Use Of Neonicotinoids Research Articles

Cytotoxicity induced by three commercial neonicotinoid insecticide formulations in differentiated human neuroblastoma SH-SY5Y cells.

Neonicotinoid insecticides are used worldwide for crop protection. They act as agonists at postsynaptic nicotinic acetylcholine receptors (nAChRs), disrupting normal neurotransmission in target insects. Human exposure is high due to the widespread use of neonicotinoids and their residues in food. This study aimed to evaluate the in vitro neurotoxicity of three neonicotinoid commercial formulations Much 600 FS® (imidacloprid 600gL-1), Evidence 700 WG® (imidacloprid 700gkg-1), and Actara 250 WG® (thiamethoxam 250gkg-1) in differentiated human neuroblastoma SH-SY5Y cell line. Cells were incubated with the pesticides for 96h, and the cytotoxicity was evaluated through the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium·bromide (MTT) reduction and neutral red (NR) uptake assays. Toxicological pathways such as reactive oxygen (ROS) and nitrogen species (RNS) production, mitochondrial membrane potential, cell death mode, and the expression of the pro-apoptotic protein Bax were also evaluated. EC50 values of 266.4, 4,175, and 653.2mgL-1 were found for Much®, Evidence® and Actara®, respectively. Significant increases in ROS and RNS generation were observed for all pesticides, while mitochondrial membrane potential and Bax protein expression showed no significant changes. Analysis of cell death mode revealed an increase in early apoptotic cells. Therefore, neonicotinoid insecticides are potentially neurotoxic, reinforcing concerns about human exposure to these commercial formulations.

Neonicotinoid insecticides in a large-scale agricultural basin system-Use, emission, transportation, and their contributions to the ecological risks in the Pearl River Basin, China

Neonicotinoid pollution has increased rapidly and globally in recent years, posing significant risks to agricultural areas. Quantifying use and emission, transport and fate of these contaminants, and risks is critical for proper management of neonicotinoids in river basin. This study elucidates use and emissions of neonicotinoid pesticides in a typical large-scale agriculture basin of China, the Pearl River Basin, as well as the resulting agricultural non-point source pollution and related ecological risks using market surveys, data analysis, and the Soil and Water Assessment Tool. Neonicotinoid use in the basin was estimated at 1361 t in 2019, of which 83.1 % was used in agriculture. After application, approximately 99.1 t neonicotinoids were transported to the Pearl River, accounting for 7.2 % of the total applied. Estimated aquatic concentrations of neonicotinoids showed three seasonal peaks. Several distinct groups of neonicotinoid chemicals can be observed in the Pearl River, as estimated by the model. An estimated 3.9 % of the neonicotinoids used were transported to the South China Sea. Based on the present risk assessment result, several neonicotinoids posed risks to aquatic organism. Therefore, the use of alternative products and/or reduced use is deemed necessary. This study provides novel insights into the fate and ecological risks of neonicotinoid insecticides in large-scale watersheds, and underscores the need for greater efficiency of use and extensive environmental monitoring.

Intake of imidacloprid in lethal and sublethal doses alters gene expression in Apis mellifera bees

Bees are important pollinators for ecosystems and agriculture; however, populations have suffered a decline that may be associated with several factors, including habitat loss, climate change, increased vulnerability to diseases and parasites and use of pesticides. The extensive use of neonicotinoids, including imidacloprid, as agricultural pesticides, leads to their persistence in the environment and accumulation in bees, pollen, nectar, and honey, thereby inducing deleterious effects. Forager honey bees face significant exposure to pesticide residues while searching for resources outside the hive, particularly systemic pesticides like imidacloprid. In this study, 360 Apis mellifera bees, twenty-one days old (supposed to be in the forager phase) previously marked were fed syrup (honey and water, 1:1 m/v) containing a lethal dose (0.081 μg/bee) or sublethal dose (0.00081 μg/bee) of imidacloprid. The syrup was provided in plastic troughs, with 250 μL added per trough onto each plastic Petri dish containing 5 bees (50 μL per bee). The bees were kept in the plastic Petri dishes inside an incubator, and after 1 and 4 h of ingestion, the bees were euthanised and stored in an ultra-freezer (−80 °C) for transcriptome analysis. Following the 1-h ingestion of imidacloprid, 1516 genes (73 from lethal dose; 1509 from sublethal dose) showed differential expression compared to the control, while after 4 h, 758 genes (733 from lethal dose; 25 from sublethal) exhibited differential expression compared to the control. All differentially expressed genes found in the brain tissue transcripts of forager bees were categorised based on gene ontology into functional groups encompassing biological processes, molecular functions, and cellular components. These analyses revealed that sublethal doses might be capable of altering more genes than lethal doses, potentially associated with a phenomenon known as insecticide-induced hormesis. Alterations in genes related to areas such as the immune system, nutritional metabolism, detoxification system, circadian rhythm, odour detection, foraging activity, and memory in bees were present after exposure to the pesticide. These findings underscore the detrimental effects of both lethal and sublethal doses of imidacloprid, thereby providing valuable insights for establishing public policies regarding the use of neonicotinoids, which are directly implicated in the compromised health of Apis mellifera bees.

Those That Remain Caught in the "Organic Matter Trap": Sorption/Desorption Study for Levelling the Fate of Selected Neonicotinoids.

With projections suggesting an increase in the global use of neonicotinoids, contemporary farmers can get caught on the "pesticide treadmill", thus creating ecosystem side effects. The aim of this study was to investigate the sorption/desorption behavior of acetamiprid, imidacloprid, and thiacloprid that controls their availability to other fate-determining processes and thus could be useful in leveling the risk these insecticides or their structural analogues pose to the environment, animals, and human health. Sorption/desorption isotherms in four soils with different organic matter (OC) content were modelled by nonlinear equilibrium models: Freundlich's, Langmuir's, and Temkin's. Sorption/desorption parameters obtained by Freundlich's model were correlated to soil physico-chemical characteristics. Even though the OC content had the dominant role in the sorption of the three insecticides, the role of its nature as well as the chemical structure of neonicotinoids cannot be discarded. Insecticides sorbed in the glassy OC phase will be poorly available unlike those in the rubbery regions. Imidacloprid will fill the sorption sites equally in the rubbery and glassy phases irrespective of its concentration. The sorption of thiacloprid at low concentrations and acetamiprid at high concentrations is controlled by hydrophilic aromatic structures, "trapping" the insecticides in the pores of the glassy phase of OC.

Toxic and Environmental Effects of Neonicotinoid Based Insecticides

The insecticide known as neonicotinoid has negative impacts on the ecosystem, human health, and the environment; specifically, its effects on the relationship between crop yields and the death rate of natural pollinators, such as bees, affect food security. The active ingredients in neonicotinoids include imidacloprid, clothianidin, thiamethoxam, acetamiprid, sulfoxaflor, and thiacloprid, which are sold under various trade names. For many of the components of these toxic insecticides, patents have been expired; however, farmers and consumers who continue to use these chemicals are unaware of the products’ toxicity and the environmental effects they have. Thus, agricultural industries are required to consider diverse methods to minimize neonicotinoid use in farming operations and move away from the current prevailing methods. In this short review, the negative effects of neonicotinoid use; the toxic components, health effects, and environmental regulations of neonicotinoids; and sustainable methods to minimize their use are examined.

To Bee, or Not to Bee: A Commentary on International Neonicotinoid Regulation

Amidst a time of dramatic climate change and exponential population growth, sustaining food production, and the pollinators essential to that production, has taken on increased importance. The current global system of industrial agriculture, however, relies on chemical pesticides, including neonicotinoids. A growing number of studies convincingly demonstrate that neonicotinoids are killing bees and their colonies. With bees and other pollinator populations in danger, an integral part of the world’s food system is at risk. 
 This paper focuses on the dangers of neonicotinoid use and the need for international neonicotinoid regulation. The paper analyzes the emergence of neonicotinoids in the global agrochemical market, their negative impact on the health of pollinators, and the current legal regulations that govern neonicotinoid use. It recommends greater use of multilateral, international agreements to more comprehensively regulate neonicotinoids to protect bees and other pollinator populations. Other environmental treaties, such as the Montreal Protocol and the Stockholm Convention, provide accessible frameworks for cooperative regulation. If international communities act quickly, there may still be time to sufficiently protect pollinator populations from further catastrophic harm from neonicotinoid use. Bees and other pollinators are essential for global food production, and this paper provides a path forward for policy-makers and law-makers to better protect these species from the harms of neonicotinoids.

Incorporation of N-doped biochar into zero-valent iron for efficient reductive degradation of neonicotinoids: mechanism and performance

The extensive use of neonicotinoids on food crops for pest management has resulted in substantial environmental contamination. It is imperative to develop an effective remediation material and technique as well as to determine the evolution pathways of products. Here, novel ball-milled nitrogen-doped biochar (NBC)-modified zero-valent iron (ZVI) composites (named MNBC-ZVI) were fabricated and applied to degrading neonicotinoids. Based on the characterization results, NBC incorporation introduced N-doped sites and new allying heterojunctions and achieved surface charge redistribution, rapid electron transfer, and higher hydrophobicity of ZVI particles. As a result, the interaction between ZVI particles and thiamethoxam (a typical neonicotinoid) was improved, and the adsorption–desorption and reductive degradation of thiamethoxam and ·H generation steps were optimized. MNBC-ZVI could rapidly degrade 100% of 10 mg·L−1 thiamethoxam within 360 min, its reduction rate constant was 12.1-fold greater than that of pristine ZVI, and the electron efficiency increased from 29.7% to 57.8%. This improved reactivity and selectivity resulted from increased electron transfer, enhanced hydrophobicity, and reduced accumulation of iron mud. Moreover, the degradation of neonicotinoids occurred mainly via nitrate reduction and dichlorination, and toxicity tests with degradation intermediates revealed that neonicotinoids undergo rapid detoxification. Remarkably, MNBC-ZVI also presented favorable tolerance to various anions, humic acid, wastewater and contaminated soil, as well as high reusability. This work offers an efficient and economic biochar-ZVI remediation technology for the rapid degradation and detoxification of neonicotinoids, significantly contributes to knowledge on the relevant removal mechanism and further advances the synthesis of highly reactive and environmentally friendly materials.Graphical

Temporal and species-specific resistance of sugar beet to green peach aphid and black bean aphid: mechanisms and implications for breeding.

Sugar beet (Beta vulgaris ssp. vulgaris), a key crop for sugar production, faces significant yield losses caused by the black bean aphid Aphis fabae (Scop.) and the green peach aphid Myzus persicae (Sulzer), which also transmits viruses. The restriction on neonicotinoid usage in Europe has intensified this problem, emphasizing the urgent need for breeding resistant crop varieties. This study evaluated 26 sugar beet germplasms for resistance against both aphid species by using performance and feeding behavior assays. Additionally, whole plant bioassays and semi-field experiments were carried out with Myzus persicae. Our findings demonstrate the presence of temporal resistance against both aphid species in the primary sugar beet gene pool. Beet yellows virus (BYV) carrying aphids showed enhanced performance. Different levels of plant defense mechanisms were involved including resistance against Myzus persicae before reaching the phloem, particularly in sugar beet line G3. In contrast, resistance against Aphis fabae turned out to be predominately phloem-located. Furthermore, a high incidence of black inclusion bodies inside the stomach of Myzus persicae was observed for approximately 85% of the plant genotypes tested, indicating a general and strong incompatibility between sugar beet and Myzus persicae in an initial phase of interaction. Sugar beet resistance against aphids involved different mechanisms and is species-specific. The identification of these mechanisms and interactions represents a crucial milestone in advancing the breeding of sugar beet varieties with improved resistance. © 2023 Julius Kühn-Institut and The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Investigation of Neonicotinoids Insecticides with LC-MS/MS in Honey Produced in Giresun

Neonicotinoids are a significant threat to the environment and the food chain given their wide commercial distribution, mode of action, systemic properties, persistence, toxicity profiles of insecticides and metabolites, and their effects on living organisms.These substances, developed as an alternative to organophosphate and carbamate insecticides, pass to all parts of plants, including pollen and nectar, and can be transferred to products produced from these plants, especially bee products. With these systemic effects, neonicotinoids lead to negative effects on living things such as honey bees and wild bees, as well as other vertebrates. Currently, studies on neonicotinoid derivatives and their effects are increasing rapidly, and according to the results of the study, bans and restrictions are imposed on their use in different countries.The aim of the study was to determine the presence and amount of neonicotinoids in honey produced in Giresun province and to measure the level of pollution in the environment and possible public health risks it is revealed. Giresun province, known as the capital of hazelnuts in Turkey, where beekeeping is widespread and many agricultural activities are carried out, has the characteristics and importance to reveal the purpose of the study. For this purpose, 50 honey samples taken during the new harvest period from growers engaged in stationary beekeeping in areas close to Giresun's nut-growing regions were used as materials. Neonicotinoid in samples the presence of (acetamiprid, clothianidin, thiacloprid, imidacloprid,nitenpyram, thiamethoxam and dinotephran) was detected by LC-MS/MS. According to the analysis results; imidacloprid was detected in 9 of 50 honey samples, thiomethoxam in 2, and both imidacloprid and thiomethoxam in 1 were above 10 ppb, which is the limit value, and neonicotinoids were determined in a total of 12 samples. As a result, the presence of possible neonicotinoids in honey, which is recommended for therapeutic consumption, a sine qua non of healthy diets with high nutritional value, is a potential danger to public health. Neonicotinoid contamination in honey and other bee products, which are often consumed, especially by children and decrepit people, is extremely important in terms of the health risks it may pose. Within the framework of good agricultural practice, the selection of beekeeping areas and the introduction of restrictions on the use of neonicotinoids in this direction in parallel with the EU are important for preventing possible risks.

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.

Residue, distribution and degradation of neonicotinoids and their metabolites in chrysanthemum plants and cultivated soils

In this study, the residue, distribution, adsorption and degradation of neonicotinoids were systematically evaluated in chrysanthemum planting sites. There were low residues of neonicotinoids in plants (<19.35 μg kg−1) and cultivated soils (<11.45 μg kg−1) without use of neonicotinoids in the past three years, but high residues were found in other chrysanthemum plants (304.66–582.15 μg kg−1) and soils (126.44–275.45 μg kg−1). Leaf and soil were more likely to accumulate neonicotinoids. The residues of imidacloprid and its metabolites in plants and soils showed positive correlations. Additionally, neonicotinoids were weakly adsorbed by soil (KOC = 249–509 L kg−1), and the degradation half-lives were 20–36 days. High residues of imidacloprid in soils had serious ecological risk to the organisms in the planting regions. It reminds us to pay more attention to neonicotinoids residues in the plants and the growing environment, which is of great significance for ensuring human dietary safety and reducing environmental risks.

S-dinotefuran affects the social behavior of honeybees (Apis mellifera)and increases their risk in the colony

The toxic effects of neonicotinoid pesticides on honeybees is a global concern, whereas little is known about the effect of stereoisomeric pesticides among honeybee social behavior. In this study, we investigated the effects of stereoisomeric dinotefuran on honeybee social behavior. We found that honeybees exhibit a preference for consuming food containing S-dinotefuran, actively engage in trophallaxis with S-dinotefuran–consuming peers, and consequently acquire higher levels of S-dinotefuran compared with R-dinotefuran. In comparison to R-dinotefuran, S-dinotefuran stimulates honeybees to elevate their body temperature, thereby attracting more peers for trophallaxis. Transcriptome analysis revealed a significant enrichment of thermogenesis pathways due to S-dinotefuran exposure. Additionally, metabolome data indicated that S-dinotefuran may enhance body temperature by promoting lipid synthesis in the lysine degradation pathway. Consequently, body temperature emerges as a key factor influencing honeybee social behavior. Our study is the first to highlight the propensity of S-dinotefuran to raise honeybee body temperature, which prompts honeybee to preferentially engage in trophallaxis with peers exhibiting higher body temperatures. This preference may lead honeybees to collect more dinotefuran-contaminated food in the wild, significantly accelerating dinotefuran transmission within a population. Proactive trophallaxis further amplifies the risk of neonicotinoid pesticide transmission within a population, making honeybees that have consumed S-dinotefuran particularly favored within their colonies. These findings may contribute to our understanding of the higher risk associated with neonicotinoid use compared with other pesticides.

Association between urinary neonicotinoid insecticide levels and dyslipidemia risk: A cross-sectional study in Chinese community-dwelling elderly

Experimental evidence has demonstrated that neonicotinoids (NEOs) exposure can cause lipid accumulation and increased leptin levels. However, the relationship between NEOs exposure and dyslipidemia in humans remains unclear, and the interactive effects of NEOs and their characteristic metabolites on dyslipidemia remain unknown. We detected 14 NEOs and their metabolites in urine samples of 500 individuals (236 and 264 with and without dyslipidemia, respectively) randomly selected from the baseline of the Yinchuan community-dwelling elderly cohort (Ningxia, China). The NEOs and their metabolites were widely detected in urine (87.2–99.6 %) samples, and the median levels ranged within 0.06–0.55 μg/g creatinine. The positive associations and dose-dependent relationships of thiacloprid, imidacloprid-olefin, and imidacloprid-equivalent total with dyslipidemia were validated using restricted cubic spline analysis. Mixture models revealed a positive association between the NEOs mixture and dyslipidemia risk, with urine desnitro-imidacloprid ranked as the top contributor. The Bayesian Kernel Machine Regression models showed that the NEOs mixtures were associated with increased dyslipidemia when the chemical mixtures were ≥ 25th percentile compared to their medians, and desnitro-imidacloprid and imidacloprid-olefin were the major contributors to the combined effect. Given the widespread use of NEOs and the dyslipidemia pandemic, further investigations are urgently needed to confirm our findings and elucidate the underlying mechanisms.

Combining Irradiation and Biological Control against Brown Marmorated Stink Bug: Are Sterile Eggs a Suitable Substrate for the Egg Parasitoid Trissolcus japonicus?

The brown marmorated stink bug (BMSB), Halyomorpha halys, is a phytophagous invasive pest native to south-eastern Asia, and it is now distributed worldwide. This species is considered to be one of the most damaging insect pests in North America and in Europe. In agriculture, the predominant approach to managing BMSB is based on the use of insecticides, specifically pyrethroids and neonicotinoids. Unfortunately, the biology of the species and its facility to develop mechanisms of resistance to available pesticides has induced farmers and scientists to develop different, least-toxic, and more effective strategies of control. In a territorial area-wide approach, the use of a classical biological control program in combination with other least-toxic strategies has been given prominent consideration. Following exploratory surveys in the native range, attention has focused on Trissolcus japonicus, a small scelionid egg parasitoid wasp that is able to oviposit and complete its larval development in a single egg of H. halys. A common method for detecting egg parasitoids in the native range involves the placement of so-called 'sentinel' egg masses of the pest in the environment for a short period, which are then returned to the laboratory to determine if any of them are parasitized. Outside of the area of origin, the use of fertile sentinel eggs of the alien species may lead to the further release of the pest species; an alternative is to use sterile sentinel eggs to record the presence of new indigenous egg parasitoids or to detect the dispersal of alien species (in this case, T. japonicus) released in a new environment to control the target insect pest species. This study evaluated the performance of three types of sterile sentinel eggs as a suitable substrate for the oviposition and larval development of the egg parasitoid T. japonicus in a context of combining classical biological control with a Sterile Insect Technique (SIT) approach.

The impact of thiamethoxam on the feeding and behavior of 2 soybean herbivore feeding guilds.

Over the past few decades, inadvertent consequences have stemmed from the intensified use of neonicotinoids in agroecosystems. Neonicotinoid applications can result in both positive (e.g., reduced persistent virus transmission) and negative (e.g., increased host susceptibility) repercussions exhibiting ambiguity for their use in crop production. In soybean, aspects of neonicotinoid usage such as the impact on nonpersistent virus transmission and efficacy against nontarget herbivores have not been addressed. This study evaluated the interaction between the neonicotinoid thiamethoxam and soybean variety and the impact on different pest feeding guilds. Feeding and behavioral bioassays were conducted in the laboratory to assess the effect of thiamethoxam on the mortality and weight gain of the defoliator, Chrysodeixis includens (Walker). Bioassays evaluated impacts dependent and independent of soybean tissue, in addition to both localized and systemic efficacy within the soybean plant. Additionally, using the electrical penetration graph technique (EPG), the probing behavior of 2 piercing-sucking pests, Aphis gossypii Glover and Myzus persicae (Sulzer), was observed. Results from defoliator bioassays revealed thiamethoxam had insecticidal activity against C. includens. Distinctions in thiamethoxam-related mortality between bioassays dependent and independent of soybean tissue (~98% versus ~30% mortality) indicate a contribution of the plant towards defoliator-related toxicity. Observations of defoliator feeding behavior showed a preference for untreated soybean tissue relative to thiamethoxam-treated tissue, suggesting a deterrent effect of thiamethoxam. EPG monitoring of probing behavior exhibited a minimal effect of thiamethoxam on piercing-sucking herbivores. Findings from this study suggest neonicotinoids like thiamethoxam may provide some benefit via insecticidal activity against nontarget defoliators.

The neonicotinoid thiacloprid leads to multiple defects during early embryogenesis of the South African clawed frog (Xenopuslaevis).

There is increasing concern about the health effects of pesticides that pollute natural waters. In particular, the use of neonicotinoids, such as thiacloprid (THD), is causing unease. THD is considered non-toxic to non-target vertebrates. Studies classify THD as carcinogenic, toxic to reproduction, and therefore harmful to the environment. A detailed study of possible THD effects during the amphibian embryogenesis is needed because leaching can introduce THD into aquatic environments. We incubated stage 2 embryos of the South African clawed frog in various THD concentrations (0.1-100mg/L) at 14°C to study the potential effects of a one-time THD contamination of waters on the early embryogenesis. We showed that THD has, indeed, negative effects on the embryonic development of the X. laevis. A treatment with THD led to a reduced embryonic body length and mobility. Furthermore, a treatment with THD resulted in smaller cranial cartilages, eyes and brains, and the embryos had shorter cranial nerves and an impaired cardiogenesis. On a molecular basis, THD led to a reduced expression of the brain marker emx1 and the heart marker mhcα. Our results underly the importance of a strict and efficient monitoring of the regulatory levels and application areas of THD.

Neonicotinoid Analysis in Sunflower (Helianthus annuus) Honey Samples Collected around Tekirdag in Turkey.

In recent years, the widespread use of neonicotinoids in agricultural areas has caused environmental pollution due to its lower toxicity to mammals. Honey bees, which are considered as biological indicators of environmental pollution, can carry these pollutants to the hives. Forager bees returning from sunflower crops that have been treated with neonicotinoids treated sunflower fields cause residue accumulation in the hives, which reason colony-level adverse effects. This study analyses neonicotinoid residues in sunflower (Helianthus annuus) honey sampled by beekeepers from Tekirdag province. Honey samples have been subjected to liquid-liquid extraction methods before liquid chromatography-mass spectrometry (LC-MS/MS). The method validation was carried out to fulfill all the necessary requirements of procedures SANCO/12571/2013. Accuracy was in the range of 93.63-108.56%, for recovery in the range of 63.04-103.19%, and for precision in the range 6.03-12.77%. Detection and quantification limits were determined according to the maximum residue limits of each analyte. No neonicotinoid residues were found above the maximum residue limit in the sunflower honey samples analysed.

Potential risk to pollinators from neonicotinoid applications to host trees for management of spotted lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae).

Neonicotinoid insecticides are used to manage spotted lanternfly (Lycorma delicatula (White); hereafter SLF), a recently introduced pest in the United States. Neonicotinoids can harm nontargets, such as pollinators potentially exposed via floral resources of treated plants. We quantified neonicotinoid residues in whole flowers of two SLF host plant species, red maple (Acer rubrum L. [Sapindales: Sapindaceae]) and tree-of-heaven (Ailanthus altissima (Mill.) [Sapindales: Simaroubaceae]), treated with post-bloom imidacloprid or dinotefuran applications that differed in timing and method of application. In red maple flowers, dinotefuran residues from fall applications were significantly higher than summer applications, while imidacloprid residues from fall applications were significantly lower than summer applications. Residues did not differ between application methods or sites. In tree-of-heaven flowers, dinotefuran residues were only detected in one of 28 samples at a very low concentration. To assess acute mortality risk to bees from oral exposure to residues in these flowers, we calculated risk quotients (RQ) using mean and 95% prediction interval residue concentrations from treatments in this study and lethal concentrations obtained from acute oral bioassays for Apis mellifera (L. (Hymenoptera: Apidae)) and Osmia cornifrons (Radoszkowski (Hymenoptera: Megachilidae)), then compared these RQs to a level of concern. For A. mellifera, only one treatment group, applied at 2X maximum label rate, had an RQ that exceeded this level. However, several RQs for O. cornifrons exceeded the level of concern, suggesting potential acute risk to solitary bees. Further studies are recommended for more comprehensive risk assessments to nontargets from neonicotinoid use for SLF management.

Efficient degradation of clothianidin and thiamethoxam in contaminated soil by peroxymonosulfate process.

The widespread use of neonicotinoids has led to their frequent detection in the environment and potential environmental risk in recent years. Clothianidin (CLO) and thiamethoxam (TMX), as the second generation of neonicotinoid insecticides, are usually used as seed agents with a high risk of residue in the soil. Efficient degradation of CLO and TMX in soil using peroxymonosulfate (PMS) process was investigated in the present study. The degradation efficiencies of CLO and TMX reached 91.4% and 98.6% in 60min with the addition of 20mM PMS at pH 5.5 and 25℃. High degradation efficiencies of CLO were achieved with a high PMS dosage and temperature or a low CLO concentration and initial pH. The degradation of CLO was reduced in the presence of high concentration of inorganic anions (Cl-, HCO3-). Soil organic matter might be one critical factor in the degradation of CLO and TMX. Radical scavenger experiments confirmed SO4•- and 1O2 were the dominant reactive species on the CLO and TMX degradation. Based on the detected degradation intermediates, the degradation pathways of CLO and TMX include dichlorination, hydroxylation, cleavage of C-N or C-C bond and further oxidation in the PMS-based soil. Overall, the PMS process is one effective and economical method for the remediation of the neonicotinoid contaminated soil.

Temperature-dependent effects of neonicotinoids on the embryonic development of zebrafish (Danio rerio)

The agricultural use of neonicotinoids is increasing worldwide and poses a threat to non-target organisms. The existing toxicity data of neonicotinoids that is mainly focused on widely used neonicotinoids ignores the influence of environmental factors, like temperature, related to climate changes, etc. To fill this data gap, the present study assessed the temperature-dependent toxicity of six neonicotinoids at four temperatures. Briefly, a fish embryo toxicity test was performed at the following temperatures—20, 23, 28, and 33°C—on zebrafish embryos to evaluate the lethal and sublethal effects of these toxicants. At 28°C, the lethal toxicity (LC50) values for these toxicants were cycloxaprid—3.36 mg/L, nitenpyram—7.08 mg/L, paichongding—17.2 mg/L, imidaclothiz—738.6 mg/L, dinotefuran—2,096 mg/L, and thiamethoxam—4,293 mg/L, respectively. Among the sublethal effects, the enzymatic activities changed significantly in neonicotinoid treatments, which revealed oxidative stress, metabolic disorders, and neurotoxicity. Particularly, acetylcholinesterase inhibition and glutathione S-transferase activation showed a significant dose–response relationship. However, cycloxaprid, nitenpyram, and paichongding were found to be more potent compared with imidaclothiz and thiamethoxam. The influence of temperature on these neonicotinoids demonstrated an inverted V-shaped relationship, in which toxicity decreased with the increase of temperature and then increased with the increase of temperature after exceeding the optimum temperature. This study provides a reference for the multiscale effects and potential mechanisms of neonicotinoids. Temperature-dependent toxicity is of great significance for future toxicity testing and risk assessment of chemicals in the face of global climate changes.