Embryotoxic Effects of Pesticides in Zebrafish (Danio rerio): Diflubenzuron, Pyriproxyfen, and Its Mixtures

Diflubenzuron (DFB) and pyriproxyfen (PPF) are larvicides used in crops to control insect plagues. However, these pesticides are known to impact non-target organisms like fish and mammals. Here, we aimed at assessing the embryotoxicity of purified DFB, PPF, and their mixtures in a non-target organism-zebrafish. Zebrafish embryos were exposed to different concentrations for 120 h: 0.025, 0.125, 0.25, 1.25, 2.5, and 10 mg/L of purified PPF and purified DFB, while we used 0.025 mg/L PPF + 10 mg/L DFB (Mix A), 0.125 mg/L PPF + 10 mg/L DFB (Mix B), and 0.25 mg/L PPF + 10 mg/L DFB (Mix C) for the mixtures of PPF + DFB. We observed mortality, teratogenicity, and cardiotoxicity. For the neurotoxicity tests and evaluation of reactive oxygen species (ROS) levels in the brain, embryos were exposed for 120 h to 0.379 and 0.754 mg/L of PPF and 0.025 and 0.125 mg/L of DFB. We established the LC50 for PPF as 3.79 mg/L, while the LC50 for DFB was not determinable. Survival and hatching were affected by PPF concentrations above 0.125 mg/L, DFB concentrations above 1.25 mg/L, and the lower pesticide mixtures. PPF exposure and mixtures induced different types of malformations, while a higher number of malformations were observed for the mixtures, suggesting a potentiating effect. Pesticides diminished avoidance responses and increased the levels of ROS across all concentrations, indicating neurotoxicity. Our findings underscore the detrimental impact of PPF and DFB exposure, spanning from biochemistry to morphology. There is a critical need to reconsider the global use of these pesticides and transition to more ecologically friendly forms of pest control, raising an alarm regarding repercussions on human and animal health and well-being.

2,4-D Herbicide-Induced Hepatotoxicity: Unveiling Disrupted Liver Functions and Associated Biomarkers

2,4-dichlorophenoxyacetic acid (2,4-D) is a widely used herbicide worldwide and is frequently found in water samples. This knowledge has prompted studies on its effects on non-target organisms, revealing significant alterations to liver structure and function. In this review, we evaluated the literature on the hepatotoxicity of 2,4-D, focusing on morphological damages, toxicity biomarkers and affected liver functions. Searches were conducted on PubMed, Web of Science and Scopus and 83 articles were selected after curation. Among these studies, 72% used in vivo models and 30% used in vitro models. Additionally, 48% used the active ingredient, and 35% used commercial formulations in exposure experiments. The most affected biomarkers were related to a decrease in antioxidant capacity through alterations in the activities of catalase, superoxide dismutase and the levels of malondialdehyde. Changes in energy metabolism, lipids, liver function, and xenobiotic metabolism were also identified. Furthermore, studies about the effects of 2,4-D in mixtures with other pesticides were found, as well as hepatoprotection trials. The reviewed data indicate the essential role of reduction in antioxidant capacity and oxidative stress in 2,4-D-induced hepatotoxicity. However, the mechanism of action of the herbicide is still not fully understood and further research in this area is necessary.

Isosteric Ring Exchange as a Useful Scaffold Hopping Tool in Agrochemistry

Replacing one ring in a molecule by a different carba- or heterocycle is an important scaffold hopping manipulation, because biologically active compounds and their analogues, which underwent such a transformation, are often similar in size, shape, and physicochemical properties and, therefore, likely in their potency as well. This review will demonstrate, how isosteric ring exchange led to the discovery of highly active agrochemicals and which ring interchanges have proven to be most successful.

Ring Closure and Ring Opening as Useful Scaffold Hopping Tools in Agrochemistry

Ring closing acyclic parts of a molecular scaffold or the opposite manipulation, opening rings to produce pseudo-ring structures, is an important scaffold hopping manipulation. Analogues derived from biologically active compounds through the utilization of such strategies are often similar in shape and physicochemical properties and, therefore, likely to exhibit similar potency. This review will demonstrate how several different ring closure techniques, such as replacing carboxylic functions by cyclic peptide mimics, incorporating double bonds into aromatic rings, tying back ring substituents to a bicyclic structure, cyclizing adjacent ring substituents to an annulated ring, bridging annulated ring systems to tricyclic scaffolds, and exchanging gem-dimethyl groups by cycloalkyl rings, but also ring opening led to the discovery of highly active agrochemicals.

Engineering Phenothiazine-Based Functional Mimics of Host Defense Peptides as New Agrochemical Candidates: Design, Synthesis, and Antibacterial Evaluation

In the protracted "arms race" between host and plant pathogenic bacteria, host organisms have evolved powerful weapons known as host defense peptides (HDPs). However, natural HDPs are not suitable for large-scale applications; therefore, researchers have chosen to develop bespoke small-molecule functional mimics. Phenothiazine derivatives were developed as functional HDPs mimics, owing to their broad biological activity and high lipophilicity. The phenothiazine analogues designed in this study exhibited excellent in vitro bioactivity against the three Gram-negative bacteria Xanthomonas oryzae pv oryzae, Xanthomonas axonopodis pv citri, and Pseudomonas syringae pv actinidiae, with optimal EC50 values of 0.80, 0.31, and 1.91 μg/mL, respectively. Preliminary evidence suggests that compound C2 may act on bacterial cell membranes and interact with bacterial Deoxyribonucleic acid in the groove binding mode. In vivo trials showed that compound C2 was highly effective against rice leaf blight (51.97-56.69%), with activity superior to those of bismerthiazol (40.7-43.4%) and thiodiazole copper (30.2-37.1%). Our study provides strong evidence to support the development of phenothiazine derivatives into pesticide candidates.

Eco-Efficient Systems Based on Nanocarriers for the Controlled Release of Fertilizers and Pesticides: Toward Smart Agriculture

The excessive application of pesticides and fertilizers has generated losses in biological diversity, environmental pollution, and harmful effects on human health. Under this context, nanotechnology constitutes an innovative tool to alleviate these problems. Notably, applying nanocarriers as controlled release systems (CRSs) for agrochemicals can overcome the limitations of conventional products. A CRS for agrochemicals is an eco-friendly strategy for the ecosystem and human health. Nanopesticides based on synthetic and natural polymers, nanoemulsions, lipid nanoparticles, and nanofibers reduce phytopathogens and plant diseases. Nanoproducts designed with an environmentally responsive, controlled release offer great potential to create formulations that respond to specific environmental stimuli. The formulation of nanofertilizers is focused on enhancing the action of nutrients and growth stimulators, which show an improved nutrient release with site-specific action using nanohydroxyapatite, nanoclays, chitosan nanoparticles, mesoporous silica nanoparticles, and amorphous calcium phosphate. However, despite the noticeable results for nanopesticides and nanofertilizers, research still needs to be improved. Here, we review the relevant antecedents in this topic and discuss limitations and future challenges.

Research Progress of Benzothiazole and Benzoxazole Derivatives in the Discovery of Agricultural Chemicals

Benzoxazole and benzothiazole have a broad spectrum of agricultural biological activities, such as antibacterial, antiviral, and herbicidal activities, which are important fused heterocyclic scaffold structures in agrochemical discovery. In recent years, great progress has been made in the research of benzoxazoles and benzothiazoles, especially in the development of herbicides and insecticides. With the widespread use of benzoxazoles and benzothiazoles, there may be more new products containing benzoxazoles and benzothiazoles in the future. We systematically reviewed the application of benzoxazoles and benzothiazoles in discovering new agrochemicals in the past two decades and summarized the antibacterial, fungicidal, antiviral, herbicidal, and insecticidal activities of the active compounds. We also discussed the structural-activity relationship and mechanism of the active compounds. This work aims to provide inspiration and ideas for the discovery of new agrochemicals based on benzoxazole and benzothiazole.

Perfluoroalkyl Group-Covered Organosilica Films for the Sensitive Detection of Sulfonylurea Herbicides in Laser Desorption/Ionization Mass Spectrometry

Simple and rapid screening of agrochemicals greatly contributes to food and environmental safety. Matrix-free laser desorption/ionization mass spectrometry (LDI-MS) is an effective tool for high-throughput analysis of low-molecular-weight compounds. In this study, we report a UV-laser-absorbing organosilica film for the sensitive detection of various sulfonylurea herbicides using LDI-MS. Organosilica films with fluoroalkyl groups on the organic part are fabricated, followed by additional modification of the silica moiety with a fluoroalkyl coupling agent to cover the film surface with hydrophobic fluoroalkyl groups. Nanoimprinting is conducted to impart nanostructures on the film surface to enhance the LDI performance. The fabricated nanostructured organosilica films accomplish sensitive detection of cyclosulfamuron and azimsulfuron at concentrations as low as 1 fmol μL^-1. The applicability of the nanostructured organosilica films is confirmed by the recovery of cyclosulfamuron and ethametsulfuron-methyl from pea sprouts (Pisum sativum) hydroponically grown in herbicide-spiked water at concentrations of 0.5 ppm.

Insertion of Small Flexible Linkers as a Useful Scaffold Hopping Tool in Agrochemistry

Inserting small flexible linkers of only one- to three-atom chain lengths into a molecular backbone is an important scaffold hopping manipulation. Analogues derived from biologically active compounds through the utilization of such a strategy are often similar in shape and physicochemical properties and, therefore, likely to exhibit similar potency. This review will demonstrate how the elongation with oxygen, amino, methylene, ethylene, vinyl, ethynyl, and CH₂O bridges led to the discovery of highly active agrochemicals.

Advancing Endodormancy Release in Temperate Fruit Trees Using Agrochemical Treatments

Endodormancy in temperate fruit trees like Prunus is a protector state that allows the trees to survive in the adverse conditions of autumn and winter. During this process, plants accumulate chill hours. Flower buds require a certain number of chill hours to release from endodormancy, known as chilling requirements. This step is crucial for proper flowering and fruit set, since incomplete fulfillment of the chilling requirements produces asynchronous flowering, resulting in low quality flowers, and fruits. In recent decades, global warming has endangered this chill accumulation. Because of this fact, many agrochemicals have been used to promote endodormancy release. One of the first and most efficient agrochemicals used for this purpose was hydrogen cyanamide. The application of this agrochemical has been found to advance endodormancy release and synchronize flowering time, compressing the flowering period and increasing production in many species, including apple, grapevine, kiwi, and peach. However, some studies have pointed to the toxicity of this agrochemical. Therefore, other non-toxic agrochemicals have been used in recent years. Among them, Erger^® + Activ Erger^® and Syncron^® + NitroActive^® have been the most popular alternatives. These two treatments have been shown to efficiently advance endodormancy release in most of the species in which they have been applied. In addition, other less popular agrochemicals have also been applied, but their efficiency is still unclear. In recent years, several studies have focused on the biochemical and genetic variation produced by these treatments, and significant variations have been observed in reactive oxygen species, abscisic acid (ABA), and gibberellin (GA) levels and in the genes responsible for their biosynthesis. Given the importance of this topic, future studies should focus on the discovery and development of new environmentally friendly agrochemicals for improving the modulation of endodormancy release and look more deeply into the effects of these treatments in plants.

Cardenolide, Potassium, and Pyrethroid Insecticide Combinations Reduce Growth and Survival of Monarch Butterfly Caterpillars (Lepidoptera: Nymphalidae)

The monarch butterfly, Danaus plexippus L., has evolved to be insensitive to milkweed cardenolides via genetic modifications of Na+/K+-ATPase. There is concern for insecticide exposures near agriculture, with little information on monarch caterpillar toxicology. It is unclear how cardenolide insensitivity may affect the sensitivity of monarch caterpillars to pyrethroid insecticides. Additionally, potassium fertilizers may affect monarch caterpillar physiology and cardenolide sequestration. Here, we investigated the growth, survival, and development of caterpillars exposed to the cardenolide ouabain, bifenthrin, and potassium chloride (KCl) alone and in combination. Caterpillars were either exposed to 1) ouabain from third- to fifth-instar stage, 2) KCl at fifth-instar stage, 3) KCl and bifenthrin at fifth-instar stage, or 4) combinations of ouabain at third-instar stage + KCl + bifenthrin at fifth-instar stage. Caterpillar weight, diet consumption, frass, and survival were recorded for the duration of the experiments. It was observed that 1-3 mg ouabain/g diet increased body weight and diet consumption, whereas 50 mg KCl/g diet decreased body weight and diet consumption. Caterpillars feeding on KCl and treated with 0.2 µg/µl bifenthrin consumed significantly less diet compared to individuals provided untreated diet. However, there was no effect on survival or body weight. Combinations of KCl + ouabain did not significantly affect caterpillar survival or body weight following treatment with 0.1 µg/µl bifenthrin. At the concentrations tested, there were no effects observed for bifenthrin sensitivity with increasing cardenolide or KCl concentrations. Further studies are warranted to understand how milkweed-specific cardenolides, at increasing concentrations, and agrochemical inputs can affect monarch caterpillar physiology near agricultural landscapes.

Redox- and Enzyme-Responsive Macrospheres Gatekept by Polysaccharides for Controlled Release of Agrochemicals

Stimuli-responsive materials afford researchers an opportunity to synthesize controlled-release carriers with various potential applications, especially for reducing the abuse of chemical reagents in farmland soil. To enhance the efficiency of agrochemical utilization, redox- and enzyme-responsive macrospheres were prepared by self-assembling β-cyclodextrin-modified zeolite and ferrocenecarboxylic acid (FcA)-grafted carboxymethyl cellulose (CMC). Scanning electron microscopy and Brunauer-Emmett-Teller analysis revealed that pores of zeolite were sealed by the surface coupling of FcA-modified CMC via the formation of an inclusion complex. Salicylic acid (SA) was loaded as a model agrochemical. The release of SA from macrospheres could be triggered in the presence of hydrogen peroxide (oxidant) and cellulase (enzyme); and the corresponding release percentages, 85.2 and 80.4%, were much higher than those of the control sample without responsive groups in water (12.6%) after 12 h. A release kinetic study showed that cellulase could promote carrier dissolution more effectively than the oxidant. The results demonstrate that the dual-responsive macrospheres are promising as a smart and effective carrier for the controlled release of agrochemicals.

Targeted Drug Delivery for Sustainable Crop Protection: Transport and Stability of Polymeric Nanocarriers in Plants

Spraying of agrochemicals (pesticides, fertilizers) causes environmental pollution on a million-ton scale. A sustainable alternative is target-specific, on-demand drug delivery by polymeric nanocarriers. Trunk injections of aqueous nanocarrier dispersions can overcome the biological size barriers of roots and leaves and allow distributing the nanocarriers through the plant. To date, the fate of polymeric nanocarriers inside a plant is widely unknown. Here, the in planta conditions in grapevine plants are simulated and the colloidal stability of a systematic series of nanocarriers composed of polystyrene (well-defined model) and biodegradable lignin and polylactic-co-glycolic acid by a combination of different techniques is studied. Despite the adsorption of carbohydrates and other biomolecules onto the nanocarriers' surface, they remain colloidally stable after incubation in biological fluids (wood sap), suggesting a potential transport via the xylem. The transport is tracked by fluorine- and ruthenium-labeled nanocarriers inside of grapevines by 19 F-magnetic resonance imaging or induced coupled plasma - optical emission spectroscopy. Both methods show that the nanocarriers are transported inside of the plant and proved to be powerful tools to localize nanomaterials in plants. This study provides essential information to design nanocarriers for agrochemical delivery in plants to sustainable crop protection.

Aedes Albopictus (Diptera: Culicidae) Susceptibility Status to Agrochemical Insecticides Used in Durian Planting Systems in Southern Thailand

High rates of dengue morbidity occur in southern Thailand. The intensive application of insecticides in orchards could affect not only agricultural insect pests, but also nontarget mosquitoes or beneficial insects. In this study, the type and quantity of insecticides commonly used across durian plantations in southern Thailand were characterized, along with the population density of Aedes albopictus (Skuse) (Diptera: Culicidae). Our primary aim was to determine the susceptibility status of field-derived Ae. albopictus to typical application concentrations of four agrochemical insecticides; cypermethrin, chlorpyrifos, carbaryl, and imidacloprid. Mosquito eggs were collected from durian cultivation sites in five provinces in southern Thailand and used to generate adults for susceptibility tests. The cultivation sites were categorized into three groups based on insecticide application: intensive application of insecticides, low application of insecticides, and no application of insecticides. Twenty ovitraps were deployed for at least three consecutive days at each study site to collect mosquito eggs and to determine Ae. albopictus population density. WHO tube assays were used to determine the susceptibility of adult mosquitoes derived from field-collected eggs to selected insecticides. This represents the first report of the susceptibility status of Ae. albopictus from durian orchards in southern Thailand to agrochemical insecticides. Results showed complete susceptibility of these Ae. albopictus to chlorpyrifos, but reduced mortality following exposure to λ-cyhalothrin, carbaryl, and imidacloprid, which is suggestive of the development of resistance. These findings provide new insights into the status of insecticide susceptibility in Ae. albopictus populations, with important implications for mosquito and mosquito-borne disease control in Thailand.

Exploring Biophysical Linkages between Coastal Forestry Management Practices and Aquatic Bivalve Contaminant Exposure

Terrestrial land use activities present cross-ecosystem threats to riverine and marine species and processes. Specifically, pesticide runoff can disrupt hormonal, reproductive, and developmental processes in aquatic organisms, yet non-point source pollution is difficult to trace and quantify. In Oregon, U.S.A., state and federal forestry pesticide regulations, designed to meet regulatory water quality requirements, differ in buffer size and pesticide applications. We deployed passive water samplers and collected riverine and estuarine bivalves Margaritifera falcata, Mya arenaria, and Crassostrea gigas from Oregon Coast watersheds to examine forestry-specific pesticide contamination. We used non-metric multidimensional scaling and regression to relate concentrations and types of pesticide contamination across watersheds to ownership and management metrics. In bivalve samples collected from eight coastal watersheds, we measured twelve unique pesticides (two herbicides; three fungicides; and seven insecticides). Pesticides were detected in 38% of bivalve samples; and frequency and maximum concentrations varied by season, species, and watershed with indaziflam (herbicide) the only current-use forestry pesticide detected. Using passive water samplers, we measured four current-use herbicides corresponding with planned herbicide applications; hexazinone and atrazine were most frequently detected. Details about types and levels of exposure provide insight into effectiveness of current forest management practices in controlling transport of forest-use pesticides.

Translation of Strigolactones from Plant Hormone to Agriculture: Achievements, Future Perspectives, and Challenges

Strigolactones (SLs) control plant development, enhance symbioses, and act as germination stimulants for some of the most destructive species of parasitic weeds, making SLs a potential tool to improve crop productivity and resilience. Field trials demonstrate the potential use of SLs as agrochemicals or genetic targets in breeding programs, with applications in improving drought tolerance, increasing yields, and controlling parasitic weeds. However, for effective translation of SLs into agriculture, understanding and exploiting SL diversity and the development of economically viable sources of SL analogs will be critical. Here we review how manipulation of SL signaling can be used when developing new tools and crop varieties to address some critical challenges, such as nutrient acquisition, resource allocation, stress tolerance, and plant-parasite interactions.

Agrochemical industry development, trends in R&D and the impact of regulation

Over the last 20 years the share of the crop protection market attributable to the leading markets (North America, EU-15 and Japan) that are the major focus of new active ingredient research and development (R&D) has declined. Greater growth has been recorded in developing markets, questioning the focus of current R&D strategy. R&D budgets within the major companies have seen a shift toward genetically modified (GM) trait development away from agrochemicals, such that the rate of new active ingredients entering development and subsequently being introduced has declined. As a result, the industry has become more reliant on older, off-patent chemistry, although the availability of older products has been affected by re-registration requirements, particularly in the EU. Current criteria often preclude the registration of broad-spectrum agrochemicals, resulting in many new active ingredients being single site active, which is perceived to increase the potential for resistance development, particularly for herbicides, although this is not always the case. © 2019 The Author. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Implementing a globally harmonized risk assessment-based approach for regulatory decision-making of crop protection products

A global, harmonized evaluation system for crop protection chemicals based on exposure and risk will improve the ability to inform risk management decisions and better support innovation. This would be achieved through harmonized risk assessment-based regulatory decision-making realized through the application of the best available science, via integration of new methods and traditional data to create tailored exposure-driven risk assessments. A requirement to achieve success is a structure that encourages direct communication between the regulatory community and the regulated industry, which would enable a more rapid incorporation of new technologies and advancing science. An approach that emulates the International Conference of Harmonization (ICH) for pharmaceuticals would bring together regulatory authorities and the regulated industry along with relevant experts from academia and Non-Governmental Organizations to discuss scientific and technical advances and their implementation. These discussions would also encourage the elimination of outmoded practices that no longer serve a purpose resulting in more uniform testing requirements and best practices for data evaluation to support safe use and scientifically defensible human health and environmental risk assessments. New and developing technologies offer exciting opportunities to improve the current toxicity testing paradigms to provide better solutions and diminish animal testing. Implementation of a harmonized approach will increase the speed, efficiency and accuracy of regulatory decision-making for human health and environmental protection while increasing the efficiency of providing safe and effective innovative products to the agriculture community. © 2020 Society of Chemical Industry.

Diaryl Ether: A Privileged Scaffold for Drug and Agrochemical Discovery

Diaryl ether (DE) is a functional scaffold existing widely both in natural products (NPs) and synthetic organic compounds. Statistically, DE is the second most popular and enduring scaffold within the numerous medicinal chemistry and agrochemical reports. Given its unique physicochemical properties and potential biological activities, DE nucleus is recognized as a fundamental element of medicinal and agrochemical agents aimed at different biological targets. Its drug-like derivatives have been extensively synthesized with interesting biological features including anticancer, anti-inflammatory, antiviral, antibacterial, antimalarial, herbicidal, fungicidal, insecticidal, and so on. In this review, we highlight the medicinal and agrochemical versatility of the DE motif according to the published information in the past decade and comprehensively give a summary of the target recognition, structure-activity relationship (SAR), and mechanism of action of its analogues. It is expected that this profile may provide valuable guidance for the discovery of new active ingredients both in drug and pesticide research.

Treatment of agrochemical wastewater by subcritical water oxidation method: chemical composition and ion analysis of treated and untreated samples

This work aimed at offering an effective and environmentally friendly approach to the real wastewater of an industrial agrochemicals production plant containing high amounts of many hazardous compounds that threaten human health. The removal of total organic carbon (TOC) (59.45%) and colour (97.92%) of the wastewater was achieved using subcritical water oxidation method. The fate of the detected compounds was followed by GC-MS analysis. Several pollutants such as phenol, fumaric acid, chlorpyrifos, penconazole, brassilexin, buprofezin, etoxazole, pyriproxyfen and 2-naphthalene-sulphonic acid which are bio-refractory and harmful to human health, were effectively degraded. Inorganic ions exist in the wastewater or formed through the process and their possible effects on the applied method were analysed. The central composite design was used to optimise the method and fully evaluate the single or combined effects of the method parameters on the removal rates. The precision of the applied design models was evaluated employing ANOVA, Regression coefficients and validation analysis. F and P and R² values were obtained as 107.43, <0.0001, and 0.9898, respectively in the TOC removal model and 39.45, <0.0001, and 0.9726 in the colour removal model.[Formula: see text].

Synthesis and Technology of Nanoemulsion-Based Pesticide Formulation

Declines in crop yield due to pests and diseases require the development of safe, green and eco-friendly pesticide formulations. A major problem faced by the agricultural industry is the use of conventional agrochemicals that contribute broad-spectrum effects towards the environment and organisms. As a result of this issue, researchers are currently developing various pesticide formulations using different nanotechnology approaches. The progress and opportunities in developing nanoemulsions as carriers for plant protection or nanodelivery systems for agrochemicals in agricultural practice have been the subject of intense research. New unique chemical and biologic properties have resulted in a promising pesticide nanoformulations for crop protection. These innovations-particularly the nanoemulsion-based agrochemicals-are capable of enhancing the solubility of active ingredients, improving agrochemical bioavailability, and improving stability and wettability properties during the application, thus resulting in better efficacy for pest control and treatment. All of these-together with various preparation methods towards a greener and environmentally friendly agrochemicals-are also discussed and summarized in this review.

Exposure of Foraging Bees (Hymenoptera) to Neonicotinoids in the U.S. Southern High Plains

Exposure to pesticides is a major threat to insect pollinators, potentially leading to negative effects that could compromise pollination services and biodiversity. The objectives of this study were to quantify neonicotinoid concentrations among different bee genera and to examine differences attributable to body size and surrounding land use. During the period of cotton planting (May-June), 282 wild bees were collected from habitat patches associated with cropland, grassland, and urban land cover and analyzed for three neonicotinoids (thiamethoxam, clothianidin, and imidacloprid). Twenty bees among eight genera contained one or more of the neonicotinoid compounds and detections occurred in all landscape types, yet with the most detections occurring in cropland-associated habitats. Apis Linnaeus (Hymenoptera: Apidae), Melissodes Latreille (Apidae), Perdita Smith (Andrenidae), and Lasioglossum Curtis (Halictidae) had multiple individuals with neonicotinoid detections. Two of the largest bees (Apis and Melissodes) had the greatest number of detections within genera, yet the relatively small-bodied genus Perdita had the three highest neonicotinoid concentrations reported. The number of detections within a genus and average generic body mass showed a marginally significant trend towards larger bees having a greater frequency of neonicotinoid detections. Overall, the relatively low percentage of detections across taxa suggests practices aimed at conserving grassland remnants in intensified agricultural regions could assist in mitigating exposure of wild bees to agrochemicals, while differences in bee traits and resource use could in part drive exposure. Further work is needed to address variable agrochemical exposures among pollinators, to support strategies for conservation and habitat restoration in affected landscapes.

Effects of the Herbicide Glyphosate on Honey Bee Sensory and Cognitive Abilities: Individual Impairments with Implications for the Hive

The honeybee Apis mellifera is an important pollinator in both undisturbed and agricultural ecosystems. Its great versatility as an experimental model makes it an excellent proxy to evaluate the environmental impact of agrochemicals using current methodologies and procedures in environmental toxicology. The increase in agrochemical use, including those that do not target insects directly, can have deleterious effects if carried out indiscriminately. This seems to be the case of the herbicide glyphosate (GLY), the most widely used agrochemical worldwide. Its presence in honey has been reported in samples obtained from different environments. Hence, to understand its current and potential risks for this pollinator it has become essential to not only study the effects on honeybee colonies located in agricultural settings, but also its effects under laboratory conditions. Subtle deleterious effects can be detected using experimental approaches. GLY negatively affects associative learning processes of foragers, cognitive and sensory abilities of young hive bees and promotes delays in brood development. An integrated approach that considers behavior, physiology, and development allows not only to determine the effects of this agrochemical on this eusocial insect from an experimental perspective, but also to infer putative effects in disturbed environments where it is omnipresent.

Chemical Modulation of Alternative Splicing for Molecular-Target Identification by Potential Genetic Control in Agrochemical Research

Alternative splicing (AS), the process of removing introns from pre-mRNA and the rearrangement of exons to produce several types of mature transcripts, is a remarkable step preceding protein synthesis. In particular, it has now been conclusively shown that up to ∼95% of genes are alternatively spliced to generate a complex and diverse proteome in eukaryotic organisms. Consequently, AS is one of the determinants of the functional repertoire of cells. Many studies have revealed that AS in plants can be regulated by cell type, developmental stage, environmental stress, and the circadian clock. Moreover, increasing amounts of evidence reveal that chemical compounds can affect various steps during splicing to induce major effects on plant physiology. Hence, the chemical modulation of AS can serve as a good strategy for molecular-target identification in attempts to potentially control plant genetics. However, the kind of mechanisms involved in the chemical modulation of AS that can be used in agrochemical research remain largely unknown. This review introduces recent studies describing the specific roles AS plays in plant adaptation to environmental stressors and in the regulation of development. We also discuss recent advances in small molecules that induce alterations of AS and the possibility of using this strategy in agrochemical-target identification, giving a new direction for potential genetic control in agrochemical research.

Palladium-Catalyzed Cross-Coupling Reactions: A Powerful Tool for the Synthesis of Agrochemicals

Pd-catalyzed cross-coupling reactions have become essential tools for the construction of carbon-carbon and carbon-heteroatom bonds. Over the last three decades, great efforts have been made with cross-coupling chemistry in the discovery, development, and commercialization of innovative new pharmaceuticals and agrochemicals (mainly herbicides, fungicides, and insecticides). In view of the growing interest in both modern crop protection and cross-coupling chemistry, this review gives a comprehensive overview of the successful applications of various Pd-catalyzed cross-coupling methodologies, which have been implemented as key steps in the synthesis of agrochemicals (on R&D and pilot-plant scales) such as the Heck, Suzuki, Sonogashira, Stille, and Negishi reactions, as well as decarboxylative, carbonylative, α-arylative, and carbon-nitrogen bond bond-forming cross-coupling reactions. Some perspectives and challenges for these catalytic coupling processes in the discovery of agrochemicals are briefly discussed in the final section. The examples chosen demonstrate that cross-coupling chemistry approaches open-up new, low-cost, and more efficient industrial routes to existing agrochemicals, and such methods also have the capability to lead the new generation of pesticides with novel modes of action for sustainable crop protection.

Cocoa Farmers' Compliance with Safety Precautions in Spraying Agrochemicals and Use of Personal Protective Equipment (PPE) in Cameroon

The inability of farmers to comply with essential precautions in the course of spraying agrochemicals remains a policy dilemma, especially in developing countries. The objectives of this paper were to assess compliance of cocoa farmers with agrochemical safety measures, analyse the factors explaining involvement of cocoa farmers in the practice of reusing agrochemical containers and wearing of personal protective equipment (PPE). Data were collected with structured questionnaires from 667 cocoa farmers from the Centre and South West regions in Cameroon. Data analyses were carried out with Probit regression and Negative Binomial regression models. The results showed that average cocoa farm sizes were 3.55 ha and 2.82 ha in South West and Centre regions, respectively, and 89.80% and 42.64% complied with manufacturers' instructions in the use of insecticides. Eating or drinking while spraying insecticides and fungicides was reported by 4.20% and 5.10% of all farmers in the two regions, respectively. However, 37.78% and 57.57% of all farmers wore hand gloves and safety boots while spraying insecticides in the South West and Centre regions of Cameroon, respectively. In addition, 7.80% of all the farmers would wash agrochemical containers and use them at home, while 42.43% would wash and use them on their farms. Probit regression results showed that probability of reusing agrochemical containers was significantly influenced (p < 0.05) by region of residence of cocoa farmers, gender, possession of formal education and farming as primary occupation. The Negative Binomial regression results showed that the log of number PPE worn was significantly influenced (p < 0.10) by region, marital status, attainment of formal education, good health, awareness of manufacturers' instructions, land area and contact index. It was among others concluded that efforts to train farmers on the need to be familiar with manufacturers' instructions and use PPE would enhance their safety in the course of spraying agrochemicals.

A cheminformatics review of auxins as herbicides

Herbicides are an important asset in ensuring food security, especially when faced with an ever-increasing demand on food production to feed the global population. The current selection of herbicides is increasingly encountering resistance in agricultural weeds they once targeted effectively. It is imperative that new compounds or more effective modes of action are discovered in order to overcome this resistance. This cheminformatics review looks at current herbicides and evaluates their physiochemical properties on a class-by-class basis. We focus in particular on the synthetic auxin herbicides, Herbicide Resistance Action Committee class O, analyzing these against herbicides more generally and for class-specific features such as mobility in plant vasculature. We summarise the physiochemical properties of all 24 compounds used commercially as auxins and relate these results to ongoing approaches to novel auxin discovery. We introduce an interactive, open source cheminformatics tool known as DataWarrior for herbicide discovery, complete with records for over 300 herbicidal compounds. We hope this tool helps researchers as part of a rational approach to not only auxin discovery but agrochemical discovery in general.

Developing Biostimulants From Agro-Food and Industrial By-Products

In modern agriculture, seeking eco-friendly ways to promote plant growth and enhance crop productivity is of priority. Biostimulants are a group of substances from natural origin that contribute to boosting plant yield and nutrient uptake, while reducing the dependency on chemical fertilizers. Developing biostimulants from by-products paves the path to waste recycling and reduction, generating benefits for growers, food industry, registration and distribution companies, as well as consumers. The criteria to select designated by-products for valorizing as biostimulant are: absence of pesticide residue, low cost of collection and storage, sufficient supply and synergy with other valorization paths. Over the years, projects on national and international levels such as NOSHAN, SUNNIVA, and Bio2Bio have been initiated (i) to explore valorization of by-products for food and agriculture industries; (ii) to investigate mode of action of biostimulants from organic waste streams. Several classes of waste-derived biostimulants or raw organic material with biostimulant components were shown to be effective in agriculture and horticulture, including vermicompost, composted urban waste, sewage sludge, protein hydrolysate, and chitin/chitosan derivatives. As the global market for biostimulants continues to rise, it is expected that more research and development will expand the list of biostimulants from by-products. Global nutrient imbalance also requires biostimulant to be developed for targeted market. Here, we review examples of biostimulants derived from agricultural by-products and discuss why agricultural biomass is a particularly valuable source for the development of new agrochemical products.

Environmental Triazole Induces Cross-Resistance to Clinical Drugs and Affects Morphophysiology and Virulence of Cryptococcus gattii and C. neoformans

Cryptococcus gattii and Cryptococcus neoformans are environmental fungi that cause cryptococcosis, which is usually treated with amphotericin B and fluconazole. However, therapeutic failure is increasing because of the emergence of resistant strains. Because these species are constantly isolated from vegetal materials and the usage of agrochemicals is growing, we postulate that pesticides could be responsible for the altered susceptibility of these fungi to clinical drugs. Therefore, we evaluated the influence of the pesticide tebuconazole on the susceptibility to clinical drugs, morphophysiology, and virulence of C. gattii and C. neoformans strains. The results showed that tebuconazole exposure caused in vitro cross-resistance (CR) between the agrochemical and clinical azoles (fluconazole, itraconazole, and ravuconazole) but not with amphotericin B. In some strains, CR was observed even after the exposure ceased. Further, tebuconazole exposure changed the morphology, including formation of pseudohyphae in C. neoformans H99, and the surface charge of the cells. Although the virulence of both species previously exposed to tebuconazole was decreased in mice, the tebuconazole-exposed colonies recovered from the lungs were more resistant to azole drugs than the nonexposed cells. This in vivo CR was confirmed when fluconazole was not able to reduce the fungal burden in the lungs of mice. The tolerance to azoles could be due to increased expression of the ERG11 gene in both species and of efflux pump genes (AFR1 and MDR1) in C. neoformans Our study data support the idea that agrochemical usage can significantly affect human pathogens present in the environment by affecting their resistance to clinical drugs.

Treatment of self-poisoning at a tertiary-level hospital in Bangladesh: cost to patients and government

OBJECTIVES

Approximately 10 000 people die from suicide annually in Bangladesh, many from pesticide poisoning. We aimed to estimate financial costs to patients and health services of treating patients with self-poisoning.

METHODS

Data on direct costs to families, sources of funds for treatment and family wealth were collected prospectively over a one-month period in 2016 at the tertiary Chittagong Medical College Hospital, Bangladesh. Aggregate operational costs to the government were calculated using annual budget, bed occupancy and length-of-stay data.

RESULTS

Agrochemicals were the most common substances ingested (58.8%). Median duration of stay and of illness was 2 and 5 days, respectively. Median total cost to patients was conservatively estimated at US$ 98.40, highest in agrochemical poisoning (US$ 179.50), with the greatest cost due to medicines and equipment. Misdiagnosis as organophosphorus poisoning in 17.0% of agrochemical cases resulted in increased cost to patients. Only 51.9% of patients had indicators of wealth; 78.1% borrowed money to cover costs. Conservatively estimated median healthcare costs (US$ 21.30 per patient) were markedly lower than costs to patients.

CONCLUSIONS

Cost to patients of treating a case of agrochemical poisoning was approximately three times the cost of one month's essential items basket. Incorrect diagnosis at admission costs families substantial sums of money and increased length of stay; it costs the national government an estimated US$ 80 428.80 annually. Widespread access to a list of pesticides used in self-poisoning plus greater focus on training doctors to better manage different forms of agrochemical poisoning should reduce the financial burden to patients and healthcare systems.

Combining Fungicides and Prospective NPR1-Based "Just-in-Time" Immunomodulating Chemistries for Crop Protection

Each year, crop yield is lost to weeds competing for resources, insect herbivory and diseases caused by pathogens. To thwart these insults and preserve yield security and a high quality of traits, conventional agriculture makes use of improved cultivars combined with fertilizer and agrochemical applications. However, given that regulatory bodies and consumers are demanding environmentally safer agrochemicals, while at the same time resistance to agrochemicals is mounting, it is crucial to adopt a "holistic" approach to agriculture by not excluding any number of management tools at our disposal. One such tool includes chemicals that stimulate plant immunity. The development of this particular type of alternative crop protection strategy has been of great interest to us. We have approached this paradigm by studying plant immunity, specifically systemic acquired resistance (SAR). The deployment of SAR immunity requires the production by the crop plant of an endogenous small molecule metabolite called salicylic acid (SA). Furthermore, immunity can only be deployed if SA can bind to its receptor and activate the genes responsible for the SAR program. The key receptor for SAR is a transcription coactivator called NPR1. Since discovering this NPR1-SA receptor-ligand pair, we have embarked on a journey to develop novel chemistries capable of deploying SAR in the field. The journey begins with the development of a scalable assay to identify these novel chemistries. One such assay, presented here, is based on differential scanning fluorimetry technology and demonstrates that NPR1 is destabilized by binding to SA.

4-Hydroxyphenylpyruvate Dioxygenase Inhibitors: From Chemical Biology to Agrochemicals

The development of new herbicides is receiving considerable attention to control weed biotypes resistant to current herbicides. Consequently, new enzymes are always desired as targets for herbicide discovery. 4-Hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27) is an enzyme engaged in photosynthetic activity and catalyzes the transformation of 4-hydroxyphenylpyruvic acid (HPPA) into homogentisic acid (HGA). HPPD inhibitors constitute a promising area of discovery and development of innovative herbicides with some advantages, including excellent crop selectivity, low application rates, and broad-spectrum weed control. HPPD inhibitors have been investigated for agrochemical interests, and some of them have already been commercialized as herbicides. In this review, we mainly focus on the chemical biology of HPPD, discovery of new potential inhibitors, and strategies for engineering transgenic crops resistant to current HPPD-inhibiting herbicides. The conclusion raises some relevant gaps for future research directions.

Field Residues and Effects of the Insect Growth Regulator Novaluron and Its Major Co-Formulant N-Methyl-2-Pyrrolidone on Honey Bee Reproduction and Development

Owing to the recent declines in honey bee (Apis mellifera L.) populations, there is a need for field and laboratory studies to investigate threats to pollinator health. This study examines the hypothesis that the organophosphate alternative, Rimon 0.83EC, can have consequences to honey bee health by combining newly acquired field residue data, laboratory bioassays, and colony level feeding studies. Following label rate applications of Rimon 0.83EC to apple trees, average residue concentrations of the active ingredient, novaluron, were found to be 3.38 ppm in tree-collected pollen. Residues of the major co-formulant in Rimon 0.83EC, N-methyl-2-pyrrolidone (NMP), were below the limit of detection in the field, but a growth chamber study described here found that NMP can persist in pollen for up to 7 d with average concentrations of 69.3 ppm. Concurrent larval rearing studies found novaluron and NMP to be toxic to developing honey bees at doses as low as 100 ppb and 100 ppm, respectively. Nucleus colony feeding studies found that chronic exposure to Rimon 0.83EC at doses as low as 200 ppm (18.6 ppm novaluron) can result in interruptions to brood production that can last for up to 2 wk after exposure. Taken together, these data indicate the use of Rimon 0.83EC on blooming flowers is a significant threat to honey bee reproduction, and suggest the need for more strict and clear usage guidelines.

Discovery of Topsentin Alkaloids and Their Derivatives as Novel Antiviral and Anti-phytopathogenic Fungus Agents

Topsentin alkaloids and their derivatives were designed, synthesized, and characterized on the basis of NMR and mass spectroscopy. The antiviral activities against tobacco mosaic virus (TMV) and anti-phytopathogenic fungus activities of these alkaloids were evaluated for the first time. Alkaloids 1c, 1e, 2b, and 2d displayed significantly higher antiviral activities against TMV than Ribavirin, emerging as new lead compounds for anti-TMV research. Further fungicidal activity tests against 14 kinds of phytopathogenic fungi revealed that these alkaloids displayed broad-spectrum fungicidal activities. Topsentin derivative 2d with 4-5 mg/kg EC₅₀ values against Sclerotinia sclerotiorum (Lib.), Rhizoctonia solani (Kuhn), and Botrytis cinerea (Pers.) emerged as a new lead compound for fungicidal research. Current studies provide support for the application of topsentin alkaloids as novel agrochemicals.

Investigating the impacts of field-realistic exposure to a neonicotinoid pesticide on bumblebee foraging, homing ability and colony growth

The ability to forage and return home is essential to the success of bees as both foragers and pollinators. Pesticide exposure may cause behavioural changes that interfere with these processes, with consequences for colony persistence and delivery of pollination services.We investigated the impact of chronic exposure (5-43 days) to field-realistic levels of a neonicotinoid insecticide (2·4 ppb thiamethoxam) on foraging ability, homing success and colony size using radio frequency identification (RFID) technology in free-flying bumblebee colonies.Individual foragers from pesticide-exposed colonies carried out longer foraging bouts than untreated controls (68 vs. 55 min). Pesticide-exposed bees also brought back pollen less frequently than controls indicating reduced foraging performance.A higher proportion of bees from pesticide-exposed colonies returned when released 1 km from their nests; this is potentially related to increased orientation experience during longer foraging bouts. We measured no impact of pesticide exposure on homing ability for bees released from 2 km, or when data were analysed overall.Despite a trend for control colonies to produce more new workers earlier, we found no overall impacts of pesticide exposure on whole colony size. Synthesis and applications. This study shows that field-realistic neonicotinoid exposure can have impacts on both foraging ability and homing success of bumblebees, with implications for the success of bumblebee colonies in agricultural landscapes and their ability to deliver crucial pollination services. Pesticide risk assessments should include bee species other than honeybees and assess a range of behaviours to elucidate the impact of sublethal effects. This has relevance for reviews of neonicotinoid risk assessment and usage policy world-wide.

Rainfastness of Poly(vinyl alcohol) Deposits on Vicia faba Leaf Surfaces: From Laboratory-Scale Washing to Simulated Rain

Rainfastness is the ability of agrochemical deposits to resist wash-off by rain and other related environmental phenomena. This work reports laboratory-scale and raintower studies of the rainfastness of fluorescently labeled poly(vinyl alcohol) (PVA) using fluorescent microscopy combined with image analysis. Samples of hydrolyzed PVA exhibit improved rainfastness over a threshold molecular weight, which correlates with PVA film dissolution, swelling, and crystalline properties. It was also established that the rainfastness of PVA scaled with the molecular weight over this threshold. These PVA samples were further characterized in order to determine the effect of the crystallinity on rainfastness. The quantification of rainfastness is of great interest to the field of agrochemical formulation development in order to improve the efficacy of pesticides and their adjuvants.

Citizen cartography, strategies of resistance to established knowledge and collective forms of knowledge building

Cultivation of genetically modified soybeans with the use of herbicides is now becoming widespread in Argentina. This work addresses an emblematic case of knowledge articulation between experts, professionals and communities, namely, the case of an association of people affected by fumigation Grupos de Pueblos Fumigados (GPF). The GPF warns against agrochemical spraying in urban areas, and its activists collect and disseminate information about its impact with a view to banning the practice. Here, we apply Parthasarathy's framework, used to analyse the strategies employed by activists to break the expertise barrier, to the case of the GPF, adding a new category to her original four strategies. There is an institutionalizing potential in these social and environmental movements, many of which are organized in the form of Civic Assemblies. The composition of the assemblies reflects a heterogeneous and multi-sectorial character; they articulate a new kind of knowledge that can be an appropriate interlocutor for traditional expert knowledge.

Nanopesticides and Nanofertilizers: Emerging Contaminants or Opportunities for Risk Mitigation?

Research into nanotechnology applications for use in agriculture has become increasingly popular over the past decade, with a particular interest in developing novel nanoagrochemicals in the form of so-called “nanopesticides” and “nanofertilizers.” In view of the extensive body of scientific literature available on the topic, many authors have foreseen a revolution in current agricultural practices. This perspective integrates scientific, regulatory, public and commercial viewpoints, and aims at critically evaluating progress made over the last decade. A number of key (and sometimes controversial) questions are addressed with the aim of identifying the products that will soon emerge on the market and analyzing how they can fit into current regulatory and commercial frameworks. Issues related to the differences in definitions and perceptions within different sectors are discussed, as well as our current ability to assess new risks and benefits relative to conventional products. Many nanoagrochemicals resemble products used currently, which raises the question whether the effect of formulation has been sufficiently taken into account when evaluating agrochemicals. This analysis identifies directions for future research and regulatory needs in order to encourage intelligent design and promote the development of more sustainable agrochemicals.

Unnatural agrochemical ligands for engineered abscisic acid receptors

Existing agrochemicals can be endowed with new applications through protein engineering of plant receptors. A recent study shows an engineered PYR1 ABA receptor can be activated by mandipropamid. Plants engineered with such PYR1 variant are responsive to this agrochemical, which confers protection against drought through activation of ABA signaling.

Metabolism of agrochemicals and related environmental chemicals based on cytochrome P450s in mammals and plants

A yeast gene expression system originally established for mammalian cytochrome P450 monooxygenase cDNAs was applied to functional analysis of a number of mammalian and plant P450 species, including 11 human P450 species (CYP1A1, CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1 and CYP3A4). The human P450 species CYP1A1, CYP1A2, CYP2B6, CYP2C18 and CYP2C19 were identified as P450 species metabolising various agrochemicals and environmental chemicals. CYP2C9 and CYP2E1 specifically metabolised sulfonylurea herbicides and halogenated hydrocarbons respectively. Plant P450 species metabolising phenylurea and sulfonylurea herbicides were also identified mainly as the CYP71 family, although CYP76B1, CYP81B1 and CYP81B2 metabolised phenylurea herbicides. The transgenic plants expressing these mammalian and plant P450 species were applied to herbicide tolerance as well as phytoremediation of agrochemical and environmental chemical residues. The combined use of CYP1A1, CYP2B6 and CYP2C19 belonging to two families and three subfamilies covered a wide variety of herbicide tolerance and phytoremediation of these residues. The use of 2,4-D-and bromoxynil-induced CYP71AH11 in tobacco seemed to enhance herbicide tolerance and selectivity.

Biophysical Characterization of α-Synuclein and Rotenone Interaction

Previous studies revealed that pesticides interact with α-synuclein and accelerate the rate of fibrillation. These results are consistent with the prevailing hypothesis that the direct interaction of α-synuclein with pesticides is one of many suspected factors leading to α-synuclein fibrillation and ultimately to Parkinson's disease. In this study, the biophysical properties and fibrillation kinetics of α-synuclein in the presence of rotenone were investigated and, more specifically, the effects of rotenone on the early-stage misfolded forms of α-synuclein were considered. The thioflavine T (ThT) fluorescence assay studies provide evidence that early-phase misfolded α-synuclein forms are affected by rotenone and that the fibrillation process is accelerated. Further characterization by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) shows that rotenone increases the amount of ordered secondary structure in this intrinsically disordered protein. Morphological characterization by transmission electron microscopy (TEM) and atomic force microscopy (AFM) provide visualization of the differences in the aggregated α-synuclein species developing during the early kinetics of the fibrillation process in the absence and presence of rotenone. We believe that these data provide useful information for a better understanding of the molecular basis of rotenone-induced misfolding and aggregation of α-synuclein.

Selective inhibition of plant serine hydrolases by agrochemicals revealed by competitive ABPP

Organophosphate and -phosphonates and their thio derivatives are often used in agroindustry as herbicides and insecticides, but their potential off-targets in the plant are poorly investigated. Here, we use competitive activity-based protein profiling (ABPP) of serine hydrolases (SHs) to detect targets of these agrochemicals and other compounds in Arabidopsis thaliana. Using broad-range and specific probes, and by overexpression of various SHs in planta, we are able to confirm eight SH-compound interactions, including selective inhibition of carboxylesterase CXE12, prolyloligopeptidase, methylesterase MES2 and tripeptidyl peptidase TPP2. These observations can be used for the design of novel probes and selective inhibitors and may help to assess physiological effects of agrochemicals on crop plants.