Interactions of traditional and biodegradable microplastics with neonicotinoid pesticides.

Neonicotinoid pesticides (NNPs) and microplastics (MPs) are two emerging contaminants in agricultural environment. However, the interaction between MPs (especially biodegradable plastics) and NNPs is currently unclear. Therefore, taking thiacloprid (THI) as an example of NNPs, this study explores the adsorption-desorption process and mechanism of NNPs on MPs (traditional and biodegradable plastics), and analyzed the main factors affecting the adsorption (pH, salinity and dissolved organic matter). In addition, by using diffusive gradients in thin-films device, this study assessed the impact of MPs on the bioavailability of NNPs in soil. The results showed that the maximum adsorption capacity of polyamide 6 (96.49 µg g-1) for THI was greater than that of poly (butylene adipate co-terephthalate) (88.78 µg g-1). Aging increased the adsorption amount of THI (5.53 %-15.8 %) due to the higher specific surface area and reduced contact angle of MPs, but the adsorption mechanism remained unchanged. The desorption amount of THI from MPs in simulated intestinal fluid is 1.30-1.36 times. The MPs in soil alter the distribution of THI in the soil, increasing the bioavailability of THI while inhibiting its degradation. The results highlighted the significance of examining the combined pollution caused by MPs and NNPs.

Different Sensitivity of Flower-Visiting Diptera to a Neonicotinoid Insecticide: Expanding the Base for a Multiple-Species Risk Assessment Approach.

Insects play an essential role as pollinators of wild flowers and crops. At the same time, pollinators in agricultural environments are commonly exposed to pesticides, compromising their survival and the provision of pollination services. Although pollinators include a wide range of species from several insect orders, information on pesticide sensitivity is mostly restricted to bees. In addition, the disparity of methodological procedures used for different insect groups hinders the comparison of toxicity data between bees and other pollinators. Dipterans are a highly diverse insect order that includes some important pollinators. Therefore, in this study, we assessed the sensitivity of two hoverflies (Sphaerophoria rueppellii, Eristalinus aeneus) and one tachinid fly (Exorista larvarum) to a neonicotinoid insecticide (Confidor®, imidacloprid) following a comparative approach. We adapted the standardized methodology of acute contact exposure in honey bees to build dose-response curves and calculate median lethal doses (LD50) for the three species. The methodology consisted in applying 1 µL of the test solution on the thorax of each insect. Sphaerophoria rueppelli was the most sensitive species (LD50 = 10.23 ng/insect), and E. aeneus (LD50 = 18,176 ng/insect) the least. We then compared our results with those available in the literature for other pollinator species using species sensitivity distribution (SSD). Based on the SSD curve, the 95th percentile of pollinator species would be protected by a safety factor of 100 times the Apis mellifera endpoint. Overall, dipterans were less sensitive to imidacloprid than most bee species. As opposed to most bee species, oviposition and fecundity of many dipteran species can be reliably assessed in the laboratory. We measured the number of eggs laid following exposure to different insecticide doses and assessed the potential trade-off between oviposition and survival through the sublethal sensitivity index (SSI). Exposure to imidacloprid had a significant effect on fecundity, and SSI values indicated that oviposition is a sensitive endpoint for the three dipteran species tested. Future studies should integrate this information related to population dynamics in simulation models for environmental risk assessment.

Effects of farmland abandonment on anthropogenic-alluvial soil microbiota and contaminant residues in Lycium barbarum fields.

AIMS: There has been an increasing tendency to abandon crop cultivation and farming in old Lycium barbarum (wolfberry) stands to allow for natural restoration. However, little research has been dedicated to deciphering how soil quality changes in L. barbarum fields following abandonment from a physicochemical and microbiological perspective. Here we assessed the effects of farmland abandonment on anthropogenic-alluvial soil microbiota and contaminant residues in L. barbarum fields in Ningxia, China. METHODS AND RESULTS: Soil microbiota, heavy metal, and neonicotinoid pesticide profiles in L. barbarum fields abandoned for one to four years were characterized. Microbial community analysis was performed by high-throughput sequencing of the bacterial 16S ribosomal RNA genes and the fungal nuclear ribosomal internal transcribed spacer region. Soil bacterial diversity increased from before abandonment to year three after abandonment, and fungal diversity peaked in year one after abandonment. Enrichment of potentially beneficial taxa (e.g. Limnobacter, Cavicella) as well as pathogenic taxa (e.g. Ilyonectria) was observed in the abandoned field soils, along with depletion of other taxa (e.g. Planococcus, Bipolaris). Soil copper, zinc, cadmium, imidacloprid, and acetamiprid concentrations all decreased with increasing time since abandonment and had varied correlations with soil quality, microbial diversity, and the relative abundances of major phyla. Soil available phosphorus, nitrate-nitrogen, and pH were the key factors shaping bacterial communities. The structuring of fungal communities was strongly influenced by soil pH, available phosphorus, and available nitrogen contents. CONCLUSIONS: There were positive consequences of farmland abandonment in L. barbarum fields, such as optimized microbial community structure, reduced heavy metal accumulation, and enhanced pesticide degradation.

Dietary risk assessment of neonicotinoid pesticide in 21 kinds of market-sold vegetables in Guangzhou City / 预防医学

Objective@#To evaluate the dietary risk of neonicotinoid insecticides in market-sold vegetables in Guangzhou City, so as to provide insights into ensuring food safety for residents.@*Methods@#Forty-five samples of 21 kinds of vegetables were collected from supermarkets and farmer's markets in Guangzhou City from June to September in 2022, and 10 kinds of neonicotinoid insecticides were determined using liquid chromatography-mass spectrometry (LC-MS). The vegetable consumption was obtained through the survey of food consumption and nutrients intake of residents in Guangzhou City. The dietary risk was evaluated by calculating daily exposure and non-carcinogenic risk quotients of neonicotinoid insecticides. @*Results@#A total of 27 samples of vegetables were detected with neonicotinoid insecticides, and the detection rate was 60.00%. Among 10 kinds of neonicotinoid insecticides, 6 kinds were identified, including clothianidin, thiamethoxam, imidacloprid, acetamiprid, dinotefuranand and nitenpyram. The detection rates of clothianidin, thiamethoxam and imidacloprid were relatively high (26.67%, 11.11% and 6.67%), and some samples exceeded the standard, with the rate of 4.44%, 2.22% and 2.22%, respectively. The total exposure of neonicotinoid pesticides (IMIRPF) was 3 053.00 ng/g, and the contents and IMIRPF of imidacloprid were the highest in roots and tubers. The daily exposure of imidacloprid, acetamiprid, dinotefuran, clothianidin, thiamethoxam and nitenpyram was 34.58, 3.85, 1.20, 6.87, 7.19 and 0.86 ng/(kg·d). Non-carcinogenic risk quotients of imidacloprid, acetamiprid, dinotefuran, clothianidin, thiamethoxam and nitenpyram was 5.76×10-4, 0.55×10-4, 0.06×10-4, 0.69×10-4, 0.90×10-4 and 0.02×10-4, respectively, which was lower than 1; and the sum of non-carcinogenic risk quotients was 7.98×10-4, which was lower than 1. @*Conclusions@#The dietary risk of neonicotinoid pesticides is low in 21 kinds of market-sold vegetables in Guangzhou City; however, the contents of neonicotinoid insecticides in some vegetable samples exceed the standard. The supervision of vegetable markets should be strengthened.

Effect of Neonicotinoid Pesticides on Japanese Water Systems: Review with Focus on Reproductive Toxicity.

Neonicotinoid pesticides (NPs) are neurotoxic substances. They are highly effective as insecticides owing to their water solubility, permeability, and long-lasting activity. These molecules are structurally similar to nicotine and act as nicotinic acetylcholine receptor agonists. The administration of NPs to experimental animals reportedly causes neuromuscular and reproductive disorders. Moreover, recently reported problems caused by NPs include damage to land-dwelling creatures (such as mammals and birds), hydrobiology, and ecosystems. This review summarizes the recent reports on NP concentrations detected in river systems in several Japanese regions. These values were lower than the environmental standard values; however, seasonal variations were observed. Furthermore, reports on NP-induced testicular and ovarian toxicity were examined, revealing that the mechanism of injury is mainly driven by oxidative stress. The use of NPs is declining worldwide, except in Japan; therefore, continuous monitoring remains necessary.

Pollution， human exposure and harmful effects of neonicotinoid pesticides / 上海预防医学

Neonicotinoid is a kind of neuroactive pesticide， and it has become the most widely used pesticide in the world. In recent years， neonicotinoid has been detected in the environment and food， suggesting that human can be exposed to this kind of pesticide through drinking water， ingestion and respiration， which poses potential health hazards to human. However， there is no comprehensive report on the pollution level of neonicotinoid pesticides in the environment and food and the impact on human health. In this paper， the pollution status， population exposure level and potential health risks of neonicotinoid pesticides in water， air and food were reviewed. We found that neonicotinoid residues are widespread in fruits and vegetables， of which imidacloprid has the highest detection rate. Except for a few samples with excessive neonicotinoid detection， the detection level in most samples did not exceed national food safety standards. A variety of neonicotinoid pesticides have been detected in the air， surface water， tap water and drinking water. External exposure studies in the population have shown that ingestion is the main route of exposure to neonicotinoid， and the external exposure level is much lower than its chronic reference dose. The internal exposure study mainly detected the concentration of neonicotinoid pesticides and their metabolites in urine. A variety of neonicotinoid pesticides and their metabolites are detected in urine， and the concentration range is ng/ml level. Internal exposure studies found that the detection rate of thiamethoxam and dinotefuran in urine is higher， and the detection rate of neonicotinoid in Asian countries is higher than that in European and American countries. Occupational exposure studies found that neonicotinoid exposure levels increased after pesticide spraying， and the exposure levels in rural areas where pesticides were commonly used were higher than those in neighboring urban areas. Animal experiments have found that neonicotinoid pesticides have reproductive toxicity， genetic toxicity， neurotoxicity， immunotoxicity， liver toxicity and nephrotoxicity to non-target organisms. Cell experiments suggest that neonicotinoid is an endocrine disruptor. The symptoms of acute exposure in humans are related to the exposure dose， route and physical condition of the exposed person， which ranges from mild symptoms （nausea， vomiting， headache and diarrhea） to death. Population epidemiological studies have shown that chronic exposure to neonicotinoid pesticides is associated with adverse health effects in humans such as neonatal tetralogy of Fallot， anencephaly， and adverse mental symptoms.

Paper-Based SERS Sensing Platform Based on 3D Silver Dendrites and Molecularly Imprinted Identifier Sandwich Hybrid for Neonicotinoid Quantification.

Real-time monitoring of neonicotinoid pesticide residues is of great significance for food security and sustainable development of the ecological environment. Herein, a paper-based surface-enhanced Raman scattering (SERS) amplified approach was proposed by virtue of multilayered plasmonic coupling amplification. The unique plasmonic SERS multilayer was constructed using three-dimensional (3D) silver dendrite (SD)/electropolymerized molecular identifier (EMI)/silver nanoparticle (AgNP) sandwich hybrids with multiple hotspots and a strong electromagnetic field in nanogaps. Dendritelike 3D silver materials with remarkably high accessible surface areas and the lightning rod effect constituted the first-order enhancement of paper-based sensors. Molecular identifiers coated upon an SD layer as the interlayer were used for target capture and enrichment. Subsequently, AgNPs featuring rough surface and local plasma resonance decorated as the top layer formed the secondary enhancement of the amplification strategy. As the most brilliant part, dendritelike 3D silver coupled with AgNPs has established double Ag layers to accomplish a multistage enhancement of SERS signals based on the superposition of their electromagnetic fields. Owning to the distinctive design of the multiple coupling amplification strategy, the fabricated SERS paper chips demonstrated impressive specificity and ultrahigh sensitivity in the detection of imidacloprid (IMI), with a detection limit as low as 0.02811 ng mL-1. More importantly, the multiple SERS enhancement paper chip holds great potential for automated screening of a variety of contaminants.

Degradation of the Neonicotinoid Pesticides in the Atmospheric Pressure Ionization Source.

During the analysis of neonicotinoid pesticide standards (thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid) by mass spectrometry, the degradation of these pesticides (M-C=N-R is degraded into M-C=O, M is the skeleton moiety, and R is NO2 or CN) was observed in the atmospheric pressure ionization interfaces (ESI and APCI). In APCI, the degradation of all the five neonicotinoid pesticides studied took place, and the primary mechanism was in-source ion/molecule reaction, in which a molecule of water (confirmed by use of H218O) attacked the carbon of the imine group accompanying with loss of NH2R (R=NO2, CN). For the nitroguanidine neonicotinoid pesticides (R=NO2, including thiamethoxam, clothianidin, and imidacloprid), higher auxiliary gas heater temperature also contributed to their degradation in APCI due to in-source pyrolysis. The degradation of the five neonicotinoid pesticides studied in ESI was not significant. In ESI, only the nitroguanidine neonicotinoid pesticides could generate the degradation products through in-source fragmentation mechanism. The degradation of cyanoamidine neonicotinoid pesticides (R=CN, including acetamiprid and thiacloprid) in ESI was not observed. The degradation of neonicotinoid pesticides in the ion source of mass spectrometer renders some adverse consequences, such as difficulty interpreting the full-scan mass spectrum, reducing the sensitivity and accuracy of quantitative analysis, and misleading whether these pesticides have degraded in the real samples. Therefore, a clear understanding of these unusual degradation reactions should facilitate the analysis of neonicotinoid pesticides by atmospheric pressure ionization mass spectrometry. Graphical Abstract.

Influence of humic substances and iron and aluminum ions on the sorption of acetamiprid to an arable soil.

Humic substances (HS) in soil and sediments, and surface water influence the behavior of organic xenobiotics in the environment. However, our knowledge of the effects of specific HS fractions, i.e., humic acids (HAs), fulvic acids (FAs), and humin (HM), on the sorption of organic xenobiotics is limited. The neonicotinoid insecticide acetamiprid is thought to contribute to the collapse of honeybee colonies. To understand the role that soil organic matter plays in the fate of acetamiprid, interactions between acetamiprid and the above HS fractions were examined. Batch experiments were conducted using various combinations of a field soil sample and the above 3 HS fractions prepared from the same soil, and differences in isotherm values for acetamiprid sorption were investigated based on the structural differences among the HS fractions. The sorption of acetamiprid to soil minerals associated with HM (MHM) (Freundlich isotherm constant, Kf: 6.100) was reduced when HAs or FAs were added (Kf: 4.179 and 4.756, respectively). This can be attributed to hydrophobic interactions between HM and HAs or FAs in which their dissociated carboxyl and phenolic groups become oriented to face the soil solution. The amount of acetamiprid that was adsorbed to (MHM+HA) or (MHM+FA) increased when aluminum ions were added (Kf: 6.933 and 10.48, respectively), or iron ions were added (Kf: 7.303 and 11.29, respectively). Since acetamiprid has no affinity for inorganic components in soil, the formation of HS-metal complexes by cation bridging may have oriented the hydrophobic moieties in the HAs or FAs to face the soil solution and may also have resulted in the formation of dense structures, resulting in an increase in the amount of acetamiprid that becomes adsorbed to these structures. These results highlight the importance of interactions among soil components in the pedospheric diffusion of acetamiprid.

Carbon Treatment as a Method to Remove Imidacloprid from Agriculture Runoff.

Use of neonicotinoid pesticides is increasing worldwide and there is growing evidence of surface water contamination from this class of insecticide. Due to their high solubility, traditional mitigation practices may be less effective at reducing neonicotinoid concentrations in agricultural runoff. In the current study, laboratory experiments were conducted to determine if granulated activated carbon (GAC) reduces concentrations of the neonicotinoid imidacloprid in water under simulated flow conditions. Imidacloprid was pumped through columns packed with GAC using flow rates scaled to mimic previously reported field studies. Treatments were tested at two different flow rates and samples were collected after 200 and 2500 mL of treated water were pumped through the column. Chemical analysis of the post-column effluent showed the GAC removed all detectable imidacloprid from solution at both flow rates and at both sample times. These results demonstrate the efficacy of GAC for treating neonicotinoids and the results are discussed in the context of incorporating this treatment into integrated vegetated treatment systems for mitigating pesticides in agricultural runoff. Future studies are being designed to evaluate this technology in full scale field trials.

Successive pH- and heat-induced homogenous liquid-liquid extraction.

A simple and efficient analytical method known as pH- and heat-induced homogenous liquid-liquid extraction combined with high-performance liquid chromatography has been successfully developed for the extraction and determination of neonicotinoid pesticides in aqueous samples. In this method, a few mL of a water-miscible basic extraction solvent is mixed with a high volume of an aqueous phase containing the analytes and passed through a tube which a portion of the tube is filled with sodium carbonate as a separating agent. By passing the solution, salt is dissolved and the fine droplets of the extraction solvent are formed. The produced droplets go up through the remained solution and collect as a separated layer. In the following, the collected organic phase is removed and placed into a micro tube. Then it is heated in a water bath to form two phases. Several experimental parameters that influence extraction efficiency such as type and volume of extraction solvent, type of phase separation agent, temperature, and extraction time were investigated. Under the optimum conditions, the extraction recoveries and enrichment factors ranged between 51 and 81% and 680 and 1080, respectively. Calibration curves showed a high-level of linearity for all target analytes with coefficients of determination ranging between 0.997 and 0.999. The repeatability of the proposed method expressed as relative standard deviation varied between 3 and 5% (n=6, C=50µgL(-1)), and the detection limits were in the range of 0.52-1.0µgL(-1). Finally, the performance of the method was evaluated by analyzing the selected pesticides in different fruit juice and vegetable samples.

Chronic sublethal stress causes bee colony failure.

Current bee population declines and colony failures are well documented yet poorly understood and no single factor has been identified as a leading cause. The evidence is equivocal and puzzling: for instance, many pathogens and parasites can be found in both failing and surviving colonies and field pesticide exposure is typically sublethal. Here, we investigate how these results can be due to sublethal stress impairing colony function. We mathematically modelled stress on individual bees which impairs colony function and found how positive density dependence can cause multiple dynamic outcomes: some colonies fail while others thrive. We then exposed bumblebee colonies to sublethal levels of a neonicotinoid pesticide. The dynamics of colony failure, which we observed, were most accurately described by our model. We argue that our model can explain the enigmatic aspects of bee colony failures, highlighting an important role for sublethal stress in colony declines.