Detections of the neonicotinoid insecticide imidacloprid in surface waters of three agricultural regions of California, USA, 2010-2011

Sensitivity Variations in Developmental Toxicity of Imidacloprid to Zebrafish Embryos at Different Neurodevelopmental Stages

Neonicotinoids are ubiquitous in global surface waters and pose a significant risk to aquatic organisms. However, information is lacking on the variations in sensitivity of organisms at different developmental stages to the neurotoxic neonicotinoids. We established a spectrum of toxicity to zebrafish embryos at four neurodevelopmental stages (1, 3, 6, and 8 h post fertilization [hpf]) and dechorionated embryos at 6 hpf based on external and internal exposure to imidacloprid as a representative neonicotinoid. Embryos at the gastrula stage (6 and 8 hpf) were more sensitive to imidacloprid than embryos at earlier developmental stages. Dechorionated embryos were more sensitive to imidacloprid than embryos with a chorion, suggesting that the chorion offers protection against pollutants. Nine sublethal effects were induced by imidacloprid exposure, among which uninflated swim bladder (USB) was the most sensitive. Water depth and air availability in the exposure chambers were critical factors influencing the occurrence of USB in zebrafish larvae. Internal residues of metabolites accounted for <10% of imidacloprid, indicating that imidacloprid was metabolized in a limited fashion in the embryos. In addition, acute toxicity of the main metabolite 5-hydroxy-imidacloprid was significantly lower than that of imidacloprid, indicating that the observed toxicity in embryos exposed to imidacloprid was mainly induced by the parent compound. Our research offers a fresh perspective on choosing the initial exposure time in zebrafish embryo toxicity tests, particularly for neurotoxicants. Environ Toxicol Chem 2024;00:1-11. © 2024 SETAC.

Aptamer-based biosensors for the detection of neonicotinoid insecticides in environmental samples: A systematic review

Neonicotinoids, sometimes abbreviated as neonics, represent a class of neuro-active insecticides with chemical similarities to nicotine. Neonicotinoids are the most widely adopted group of insecticides globally since their discovery in the late 1980s. Their physiochemical properties surpass those of previously established insecticides, contributing to their popularity in various sectors such as agriculture and wood treatment. The environmental impact of neonicotinoids, often overlooked, underscores the urgency to develop tools for their detection and understanding of their behavior. Conventional methods for pesticide detection have limitations. Chromatographic techniques are sensitive but expensive, generate waste, and require complex sample preparation. Bioassays lack specificity and accuracy, making them suitable as preliminary tests in conjunction with instrumental methods. Aptamer-based biosensor is recognized as an advantageous tool for neonicotinoids detection due to its rapid response, user-friendly nature, cost-effectiveness, and suitability for on-site detection. This comprehensive review represents the inaugural in-depth analysis of advancements in aptamer-based biosensors targeting neonicotinoids such as imidacloprid, thiamethoxam, clothianidin, acetamiprid, thiacloprid, nitenpyram, and dinotefuran. Additionally, the review offers valuable insights into the critical challenges requiring prompt attention for the successful transition from research to practical field applications.

Towards solving the reproducibility crisis in surface-enhanced Raman spectroscopy-based pesticide detection

Growing concerns about pesticide residues in agriculture are pushing the scientific community to develop innovative and efficient methods for detecting these substances at low concentrations down to the molecular level. In this context, surface-enhanced Raman spectroscopy (SERS) is a powerful analytical method that has so far already undergone some validation for its effectiveness in pesticide detection. However, despite its great potential, SERS faces significant difficulties obtaining reproducible and accurate pesticide spectra, particularly for some of the most widely used pesticides, such as malathion, chlorpyrifos, and imidacloprid. Those inconsistencies can be attributed to several factors, such as interactions between pesticides and SERS substrates and the variety of substrates and solvents used. In addition, differences in the equipment used to obtain SERS spectra and the lack of standards for control experiments further complicate the reproducibility and reliability of SERS data. This review systematically discusses the problems mentioned above, including a comprehensive analysis of the challenges in precisely evaluating SERS spectra for pesticide detection. We not only point out the existing limitations of the method, which can be traced in previous review works, but also offer practical recommendations to improve the quality and comparability of SERS spectra, thereby expanding the potential applications of the method in such an essential field as pesticide detection.

Transitioning to Microplastic-Free Seed Coatings: Challenges and Solutions

This review addresses the issue of replacing manufactured microplastics in seed coatings used in agriculture. Firstly, it focuses on the policy and regulatory actions taken on microplastics at a global level. There is no consensus within the scientific community on the definition of a microplastic and, more generally, on the classification of plastic debris. Nevertheless, several decision schemes have been proposed in an attempt to define the notion of microplastics. The different criteria relevant to this definition, such as the size, physical state, chemical structure, origin, and persistence of microplastics, are discussed, with a comparison being made between the REACH regulation and the scientific literature. Seed production and processing are also discussed, with the functions of seed coatings being explained in order to gain a better understanding of the properties to be considered in a substitution strategy for currently used microplastics. The main challenges are multiple; substitutes must provide the same performance as microplastics: (i) improving the adherence of the treatment to the seed, (ii) distributing the treatment more evenly over the seed, (iii) reducing the amount of dust-off when handling treated seed, and (iv) improving the seed flowability, which is particularly important during the sowing stage, all while preserving the physiological properties of the seed. Substitute polymers are proposed according to the desired performance and functional properties: two main chemical families of biopolymers were identified in the literature: polysaccharides and proteins. Among them, 13 and 6 polymers, respectively, complied with REACH regulation, demonstrating adhesion, dust reduction performances, and preservation of seed physiological quality in particular. This work aims to guide future studies on microplastic substitution in seed coatings, and to highlight research needs in this area. It is based on an analysis and discussion of the literature, identifying and listing potential substitutes.

Imidacloprid-induced lung injury in mice: Activation of the PI3K/AKT/NF-κB signaling pathway via TLR4 receptor engagement

Significant impairment of pulmonary function has been demonstrated through long-term exposure to neonicotinoid insecticides, such as imidacloprid (IMI). However, the underlying mechanisms of lung injury induced by IMI remain unclear. In this study, a mouse model of IMI-induced pulmonary injury was established, and the toxicity and lung damage were assessed through mouse body weight, organ index, hematological parameters, and histopathological analysis of lung tissues. Furthermore, metabolomics and transcriptomics techniques were employed to explore the mechanistic aspects. Results from the toxicity assessments indicated that mouse body weight was significantly reduced by IMI, organ index was disturbed, and hematological parameters were disrupted, resulting in pulmonary injury. The mechanistic experimental results indicate that the differences in metabolites and gene expression in mouse lungs could be altered by IMI. Validation of the results through combined analysis of metabolomics and transcriptomics revealed that the mechanism by which IMI induces lung injury in mice might be associated with the activation of the TLR4 receptor, thereby activating the PI3K/AKT/NF-κB signaling pathway to induce inflammation in mouse lungs. This study provided valuable insights into the mechanisms underlying IMI-induced pulmonary damage, potentially contributing to the development of safer pest control strategies. The knowledge gained served as a robust scientific foundation for the prevention and treatment of IMI-related pulmonary injuries.

Application of novel magnetic lignin hydrogels: Activated persulfate degrades pesticide contaminants

Lignin hydrogels have garnered significant attention due to their distinctive three-dimensional structures and potent swelling ability. In this work, a novel magnetic nanocomposite lignin hydrogel (MNLH) was fabricated through organic synthesis and solution immersion reduction. The obtained MNLH was used to activate persulfate(PDS) for pesticide degradation. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the structure and morphology of MNLH. The influence of factors such as the lignin hydrogel to nano-zero-valent iron (nZVI) and copper oxide (CuO) mass ratio, MNLH dosage, initial pH on the MNLH/PDS/imidacloprid (IMI) system. Remarkably, the MNLH/PDS/IMI system has a removal rate of up to 100%. Quenching and electron paramagnetic resonance (EPR) studies disclosed that the MNLH/PDS system degraded IMI through a combination of free radical and non-free radical pathways, with the latter being dominant. More importantly, in this study, the toxicity and hydrolysis sites of IMI were analyzed using ECOSAR and Gaussian09, respectively, confirming the feasibility of activating persulfate with MNLH. These findings underscore the potential of MNLH as a function material suitable for facilitating the persulfate-activated degradation of organic pollutants.

Spatiotemporal variation, fluxes and risk evaluation of neonicotinoid insecticides within the midsection of Yangtze River, China: An exploration as ecological protection threshold

Neonicotinoid insecticides (NNIs) have attracted global concern due to its extensive use in agricultural activities and their potential risks to the animal and human health, however, there is limited knowledge on the regional traits and ecological risks of NNIs in the aquatic environments. We herein investigated the occurrence of NNIs within the midsection of Yangtze River in China, offering the inaugural comprehensive report on NNIs within this region. In this study, eleven NNIs were analyzed in 108 river water and sediment samples from three seasons (normal, dry and wet season). We detected a minimum of seven NNIs in the water and four NNIs in the sediment, with total concentrations ranging from 12.33 to 100.5 ng/L in water and 0.08-5.68 ng/g in sediment. The levels of NNIs in both river water and sediment were primarily influenced by the extent of agricultural activities. The estimated annual load of NNIs within the midsection of Yangtze River totaled 40.27 tons, April was a critical contamination period. Relative potency factor (RPF) analysis of the human exposure risk revealed that infants faced the greatest exposure risk, with an estimated daily intake of 11.27 ng kg-1∙bw∙d-1. We established the acute and chronic thresholds for aquatic organisms by employing the Species Sensitive Distribution (SSD) method (acute: 384.1 ng/L; chronic: 168.9 ng/L). Based on the findings from this study, 33% of the river water samples exceeded the chronic ecological risks thresholds, indicating the urgent need for intervention programs to guarantee the safety of the river for aquatic life in the Yangtze River Basin.

Integration of transcriptome, gut microbiota, and physiology reveals toxic responses of the red claw crayfish (Cherax quadricarinatus) to imidacloprid

Imidacloprid enters the water environment through rainfall and causes harm to aquatic crustaceans. However, the potential chronic toxicity mechanism of imidacloprid in crayfish has not been comprehensively studied. In this study, red claw crayfish (Cherax quadricarinatus) were exposed to 11.76, 35.27, or 88.17 μg/L imidacloprid for 30 days, and changes in the physiology and biochemistry, gut microbiota, and transcriptome of C. quadricarinatus and the interaction between imidacloprid, gut microbiota, and genes were studied. Imidacloprid induced oxidative stress and decreased growth performance in crayfish. Imidacloprid exposure caused hepatopancreas damage and decreased serum immune enzyme activity. Hepatopancreatic and plasma acetylcholine decreased significantly in the 88.17 μg/L group. Imidacloprid reduced the diversity of the intestinal flora, increased the abundance of harmful flora, and disrupted the microbiota function. Transcriptomic analysis showed that the number of up-and-down-regulated differentially expressed genes (DEGs) increased significantly with increasing concentrations of imidacloprid. DEG enrichment analyses indicated that imidacloprid inhibits neurotransmitter transduction and immune responses and disrupts energy metabolic processes. Crayfish could alleviate imidacloprid stress by regulating antioxidant and detoxification-related genes. A high correlation was revealed between GST, HSPA1s, and HSP90 and the composition of gut microorganisms in crayfish under imidacloprid stress. This study highlights the negative effects and provides detailed sequencing data from transcriptome and gut microbiota to enhance our understanding of the molecular toxicity of imidacloprid in crustaceans.

Identification of key factors affecting neonicotinoid residues in crops and risk of dietary exposure

Neonicotinoids, widely used on farmland, are ubiquitous in food; however, their distribution among various crops and associated exposure risks at the provincial level in China remain unclear. We collected 19 types of crop samples (fruits, vegetables, and tea) from farmland in nine prefectural cities in Zhejiang Province, China. We analyzed nine commonly used neonicotinoids in the edible portions of these crops. A notable detection rate (42.1 %-82.9 %) and high residual neonicotinoid concentrations (278 ± 357 ng/g) were observed. Tea exhibited the highest residue, followed by fruits, and vegetables showed the lowest (P < 0.05). Neonicotinoid ratios in crops to soil (R_C/S) and soil to water (R_S/W) were defined to discern insecticide distribution across different environments. Increased water solubility leads to increased migration of neonicotinoids (R_S/W) from agricultural soils to water through runoff, thereby increasing the relative contribution of nitenpyram and dinotefuran in water. In comparison with other studied compounds, all crops demonstrated the strongest soil uptake of thiamethoxam, denoted by the highest R_C/S value. Elevated R_C/S values in tea, pickled cabbage, and celery suggest increased susceptibility of these crops to neonicotinoid absorption from the soil (P < 0.05). Estimated dietary intake for teenagers, adults and elders was 8.9 ± 0.5, 8.9 ± 0.6, and 8.8 ± 0.3 μg/kg/d, respectively, below the reference dose (57 μg/kg/d). Teenagers, compared to adults and elders, exhibited significantly higher neonicotinoid exposure through fruit consumption, emphasizing the need for increased attention to neonicotinoid exposure among vulnerable populations.

Removal of neonicotinoid insecticides in a large-scale constructed wetland system

Neonicotinoid insecticides are among the most used insecticides and their residues are frequently found in surface water due to their persistence and mobility. Neonicotinoid insecticides exhibit toxicity to a wide range of aquatic invertebrates at environmentally relevant levels, and therefore their contamination in surface water is of significant concern. In this study, we investigated the spatiotemporal distribution of six neonicotinoids in a large wetland system, the Prado Wetlands, in Southern California, and further evaluated the wetlands' efficiency at removing these insecticides. Total neonicotinoid concentrations in water ranged from 3.17 to 46.9 ng L-1 at different locations within the wetlands, with imidacloprid and dinotefuran among the most detected. Removal was calculated based on concentrations as well as mass flux. The concentration-based removal values for a shallow pond (vegetation-free), moderately vegetated cells, densely vegetated cells, and the entire wetland train were 16.9%, 34.2%, 90.2%, and 61.3%, respectively. Principal component analysis revealed that pH and temperature were the primary factors affecting neonicotinoids removal. Results from this study demonstrated the ubiquitous presence of neonicotinoids in surface water impacted by urban runoff and wastewater effluent and highlighted the efficiency of wetlands in removing these trace contaminants due to concerted effects of uptake by wetland plants, photolysis, and microbial degradation.

Photolysis of dinotefuran in aqueous solution: Kinetics, influencing factors and photodegradation mechanism

The environmental behaviour of neonicotinoid insecticides (NNIs) is of momentous concern due to their frequent detection in aquatic environment and their biotoxicity for non-target organisms. Phototransformation is one of the most significant transformation processes, which is directly related to NNIs exposure and environmental risks. In this study, the photodegradation of dinotefuran (DIN, 1-Methyl-2-nitro-3-(tetrahydro-3-furanylmethyl)-guanidine), one of the most promising NNIs, was conducted under irritated light in the presence of Cl-, DOM along with the effect of pH and initial concentration. The findings demonstrated that in ultra-pure (UP) water, the photolysis rate constants (k) of DIN rose with increasing initial concentration. Whereas, in tap water, at varied pH levels, and in the presence of Cl-, the outcomes were reversed. At the same time, lower concentration of DOM promoted DIN photolysis processes due to the production of reactive oxygen species, while higher concentrations of DOM inhibited the photolysis by the predominance of light shielding effects. The singlet oxygen (1O2) was produced in the photolysis processes of DIN with Cl- and DOM, which was confirmed by electron spin resonance (EPR) analysis. Four main photolysis products and three intermediates were identified by UPLC-Q-Exactive Orbitrap MS analysis. The possible photodegradation pathways of DIN were proposed including the oxidation by 1O2, reduction and hydrolysis after the removal of nitro group from parent compounds. This study expanding our understanding of transformation behavior and fate of NNIs in the aquatic environment, which is essential for estimating their environmental risks.

Neonicotinoids Persisting in the Sea Pose a Potential Chronic Risk to Marine Organisms: A Case from Xiangshan Bay, China (2015-2019)

Neonicotinoid insecticides (neonics) are extensively employed in agriculture and pervade various environmental matrices. However, few studies have documented the occurrence and potential chronic ecological risks of these chemicals in the marine environment. We collected 720 seawater samples from Xiangshan Bay during 2015-2019 and the integrated concentrations of seven neonics were determined using the relative potency factor method. Trend analyses using the Mann-Kendall test in time series, along with the estimation of the flux of neonics into the sea, were conducted. At last, the ecological risk of neonics was evaluated by water quality criteria derivation based on species sensitivity distribution. Our findings revealed that 47.6% of samples contained at least one neonic, with the integrated concentration of neonics ranging from 63.30 to 1684.14 ng/L. Imidacloprid and dinotefuran exhibited the highest frequency of detection in the analysis. The significance level of the Mann-Kendall test ranged from 2.16 × 10-10 to 1.21 × 10-5 (S > 0), indicating all neonics behaved with sharply increasing trends. Approximately 8.47 × 10-2 tons of neonics were discharged into Xiangshan Bay. Notably, the integrated concentrations of neonics represented a potential chronic ecological risk to marine organisms. This study provided novel insights into the spatial distribution, source, and migration of neonic species and their impacts on marine ecosystems.

Effects of chronic exposure to sublethal doses of neonicotinoids in the social wasp Polybia paulista: Survival, mobility, and histopathology

Several studies have investigated the consequences of exposure to neonicotinoids in honeybees. Given the lack of studies concerning the consequences of exposure of social wasps to neonicotinoids, as well as the ecological importance of these insects, the objective of this study was to test the hypothesis that chronic exposure to sublethal concentrations of thiamethoxam decreases survival and mobility by causing damage to the brain and midgut of the social wasp Polybia paulista. The wasps were exposed to different concentrations of thiamethoxam, in order to obtain the mean lethal concentration (LC50), which was used as a reference for calculation of two sublethal concentrations (LC50/100 and LC50/10) employed in subsequent experiments. To calculate survival, groups of exposed (EW) and unexposed (UW) wasps were monitored until death, allowing calculation of the average lethal time. The EW and UW groups were evaluated after 12, 24, 48, and 72 h of exposure, considering their mobility and histopathological parameters of the midgut and brain. A lesion index based on semiquantitative analyses was used for comparison of histopathological damage. The results demonstrated that exposure to the LC50/10 led to a significantly shorter survival time of the P. paulista workers, compared to unexposed wasps. In addition, both sublethal concentrations decreased mobility and caused damage to the intestine (loss of brush border, presence of spherocrystals, loss of cytoplasmic material, and pyknosis) and the brain (loss of cell contact and pyknosis), regardless of the exposure time. The findings showed that, like bees, social wasps are nontarget insects susceptible to the detrimental consequences of neonicotinoid use, with exposure leading to impaired survival, locomotion, and physiology.

Chronic Exposure to Environmentally Relevant Concentrations of Imidacloprid Impact Survival and Ecologically Relevant Behaviors of Fathead Minnow Larvae

Imidacloprid (IM) has emerged as a contaminant of concern in several areas within the United States due to its frequent detection in aquatic ecosystems and its pseudo-persistence, which pose potential risks to nontarget species. We evaluated the sublethal toxicity of IM to fathead minnow larvae following chronic exposure beginning just after fertilization. Our in silico analysis and in vivo bioassays suggest that IM has a low binding affinity for the vertebrate nicotinate acetylcholine receptor (nAChR), as expected. However, chronic exposure to ≥0.16 µg IM/L reduced survival by 10%, and exposure to ≥18 µg IM/L reduced survival by approximately 20%-40%. Surviving fish exposed to ≥0.16 µg IM/L showed reduced growth, altered embryonic motor activity, and premature hatching. Furthermore, a significant proportion of fish exposed to ≥0.16 µg IM/L were slower to respond to vibrational stimuli and slower to swim away, indicating that chronic exposure to IM has the potential to impair the ability of larvae to escape predation. The adverse health effects we observed indicate that chronic exposure to environmentally relevant concentrations of IM may elicit sublethal responses that culminate in a significant increase in mortality during early life stages, ultimately translating to reduced recruitment in wild fish populations. Environ Toxicol Chem 2023;42:2184-2192. © 2023 SETAC.

Biochar Derived from Pineapple Leaf Non-Fibrous Materials and Its Adsorption Capability for Pesticides

Non-fibrous materials (NFMs) are typically discarded during pineapple leaf fiber processing. The underutilized NFM waste was proposed for use in this work as a raw material for the production of biochar . The removal of pesticides (acetamiprid, imidacloprid, or methomyl) from water was then investigated using the NFM derived biochar (NFMBC). The pseudo-second-order kinetic data suggested chemisorption of pesticide on NFMBC. While acetamiprid or imidacloprid adsorption on NFMBC occurred primarily via multi-layered adsorption (best fitted with the Freundlich isotherms), the Sips adsorption isotherms matched with the experimental data, implying heterogeneous adsorption of methomyl on the biochar surface. The adsorption capacities for acetamiprid, methomyl, and imidacloprid are 82.18, 36.16, and 28.98 mg g^-1, respectively, which are in agreement with the order of the polarity (low to high) of pesticides. Adsorption capacities indicated that the NFMBC preferably removed low-polarity pesticides from water sources. Since pineapple leaves provide fibers and NFMs for materials development, this study should promote an extended agro-waste utilization approach and full-cycle resource management in pineapple fields.

Absorption and Distribution of Imidacloprid and Its Metabolites in Goldfish (Carassius auratus Linnaeus)

Imidacloprid (IMI) is the first-generation neonicotinoid insecticide. But, the long-term use of IMI as a pesticide has caused severe water pollution. Recently, the toxicity of IMI to aquatic organisms has received increasing attention. This study aimed to investigate the absorption and distribution of IMI in various tissues (gills, intestine, liver, muscle, brain and gonads) of goldfish through short-term and continuous exposure tests over 28 days. The results of short-term exposure indicated that the concentration of IMI and its metabolites in tissues at the transfer stage decreased steadily after 1 day of 40 mg/L IMI water treatment and was below the detection limit after 3 days. Continuous exposure for 28 days at various treatment concentrations showed that the concentrations of IMI and its metabolites differed significantly among the different tissues of the goldfish. In the 20 mg/L treatment group (S1), the highest concentration of IMI was found in the liver (12.04 μg/g_tissue), followed by the intestine (9.91 μg/g_tissue), muscle (6.20 μg/g_tissue), gill (6.11 μg/g_tissue), gonads (5.22 μg/g_tissue) and brain (2.87 μg/g_tissue). In the 40 mg/L treatment group (S2), the order of the tissue concentrations was similar to that of the S1 group, with the highest concentration observed in the liver (12.04 μg/g_tissue), followed by the intestine (9.91 μg/g_tissue), muscle (6.20 μg/g_tissue), gill (6.11 μg/g_tissue), gonads (5.22 μg/g_tissue) and brain (2.87 μg/g_tissue). Furthermore, the study detected 5-hydroxy-IMI, IMI urea and 6-chloronicotinic acid in IMI metabolites in all tissues, while IMI was detected only in the intestine and liver. Overall, the results of this study contribute to a better understanding of the metabolic behavior of IMI in organisms and provide new data to support the assessment of IMI toxicity in fish.

Study effect and mechanism of levofloxacin on the neurotoxicity of Rana nigromaculata tadpoles exposed to imidacloprid based on the microbe-gut-brain axis

Aquatic organisms may be simultaneously exposed to antibiotics and pesticides. After levofloxacin (LVFX), imidacloprid (IMI) exposure and co-exposure at environmental levels, we found LVFX and IMI had antagonistic effect on the neurotoxicity of tadpoles. IMI-induced neurotoxicity on tadpoles can be explained by oxidative stress and hormone levels in some degree. By regulating ornithine, l-asparagine, putrescine and tryptamine in the intestine, LVFX affected glutathione metabolism, arginine and proline metabolism, alanine, aspartate and glutamate metabolism, tyrosine metabolism and aminoacyl tRNA biosynthesis, so then eased the neurotoxicity caused by IMI. More interestingly, Fusobacteriota and Cetobacterium might play an important role on easing the neurotoxicity caused by IMI. In addition, LVFX might have a laxation effect on the increased relative abundance of Bacteroidota caused by IMI. In conclusion, IMI not only affected oxidative stress and hormone levels in the brain, but also affected the synthesis of neurotransmitters in the intestine by regulating intestinal microbiota. In LVFX and IMI co-exposed groups, LVFX alleviated the neurotoxicity caused by IMI through regulating the intestinal microbiota, showing as an antagonistic effect. Our results provided a new perspective for aquatic ecological risk assessment under co-exposure of antibiotics and pesticides.

Selective detection of nitenpyram by silica-supported carbon quantum dots

In this study, a fluorescent sensor of nitrogen-doped carbon quantum dots (N-CQDs) and silica gel hybrid was developed for the quantitative detection of nitenpyram, a toxic neonicotinoid existing in groundwater and/or surface water.The prepared N-CQDs@SiO₂ sensor exhibited remarkable sensing selectivity and sensitivity towards nitenpyram among the four pesticides and six metal ions. A prominent fluorescence quenching of N-CQDs@SiO₂ at 445 nm was observed in the presence of nitenpyram with a linear response range of 0-300.0 mg L^-1 and an estimated limit of detection of 1.53 mg L^-1. The main cause for selective sensing is that nitenpyram absorbs the excitation light of N-CQDs@SiO₂, leading to fluorescence quenching of the sensor through the inner filter effect.

Insights into the ubiquity, persistence and microbial intervention of imidacloprid

Imidacloprid, a neonicotinoid pesticide, is employed to increase crop productivity. Meanwhile, its indiscriminate application severely affects the non-target organisms and the environment. As an eco-friendly and economically workable option, the microbial intervention has garnered much attention. This review concisely outlines the toxicity, long-term environmental repercussions, degradation kinetics, biochemical pathways, and interplay of genes implicated in imidacloprid remediation. The studies have highlighted imidacloprid residue persistence in the environment for up to 3000 days. In view of high persistence, effective intervention is highly required. Bacteria-mediated degradation has been established as a viable approach with Bacillus spp. being among the most efficient at 30 ℃ and pH 7. Further, a comparative metagenomic investigation reveals dominant neonicotinoid degradation genes in agriculture compared to forest soils with distinctive microbial communities. Functional metabolism of carbohydrates, amino acids, fatty acids, and lipids demonstrated a significantly superior relative abundance in forest soil, implying its quality and fertility. The CPM, CYP4C71v2, CYP4C72, and CYP6AY3v2 genes that synthesize cyt p450 monooxygenase enzyme play a leading role in imidacloprid degradation. In the future, a systems biology approach incorporating integrated kinetics should be utilized to come up with innovative strategies for moderating the adverse effects of imidacloprid on the environment.

Neonicotinoids in draining micro-watersheds dominated by rice-vegetable rotations in tropical China: Multimedia occurrence, influencing factors, transport, and associated ecological risks

Multimedia contamination by neonicotinoid (NEO) residues has attracted global attention. However, data regarding the multimedia polluted status under certain typical cropping scenarios and the associated risks are scarce. Here, the multimedia occurrence, spatiotemporal distribution, driving factors, transport, and ecological risks of NEOs from tropical rice-vegetable rotation fields were characterized. The heavy NEOs resided in multiple media, and imidacloprid and acetamiprid were the prevailing NEOs, with concentration contributions of 65-80%. The pollution levels of the NEOs, rather than their compositions, exhibited significant spatiotemporal heterogeneity and were highly correlated with the collective (agricultural practices and climate conditions) and differential (e.g., media properties) factors identified using an auto linear regression model. Furthermore, the multimedia transport of NEOs was largely similar but non-negligibly different during the rainy and dry seasons. A new multimedia ecological risk assessment revealed that 50.6% sites were at high risk, and the risk hotspots occurred in the central areas and the winter planting period. The risks were largely contributed by imidacloprid and thiamethoxam, indicating that there were non-ignorable ecological risks. Our results highlight the differential pollution patterns (distribution, transport, and driving factors) of the prevailing NEOs under tropical agricultural scenarios, and the fact that special attention should be paid to the risks posed by NEOs.

Environmental occurrence, toxicity concerns, and biodegradation of neonicotinoid insecticides

Neonicotinoids (NEOs) are fourth generation pesticides, which emerged after organophosphates, pyrethroids, and carbamates and they are widely used in vegetables, fruits, cotton, rice, and other industrial crops to control insect pests. NEOs are considered ideal substitutes for highly toxic pesticides. Multiple studies have reported NEOs have harmful impacts on non-target biological targets, such as bees, aquatic animals, birds, and mammals. Thus, the remediation of neonicotinoid-sullied environments has gradually become a concern. Microbial degradation is a key natural method for eliminating neonicotinoid insecticides, as biodegradation is an effective, practical, and environmentally friendly strategy for the removal of pesticide residues. To date, several neonicotinoid-degrading strains have been isolated from the environment, including Stenotrophomonas maltophilia, Bacillus thuringiensis, Ensifer meliloti, Pseudomonas stutzeri, Variovorax boronicumulans, and Fusarium sp., and their degradation properties have been investigated. Furthermore, the metabolism and degradation pathways of neonicotinoids have been broadly detailed. Imidacloprid can form 6-chloronicotinic acid via the oxidative cleavage of guanidine residues, and it is then finally converted to non-toxic carbon dioxide. Acetamiprid can also be demethylated to remove cyanoimine (=N-CN) to form a less toxic intermediate metabolite. A few studies have discussed the neonicotinoid toxicity and microbial degradation in contaminated environments. This review is focused on providing an in-depth understanding of neonicotinoid toxicity, microbial degradation, catabolic pathways, and information related to the remediation process of NEOs. Future research directions are also proposed to provide a scientific basis for the risk assessment and removal of these pesticides.

Pesticide Prioritization by Potential Biological Effects in Tributaries of the Laurentian Great Lakes

Watersheds of the Great Lakes Basin (USA/Canada) are highly modified and impacted by human activities including pesticide use. Despite labeling restrictions intended to minimize risks to nontarget organisms, concerns remain that environmental exposures to pesticides may be occurring at levels negatively impacting nontarget organisms. We used a combination of organismal-level toxicity estimates (in vivo aquatic life benchmarks) and data from high-throughput screening (HTS) assays (in vitro benchmarks) to prioritize pesticides and sites of concern in streams at 16 tributaries to the Great Lakes Basin. In vivo or in vitro benchmark values were exceeded at 15 sites, 10 of which had exceedances throughout the year. Pesticides had the greatest potential biological impact at the site with the greatest proportion of agricultural land use in its basin (the Maumee River, Toledo, OH, USA), with 72 parent compounds or transformation products being detected, 47 of which exceeded at least one benchmark value. Our risk-based screening approach identified multiple pesticide parent compounds of concern in tributaries of the Great Lakes; these compounds included: eight herbicides (metolachlor, acetochlor, 2,4-dichlorophenoxyacetic acid, diuron, atrazine, alachlor, triclopyr, and simazine), three fungicides (chlorothalonil, propiconazole, and carbendazim), and four insecticides (diazinon, fipronil, imidacloprid, and clothianidin). We present methods for reducing the volume and complexity of potential biological effects data that result from combining contaminant surveillance with HTS (in vitro) and traditional (in vivo) toxicity estimates. Environ Toxicol Chem 2023;42:367-384. Published 2022. This article is a U.S. Government work and is in the public domain in the USA. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Assessing Effects of Genetically Modified Plant Material on the Aquatic Environment Using higher-tier Studies

Genetically modified organisms are used extensively in agriculture. To assess potential side effects of genetically modified (GM) plant material on aquatic ecosystems, only a very small number of higher-tier studies have been performed. At the same time, these studies are particularly important for comprehensive risk assessment covering complex ecological relationships. Here we evaluate the methods of experimental higher-tier effect studies with GM plant material (or Bt toxin) in comparison to those well-established for pesticides. A major difference is that nominal test concentrations and thus dose-response relationships cannot easily be produced with GM plant material. Another important difference, particularly to non-systemic pesticides, is that aquatic organisms are exposed to GM plant material primarily through their feed. These and further differences in test requirements, compared with pesticides, call for a standardisation for GM-specific higher-tier study designs to assess their potentially complex effects in the aquatic ecosystems comprehensively.

Embryonic toxicity of Imidacloprid: Impact on hatchability, survivability, swimming speed and cardiac function of catfish, Clarias gariepinus

Imidacloprid is a systemic insecticide that belongs to the neonicotinoid class of chemicals that act on the central nervous system of insects. Imidacloprid is used to control sucking insects, chewing insects such as termites, soil insects, and fleas on pets, as well as to treat structures, crops, soil, and seeds. As a result of these factors, this pesticide may end up in the aquatic environment via municipal discharges and runoff. Although the presence of imidacloprid in aquatic environments has been underreported as widespread, the toxic effects of this pesticide may have serious implications on aquatic organisms, particularly at environmentally relevant concentrations and demand more attention. Given this knowledge, the goal of this study was to investigate the effects of imidacloprid on Clarias gariepinus embryonic development. Clarias gariepinus embryos (3 h post-fertilization) were exposed to environmentally relevant concentrations of imidacloprid (10, 30, 100, and 500 µg/L) until 48 h post-fertilization using a modified fish embryo acute toxicity test (OECD TG 236). A stereomicroscope was used to assess hatchability, deformity, heart rate, and swimming speed as endpoints. According to our results of the developmental acute toxicity test, imidacloprid significantly reduced the hatching rate and heartbeats of C. gariepinus embryos. It also influenced the swimming kinematics of exposed embryos and caused teratogenic effects such as yolk sac rupture, pericardial oedema, lordosis, an abnormally shaped head, and altered epiboly. Our results allow us to conclude that imidacloprid is a toxic pesticide in the early life stages of C. gariepinus due to its high teratogenic potential.

Iron-modified biochar derived from sugarcane bagasse for adequate removal of aqueous imidacloprid: sorption mechanism study

Adsorption has been considered as a promising remediation technology to separate organic and inorganic agrochemicals from contaminated soil and water. Low-cost adsorbents, including waste derived materials, clay composites, biochar, and biochar modified materials, have attracted enormous attention for the removal of organic contaminants, including pesticides. In this study, iron-modified base-activated biochar (FeBBC) was prepared by pyrolysis (at 400 °C for 1 h) of iron-doped base (KOH) activated sugarcane bagasse for the removal of a widely used insecticide, namely imidacloprid (IMI) from water. The maximum adsorption capacity of the adsorbent (FeBBC) was calculated as 10.33 (± 1.57) mg/g from Langmuir isotherm model. The adsorbents could remove up to ~ 92% of IMI from aqueous solution at 23.8 mg/L IMI. Experimental data fitted well with the Freundlich model and pseudo-second-order model, demonstrating physisorption, as well as chemosorption, contributed to the sorption process. Even at highly acidic/basic solution pH, the FeBBC could remove substantial amount of IMI demonstrating hydrophobic interaction and pore diffusion play vital role for removal of IMI. The slight improving of IMI sorption with increasing solution pH indicated the sorption was also facilitated through ionic interaction alongside physical sorption. However, physical sorption including hydrophobic interaction and pore-filling interaction plays a vital role in the sorption of IMI.

Comparing imidacloprid, clothianidin, and azoxystrobin runoff from lettuce fields using a soil drench or treated seeds in the Salinas Valley, California

Neonicotinoid insecticide use has increased over the last decade, including as agricultural seed treatments (application of chemical in a coating to the seed prior to planting). In California, multiple crops, including lettuce, can be grown using neonicotinoid treated seeds or receive a direct neonicotinoid soil application (drenching) at planting. Using research plots, this study compared pesticide runoff in four treatments: (1) imidacloprid seed treatment; (2) clothianidin seed treatment; (3) imidacloprid drench and an azoxystrobin seed treatment; and (4) a control with no pesticidal treatment. Neonicotinoid and azoxystrobin concentrations were measured in surface water runoff during six irrigations events in the 2020 growing seasons. Results showed runoff concentrations up to 1308 (±1200) ng L-1 for imidacloprid drench treatment, 431 (±100) ng L-1 for clothianidin seed treatment, 135 (±60) ng L-1 for imidacloprid seed treatment, and 13 (±10) ng L-1 for azoxystrobin seed treatment (treatments averaged). The percent of applied mass in runoff over the entire sampling period varied by compound; the imidacloprid seed treatment and drench were similar (0.015 and 0.019%, respectively) to the clothianidin seed treatment (0.036%) while the azoxystrobin seed treatment was much higher (15%). Although the proportion of imidacloprid in runoff was similar for imidacloprid treatments, the mass applied during soil drench was > 4x the amount applied from the imidacloprid seed treatment. Surface soils were collected before planting and at the end of the trial. The neonicotinoids were detected in soil throughout the study and average maximum concentrations were 9-13 ng g-1; azoxystrobin was detected in only two soils at concentrations up to 0.57 ng g-1. These results elucidate the comparative mass runoff resulting from planting treated seed and soil drench applications and highlight the value of additional work to characterize off-site transport from the many commodities that may be utilizing treated seeds.

Identification of Glucocorticoid Receptor Antagonistic Activities and Responsible Compounds in House Dust: Bioaccessibility Should Not Be Ignored

More and more contaminants in dust have been found to be glucocorticoid receptor (GR) disrupting chemicals. However, little is known about the related potency and responsible toxicants, especially for the main bioaccessible ones in dust. An effect-directed analysis (EDA)-based workflow was developed, including solvent-based exhaustive extraction/tenax-assisted bioaccessible extraction (TBE), high-throughput bioassays, suspect and non-target analysis, as well as in silico candidate selection, for a more realistic identification of responsible contaminants in dust. None of the 39 dust samples from 23 cities in China exhibited GR agonistic activity, while GR antagonistic potencies were detected in 34.8% of samples, being significantly different from the high detection frequency of GR agonistic activities in other environmental media. The GR antagonistic potencies of the dust samples were all reduced after bioaccessible extraction. The mean bioaccessibility of GR antagonistic potency compared with the related exhaustive extracts was 36.8%, and the lowest value was 9%. By using in silico candidate selection, greater than 99% candidate chemical structures which were found by a non-target screening strategy were removed. Di-n-butyl phthalate (DnBP), diisobutyl phthalate (DiBP), and nicotine (NIC) were responsible for the activities of the exhaustive extracts of dust, contributing up to 91% potencies. DiBP and DnBP were also responsible for the bioaccessible activities, contributing up to 79% potencies. However, the contribution from NIC decreased significantly and can be ignored because of its low bioaccessibility. This study suggests that the improved workflow combining extraction, reporter gene bioassays, suspect and non-target analysis, as well as in silico candidate selection is useful for EDA analysis in dust samples. In addition, exhaustive extraction may overestimate the risk of contaminants, while bioaccessibility evaluation based on bioaccessible extraction is essential in both effect evaluation and toxicant identification.

Surface water contamination from pesticide mixtures and risks to aquatic life in a high-input agricultural region of Brazil

The environmental risks of pesticides found in surface waters of an important agricultural basin in Brazil were estimated by adopting two approaches: individual pesticides risk quotients (RQ) and concentration addition model for pesticide mixtures (∑RQs) contained in each water sample. Monitoring was carried out in the Mogi Guaçu River basin, Brazil, from October 2017 to May 2018. Four sampling points were selected in the Mogi Guaçu River and seven in its tributaries A multiresidue method with solid-phase extraction and subsequent analysis by UPLC-ESI-QqQ-MS/MS was developed to quantify 19 pesticides. Herbicides, except for simazine, presented the highest detection frequencies with values above 70%. Tebuthiuron was found in all 55 analyzed samples, presenting the highest concentration (6437 ng L^-1) over the monitoring period. Fungicides and insecticides showed similar detection frequency (DF) values, ranging from 1.8% to 21.8%. Tebuconazole and carbofuran were the fungicides and insecticides most frequently detected, respectively. January 2018 sampling showed the highest total concentration of pesticides, differing from March 2018 and May 2018 (p < 0.05). The MG2 > TMG8 > MG1 > TMG6 sites showed the highest concentration total of pesticides while MG4 > TMG4 > TMG3 (p < 0.05) sites showed the lowest values: MG4 > TMG4 > TMG3 (p < 0.05). Most pesticide occurrences presented no risks to aquatic organisms. Only 19 out of the 175 pesticide occurrences > LOQ presented individual risks to aquatic biota. Contrary to the results obtained by the individual risk assessment, most pesticide mixtures presented risks to aquatic biota. In 36 out of the 55 samples analyzed during monitoring, pesticide mixtures presented risks to aquatic life.

Polystyrene microplastic particles in combination with pesticides and antiviral drugs: Toxicity and genotoxicity in Ceriodaphnia dubia

Freshwater ecosystems are recognized as non-negligible sources of plastic contamination for the marine environment that is the final acceptor of 53 thousand tons of plastic per year. In this context, microplastic particles are well known to directly pose a great threat to freshwater organisms, they also indirectly affect the aquatic ecosystem by adsorbing and acting as a vector for the transport of other pollutants ("Trojan horse effect"). Polystyrene is one of the most widely produced plastics on a global scale, and it is among the most abundant microplastic particles found in freshwaters. Nevertheless, to date few studies have focused on the eco-genotoxic effects on freshwater organisms caused by polystyrene microplastic particles (PS-MPs) in combination with other pollutants such as pharmaceuticals and pesticides. The aim of this study is to investigate chronic and sub-chronic effects of the microplastic polystyrene beads (PS-MP, 1.0 μm) both as individual xenobiotic and in combination (binary/ternary mixtures) with the acicloguanosine antiviral drug acyclovir (AC), and the neonicotinoid broad-spectrum insecticide imidacloprid (IMD) in one of the most sensitive non-target organisms of the freshwater food chain: the cladoceran crustacean Ceriodaphnia dubia. Considering that the individually selected xenobiotics have different modes of action and/or different biological sites, the Bliss independence was used as reference model for this research. Basically, when C. dubia neonates were exposed for 24 h to the mixtures during Comet assay, mostly an antagonistic genotoxic effect was observed. When neonates were exposed to the mixtures for 7 days, mostly an additive chronic toxic effect occurred at concentrations very close or even overlapping to the environmental ones ranging from units to tens of ng/L for PS-MPs, from tenths/hundredths to units of μg/L for AC and from units to hundreds of μg/L for IMD, revealing great environmental concern.

Covalent-anion-driven self-assembled cadmium/ molybdenum sulfide hybrids for efficient nitenpyram degradation

Photocatalytic technology is an attractive and promising approach for nitenpyram degradation; however, how to ensure the carrier separation efficiency and catalytic sites exposure is still great challenges. In this study, we construct CdS@MoS₂ (CM) nanohybrids with a 3D hierarchical configuration to enhance the separation and transfer efficiency of the photo-induced electron by a covalent-anion-driven self-assembly method. The vertical orientation of MoS₂ ultrathin nanosheets not only provides a large specific surface area for the oxidation and reduction reactions but also enables the active edge sites of MoS₂ to be maximally exposed. As a result, this structure drastically facilitates the exposure of the catalytic active region and the performance of the carrier transfer and injection into photocatalytic degradation for nitenpyram (NTP). The optimal CdS-MoS₂ has an impressive and stable NTP removal efficiency with a high reaction rate constant up to 0.078 min^-1, which is 3.25 times higher than that of pure cadmium sulfide. The photocatalytic degradation mechanism and degradation pathway of NTP were presented by synthesizing the results of experimental analysis and density flooding theory (DFT) calculations. In further, for the first time, the cytotoxicity and genotoxicity of NTP on moving bed biofilm reactors (MBBRs) was disclosed and a continuous photocatalytic wastewater pretreatment device based on the CM is proposed for the stable biological nitrogen removal activity of MBBRs, which can degrade more than 80% NTP per hour.

Eucalyptol relieves imidacloprid-induced autophagy through the miR-451/Cab39/AMPK axis in Ctenopharyngodon idellus kidney cells†

Imidacloprid (IMI) is a widely used neonicotinoid insecticide that has toxic effects on nontarget organisms. 1,8-Cineole (eucalyptol) is purified from essential oils in several aromatic plants and can prevent xenobiotic toxicity. The kidney is a major organ for xenobiotic elimination and thus has high risk of exposure. The purpose of this research was to clarify the effect of IMI exposure on autophagy in fish kidney cells, determine the potential of eucalyptol to provide cytoprotection from the toxicity of the neonicotinoid pesticide IMI, and identify its mechanism of action. Therefore, the Ctenopharyngodon idellus kidney cell line (CIK cell) was treated with 20 mg/L IMI and/or 20 μM eucalyptol for 48 h as the research objective. The results showed that IMI exposure induced autophagy accompanied by advanced autophagy markers BNIP3, Beclin1 and LC3Ⅱ/Ⅰ in CIK cells, reduced the levels of miR-451, increased the expression of Cab39 and AMPK, inhibited AKT/mTOR signaling, and activated the JNK pathway. Eucalyptol treatment alleviated IMI-induced autophagy and relieved the activation of autophagy-associated signals. These results indicate that eucalyptol could alleviate IMI-induced autophagy through the miR-451/Cab39/AMPK axis in fish kidney cells. These results partly explained the mechanism of biological threat on fish under IMI exposure and the potential application value of EUC in aquaculture.

Comparative study of neonicotinoid insecticides (NNIs) and NNI-Related substances (r-NNIs) in foodstuffs and indoor dust

Comparative studies of neonicotinoid insecticides (NNIs) and NNI-related substances (r-NNIs) in foodstuffs and indoor dust are rare. Herein, we investigated the feature fragmentations of nine NNIs in high-energy collision dissociation cells via high-resolution orbitrap mass spectrometry and observed that NNIs can consistently generate several feature fragments (e.g., C6H5NCl+, C4H3NSCl+, and C6H5NF3+). Consequently, NNIs and r-NNIs were comprehensively (targeted, suspect, and feature fragment-dependent) detected in 107 foodstuff and 49 indoor dust samples collected from Nanjing City (eastern China). We fully or tentatively identified 9 target NNIs and 5 r-NNIs in these samples. NNIs and r-NNIs were detected in 93.5% of the analyzed foodstuff samples, and high concentrations were detected in vegetables (mean: 409 ng/g wet weight [ww]) and fruits (127 ng/g ww). Regarding indoor dust, imidacloprid and acetamiprid exhibited extremely high detection frequencies and contamination levels, and the highest mean concentrations of NNIs and r-NNIs were detected in dormitory samples. Based on the NNI and r-NNI concentrations in the analyzed samples, the mean estimated daily intake values for Chinese adults and children via dietary intake and dust ingestion were 2080-8190 ng/kg bw/day and 378-2680 pg/kg bw/day, respectively.

Efficient degradation of imidacloprid in soil by thermally activated persulfate process: Performance, kinetics, and mechanisms

Imidacloprid (IMI) as a first-generation commercial neonicotinoid has been frequently detected in the environment in recent years. In this study, the efficient degradation of IMI in soil by a thermally activated persulfate (PS) process was investigated. The degradation efficiencies of IMI were in the range of 82-97% with the PS dosage of 10 mM, when the initial concentrations of IMI were 5-50 mg/kg in the soil. Degradation of the IMI was fitted with a pseudo-first-order kinetic model under different reaction temperatures. Inhibition effects of the common inorganic anions on the IMI degradation in the system followed the order Cl^- > HCO₃^- > H₂PO₄^- > NO₃^-. Soil pH and soil organic matter were also main factors affecting the degradation of IMI. The degradation efficiencies (64-97%) of three other typical neonicotinoids (acetamiprid, clothianidin, and dinotefuran) indicated that the thermally activated persulfate process could be used for remediation of neonicotinoid-contaminated soil. Quenching experiments indicated that the major reactive species in IMI degradation were SO₄^•-, O₂^•-, and •OH. Six degradation intermediates of IMI were inferred in the soil, and degradation pathways of IMI included hydroxylation, denitrification, C-N bond break and further oxidation.

Exploratory analysis of the associations between neonicotinoids and measures of adiposity among US adults: NHANES 2015-2016

BACKGROUND

Toxicology studies suggest that neonicotinoids may be associated with adiposity development via thyroid hormone disruption and increased oxidative stress. Prior epidemiological studies report mixed results for the association between neonicotinoids and adiposity measures.

OBJECTIVE

To examine the association between detectable concentrations of parent neonicotinoids (imidacloprid, acetamiprid, clothianidin) and neonicotinoid metabolites (5-hydroxy-imidacloprid, N-desmethyl-acetamiprid) with adiposity measures among US adults, and whether sex modifies the associations for neonicotinoid metabolites with adiposity.

METHODS

National Health and Nutrition Examination Survey (NHANES) 2015-2016 data was utilized to estimate covariate-adjusted associations between detectable neonicotinoids and fat mass index (FMI), lean mass index (LMI), waist circumference, body fat percentage, and body mass index (BMI) using multiple linear regression. We estimated incidence rate ratios (IRRs) for overweight or obese status with detectable neonicotinoid concentrations using Poisson's modified regression. Sampling strategies were accounted for in the regression models.

RESULTS

Detectable levels of acetamiprid were associated with a decrease in FMI (β = -3.17 kg/m², 95% CI [-4.79, -1.54]), LMI (β = -3.17 kg/m², 95% CI [-5.17, -1.17]), body fat percentage (β = -4.41, 95% CI [-8.20, -0.62]), waist circumference (β = -9.80 cm, 95% CI [-19.08, -0.51]), and BMI (β = -3.88kg/m², 95% CI [-7.25, -0.51]) among adults. In contrast, detectable levels of 5-hydroxy-imidacloprid were associated with greater rates of being overweight/obese (IRR = 1.11, 95% CI [1.04, 1.18)) and increased LMI (β = 0.67 kg/m², 95% CI [0.04, 1.29]). Sex modified the association between N-desmethyl-acetamiprid and LMI (p_int = 0.075) with a positive association among males (β = 1.14 kg/m², 95% CI [0.38, 1.90]), and an insignificant inverse association in females. Sex also modified the association for N-desmethyl-acetamiprid with FMI (p_int = 0.095) and body fat percentage (p_int = 0.072), with suggestive evidence showing positive associations for males and inverse associations for females.

CONCLUSION

Detectable concentrations of acetamiprid were inversely associated with adiposity, while there were mixed findings for 5-hydroxy-imidacloprid. Findings suggest sex differences, though results are not clear with regard to the directionality of the association by sex.

Pesticide occurrence in an agriculturally intensive and ecologically important coastal aquatic system in Australia

Coastal agricultural practices are often located in catchments upstream of ecologically important aquatic systems. Here, we investigate the occurrence of pesticides in a coastal creek flowing into a habitat-protected area within the Solitary Islands Marine Park, Australia. Water samples were collected from six sites along a creek transect during three sampling periods. Samples were analysed for 171 pesticide analytes, including organochlorines, organophosphates, herbicides, and fungicides. Five insecticides, two herbicides, and two fungicides were detected. The neonicotinoid imidacloprid was detected at 5 out of 6 sites, with concentrations reaching 294 μg L^-1, the highest yet detected in Australian waterways. The organophosphate insecticide dimethoate was detected at 4 sites, which occurred at the 2nd highest detected concentration in the study (12.8 μg L^-1). The presence of these pesticides in the aquatic environment downstream of horticulture in this and other regions may have serious implications for stream biota and ecologically important marine ecosystems.

Deriving freshwater guideline values for neonicotinoid insecticides: Implications for water quality guidelines and ecological risk assessment

The increased use of neonicotinoid insecticides in aquatic environments poses a significant threat to non-target freshwater species. However, the existing water quality guidelines (WQGs) for neonicotinoids mainly focus on imidacloprid, and only a few authoritative institutions have established WQGs for other neonicotinoids. There is a critical need to develop WQGs and conduct ecological risk assessment (ERA) of different neonicotinoids in global freshwater environments. In this study, we derived interim acute and chronic guideline values and acute-to-chronic ratios (ACRs) for six neonicotinoids based on publicly available acute and chronic toxicity data. The exposure concentrations of neonicotinoids were obtained from published literature worldwide, and ERA was conducted for neonicotinoids in global freshwater ecosystems using a tiered approach. The derived chronic guideline values (95% confidence interval (CI), ng/L) were 0.63 (0.02-5.47) for thiacloprid (the lowest) and 16.4 for dinotefuran (the highest). The identified ACRs (95% CI) ranged from 90.9 (47.0-180) to 957 (102-3350), which can be used to extrapolate scarce chronic data from the acute data. Neonicotinoid concentrations in global freshwater were predicted from 10.6 (6.88-23.4) (thiacloprid) to 339 (211-786) ng/L (thiamethoxam). The estimated risk quotients ranged from 3.23 (dinotefuran) to 21.73 (thiacloprid), and the probability of exceeding WQGs ranged from 27.1% (dinotefuran) to 77.1% (thiacloprid). The ERA results indicated that the six neonicotinoids posed negligible acute risks but high chronic risks to global freshwater ecosystems, especially acetamiprid (65.8%) and thiacloprid (28.1%). The key findings of this study provide critical scientific information regarding the ecological risks of long-term neonicotinoid exposure and key insights for policy development and water quality control.

Temporal variation of imidacloprid concentration and risk in waterways discharging to the Great Barrier Reef and potential causes

The widely used neonicotinoid insecticide imidacloprid has emerged as a significant risk to surface waters and the diverse aquatic and terrestrial fauna these ecosystems support. While herbicides have been the focus of research on pesticides in Australia's Great Barrier Reef catchment area, imidacloprid has been monitored in catchments across the region since 2009. This study assessed the spatial and temporal dynamics of imidacloprid in 14 waterways in Queensland, Australia over seven years in relation to land use and concentration trends. Imidacloprid could be quantified (i.e., concentrations were greater than the limit of reporting) in approximately 54% of all samples, but within individual waterways imidacloprid was quantified in 0 to 99.7% of samples. The percent of each catchment used to grow bananas, sugar cane and urban explained approximately 45% of the variation in imidacloprid concentrations and waterway discharge accounted for another 18%. In six waterways there were significant increases in imidacloprid concentrations and the frequency and magnitude of exceedances of aquatic ecosystem protection guidelines over time. Overall, the risk posed by imidacloprid was low with 74% of samples protecting at least 99% of species but it was estimated that upto 42% of aquatic species would experience harmful chronic effects. Potential explanations of the changes in imidacloprid were examined. Not surprisingly, the only plausible explanation of the increases was increased use of imidacloprid. While field-based measurement of the effects of imidacloprid are limited in the Great Barrier Reef Catchment Area (GBRCA) the risk assessment indicates that biological harm to aquatic organisms is highly likely. Action to reduce imidacloprid concentrations in the GBRCA waterways is urgently required to reverse the current trends and mitigate environmental impacts.

Environmental photochemical fate of pesticides ametryn and imidacloprid in surface water (Paranapanema River, São Paulo, Brazil)

In addition to direct photolysis studies, in this work the second-order reaction rate constants of pesticides imidacloprid (IMD) and ametryn (AMT) with hydroxyl radicals (HO^●), singlet oxygen (¹O₂), and triplet excited states of chromophoric dissolved organic matter (³CDOM^*) were determined by kinetic competition under sunlight. IMD and AMT exhibited low photolysis quantum yields: (1.23 ± 0.07) × 10^-2 and (7.99 ± 1.61) × 10^-3 mol Einstein^-1, respectively. In contrast, reactions with HO^● radicals and ³CDOM* dominate their degradation, with ¹O₂ exhibiting rates three to five orders of magnitude lower. The values of k_IMD,HO● and k_AMT,HO● were (3.51 ± 0.06) × 10⁹ and (4.97 ± 0.37) × 10⁹ L mol^-1 s^-1, respectively, while different rate constants were obtained using anthraquinone-2-sulfonate (AQ2S) or 4-carboxybenzophenone (CBBP) as CDOM proxies. For IMD this difference was significant, with k_IMD,3AQ2S* = (1.02 ± 0.08) × 10⁹ L mol^-1 s^-1 and k_IMD,3CBBP* = (3.17 ± 0.14) × 10⁸ L mol^-1 s^-1; on the contrary, the values found for AMT are close, k_AMT,3AQ2S* = (8.13 ± 0.35) × 10⁸ L mol^-1 s^-1 and k_AMT,3CBBP* = (7.75 ± 0.80) × 10⁸ L mol^-1 s^-1. Based on these results, mathematical simulations performed with the APEX model for typical levels of water constituents (NO₃^-, NO₂^-, CO₃^2-, TOC, pH) indicate that the half-lives of these pesticides should vary between 24.1 and 18.8 days in the waters of the Paranapanema River (São Paulo, Brazil), which can therefore be impacted by intensive agricultural activity in the region.

Acute and Chronic Effects of Clothianidin, Thiamethoxam and Methomyl on Chironomus dilutus

Organism tolerance thresholds for emerging contaminants are vital to the development of water quality criteria. Acute (96-h) and chronic (10-day) effects thresholds for neonicotinoid pesticides clothianidin and thiamethoxam, and the carbamate pesticide methomyl were developed for the midge Chironomus dilutus to support criteria development using the UC Davis Method. Median lethal concentrations (LC50s) were calculated for acute and chronic exposures, and the 25% inhibition concentrations (IC25) were calculated for the chronic exposures based on confirmed chemical concentrations. Clothianidin effect concentrations were 4.89 µg/L, 2.11 µg/L and 1.15 µg/L for 96-h LC50, 10-day LC50 and 10-day IC25, respectively. Similarly, thiamethoxam concentrations were 56.4 µg/L, 32.3 µg/L and 19.6 µg/L, and methomyl concentrations were 244 µg/L, 266 µg/L and 92.1 µg/L. Neonicotinoid effect concentrations compared favorably to previously published 96-h and 14-day LC50 concentrations, and methomyl effect concentrations were within the acute survival range reported for Chironomus species and other organisms.

Adsorption Kinetics of Imidacloprid, Acetamiprid and Methomyl Pesticides in Aqueous Solution onto Eucalyptus Woodchip Derived Biochar

This work reports the application of a biochar (BC) derived from eucalyptus wood chips to remove pesticides (imidacloprid, acetamiprid and methomyl) from water. The pseudo-second order kinetic adsorption model is the best fit describing the adsorption of pesticides on BC. Furthermore, the Langmuir model correlated well with the adsorption isotherm data for acetamiprid and methomyl, while the Freundlich model was selected to explain the adsorption of imidacloprid on BC. The maximum adsorption capacities for methomyl, imidacloprid and acetamiprid on the BC material are 32.42, 14.75 and 4.87 mg g−1, respectively. The highest adsorption capacity of methomyl on the BC surface could be the result of multilayer adsorption suggested by the adsorption isotherm studies, with imidacloprid (or acetamiprid) monolayer being adsorbed on the BC surface. The structure, functional groups of pesticides, including their polarity, all played an important role contributing to the performance of biochar sorbent. Preferable interactions between the studied pesticides and the BC surface may include π-π interactions and hydrogen bonding. The steric aromatic entity in adsorbed imidacloprid and acetamiprid on the BC surface may hinder the possibility of other pesticide molecules approaching the available sorption sites on the surface.

An efficient, green and sustainable potassium hydroxide activated magnetic corn cob biochar for imidacloprid removal

The extensive use of imidacloprid (IMI) has led to its being frequently detected in natural water, also caused the potential damage to the ecosystem. Development of efficient, green and sustainable technique is demanded to eliminate this problem. A novel biochar (KMCBC) derived from agriculture waste of corn cob was first time co-modified by potassium hydroxide (KOH), ferric chloride (FeCl₃) and zinc chloride (ZnCl₂), which showed the greater adsorption amount (410 mg g^-1 at 298 K) for imidacloprid (IMI). Pseudo-second-order kinetic and Langmuir isotherm models fitted well with the experimental data, together with the physicochemical characterization analysis, demonstrating that the adsorption process of IMI by KMCBC might be mainly controlled by micropore filling, π-π electron donor-acceptor and functional groups interactions (H-bonding and complexation). Additionally, the thermodynamics parameters suggested that IMI adsorption in this study was a spontaneous, endothermic and randomly increasing process. Besides, KMCBC owned the easy separation performance and promising environmental safety, also exhibited a high selective adsorption capacity regardless of solution pH (its optimum adsorption performance for IMI was obtained at pH = 5), inorganic ions strength and humic acid (HA) concentrations. The regenerated KMCBC (synergistic ultrasound/ethanol) could sustainably and efficiently adsorb IMI in the reuse cycles. Therefore, this study provided an efficient, green and sustainable adsorbent of KMCBC for IMI removal.

Greenhouse production contributes to pesticide occurrences in Swedish streams

Greenhouse and other covered cultivation systems have increased globally over the past several decades, leading to considerably improved product quality and productivity per land area unit. However, there is a paucity in information regarding the environmental impacts of covered production systems, especially regarding pesticides entering the surrounding environment. Aiming to address this knowledge gap, we collected grab samples downstream of greenhouses from seven Swedish streams every 14 days during a 12 month period. In three of the streams, samples were also taken upstream of the greenhouses and in four of the streams time-integrated samples were collected by TIMFIE samplers in the period between grab sampling occasions. The samples were analyzed for 28 substances (27 that were permitted for use in greenhouse production systems in Sweden and one degradation product to a permitted substance). Pesticide use journals were collected from the greenhouse producers for the 12 month period. The results were examined for indications of greenhouse contributions to detection frequencies, maximum and average concentrations, and potential ecotoxicicity in several ways: (1) comparing locations downstream of greenhouses with registered use of a substance with those without registered use, (2) comparing results from this study with those from the Swedish environmental monitoring program of pesticides in surface water from catchments with no greenhouses from the same period and region, (3) comparing concentration trends with registered pesticide application times in the greenhouses, and (4) comparing up- and downstream concentrations. The results strongly suggest that greenhouse applications do contribute to pesticide occurrences, maximum and median concentrations for most of the pesticides included in this study, and to potential toxicity to aquatic organisms for several of them, most notably imidacloprid, acetamiprid, carbendazim, and pirimicarb.

Impact of imidacloprid exposure on the biochemical responses, transcriptome, gut microbiota and growth performance of the Pacific white shrimp Litopenaeus vannamei

The widespread use of neonicotinoid insecticides, such as imidacloprid, in agriculture is one of the key factors for the drop in the survival of invertebrates, including decapod crustaceans. However, there is currently a lack of comprehensive studies on the chronic toxicity mechanisms in decapod crustaceans. Here, the concentration-dependent effects of imidacloprid on the physiology and biochemistry, gut microbiota and transcriptome of L. vannamei , and the interaction between imidacloprid, gut microbiota and genes were studied. Imidacloprid caused oxidative stress, leading to reduced growth and to immunity and tissue damage in L. vannamei . Imidacloprid increased the gut pathogenic microbiota abundance and broke the steady state of the gut microbiota interaction network, resulting in microbiota function disorders. Chronic imidacloprid exposure induced overall transcriptome changes in L. vannamei . Specifically, imidacloprid caused a large number of differentially expressed genes (DEGs) to be significantly downregulated. The inhibition of autophagy-related pathways revealed the toxic process of imidacloprid to L. vannamei . The changes in phase I and II detoxification gene expression clarified the formation of a detoxification mechanism in L. vannamei . The disturbance of circadian rhythm (CLOCK) caused by imidacloprid is one of the reasons for the increase in gut pathogenic microbiota abundance.

Assessment of Five Pesticides as Endocrine-Disrupting Chemicals: Effects on Estrogen Receptors and Aromatase

Pesticides are widely applied all over the world, and pesticide exposure can induce different biological effects posing a possible threat to human health. Due to their effects on the endocrine system, some pesticides are classified as endocrine disruptors. The aim of the study is to assess the interference of five pesticides on estrogen biosynthesis and estrogen signaling. Three neonicotinoid insecticides (Acetamiprid, Clothianidin, and Thiamethoxam), a carbamate insecticide (Methiocarb) and a herbicide (Oxadiazon) were tested. The effect of pesticides on estrogen biosynthesis was studied through an ELISA assay using a recombinant form of human aromatase, the enzyme that catalyzes the transformation of androgens to estrogens. Moreover, the effect of pesticides on estrogen signaling was assessed using a gene reporter assay on MELN cells, which measures estrogen receptor-mediated estrogenic activity. The results of the ELISA assay showed that the pesticides did not alter aromatase activity (no interference with estrogen biosynthesis), while the results of the gene reporter assay showed that only Methiocarb was able to alter estrogen signaling at high doses. The estrogenic activity of Methiocarb, expressed as 17β-estradiol equivalency factor (EEF), was equal to 8.0 × 10⁻⁸. In conclusion, this study suggested that Methiocarb should be considered a potential endocrine disruptor.

New-generation pesticides are prevalent in California's Central Coast streams

Pesticides are widely recognized as important biological stressors in streams, especially in heavily developed urban and agricultural areas like the Central California Coast region. We assessed occurrence and potential toxicity of pesticides in small streams in the region using two analytical methods: a broad-spectrum (223 compounds) method in use since 2012 and a newly developed method for 30 additional new-generation fungicides and insecticides. At least one pesticide compound was identified in 83 of the 85 streams sampled. About one-half (48%) of the 253 pesticides measured were detected at least once and 27 were detected in 10% or more of samples. Three of the top 4, and 6 of the top 10 most frequently detected compounds (chlorantraniliprole, dinotefuran, boscalid, thiamethoxam, clothianidin and the fluopicolide degradate 2,6-dichlorobenzamide) were analyzed by the new method. Pesticide mixtures were common, with two or more pesticide compounds detected in 81% of samples and 10 or more in 32% of samples. The pesticide count at a site was relatively consistent over the 6-week study. Four sites with mixed land-use in the lower basin (<5 km from the sampling site) tended to have the highest pesticide counts and the highest concentrations. Potential toxicity (assessed by comparison to benchmarks) to invertebrates was much more common than potential toxicity to fish or plants and was associated with a wide array of insecticides. The common occurrence of new-generation pesticides highlights the need to continuously update analytical methods to keep pace with changing pesticide use for a fuller assessment of pesticide occurrence and effects on the environment.

Seasonal distribution of multiclass pesticide residues in the surface waters of northwest Croatia

As part of our OPENTOX project, we evaluated the incidence and mass concentrations of multiclass pesticide residues in 23 river/stream water samples collected in urban and agricultural areas of northwest Croatia at various points of the pesticide application season in 2015. The study included 16 compounds of five herbicide classes and seven compounds of three insecticide classes. Pesticide residues were accumulated from water by solid-phase extraction and analysed using high performance liquid chromatography with UV-diode array detection and/or gas chromatography-mass spectrometry. Herbicide residues were more common than the insecticide ones, and, as expected, they peaked in the middle of the application season. Metolachlor showed the highest concentrations and was found in 91 % of all samples, followed by terbuthylazine, found in 70 % of the samples. The highest total mass concentration of detected pesticides was measured in the water samples of the Krapina (3992 ng/L) and Sutla (3455 ng/L) collected in rural areas with intensive agriculture. Our findings strongly speak in favour of continued monitoring of surface waters and possibly extending the list of priority water pollutants.

Imidacloprid and thiamethoxam affect synaptic transmission in zebrafish

Imidacloprid (IMI) and thiamethoxam (THM) are two commonly applied neonicotinoid insecticides. IMI and THM could cause negative impacts on non-target organisms like bees. However, the information about neurotoxicity of IMI and THM in fish is still scarce. Here we investigated the effects of IMI and THM on locomotor behavior, AChE activity, and transcription of genes related to synaptic transmission in zebrafish exposed to IMI and THM with concentrations of 50 ng L^-1 to 50,000 ng L^-1 at 14 day post fertilization (dpf), 21 dpf, 28 dpf and 35 dpf. Our results showed that IMI and THM significantly influenced the locomotor activity in larvae at 28 dpf and 35 dpf. THM elevated AChE activity at 28 dpf. The qPCR data revealed that IMI and THM affected the transcription of marker genes belonging to the synapse from 14 dpf to 35 dpf. Furthermore, IMI and THM mainly affected transcription of key genes in γ-aminobutyric acid, dopamine and serotonin pathways in larvae at 28 dpf and 35 dpf. These results demonstrated the neurotoxicity of IMI and THM in zebrafish. The findings from this study suggested that IMI and THM in the aquatic environment may pose potential risks to fish fitness and survival.

Method Validation and Evaluation of Safrole Persistence in Cowpea Beans Using Headspace Solid-Phase Microextraction and Gas Chromatography

Bioinsecticides are regarded as important alternatives for controlling agricultural pests. However, few studies have determined the persistence of these compounds in stored grains. This study aimed at optimizing and validating a fast and effective method for extraction and quantification of residues of safrole (the main component of Piper hispidinervum essential oil) in cowpea beans. It also sought to assess the persistence of this substance in the grains treated by contact and fumigation. The proposed method used headspace solid-phase microextraction (HS-SPME) and gas chromatography with a flame ionization detector (GC/FID). Factors such as temperature, extraction time and type of fiber were assessed to maximize the performance of the extraction technique. The performance of the method was appraised via the parameters selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy. The LOD and LOQ of safrole were 0.0057 and 0.019 μg kg⁻¹, respectively and the determination coefficient (R²) was >0.99. The relative recovery ranged from 99.26 to 104.85, with a coefficient of variation <15%. The validated method was applied to assess the persistence of safrole residue in grains, where concentrations ranged from 1.095 to 0.052 µg kg⁻¹ (contact) and from 2.16 to 0.12 µg kg ⁻¹ (fumigation). The levels measured up from the fifth day represented less than 1% of the initial concentration, proving that safrole have low persistence in cowpea beans, thus being safe for bioinsecticide use. Thus, this work is relevant not only for the extraction method developed, but also for the possible use of a natural insecticide in pest management in stored grains.