and the attraction of beneficial insects, both of which are essential elements in integrated pest management and healthy ecosystems.

Risk in the circular food economy: Glyphosate-based herbicide residues in manure fertilizers decrease crop yield

Glyphosate-based herbicides (GBHs) are the most frequently used herbicides globally. They were launched as a safe solution for weed control, but recently, an increasing number of studies have shown the existence of GBH residues and highlighted the associated risks they pose throughout ecosystems. Conventional agricultural practices often include the use of GBHs, and the use of glyphosate-resistant genetically modified crops is largely based on the application of glyphosate, which increases the likelihood of its residues ending up in animal feed. These residues persist throughout the digestive process of production animals and accumulate in their excretion products. The poultry industry, in particular, is rapidly growing, and excreted products are used as plant fertilizers in line with circular food economy practices. We studied the potential effects of unintentional glyphosate contamination on an agronomically important forage grass, meadow fescue (Festuca pratensis) and a horticulturally important strawberry (Fragaria x vescana) using glyphosate residues containing poultry manure as a plant fertilizer in a common garden experiment. Glyphosate in the manure decreased plant growth in both species and vegetative reproduction in F. x vescana. Furthermore, our results indicate that glyphosate residues in organic fertilizers might have indirect effects on sexual reproduction in F. pratensis and herbivory in F. x vescana because they positively correlate with plant size. Our results highlight that glyphosate can be unintentionally spread via organic fertilizer, counteracting its ability to promote plant growth.

Asteraceae family: a review of its allelopathic potential and the case of Acmella oleracea and Sphagneticola trilobata

Abstract Asteraceae family is as an interesting target for researching natural alternatives for crop protection. Many species from this family grow as weeds, and some of them can influence the development of other species by the allelopathy phenomenon. This paper aimed to review the literature for the main genera and species of the Asteraceae family with allelopathic or phytotoxic potential, as well as the classes of secondary metabolites present in this family and responsible for such activity. Artemisia, Ambrosia, Bellis, Bidens, Helianthus and Tagetes were identified as the main genera with phytotoxic or allelopathic activity. Among the secondary metabolites from this family, terpenes, polyacetylenes, saponins, sesquiterpene lactones, phenolic acids and flavonoids were described as responsible for inhibiting the development of other species. In addition, the phytotoxic potential of Acmella oleracea and Sphagneticola trilobata against the weeds Calopogonium mucunoides. and Ipomoea purpurea was described for the first time. At 0.2 mg/mL, crude extract and fractions of A. oleracea inhibited above 60% of C. mucunoides root growth. Hydroalcoholic extract and fractions of S. trilobata, except hexane, significantly affected I. purpurea root growth, ranging from 38 ± 14% to 59 ± 8% of inhibitory effect at different concentrations (0.19 mg/mL to 1.13 mg/mL).