Roundup Research Articles

A Review on the Sublethal Effects of Pure and Formulated Glyphosate on Bees, with a Focus on Social Bee Species

Glyphosate, one of the most widely used herbicides globally, has been extensively applied in agriculture due to its efficacy in weed control. However, recent studies have raised concerns about its sublethal effects on non-target organisms, particularly social bee species such as honeybees (Apis mellifera), bumblebees (Bombus spp.), and stingless bees (e.g., Melipona, Trigona). While glyphosate's primary mechanism targets the shikimate pathway, which is absent in animals, emerging evidence suggests it can indirectly impact bees by altering their gut microbiota, immune responses, and behavior. Research shows that even at sublethal doses, glyphosate can impair navigation, learning, and foraging efficiency, leading to reduced colony growth and survival rates. Field and laboratory studies indicate that the impact is exacerbated when bees are exposed to formulated products containing surfactants, which increase glyphosate’s toxicity. Furthermore, the disruption of social behaviors within colonies, such as communication through the waggle dance in honeybees, has profound implications for hive health and productivity. Despite growing evidence, there remain significant gaps in our understanding of glyphosate’s long-term and chronic effects, especially across diverse ecosystems and bee species. Current research is limited by a lack of longitudinal field studies that assess the cumulative impact of low-dose exposure over multiple generations. Most studies have focused on honeybees, with less attention given to wild and native bee populations, which may respond differently to glyphosate. To address these challenges, future research must prioritize mechanistic studies, explore eco-friendly alternatives to glyphosate, and implement integrated pest management strategies to reduce agrochemical dependence. Collaboration among scientists, policymakers, and stakeholders is critical to developing evidence-based regulations that protect pollinator health. Given the essential role bees play in global food security through pollination, protecting these vital species from the sublethal effects of glyphosate is not only an ecological imperative but also a socioeconomic necessity. Immediate actions in research, policy reform, and sustainable agricultural practices are needed to mitigate the risks posed by glyphosate and safeguard the future of pollinators.

The combined effect of environmentally relevant doses of glyphosate and high temperature: An integrated and multibiomarker approach to delineate redox status and behavior in Danio rerio.

Glyphosate, a pesticide commonly found in aquatic ecosystems, affects this habitat and nontarget organisms such as fish. The increase in water temperature, linked to factors such as climate change, poses a considerable threat. Despite extensive ecotoxicological research, we still do not know the real individual and specific consequences of continued exposure to glyphosate and high temperatures, simulating a scenario where the aquatic environment remains contaminated and temperatures continue to rise. Therefore, in this study, we examined the effects of exposure to environmentally relevant concentrations of glyphosate, active ingredient glyphosate (GAI), and glyphosate-based herbicide (GBH) in combination with high temperature (34 °C) in adult zebrafish (Danio rerio). The fish were acclimated to 28 or 34 °C for 96 h. The exposure to 225 and 450 μg L-1 (GBH or GAI) at 28 or 34 °C for 7 days. We analyzed behavioral endpoints (anxiety-like response, sociability, and aggressivity) and biochemical biomarkers of the brain and muscle (oxidative stress). Anxiety-like responses and decreased sociability were disrupted by the combination of glyphosate and high temperature. Furthermore, there is a decrease in Acetylcholinesterase activity in the brain, and an increase in Lipid Peroxidation, Protein Carbonylation, Acetylcholinesterase activity, and Glutathione S-Transferase activity in the muscle. These results demonstrated oxidative stress, anxiety-like behavior and decreased sociability caused by glyphosate and high temperature. We concluded that the combined effects of glyphosate and high temperature affected redox homeostasis and behavior, emphasizing that the field of glyphosate pollution should be carefully considered when evaluating the effects of climate change.

Health effects of a glyphosate-based herbicide on Elliptio complanata: multi-biomarker approach

The active ingredient (a.i.) glyphosate is frequently detected in waterways at relatively high concentrations, posing a risk to aquatic organisms including freshwater mussels, North America's most endangered animal group. This research aims to evaluate for the first time the effect of a glyphosate-based herbicide on a freshwater mussel (Unionid) using a battery of biomarkers. The mussel Elliptio complanata was exposed for 21 days to Credit® Xtreme (at 0, 50, 100, and 150 µg/L a.i. of glyphosate). An integrated biomarker response (IBRv2) was used to visualize the overall impact of each glyphosate-based herbicide concentration on mussels’ health conditions. The biomarker results showed that glyphosate (used at 100 µg/L and 150 µg/L) induced lipid peroxidation in the gills and digestive gland and inhibited acetylcholinesterase in the foot and gills, indicating oxidative damage and neurotoxicity. Other biomarkers were influenced at the lowest concentration of glyphosate tested (50 µg/L): lipids (decrease), triglycerides (increase) and, to a lesser extent, vitellogenin (decrease). For the latter biomarkers, the sexes were not affected similarly, and they were only sensitive at 50 µg/L, only females showed a trend toward a decrease for vitellogenin and a decrease for lipids. Using IBRv2, we found a clear discrimination between concentrations, and the index values increased with glyphosate concentration, attesting to the deterioration in biomarker-defined mussel health when exposed to Credit® Xtreme at realistic glyphosate concentrations in agricultural rivers. This study shows that glyphosate-based herbicides can alter neurological function, induce oxidative damage, and selectively modify the E. complanata metabolism at relatively low concentrations.

Glyphosate and glyphosate-based herbicides induce Poecilia reticulata to maintain redox equilibrium during and after coexposure to iron oxide nanoparticles (y-Fe2O3)

Iron oxide nanoparticles (IONPs) are being increasingly recognized as viable materials for environmental remediation due to their capacity to adsorb contaminants such as glyphosate (GLY) on their surfaces. Nevertheless, the ecotoxicological implications of IONPs associated with GLY necessitate thorough evaluation to ascertain the safety of such remediation strategies. In this context, the present investigation was conducted to examine hepatic biomarkers pertinent to the redox system, as well as ultrastructural hepatic alterations in Poecilia reticulata, following a 21-day exposure to environmentally relevant concentrations of IONPs, iron ions (Fe), and glyphosate in its pure form (GLY) as well as a commercial glyphosate-based herbicide (GBH). After this exposure, the fish underwent a 21-day recovery in uncontaminated water. The results indicated an increase in the activity of catalase (CAT) and glutathione S-transferase (GST) and in the concentration of glutathione (GSH) in the animals subjected to IONP+GBH and IONP+GLY treatments. This biochemical response persisted for the duration of both the exposure and recovery phases. Concurrently, hepatocytes displayed mitochondria with increased electron density, augmented lipid droplet accumulation, and expanded necrotic areas within the hepatic tissue. In contrast, fish exposed solely to IONPs exhibited sustained redox homeostasis throughout the investigative timeline. These findings suggest that the coexposure toxicity of IONP+GLY and IONP+GBH is attributable to the agent adsorbed onto the IONPs and that P. reticulata could maintain an active antioxidant defense mechanism throughout the entire study period.

Herbicidal interference: glyphosate drives both the ecology and evolution of plant-herbivore interactions.

The coevolution of plants and their insect herbivores reflects eco-evolutionary dynamics at work - ecological interactions influence adaptive traits, which feed back to shape the broader ecological community. However, novel anthropogenic stressors like herbicide, which are strong selective agents, can disrupt these dynamics. Little is known about how the evolution of herbicide resistance may impact plant-herbivore interactions. We performed a common garden field experiment using Ipomoea purpurea (common morning glory) and the herbicide glyphosate (Roundup) to investigate the ecological effects of herbicide exposure on insect herbivory patterns and assess the potential evolutionary consequences. We find that plants treated with glyphosate experienced higher levels of herbivory and altered chewing herbivory damage patterns. Additionally, we found that glyphosate resistance is positively associated with herbivory resistance, and uncovered positive selection for increased glyphosate resistance, suggesting that selection for increased glyphosate resistance has the potential to lead to increased herbivory resistance. Positive selection for glyphosate resistance, coupled with the detection of genetic variation for this trait, suggests there is potential for glyphosate resistance - and herbivory resistance via hitchhiking - to further evolve. Our results show that herbicides cannot just influence, but potentially drive the eco-evolutionary dynamics of plant-herbivore interactions.

Decontamination of water contaminated by the herbicide glyphosate through adsorption technology: a critical review

One of the biggest problems facing today's society is the rampant use of herbicides, as agricultural overproduction increasingly relies on these chemicals. Despite having a targeted application, their release into soil particles and water resources is inevitable, leading to damage at environmental and social levels. Therefore, adsorption technology presents itself as an alternative to decontaminating wastewater, presenting a high advantage in the removal and cost-benefit of the process. This study provides a qualitative exploratory analysis, where the understanding of the topic is achieved based on a thorough bibliographical survey focused on the removal of glyphosate using different adsorbent materials. Work related to glyphosate adsorption analyzes several parameters such as pH, adsorbent dosage and adsorbate concentration, kinetic time, and temperature effect. It was observed that when the herbicide concentration was increased, the adsorption capacity also increased, whereas removal showed the opposite behavior, decreasing with increasing concentration. The ideal pH value depends largely on the characteristics of the adsorbent such as surface area, and functional groups present on the surface, among others. The kinetic studies showed a better fit to the Pseudo-second order model, while the adsorption equilibrium studies showed a better fit to the Freundlich and Langmuir model. Therefore, current literature shows that several materials can be used as alternative sources of adsorbents for the remediation of glyphosate present in water

Ecotoxicological effects of a glyphosate-based herbicide on Gryllus (Gryllus) assimilis (Orthoptera: Gryllidae) ontogeny: a study on antioxidant system, oxidative stress and cholinergic system.

Brazil is an important global agricultural producer and to increase production the country has extensively used glyphosate-based herbicides (GBH), surpassing consumption and sales records. Consequently, concerns have arisen regarding the potential impact of GBH on ecosystems and non-target organisms. Thus, the effects of GBH exposure were evaluated throughout the cricket Gryllus (Gryllus) assimilis ontogeny, with five developmental stages. Each period contained 3 control and 3 treated boxes, with 15 crickets each, resulting in 90 insects at a time. The control groups received water, while the treated ones were continuously exposed to GBH (0.864 mg.GBH.L-1), with the solutions changed every 48 h. After each exposure time the crickets' group were euthanized to assess the activity of antioxidant enzymes (GST, GR, GPx, and CAT), cholinergic enzymes (ChE), and lipid peroxidation (LPO). The results revealed changes in the systems throughout different developmental phases. Specifically, CAT activity exhibited a significant increase during the nymphal phase, associated with the dismutation of hydrogen peroxide. The GBH increased GST, indicating its role in cellular detoxification, particularly during adulthood. In the senescence stage there was a considerable rise in ChE enzymes, suggesting their involvement in both, choline esters breakdown and potential pesticide detoxification. The action of these enzymes to effectively control lipid peroxidation shows the adaptability of this species to environmental contamination. These findings underscore the long-term effects of agrochemical pollution and emphasize the importance of sustainable practices, effective regulations, and alternative weed control methods.

Glyphosate contact alters the expression of genes in the head of africanized Apis mellifera bees

The increase in the world population results in a greater demand for food, intensifying the dependence on pesticides use. Glyphosate, a pesticide widely used in crops, can contaminate resources collected by bees. In this context, this study aimed to analyze the transcriptome of the head of Africanized Apis mellifera bees during the foraging phase to determine whether contact with the herbicide glyphosate, in lethal and sublethal doses, causes changes in the gene expression profile. For this, 180 marked bees were collected from their hives, aged 21 days, and distributed into three treatment groups: 1) bees in contact with the lethal dose of glyphosate (255.73 µg/bee); 2) bees in contact with the sublethal dose of glyphosate (2.5573 µg/bee); 3) control group with distilled water. Transcriptome analysis was performed on 12 bees from each treatment after one and four hours of exposure. The results show that one hour of contact with glyphosate resulted in 57 genes presenting differential expression in relation to the control (11 lethal and 53 sublethal), interfering in the signaling, communication and metabolism processes, while four hours of exposure, 38 genes (32 lethal and 11 sublethal) related, mainly, to the stimulation of the immune response. In summary, glyphosate affects the gene expression of honey bees during the foraging phase, at both doses, resulting in negative effects on behavior, metabolism and immune system, which compromises the health, activity and development of the colonies, also compromising the process of pollination.

Allelopathic and phytotoxic activity of essential oil of Elaeagnus angustifolia flowers and its major constituents on Amaranthus retroflexus and Lolium perenne

This study investigated the allelopathic and phytotoxic effects of Elaeagnus angustifolia flower essential oil (EO) and its major constituents. Forty-one compounds were identified by GC–MS, accounting for 96.93% of the total oil, with the main compounds being ethyl cinnamate and methyl cinnamate. The allelopathic assay of the EO completely suppressed the seed germination of Lolium perenne and Amaranthus retroflexus at 22.22 mg/mL air treatment. Phytotoxic activities of ethyl cinnamate and methyl cinnamate were much stronger than those of the EO against L. perenne, with IC50 values of 0.386, 0.396, and 7.159 mg/mL, respectively. The strength of the phytotoxic activity of the major constituent ethyl cinnamate, and the mixture of ethyl cinnamate and methyl cinnamate was comparable to that of the commercial herbicide glyphosate in terms of suppressing root elongation in A. retroflexus, with IC50 values of 0.049, 0.076, and 0.017 mg/mL, respectively, indicating a possible synergistic effect of the major compounds.

Comparative cytotoxicity and mitochondrial disruption in H9c2 cardiomyocytes induced by common pesticides

Chronic exposure to pesticides is believed to be associated with various human diseases, including cardiovascular diseases. However, the mechanisms by which pesticides lead to cardiovascular diseases remain unclear. In our study, we selected the following commonly used pesticides as typical examples: the herbicides glyphosate (GLY) and glufosinate ammonium (GLA); the insecticides imidacloprid (IMI) and thiamethoxam (THM); and the fungicides pyraclostrobin (PYR) and azoxystrobin (AZO). We employed H9c2 cells as a model to investigate the cytotoxic effects of these pesticides on myocardial cells at concentrations of 1, 10, 100, and 1000 mg/L. The results indicate that these pesticides can affect cell viability, alter the cell cycle, and significantly impact ATP content and mitochondrial complex levels, ultimately triggering oxidative stress responses in the cells. However, compared to herbicides GLY and GLA, insecticides IMI and THM, and fungicides PYR and AZO pesticides are more toxic to H9c2 cells. Additionally, GLY, GLA, IMI, THM, PYR, and AZO were found to cause structural changes in the mitochondria of H9c2 cells. Molecular docking results suggest that these pesticides can bind to proteins related to mitochondrial dynamics. Furthermore, IMI, THM, PYR, and AZO exhibit stronger binding abilities to mitochondrial dynamics-related proteins. These findings indicate that these pesticides significantly adverse effects on myocardial cells, mainly by causing mitochondrial dysfunction and inducing oxidative stress. Our findings highlight the importance of considering the differential toxicity of various classes of pesticides when assessing their risks to human health, particularly concerning cardiovascular diseases.

Developing Strategies to Mitigate Squash Injury from the Soil Residual Activity of Glyphosate in Bareground Systems

Fresh market vegetables are an essential component of the human diet. Maximizing yield is critical, and to achieve this goal, fields must be weed-free when vegetable crops are planted. Historically, removing emerged weeds just before planting has been accomplished using the herbicide glyphosate. However, recent research has indicated that glyphosate applied to sandy, low-organic-matter soils just before transplanting vegetables can be injurious. Two field experiments investigated 1) the response of transplanted squash to the residual activity of glyphosate, and 2) the effects of implementing tillage, irrigation, or extending the plant-back interval after application and before planting to mitigate injury from glyphosate. Glyphosate applied at 1.3, 2.5, or 3.8 kg ae/ha 1 day before transplanting injured squash 13%, 29%, and 53%, respectively; extending the interval between application and planting to 7 days reduced injury to 1%, 11%, and 28% at the same rates. An interaction between application rate and planting interval was also observed on squash plant widths and biomass, as well as early-season and total marketable fruit numbers and weights. Total marketable fruit number was reduced 29% and 52% by glyphosate at 2.5 or 3.8 kg ae/ha, respectively, and a reduction in fruit production of 36%, 28%, and 23% was observed when glyphosate was applied 1, 4, or 7 days before transplanting, respectively. In a separate study, light tillage (5 cm deep) was the most effective cultural practice evaluated because it eliminated damage by glyphosate. Overhead irrigation of 0.6 cm was not beneficial in mitigating injury by glyphosate. Recommendations from this research will help vegetable growers avoid injury from the residual activity of glyphosate through a FIFRA 2(ee) recommendation label.

Acute glyphosate and aminomethylphosphonic acid (AMPA), its major metabolite, impaired spatial orientation, navigation, learning and/or memory in female rats

Human exposure to glyphosate-based herbicides (GBH) has been associated with a range of toxicological effects involving the central nervous system (CNS) such as alterations in learning and memory. Nevertheless, the effects of aminomethylphosphonic acid (AMPA), the main metabolite of glyphosate, remain essentially obscure. Previous preclinical reports suggest that acute intoxication with AMPA and glyphosate exerts decrease on hippocampal acetylcholinesterase activity and produces more metabolomic alterations in the female brain over the male one. Therefore, this work explored the effects of acute AMPA and glyphosate on spatial learning, memory and navigation in female rats. Sprague Dawley rats received a single injection (i.p.) of: (i) vehicle; (ii) 10 or 100mg/kg of AMPA; or (iii) 10 or 100mg/kg of glyphosate; subsequently, the Barnes maze paradigm was performance. Animals from the control group decreased latency and the attempts to solve the Barnes maze; and increased the degree of orientation when compared first training sessions (S1) vs. the last one (S4; p < 0.05). In contrast, both 10 and 100mg/kg of glyphosate and 100mg/kg of AMPA prevented the decrease in latency and attempts; and the increase of orientation (p>0.05 S1 vs. S4). Both treatments decreased the use of the spatial navigation strategy (p < 0.05). Besides, glyphosate at the higher dose but not AMPA impaired the spatial memory during the test. Our findings suggest that acute exposure to glyphosate and AMPA similarly affected spatial orientation, navigations, learning and/or memory.

Heart Transplant Rejection in the Setting of Glyphosate Herbicide Exposure; A Case Report

Glyphosate is a common herbicide utilized worldwide with known exposure related toxicities. Numerous adverse effects related to glyphosate exposure have been documented, specifically in non-human models, however literature is lacking on cardiotoxic effects specific to heart transplant patients. Rejection is the most common post-transplant complication and the diagnosis of such is vital in order to guide immediate and appropriate treatment. In addition to the endomyocardial biopsy, noninvasive genetic testing can aid in rejection diagnosis and distinguish between cell-mediated and antibody-mediated rejection. We describe a case of glyphosate exposure in a post orthotopic heart transplant and the subsequent heart transplant rejection, patient’s clinical course, treatment, and follow up.

Glyphosate Herbicide Impacts on the Seagrasses Halodule wrightii and Ruppia maritima from a Subtropical Florida Estuary

Seagrass meadows are among the most threatened ecosystems on Earth, with losses attributed to increasing coastal populations, degraded water quality and climate change. As coastal communities work to improve water quality, there is increased concern regarding the use of herbicides within the watersheds of these sensitive ecosystems. Glyphosate is the most widely used herbicide on Earth because it is non-selective and lethal to most plants. Also, the targeted amino acid synthesis pathway of glyphosate is not carried out by vertebrates, and it is generally considered one of the safer but effective herbicides on the market. At least partially due to its cost-effectiveness compared to other techniques, including mechanical harvesting, glyphosate use in the aquatic environment has increased in coastal areas to manage aquatic weeds, maintain navigable waterways and mitigate upland flooding. This has prompted concerns regarding potential ecosystem-level impacts. To test the acute toxicity of glyphosate to seagrasses, mesocosm experiments exposed Ruppia maritima and Halodule wrightii to 1 ppm, 100 ppm and 1000 ppm of glyphosate (as glyphosate acid). No significant decrease in leaf chlorophyll a (Chl a) was identified for either species at 1 ppm versus a control; however, significant decreases were observed at higher concentrations. In all except 1000 ppm mesocosms, water column Chl a increased, with a 7-fold increase at 100 ppm. These data demonstrate that at very high glyphosate concentrations, both acute toxicity and light limitation from enhanced algal biomass may have adverse impacts on seagrasses. Despite these observations, no significant adverse impacts attributed to acute toxicity were observed at 1 ppm, which is &gt;1000 times higher than concentrations measured in the Indian River Lagoon system. Overall, herbicide use and associated decaying biomass contribute nutrients to these systems, in contrast to the removal of nutrients when mechanical harvesting is used. Based on our data and calculations, when used at recommended application rates, contributions to eutrophication, degraded water quality and harmful algal blooms were more likely to impact seagrasses than acute toxicity of glyphosate.

Glyphosate formulations cause mortality and diverse sublethal defects during embryonic development of the amphibian Xenopuslaevis

The human impact on environmental landscapes, such as land use, climate change or pollution, is threatening global biodiversity and ecosystems maintenance. Pesticides like the herbicide glyphosate have garnered considerable attention due to their well-documented harmful effects on non-target species. During application, the active ingredient glyphosate is utilized in various formulations, each containing different additive adjuvants. However, the possible effects of these formulations on amphibians - the group with the highest decline rates among vertebrates - remain largely unknown.Therefore, the present study investigated the effects of four glyphosate formulations (Glyphosat TF, Durano TF, Helosate 450 TF, Kyleo) on the embryonic development of the model organism Xenopus laevis (South African clawed frog). Embryos at the 2-cell stage were exposed to various concentrations of glyphosate formulations (glyphosate: 0.01–100 mg/L), and mortality as well as sublethal effects on different organs and tissues were analyzed. The results indicated that the formulations had different effects, particularly on the mortality of Xenopus laevis embryos. At sublethal concentrations, the formulations altered the embryos' external appearance, leading to malformations such as reduced eye and head size. In addition, exposure to formulations impaired heart morphology and function, and the expression of heart-specific genes was altered at a molecular level.Our results confirmed that glyphosate formulations had a stronger effect on Xenopus laevis embryogenesis than pure glyphosate. Therefore, it is crucial to evaluate the active ingredient and the co-formulations independently, as well as the combined, commercially available products, during pesticide risk assessments and renewal procedures of agrochemicals. The severe global decline of amphibians, partly due to herbicide use, highlights the need for strict and efficient monitoring of environmental pesticide loads and application areas.

Field and biochemical evaluation of glyphosate tolerant chickpea (Cicer arietinum L.) mutants developed through induced mutagenesis

Weed control in chickpea (Cicer arietinum L.) is challenging due to narrow genetic base of available germplasm and limited herbicide options. In this view, present research was focused on induced mutagenesis in chickpea for development of herbicide (glyphosate) tolerant mutants and subsequent screening under field conditions. Further, objective was to analyze the defence response and biochemical adjustments in selected glyphosate tolerant chickpea mutants. Initially, 376 chickpea mutants (M6 populations developed through EMS and gamma rays) were screened for glyphosate tolerance under filed conditions and scored on a 1 to 5 scale based on plant injury related traits. Among tested mutants, 40 were found highly tolerant (score = 5), 32 as tolerant (score = 4) and 20 as highly sensitive (score = 1) to glyphosate. Chickpea mutants with variable glyphosate tolerance also differed significantly (Tukey test, p < 0.05) in leaf biochemical profiles. For instant, lowest total oxidant status (4175.µM/g f. wt.) was detected in glyphosate tolerant mutant developed from desi chickpea genotype “D3009” using 0.3% EMS and in highly tolerant mutant (1775. µM/g f. wt.) developed from kabuli genotype “K709” using 0.2% EMS. In general, highly tolerant chickpea mutants exhibited highest antioxidant potential (SOD, POD, CAT, TAC) that contributed in glyphosate tolerance. Desi i.e. D1M1HT-2 and Kabuli i.e. KM3HT-2 type mutants with highest seed yield had maximum catalase activity (4200 Units/g f. wt and 540 Units/g f. wt.). Mutants developed from desi type genotypes were comparably superior to mutants derive from Kabuli in terms of herbicide tolerance.

Effect of Fall- and Spring-Planted Cover Crops and Residual Herbicide on Emergence Dynamics of Glyphosate-Resistant Kochia (Bassia scoparia)

Abstract Two separate field experiments were conducted during the 2021-22 and 2022-23 growing seasons at Kansas State University Agricultural Research Center near Hays, KS to understand the emergence dynamics of glyphosate-resistant (GR) kochia [Bassia scoparia (L.) A. J. Scott] as influenced by fall- and spring-planted cover crops (CC) and residual herbicide. Study sites were under winter wheat (Triticum aestivum L.)-sorghum [Sorghum bicolor (L.) Moench]-fallow rotation with a natural seedbank of GR B. scoparia. In experiment 1, fall-planted CC mixture (triticale/winter peas/radish/rapeseed) was planted after wheat harvest and terminated at triticale [xTriticosecale Wittm. Ex A. Camus [Secale x Triticum] heading stage (next spring before sorghum planting). In experiment 2, spring-planted CC mixture (oats/barley/spring peas) was planted in sorghum stubbles and terminated at oats (Avena sativa L.) heading stage. Four treatments were established in each experiment: (1) nontreated control (no CC and no herbicide), (2) chemical fallow (no CC but glyphosate + acetochlor/atrazine or flumioxazin/pyroxasulfone + dicamba were used to control weeds), (3) CC terminated with glyphosate, and (4) CC terminated with glyphosate plus residual herbicide (acetochlor/atrazine for fall-planted CC and flumioxazin/pyroxasulfone for spring-planted CC). Results indicated that fall-planted CC delayed GR B. scoparia emergence by 3 to 5 weeks whereas spring-planted CC delayed emergence by 0 to 2 weeks compared to nontreated. Fall-planted CC terminated with glyphosate plus acetochlor/atrazine reduced the cumulative emergence of GR B. scoparia by 90 to 95% compared to nontreated across both yrs. Similarly, spring-planted CC terminated with glyphosate plus flumioxazin/pyroxasulfone reduced the cumulative emergence of GR B. scoparia by 83 to 90% compared to nontreated. These results suggest that fall- or spring-planted CC in combination with residual herbicide at termination can be utilized for GR B. scoparia suppression. Results from this study will help in developing prediction models for GR B. scoparia emergence under different CC strategies.

Oxidative stress and cytotoxicity of co-formulants of glyphosate-based herbicides in HMWB cells

Abstract Background Glyphosate-based herbicides (GBHs) are widely used worldwide because of their effectiveness and low cost. However, there is a growing concern regarding the potential health risks associated with glyphosate exposure. Glyphosate is always marketed in formulations containing ingredients other than the active substance. These co-formulants may have toxic effects on humans and animals. Although several studies have assessed the health risks related to glyphosate, the toxicological effects of the co-formulants must be analysed in more detail to ensure the health and safety of pesticide users and the general population. This study aimed to characterize and compare the cytotoxic effects of co-formulants with those of the active substance and GBH formulations. Methods Human mononuclear white blood (HMWB) cells were exposed to varying concentrations (0.1 µM, 1µM, 10 µM, 100 µM, 1 mM, 10 mM) of glyphosate, three GBHs (Fozat 480, Roundup, and Glyfos), and two co-formulants for 4- and 20-hours. Cytotoxicity was assessed using the CCK-8 assay, and oxidative stress levels in HMWB cells were evaluated using the superoxide dismutase (SOD) assay. Cell viability and SOD activity were analysed using a spectrophotometer at 460 nm absorbance. Results Glyphosate alone did not significantly affect the cell viability. However, notable cytotoxic effects were observed in response to GBHs and adjuvants at concentrations as low as 100 µM. Furthermore, the Oxidative stress levels in cells treated with GBHs or adjuvants were significantly higher than those treated with glyphosate alone. Conclusions These findings suggest that the cytotoxic effects of GBHs are likely attributed to the adjuvants present in the formulations, which promote oxidative stress. Further studies are necessary to evaluate the health risks associated with using glyphosate-based herbicides, and co-formulants should be considered when assessing their safety. Key messages • The safety of GBHs cannot be solely attributed to glyphosate itself but also to the other components in the formulation. • Toxicity evaluation should take into account not only glyphosate but also the co-formulants present in these herbicides when assessing their safety.

Effects of glyphosate based herbicide exposure in early developmental stages of Physalaemus gracilis

The impact of environmental pollutants has been a focus of investigation in recent years. Studies assessing the effects of these pollutants are essential for understanding the challenges faced by non-target species. Among the many substances used for agricultural purposes, the herbicide glyphosate is one of the most widely marketed in recent years. This broad-spectrum herbicide is commonly used to protect a variety of crops. In this study, we evaluated the effects of chronic glyphosate exposure on a native amphibian species, Physalaemus gracilis. Amphibians, which develop in aquatic environments, are highly sensitive to pesticides. Because of this, we investigated morphological, physiological, behavioral, and biochemical parameters in the early stages of development. The animals were exposed to environmentally relevant concentrations of a glyphosate-based herbicide (0, 100, 350, and 700 µg L⁻¹) during their first seven days of life. As a result, we observed impairments in anti-predatory behavior, reduced body mass index, and scaled mass index, malformations of the mouth and intestine, increased acetylcholinesterase activity, cardiotoxicity, and oxidative stress. These findings underscore the importance of studying native non-target species and highlight the need to evaluate the effects of environmentally relevant concentrations, as well as to review legislation regarding permissible levels of glyphosate in surface water and public water supplies.

Unraveling the mechanisms of multiple resistance across glyphosate and glufosinate in Eleusine indica

The herbicides glyphosate and glufosinate are commonly used in citrus and sugarcane orchards in Guangxi Province, China, wherein the C4 plant Eleusine indica (L.) Gaertn. is known to be a dominant weed species. However, high selection pressure has resulted in failure of control. In the present study, experiments were conducted to clarify resistance levels for the suspected populations and elucidate the mechanisms for multiple resistance. The resistance index to glyphosate was calculated for eight populations and ranged from 5.4 to 21.3, with a low-level shikimate content of 0.24–0.50 μg g−1. In addition, three populations showed low-level resistance to glufosinate, with a resistance index ranging from 2.6 to 3.9. The amplification of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene with a double-mutation T102I + P106S (TIPS) or a single-mutation (P106S and P106A) was observed in most populations. The target genes of glufosinate (GS1–1, GS1–2, and GS1–3) showed high-level expression, namely 145.5-fold that of susceptible plants. The content of EPSPS and glutamine synthetase (GS) protein in resistant plants can reach to 3.6 and 2.1 times higher than those in susceptible plants, respectively. The overexpression of the EPSPS gene with double (T102I + P106S) or single (P106S and P106A) mutations, plus the overexpression of GS1–1, GS1–2, and GS1–3, responded to multiple resistance mechanisms. Altogether, these results demonstrate that overexpression of GS1 is a novel form of resistant mechanism to glufosinate in weeds.