Disposition and acute toxicity of imidacloprid in female rats after single exposure

Structural gonadal lesions observed in Japanese quail (Coturnix coturnix japonica) following exposure during puberty to the neonicotinoid pesticide, imidacloprid

Exposure to the neonicotinoid insecticide, imidacloprid (IMI), causes reproductive toxicity in mammals and reptiles. However, reports on the effects of IMI on the gonads in birds are grossly lacking. Therefore, this study investigated the effects of pubertal exposure to IMI on the histology, ultrastructure, as well as the cytoskeletal proteins, desmin, smooth muscle actin and vimentin, of the gonads of Japanese quail (Coturnix coturnix japonica). Quails were randomly divided into four groups at 5 weeks of age. The control group was given only distilled water, whereas, the other three experimental groups, IMI was administered by oral gavage at 1.55, 3.1, and 6.2 mg/kg, twice per week for 4 weeks. Exposure to IMI doses of 3.1 and 6.2 mg/kg caused dose-dependent histopathological changes in the ovary and testis. In the ovary, accumulation of lymphocytes, degenerative changes, and necrosis with granulocyte infiltrations were observed, while in the testis, distorted seminiferous tubules, germ cell sloughing, vacuolisations, apoptotic bodies, autophagosomes, and mitochondrial damage were detected. These changes were accompanied by a decreased number of primary follicles (P ≤ 0.05) in the ovary and a decrease (P ≤ 0.05) in the epithelial height, luminal, and tubular diameters of seminiferous tubules at the two higher dosages. In addition, IMI had a negative effect on the immunostaining intensity of desmin, smooth muscle actin, and vimentin in the ovarian and testicular tissue. In conclusion, exposure to IMI during puberty can lead to a range of histopathological alterations in the gonads of Japanese quails, which may ultimately result in infertility.

Thymol's modulation of cellular macromolecules, oxidative stress, DNA damage, and NF-kB/caspase-3 signaling in the liver of imidacloprid-exposed rats

We evaluated whether thymol (THY) (30 mg/kg b.wt) could relieve the adverse effects of the neonicotinoid insecticide imidacloprid (IMD) (22.5 mg/kg b.wt) on the liver in a 56-day oral experiment and the probable underlying mechanisms. THY significantly suppressed the IMD-associated increase in hepatic enzyme leakage. Besides, the IMD-induced dyslipidemia was considerably corrected by THY. Moreover, THY significantly repressed the IMD-induced hepatic oxidative stress, lipid peroxidation, DNA damage, and inflammation. Of note, the Feulgen, mercuric bromophenol blue, and PAS-stained hepatic tissue sections analysis declared that treatment with THY largely rescued the IMD-induced depletion of the DNA, total proteins, and polysaccharides. Moreover, THY treatment did not affect the NF-kB p65 immunoexpression but markedly downregulated the Caspase-3 in the hepatocytes of the THY+IMD-treated group than the IMD-treated group. Conclusively, THY could efficiently protect against IMD-induced hepatotoxicity, probably through protecting cellular macromolecules and antioxidant, antiapoptotic, and anti-inflammatory activities.

Neonicotinoids differentially modulate nicotinic acetylcholine receptors in immature and antral follicles in the mouse ovary1

Neonicotinoids are the most widely used insecticides in the world. They are synthetic nicotine derivatives that act as nicotinic acetylcholine receptor (nAChR) agonists. Although parent neonicotinoids have low affinity for the mammalian nAChR, they can be activated in the environment and the body to positively charged metabolites with high affinity for the mammalian nAChR. Imidacloprid (IMI), the most popular neonicotinoid, and its bioactive metabolite desnitro-imidacloprid (DNI) differentially interfere with ovarian antral follicle physiology in vitro, but their effects on ovarian nAChR subunit expression are unknown. Furthermore, ovarian nAChR subtypes have yet to be characterized in the ovary. Thus, this work tested the hypothesis that ovarian follicles express nAChRs and their expression is differentially modulated by IMI and DNI in vitro. We used PCR, RNA in situ hybridization, and immunohistochemistry to identify and localize nAChR subunits (α2, 4, 5, 6, 7 and β1, 2, 4) expressed in neonatal ovaries and antral follicles. Chrnb1 was expressed equally in neonatal ovaries and antral follicles. Chrna2 and Chrnb2 expression was higher in antral follicles compared to neonatal ovaries and Chrna4, Chrna5, Chrna6, Chrna7 and Chrnb4 expression was higher in neonatal ovaries compared to antral follicles. The α subunits were detected throughout the ovary, especially in oocytes and granulosa cells. IMI and DNI dysregulated expression of multiple nAChR subunits in neonatal ovaries, but only dysregulated one subunit in antral follicles. These data indicate that mammalian ovaries contain nAChRs, and their susceptibility to IMI and DNI exposure varies with the stage of follicle maturity.

Imidacloprid disrupts larval molting regulation and nutrient energy metabolism, causing developmental delay in honey bee Apis mellifera

Imidacloprid is a global health threat that severely poisons the economically and ecologically important honeybee pollinator, Apis mellifera. However, its effects on developing bee larvae remain largely unexplored. Our pilot study showed that imidacloprid causes developmental delay in bee larvae, but the underlying toxicological mechanisms remain incompletely understood. In this study, we exposed bee larvae to imidacloprid at environmentally relevant concentrations of 0.7, 1.2, 3.1, and 377 ppb. There was a marked dose-dependent delay in larval development, characterized by reductions in body mass, width, and growth index. However, imidacloprid did not affect on larval survival and food consumption. The primary toxicological effects induced by elevated concentrations of imidacloprid (377 ppb) included inhibition of neural transmission gene expression, induction of oxidative stress, gut structural damage, and apoptosis, inhibition of developmental regulatory hormones and genes, suppression of gene expression levels involved in proteolysis, amino acid transport, protein synthesis, carbohydrate catabolism, oxidative phosphorylation, and glycolysis energy production. In addition, we found that the larvae may use antioxidant defenses and P450 detoxification mechanisms to mitigate the effects of imidacloprid. Ultimately, this study provides the first evidence that environmentally exposed imidacloprid can affect the growth and development of bee larvae by disrupting molting regulation and limiting the metabolism and utilization of dietary nutrients and energy. These findings have broader implications for studies assessing pesticide hazards in other juvenile animals.

Physiological responses of oxidative damage, genotoxicity and hematological parameters of the toxic effect of neonicotinoid-thiamethoxam in Oreochromis niloticus

The purpose of investigation assessed the impacts of neonicotinoid thiamethoxam (TMX) at sublethal concentrations in hematological profile and renal function of Oreochromis niloticus. In the experiment, fish were exposed to TMX in four groups (0, 50, 100 and 150 ppm) for 7 days. At the end of the experiment, biochemical analysis of blood samples showed that the parameters indicating renal function showed a significant increase in serum enzymes ALT, AST, ALP and metabolites (BUN, urea, uric acid, creatinine and cortisol) concentrations, while albumin concentration decreased in a dose-dependent manner compared to the control group. In parallel with the decrease in Na+, K+ and Ca+2 in blood ion levels, there was a significant decrease in the activity of Na+/K+ ATPase, Ca+2 ATPase and AChE enzyme, levels of GSH and HSP70 in kidney tissue in TMX groups compared to the control group. It was determined that the toxic effect of TMX caused a significant increase in TBARS, PC, 8-OHdG levels, respectively. In conclusion, our study shows that TMX causes dose-dependent toxic effects, with knock-on effects on physiological processes regarding the hematological profile and renal function of O. niloticus.

Aquatic ecological risk assessment of imidacloprid and thiacloprid in an urban river of Qingdao, China

Imidacloprid and thiacloprid, two neonicotinoid insecticides that are extensively used in urban areas, are potentially toxic to non-target aquatic organisms. In this study, the concentrations of imidacloprid and thiacloprid in surface runoff after rainfall were 20.79-43.77 ng/L and 25.13-63.84 ng/L, respectively, whereas the levels for the Licun River were 10.78-41.70 ng/L and 2.66-39.68 ng/L, respectively. The acute and chronic criteria for imidacloprid and thiacloprid are 0.865, 0.006, 0.83, and 0.012 μg/L, respectively. Tiered ecological risk assessments revealed the chronic ecological risks of these micropollutants to local aquatic species. There was a moderate chronic toxicity risk associated with imidacloprid and thiacloprid in the Licun River, and the joint probability curves showed a probability of chronic ecological risk to 5 % of the aquatic organisms at 68 %-97 %. The results provide evidence of urban surface runoff transporting micropollutants from surface into rivers and estuaries, highlighting the ecological risks to aquatic ecosystems.

Behavioral and physiological changes in the passerine Agelaioides badius following the ingestion of coated seeds with imidacloprid in a 30-day experiment

The wide use of neonicotinoid seed treatment represents a hazard for farmland birds that feed on treated seeds. This study aimed to characterize the long-term effects of the neonicotinoid imidacloprid (IMI) in the passerine grayish baywing (Agelaioides badius). The birds were fed ad libitum for 32 days only with seeds treated with 53.1 (Low, 11 % of LD50) and 514 (High, (112 % of LD50) mg IMI/kg seed; these concentrations representing respectively, 1.8 and 17.1 % of 3 g IMI/kg, an average application rate used to treat crop seeds in Argentina. The effects exerted by IMI on birds were evaluated at behavioral, physiological, hematological, genotoxic, and biochemical levels. No differences in food consumption were observed between Control and Low treatments birds, indicating a lack of aversion to treated seeds. High treatment birds only decreased their food consumption by 20 % in the first 3 days of exposure. Birds from High treatment experienced an early loss of body weight, reduction in their mobility, lack of response to threats (i.e., predator call and approaching person), and altered their use of the cage. On the contrary, birds from Low treatment experienced a delay in the onset of effects like reduction in mobility, lack of response to threats, and a tendency to reduce their body weight. At the end of exposure, glutathione S transferase activity in the plasma of treated birds decreased, and cholinesterase activity increased in the liver of treated birds. This study highlights that consumption equivalent to 1.8 % of the daily diet of baywings as IMI-treated seeds, is sufficient to generate behavioral and physiological alterations and death. In the wild, these effects may have ecological consequences, by impairing the survival of birds, representing a risk to farmland bird populations.

Ovarian antral follicles metabolize imidacloprid in vitro

Neonicotinoid insecticides are synthetic nicotine derivatives that have high affinity for invertebrate nicotine receptors and low affinity for mammalian nicotine receptors. However, imidacloprid (IMI), the most commonly used neonicotinoid, can be bioactivated by the liver in mammals to desnitro-imidacloprid, an intermediate metabolite that effectively binds and activates mammalian receptors. However, it is not known if other tissues such as the ovaries can metabolize IMI. Thus, the present study tested the hypothesis that ovarian antral follicles metabolize and bioactivate IMI. Antral follicles were dissected from the ovaries of CD-1 mice and cultured in media containing dimethyl sulfoxide or IMI (0.2-200 µg/ml) for 48 and 96 h. Media were subjected to liquid chromatography-mass spectrometry for detection of phase I IMI metabolites. Follicles from the cultures were used for gene expression analysis of metabolic enzymes associated with IMI metabolism. All IMI metabolites were detected at 48 and 96 h. Oxidized IMI intermediates were detected in media from cultured follicles, but not environmental controls. Reduced IMI intermediates were detected in media from cultured follicles and the environmental controls. At 48 h, IMI did not affect expression of any metabolic enzymes compared with control. At 96 h, IMI induced Cyp2e1 and Cyp4f18 compared with control. These data indicate that mouse ovarian follicles metabolize IMI and that IMI induces ovarian Cyp expression over time.

Imidacloprid and Its Bioactive Metabolite, Desnitro-Imidacloprid, Differentially Affect Ovarian Antral Follicle Growth, Morphology, and Hormone Synthesis In Vitro

Imidacloprid is a neonicotinoid pesticide used in large-scale agricultural systems, home gardens, and veterinary pharmaceuticals. Imidacloprid is a small molecule that is more water-soluble than other insecticides, increasing the likelihood of large-scale environmental accumulation and chronic exposure of non-targeted species. Imidacloprid can be converted to the bioactive metabolite desnitro-imidacloprid in the environment and body. Little is known about the mechanisms by which imidacloprid and desnitro-imidacloprid induce ovarian toxicity. Thus, we tested the hypothesis that imidacloprid and desnitro-imidacloprid differentially affect antral follicle growth and steroidogenesis in vitro. Antral follicles were dissected from the ovaries of CD-1 mice and cultured in media containing vehicle control or 0.2 µg/mL-200 µg/mL of imidacloprid or desnitro-imidacloprid for 96 h. Follicle morphology was monitored, and follicle size was measured every 24 h. At the end of the culture periods, media were used to quantify follicular hormone levels, and follicles were used for gene expression analysis of steroidogenic regulators, hormone receptors, and apoptotic factors. Imidacloprid did not affect follicle growth or morphology compared to the control. Desnitro-imidacloprid inhibited follicle growth and caused follicles to rupture in culture compared to the control. Imidacloprid increased progesterone, whereas desnitro-imidacloprid decreased testosterone and progesterone compared to the control. Desnitro-imidacloprid also changed estradiol compared to the control. At 48 h, IMI decreased the expression of Star, Cyp17a1, Hsd17b1, Cyp19a1, and Esr2 and increased the expression of Cyp11a1, Cyp19a1, Bax, and Bcl2 compared to the control. IMI also changed the expression of Esr1 compared to the control. At 48 h, DNI decreased the expression of Cyp11a1, Cyp17a1, Hsd3b1, Cyp19a1, and Esr1 and increased the expression of Cyp11a1, Hsd3b1, and Bax compared to the control. At 72 h of culture, IMI significantly decreased the expression of Cyp19a1 and increased the expression of Star and Hsd17b1 compared to the control. At 72 h, DNI significantly decreased the expression of Cyp11a1, Cyp17a1, Hsd3b1, and Bax and increased the expression of Esr1 and Esr2. At 96 h, IMI decreased the expression of Hsd3b1, Cyp19a1, Esr1, Bax, and Bcl2 compared to the control. At 96 h, DNI decreased the expression of Cyp17a1, Bax, and Bcl2 and increased the expression of Cyp11a1, Hsd3b1, and Bax compared to the control. Together, these data suggest mouse antral follicles are targets of neonicotinoid toxicity, and the mechanisms of toxicity differ between parent compounds and metabolites.

First evidence of neonicotinoid insecticides in human bile and associated hepatotoxicity risk

Neonicotinoids (NEOs) are widely applied in agricultural lands and are widespread in different environments, accelerating threats to ecosystems and human health. A number of in vitro/in vivo studies have reported adverse effects of NEOs on mammalian health, but the link between NEO exposure and toxic effects on human liver remains unclear. We randomly recruited 201 participants and quantified eight commercialized NEOs in bile. High frequency and concentration of detection indicate low degradation of human liver on NEOs. The main NEOs are nitenpyram and dinotefuran, which contribute to about 86% of the total residual levels of eight NEOs, due to the highest solubility in bile and are not degraded easily in liver. In contrast, imidacloprid and thiacloprid are major compounds in human blood, according to previous studies, suggesting that individual NEOs behave differently in blood and bile distribution. There was no statistical difference in NEO residues between cancer and non-cancer participants and among the different participant demographics (e.g., age, gender, and body mass index). The serum hematological parameters -bile acid, total bilirubin, cholesterol and alkaline phosphatase -were positively correlated with individual NEO concentrations, suggesting that NEO exposure affects liver metabolism and even enterohepatic circulation. The study first examined the NEO residues in human bile and provided new insights into their bioavailability and hepatoxicity risk.

Neonicotinoid insecticides promote breast cancer progression via G protein-coupled estrogen receptor: In vivo, in vitro and in silico studies

Neonicotinoid insecticides (NIs) have been widely detected in environmental media and human body with concentrations reaching hundreds of nanomolar to micromolar levels. However, the information about their human health toxicology and mechanism is deficient. Previous studies have implied that NIs might exert estrogenic disruption and promote breast cancer progression, but the molecular mechanism is unclear, especially the molecular initiating event. G protein-coupled estrogen receptor (GPER), as a candidate therapeutic target, plays vital roles in the development of breast cancer. This work aimed to reveal the potential mechanism through GPER pathway. Firstly, we screened the activities of seven most common NIs on GPER signal pathway by calcium mobilization assay. Clothianidin, acetamiprid (ACE), and dinotefuran activated GPER most potently and ACE displayed the highest agonistic activity with the lowest observed effective concentration (LOEC) of 1 μM. The molecular docking and dynamics simulation showed favored interaction trend between the NIs and GPER. The three NIs with GPER activity induced 4T1 breast cancer cells migration and ACE showed the highest potency with LOEC of 100 nM. ACE also induced 4T1 cells proliferation at high concentration of 50 μM and up-regulated GPER expression in a dose-dependent manner. We speculated that both the induction effects of ACE on 4T1 cells proliferation and migration might be owing to the activation and up-regulation of GPER. By using 4T1-Luc cells injected orthotopic tumor model, we found that ACE also promoted in-situ breast cancer growth and lung metastasis in normal mouse dependent on GPER. However, ACE only promoted in-situ breast cancer growth through GPER but not lung metastasis in ovariectomized mice, implying that the ACE-induced lung metastasis should be related to endogenous estrogen from ovary. Overall, we demonstrated that NIs promoted breast cancer progression via GPER pathway at human related exposure levels and their female health risks need urgent concerns.

Inhibition of the Nrf2 signaling pathway involved in imidacloprid-induced liver fibrosis in Coturnix japonica

Imidacloprid (IMI) is a kind of widely used neonicotinoid insecticide. However, the toxicity of IMI is not only applied to target pests but also causes serious negative effects on birds and other creatures. Our previous studies have shown that long-term exposure to IMI can induce liver fibrosis in quails. However, the specific mechanism of quail liver fibrosis induced by IMI is not completely clear. Accordingly, the purpose of this study is to further clarify the potential molecular mechanism of IMI-induced liver fibrosis in quails. Japanese quails (Coturnix japonica) were treated with/without IMI (intragastric administration with 6 mg/kg body weight) in the presence/absence of luteolin (Lut) (fed with 800 mg/kg) for 90 days. The results reveal that IMI can induce hepatic fibrosis, oxidative stress, fatty degeneration, inflammation, and the down-expression of nuclear factor-E2-related factor-2 (Nrf2). Furthermore, the treatment of Lut, a kind of Nrf2 activator, increased the expression of Nrf2 in livers and alleviated liver fibrosis in quails. Altogether, our study demonstrates that inhibition of the Nrf2 pathway is the key to liver fibrosis induced by IMI in quails. These results provide a new understanding for the study of the toxicity of IMI and a practical basis for the treatment of liver fibrosis caused by IMI.

Tissue distribution and sublethal effects of imidacloprid in the South American grayish baywing (Agelaioides badius)

The neonicotinoids are globally used insecticides, which have been shown to cause negative impacts on birds. The current study aimed to evaluate the distribution of the neonicotinoid imidacloprid (IMI) in the tissues of a songbird and identify related physiological effects. Adults of the grayish baywing (Agelaioides baduis) were administered with a single dose of 35 mg IMI/kg, and the IMI concentration was evaluated in liver, kidney and plasma at 4, 12, 24, and 48 h after dosing. At the same time points, effects on hematological, genetic and enzymatic parameters were assessed. Results showed that IMI was absorbed before 4 h, and eliminated at 48 h, in every tissue, and the highest concentrations were detected in plasma. Baywings showed intoxication signs and reduced mobility within the first 5 min post-dosing. Hematological parameters: red blood cells, packed cell volume, hemoglobin, and their derived indices exhibited a transient elevation 24 h after dosing, which coincided with maximum concentrations of IMI in the tissues. No effects were observed on the genotoxicity parameters evaluated: micronuclei and comet assay. Treated birds exhibited an alteration of cholinesterases activity in the muscle and plasma, and of glutathione-S-transferase (GST) activity in the plasma, brain, liver, and muscle. Based on the results obtained, the combined detection of IMI and inhibition of GST activity in the plasma is suggested as a non-lethal biomarker of IMI exposure in wild birds. As efficient field monitoring depends on the availability of proven biomarkers, the current study provides valuable tools for bird conservation in agroecosystems.

Effects of imidacloprid on viability and increase of reactive oxygen and nitrogen species in HepG2 cell line

Imidacloprid (IMD) is a neonicotinoid insecticide used in large quantities worldwide in both veterinary and agronomic applications. Several studies have shown adverse effects of IMD on non-target organisms, with the liver being identified as the main affected organ. This study aimed to evaluate the effects of IMD on human hepatoblastoma (HepG2) cells. HepG2 were exposed to IMD (0.25-2.0 mM) for 24 and 48 h. IMD treatment resulted in cytotoxicity in the HepG2, inhibiting cell proliferation in a dose- and time-dependent manner, starting at concentrations of 0.5 mM (24 h) and 0.25 mM (48 h), and reducing cell viability from 0.5 mM onwards (24 and 48 h). IMD significantly decreased the mitochondrial membrane potential at both time points investigated (2.0 mM), and also induced damage to the cell membrane, demonstrated by significant dose and time-dependent increases in lactate dehydrogenase (LDH) release from concentrations of 1.0 mM (24 h) and 0.5 mM (48 h) upwards. IMD treatment also increased the production of reactive oxygen and nitrogen species (ROS/RNS) at rates above 50% following 0.5 mM (24 h) or 0.25 mM (48 h) concentrations, and caused a significant decrease in reduced/oxidized glutathione ratio (GSH/GSSG), indicating oxidative stress. Furthermore, the antioxidant dithiothreitol, which reacts with ROS/RNS and acts as a thiol reducing agent, inhibited the cytotoxic effect of IMD. In addition, the metabolite IMD-olefin was more toxic than IMD. Our results indicate that IMD induces cytotoxicity in HepG2 cells and that this effect may be associated with an increase in the generation of ROS/RNS.

The protective role of resveratrol against sulfoxaflor-induced toxicity in testis of adult male rats

This work was designed to explore the protective role of resveratrol (RES) against sulfoxaflor (Sulfx)-induced reproductive toxicity in adult male rats. The animals were divided into six groups: Control group, Sulfx treated groups (79.5 and 205 mg/kg/day), RES treated group (20 mg/kg/day), RES + Sulfx treated groups (20 mg/kg Res + 79.5 or 205 mg/kg Sulfx) orally for 28 consecutive days. Testicular samples were collected from all groups at the end of the treatment period. Tissue supernatants were isolated for oxidative stress and cellular energy parameters; tissue samples were prepared for histopathological examination. In addition, caspase-3 activity was calculated to assess spermatogenesis. Finally, DNA laddering assay was performed to detect DNA fragmentation as a hallmark of apoptosis. Our results showed that Sulfx treatment induced a significant increase in testicular levels of MDA, NOx, GSSG and reduced GSH level and cellular energy parameters in a dose-dependent manner compared to the control group. The results were confirmed by histopathological study which showed pathological changes in Sulfx treated groups. A significant increase in caspase 3 and DNA fragmentation was also observed. However, concomitant administration of RES to Sulfx -treated rats showed significant modulation against Sulfx-induced reproductive toxicity and attenuated the biochemical, apoptotic and histopathological changes. In conclusion, our results suggest that exposure to Sulfx at the two selected doses induces testicular toxicity and these effects can be ameliorated by supplementation of RES.

Neurotoxic Effects of Neonicotinoids on Mammals: What Is There beyond the Activation of Nicotinic Acetylcholine Receptors?-A Systematic Review

Neonicotinoids are a class of insecticides that exert their effect through a specific action on neuronal nicotinic acetylcholine receptors (nAChRs). The success of these insecticides is due to this mechanism of action, since they act as potent agonists of insect nAChRs, presenting low affinity for vertebrate nAChRs, which reduces potential toxic risk and increases safety for non-target species. However, although neonicotinoids are considered safe, their presence in the environment could increase the risk of exposure and toxicity. On the other hand, although neonicotinoids have low affinity for mammalian nAChRs, the large quantity, variety, and ubiquity of these receptors, combined with its diversity of functions, raises the question of what effects these insecticides can produce in non-target species. In the present systematic review, we investigate the available evidence on the biochemical and behavioral effects of neonicotinoids on the mammalian nervous system. In general, exposure to neonicotinoids at an early age alters the correct neuronal development, with decreases in neurogenesis and alterations in migration, and induces neuroinflammation. In adulthood, neonicotinoids induce neurobehavioral toxicity, these effects being associated with their modulating action on nAChRs, with consequent neurochemical alterations. These alterations include decreased expression of nAChRs, modifications in acetylcholinesterase activity, and significant changes in the function of the nigrostriatal dopaminergic system. All these effects can lead to the activation of a series of intracellular signaling pathways that generate oxidative stress, neuroinflammation and, finally, neuronal death. Neonicotinoid-induced changes in nAChR function could be responsible for most of the effects observed in the different studies.

Effect of resveratrol on the inflammatory status and oxidative stress in thymus gland and spleen of sulfoxaflor-treated rats

Resveratrol (Res), a polyphenolic compound that exerts mitigating consequences against various insults due to its antioxidant, anti-inflammatory, and immunomodulatory properties. Sulfoxaflor (SFX), a neonicotinoid insecticide, has been used worldwide and leading to deleterious effects on the environment and public health. The current study aimed to investigate the protective effect of Res on the inflammatory response and oxidative stress induced by SFX in the thymus and spleen of rats. Thirty-six Sprague Dawley rats were divided randomly into six groups; control group, SFX treated groups (24.8 mg/kg or 79.4 mg/kg/day), Res (alone) treated group (20 mg/kg/day), Res + SFX treated groups (20 mg /kg Res + 24.8 mg/kg SFX or 20 mg/kg Res + 79.4 mg/kg SFX) orally for 28 days. Res treatment reversed the significantly elevated white blood cells' count and the reduced count of red blood corpuscles, platelets as well as hemoglobin content of SFX treated rats. Biochemically, Res administration inhibited the remarkably increased serum levels of the inflammatory cytokines as well as thymic and splenic levels of malondialdehyde following SFX treatment. Res treatment ameliorated the conspicuously reduced antioxidant enzymes' activities due to SFX supplementation. The immunomodulatory effect of Res treatment was detected by suppressing the upregulation of the cluster of differentiation (CD)11b and CD3 gene expressions. Histopathological alterations attributed to SFX administration were ameliorated by Res treatment. In conclusion, Res can be used as a protective agent to counteract SFX toxic effects on lymphatic organs through alleviation of the antioxidant defense mechanism and modulation of the inflammatory response.

Acute toxicity, accumulation and sublethal effects of four neonicotinoids on juvenile Black Tiger Shrimp (Penaeus monodon)

Neonicotinoid pesticides have been detected in aquatic habitats, and exposure may impact the health of aquatic organisms such as commercially-important crustaceans. Black Tiger Shrimp (Penaeus monodon) is a broadly distributed and high-value shrimp species that rely on estuaries for early life stages. Differences in the acute toxicity and accumulation of different neonicotinoids in tissues of commercial crustaceans have not been widely investigated. This study compared acute toxicity, uptake, and depuration of four neonicotinoids; thiamethoxam, clothianidin, acetamiprid, and imidacloprid, on juvenile P. monodon and their effects on enzyme biomarkers. Acute toxicity (48-h LC₅₀) was determined as 190 μg L^-1 (clothianidin), 390 μg L^-1 (thiamethoxam), 408 μg L^-1 (imidacloprid), and >500 μg L^-1(acetamiprid). To assess uptake and elimination, shrimp were exposed to a fixed 5 μg L^-1 water concentration for eight days (uptake) or four days of exposure followed by four days of depuration (elimination). Neonicotinoid water and tissue concentrations were measured by liquid chromatography-mass spectrometry following solid-phase extraction and QuEChER extraction respectively. The lower toxicity associated with acetamiprid could be associated with lower accumulation in the tissue, with concentrations remaining below 0.01 μg g^-1. The activity of acetylcholinesterase, catalase and glutathione S-transferase in abdominal tissues was determined by spectrophotometric assay, with significant sublethal effects detected for all four neonicotinoids. Depuration reduced the tissue concentration of the active ingredient and reduced the activity of oxidative stress enzymes. Given acetamiprid showed no acute toxicity and reduced impact on the enzymatic activity of P. monodon, it may be an appropriate alternative to other neonicotinoids in shrimp producing areas.

Pro-oxidant potency of clothianidin in rainbow trout

Clothianidin is a systemic neonicotinoid insecticide interfering with the central nervous system by acting as a nicotinic acetylcholine receptor agonist. Although previous studies on fish report low toxicity, its proven toxic potential for aquatic invertebrates and lack of data on its effect on juvenile fish have prompted us to investigate its adverse effects in environmentally relevant concentrations of 3, 15 and 30 μg/L for 7, 14 and 21 days on heart and spleen tissues of 10-month-old rainbow trout (Oncorhynchus mykiss). We detected a conspicuous increase in protein carbonyl and malondialdehyde (MDA) levels, which triggered antioxidant response of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), resulting in increased levels of glutathione (GSH). Clothianidin inhibited the activity of acetylcholinesterase (AChE) and lowered tissue protein levels. Heart tissue weight increased, while that of spleen decreased significantly. The effects were time- and concentration-dependent. What raises particular concern is the inhibition of AChE in the trout, even though clothianidin is claimed to be selective for insect receptors. Increased antioxidant activity in response to oxidative stress was clearly insufficient to keep MDA and protein carbonyl at normal levels, which evidences the pro-oxidant potency of the insecticide. All this calls for further investigation into potential adverse effects on biological pathways in different fish species.

Effects of low-level imidacloprid oral exposure on cholinesterase activity, oxidative stress responses, and primary DNA damage in the blood and brain of male Wistar rats

Imidacloprid is a neonicotinoid insecticide that acts selectively as an agonist on insect nicotinic acetylcholine receptors. It is used for crop protection worldwide, as well as for non-agricultural uses. Imidacloprid systemic accumulation in food is an important source of imidacloprid exposure. Due to the undisputable need for investigations of imidacloprid toxicity in non-target species, we evaluated the effects of a 28-day oral exposure to low doses of imidacloprid (0.06 mg/kg b. w./day, 0.8 mg/kg b. w./day and 2.25 mg/kg b. w./day) on cholinesterase activity, oxidative stress responses and primary DNA damage in the blood and brain tissue of male Wistar rats. Exposure to imidacloprid did not cause significant changes in total cholinesterase, acetylcholinesterase and butyrylcholinesterase activities in plasma and brain tissue. Reactive oxygen species levels and lipid peroxidation increased significantly in the plasma of rats treated with the lowest dose of imidacloprid. Activities of glutathione-peroxidase in plasma and brain and superoxide dismutase in erythrocytes increased significantly at the highest applied dose. High performance liquid chromatography with UV diode array detector revealed the presence of imidacloprid in the plasma of all the treated animals and in the brain of the animals treated with the two higher doses. The alkaline comet assay results showed significant peripheral blood leukocyte damage at the lowest dose of imidacloprid and dose-dependent brain cell DNA damage. Oral 28-day exposure to low doses of imidacloprid in rats resulted in detectable levels of imidacloprid in plasma and brain tissue that directly induced DNA damage, particularly in brain tissue, with slight changes in plasma oxidative stress parameters.

Characterizing imidacloprid and metabolites in songbird blood with applications for diagnosing field exposures

Neonicotinoids are the most widely used insecticides globally, but their rapid metabolism in vertebrates makes diagnosing wildlife exposure challenging. More detailed information on the pattern of imidacloprid metabolites over time could be used to better approximate the timing and level of exposure. Here, we applied recently developed sensitive analytical methods to measure imidacloprid (IMI) parent compound along with an expanded suite of metabolites (5-OH-IMI, IMI-olefin, desnitro-IMI, IMI-urea, 6-chloronicotinic acid, 5-AMCP, 6-OH nicotinic acid) and six other neonicotinoids in adult red-winged blackbirds (Agelaius phoeniceus) that were experimentally exposed to one of two field-realistic concentrations of imidacloprid (0.8 or 6.9 mg/kg bw). We measured concentrations in small (25 μL) plasma samples collected pre-exposure and at 1-, 6-, 24- and 48-h post-exposure. Imidacloprid was rapidly absorbed and metabolized within 48 h at both doses, with the largest decrease within 6 h post-exposure. The average proportion of parent IMI decreased from 68% of total detectable residues at 1-h to 34% at 6-h post-exposure. Two primary metabolites in blood were 5-OH-IMI and IMI-olefin, and 5-OH-IMI was the most persistent marker of exposure at 48-h. Desnitro-IMI was consistently detected following very recent (≤ 1-h) IMI exposure, and a higher ratio of parent IMI to metabolites also indicated recent exposure. Other metabolites were only detected in the higher dose group, and could be used as indicators of exposure to higher IMI concentrations. This sensitive analytical method and the observed metabolite patterns could be used to inform a growing body of field studies linking neonicotinoid exposure and effects in free-living birds.

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 2: impacts on organisms and ecosystems

New information on the lethal and sublethal effects of neonicotinoids and fipronil on organisms is presented in this review, complementing the previous Worldwide Integrated Assessment (WIA) in 2015. The high toxicity of these systemic insecticides to invertebrates has been confirmed and expanded to include more species and compounds. Most of the recent research has focused on bees and the sublethal and ecological impacts these insecticides have on pollinators. Toxic effects on other invertebrate taxa also covered predatory and parasitoid natural enemies and aquatic arthropods. Little new information has been gathered on soil organisms. The impact on marine and coastal ecosystems is still largely uncharted. The chronic lethality of neonicotinoids to insects and crustaceans, and the strengthened evidence that these chemicals also impair the immune system and reproduction, highlights the dangers of this particular insecticidal class (neonicotinoids and fipronil), with the potential to greatly decrease populations of arthropods in both terrestrial and aquatic environments. Sublethal effects on fish, reptiles, frogs, birds, and mammals are also reported, showing a better understanding of the mechanisms of toxicity of these insecticides in vertebrates and their deleterious impacts on growth, reproduction, and neurobehaviour of most of the species tested. This review concludes with a summary of impacts on the ecosystem services and functioning, particularly on pollination, soil biota, and aquatic invertebrate communities, thus reinforcing the previous WIA conclusions (van der Sluijs et al. 2015).

Metabolomic Profiling of Poor Ovarian Response Identifies Potential Predictive Biomarkers

OBJECTIVE

To characterize the serum metabolomic profile and its role in the prediction of poor ovarian response (POR).

PATIENTS

Twenty-five women with normal ovarian reserve (24-33 years, antral follicle count [AFC] ≥5, anti-Müllerian hormone [AMH] ≥1.2 ng/ml) as the control group and another twenty-five women with POR (19-35 years, AFC <5, AMH < 1.2 ng/ml) as the study group were collected in our study. The serum levels of the women in both groups were determined from their whole blood by untargeted liquid chromatography-mass spectrometry (LC-MS). Multivariate statistical analysis and cell signal pathways analysis were used to reveal the results.

RESULTS

A total of 538 different metabolites were finally identified in the two groups. Tetracosanoic acid, 2-arachidonoylglycerol, lidocaine, cortexolone, prostaglandin H2,1-naphthylamine, 5-hydroxymethyl-2-furancarboxaldehyde, 2,4-dinitrophenol, and D-erythrulose1-phosphate in POR were significantly different from control as were most important metabolites in support vector machines (p <0.05). Metabolomic profiling, together with support vector machines and pathway analysis found that the nicotinate and nicotinamide metabolism pathway, including L-aspartic acid, 6-hydroxynicotinate, maleic acid, and succinic acid semialdehyde, was identified to have significant differences in POR women compared to control women, which may be associated with ovarian reserve.

CONCLUSION

This study indicated that LC-MS-based untargeted metabolomics analysis of serum provided biological markers for women with POR. The nicotinate and nicotinamide metabolism pathway may offer new insight into the complementary prediction and therapeutic potential of POR. The functional associations of these metabolites need further investigation.

In Vitro Investigation of the Effects of Imidacloprid on AChE, LDH, and GSH Levels in the L-929 Fibroblast Cell Line

Objectives

There are several types of pesticides to control pests and several new types coming into use that could be less toxic compared to the old ones. Pesticide-induced oxidative stress, which is one of the main mechanisms of toxicity, is the research area focused most on over the last decade. There are several different studies in the literature on whether pesticide exposure induces oxidative stress parameter-mediated toxicity. Pesticide-induced oxidative stress level depends on the biochemical features of mammalian systems. Imidacloprid is a neonicotinoid pesticide in wide use that is considered safe; however, it has been reported in different studies that it may cause changes in oxidative stress parameters.

Materials and Methods

We investigated the dose- and time-dependent effects of imidacloprid on acetylcholinesterase (AChE), lactate dehydrogenase (LDH), and glutathione (GSH) levels in the L-929 fibroblast cell line. The effects of 1-500 μg imidacloprid dose range on AChE, GSH, and LDH were investigated.

Results

LDH levels were significantly increased dose dependently in the 250 and 500 ng imidacloprid groups compared to the control group. GSH levels nonsignificantly decreased dose dependently and GSH levels were lower in the 500 ng imidacloprid group compared to the control group. There were no significant differences between the groups in AChE levels.

Conclusion

These results indicated that high doses of imidacloprid may induce oxidative stress in fibroblast cells.

Exposure Level of Neonicotinoid Insecticides in the Food Chain and the Evaluation of Their Human Health Impact and Environmental Risk: An Overview

Neonicotinoid insecticides (neonics) were the most rapidly growing class of insecticides over the past few decades, and are used mainly for vegetables, fruits, and grains. Although neonics exhibit lower toxicity in mammals and humans compared to traditional insecticides, increasing numbers of studies are demonstrating that neonics may accumulate in the food chain and environmental media. Long-term exposure to neonics may raise potential risks to animals and even to humans. The present report reviews the development, application, and prohibition of neonics in the farmland ecosystem, and summarizes the exposure level and harmful effects of these insecticides in the food chain. In addition, the present review analyzes and summarizes the evaluation of the human health impact and environmental risk of the neonics, and overviews the unresolved problems and future research directions in this field. The aim of the present report was to review the exposure level, potential toxicity, human health impact, and environmental risk assessment of neonics in various media in order to provide reliable technical support for strengthening the environmental and food safety supervision and green pesticide designing.

Metabolic disturbance in hippocampus and liver of mice: A primary response to imidacloprid exposure

Imidacloprid (IMI) is one of the most frequently used neonicotinoid insecticides, but recent studies have shown adverse effects on mammals. IMI was found to be neurotoxic and hepatotoxic. In the present study, the effects of repeated oral administration of two doses of IMI (5 and 20 mg/kg/day) for 28 days on hippocampus and liver of female KM mice were studied. The histopathological and biochemical experiments indicated obvious damages to the hippocampus and liver of mice in the high-dose group (20 mg/kg/day). Using a high-throughput metabolomics platform based on ultrahigh performance liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS), we studied effects of IMI on metabolic profiles in the hippocampus and liver of mice. Significant differences among the control group, the low-dose group and the high-dose group were clearly presented using multivariate analysis. The changed metabolic profile in the low-dose group (5 mg/kg/day) revealed that the metabolic disturbance in the hippocampus and liver of mice had been induced by low-dose of IMI, although no significant histopathological changes were observed in the low-dose group. Six differential metabolites in the hippocampus and 10 differential metabolites in the liver were identified as the possible biomarkers to distinguish IMI exposure from the control group using the variable importance in projection (VIP) value and receiver operating characteristic (ROC) analysis. The metabolism disturbances of important biochemical pathways in the hippocampus and liver of mice in the exposed groups were elucidated, mostly concentrated in lipid metabolism, amino acid metabolism, nucleotide metabolism, carbohydrate metabolism, and energy metabolism (p < 0.05). Such investigations give out a global view of IMI-induced damages in the hippocampus and liver of mice and imply a health risk associated with early metabolic damage in mice.

Enhanced cytotoxicity of imidacloprid by biotransformation in isolated hepatocytes and perfused rat liver

Imidacloprid (IMD) is a neonicotinoid insecticide widely used in crops, pets, and on farm animals for pest control, which can cause hepatotoxicity in animals and humans. In a previous study using isolated rat liver mitochondria, we observed that IMD inhibited the activity of F_oF₁-ATP synthase. The aim of this study was to evaluate the effects of IMD on rat isolated hepatocytes and perfused rat liver, besides the influence of its biotransformation on the toxicological potential. For the latter goal, rats were pretreated with dexamethasone or phenobarbital, two classical cytochrome P-450 stimulators, before hepatocytes isolation or liver perfusion. IMD (150 and 200 μM) reduced state 3 mitochondrial respiration in digitonin-permeabilized cells that were energized with glutamate plus malate but did not dissipate the mitochondrial membrane potential. In intact (non-permeabilized) hepatocytes, the intracellular ATP concentration and cell viability were reduced when high IMD concentrations were used (1.5-3.0 mM), and only in cells isolated from dexamethasone-pretreated rats, revealing that IMD biotransformation increases its toxicity and that IMD itself affects isolated mitochondria or mitochondria in permeabilized hepatocytes in concentrations that do not affect mitochondrial function in intact hepatocytes. Coherently, in the prefused liver, IMD (150 and 250 μM) inhibited gluconeogenesis from alanine, but without affecting oxygen consumption and urea production, indicating that such effect was not of mitochondrial origin. The gluconeogenesis inhibition was incomplete and occurred only when the rats were pretreated with phenobarbital, signs that IMD biotransformation was involved in the observed effect. Our findings reveal that changes in hepatic energy metabolism may be acutely implicated in the hepatotoxicity of IMD only when animals and humans are exposed to high levels of this compound, and that IMD metabolites seem to be the main cause for its toxicity.

Evaluation of the ameliorative effects of Phyllanthus niruri on the deleterious insecticide imidacloprid in the vital organs of chicken embryos

Background

Insecticides are widely used in agriculture to curb the loss caused by insects. These insecticides are incorporated into the food chain and accumulate in the human body, as well disturb the various metabolic pathways. Imidacloprid is an insect neurotoxin commonly used in agriculture to control the insect pests. P. niruri is a traditional medicinal shrub widely used as an anti-inflammatory, antipyretic, and anti-lethality agent.

Objective

The present study is designed to evaluate the ameliorative effects of Phyllanthus niruri (Bhumi amla) on the deleterious Insecticide imidacloprid in the vital organs of Chicken embryos.

Materials and methods

The embryonated chicken eggs were divided into the four groups (one control and three treated groups); the chorioallantoic membranes of control received 200 μl phosphate buffer saline, whereas group I and group II received 100 μg imidacloprid and 200 μl aqueous extract of P. niruri (PNE) respectively. Group III received both 100 μg imidacloprid and 200 μl PNE. The serum was collected on the 18th day its development; which was subjected to the biochemical analysis based on colorimetric assay in semi-automated biochemical analyzer using commercial kits.

Results

We observed significant in ovo effects of imidacloprid on chicken embryos; the values of aspartate aminotransferase (AST), alanine aminotransferase (ALT), were increased in imidacloprid treated group I; histopathology also revealed damage to the liver (necrotic areas and dilated blood sinusoids). Alkaline phosphatase (ALP), amylase, cholesterol, triglycerides protein and albumin levels were also altered significantly (p < 0.05).

Conclusion

The serum biochemicals were returned back to the nearly normal levels. PNE has ameliorated and overcome the effects of imidacloprid reasonably with the subsequent treatment among group III. Hence, P. niruri may be used to minimize the effects of an accidental exposure of imidacloprid.

Deciphering the mode of action of pollutants impairing the fish larvae escape response with the vibrational startle response assay

The escape response evoked by vibrational stimuli and its habituation, essential behaviors for fish larvae survival, can be altered by neurotoxic environmental pollutants commonly found in our aquatic ecosystems. In this study we have analyzed the suitability of the Vibrational Startle Response Assay (VSRA) to obtain mechanistic information about the mode of action (MoA) of the chemicals impairing the escape response and its habituation. As a proof of concept, the pathophysiological mechanisms behind the action of two common neurotoxic pesticides, chlorpyrifos-oxon (CPO) and imidacloprid, over their effects on arousal and habituation of the escape response were studied by using pharmacological antagonists of the nicotinic and muscarinic acetylcholine receptors, mecamylamine (MCA) and scopolamine, respectively. Furthermore, potential changes in the neurotransmitter profile were analyzed. Results revealed that whereas the effect of CPO on arousal was mainly mediated by the activation of nAChRs, its effect on habituation was mainly mediated by mAChRs. On the other hand, imidacloprid only affected larvae arousal which was found to be mediated by a cholinergic independent mechanism. No association between behavioral effects on arousal or habituation in affected larvae was found with their corresponding neurotransmitter profile. These results confirm the suitability of VSRA to provide mechanistic information about the potential MoA of neuroactive compounds.

A large-scale survey of house sparrows feathers reveals ubiquitous presence of neonicotinoids in farmlands

The massive use of neonicotinoid insecticides has been repeatedly incriminated for their impacts to avian populations. Some studies have reported contamination of granivorous birds by neonicotinoids but very little is known about exposure to neonicotinoids in other bird species. To fill this lack of knowledge, we trapped house sparrows Passer domesticus, an omnivorous bird whose diet is composed of both grains and insects, and we collected 617 feathers from individuals living on 47 conventional, integrated-production (IP-Suisse) and organic farms distributed all over the Swiss plateau, the country's main agricultural area. We then assessed the concentration of five neonicotinoids in 146 pools of feathers. We found that all feather samples were contaminated by at least one neonicotinoid at measurable concentration (>LOQ), with thiacloprid accounting for most of the prevalence (99%), while clothianidin was found at highest concentrations (with averages ranging from 1.68 to 9.2 ppb). Additionally, house sparrows living on conventional farms showed higher concentrations of neonicotinoids (15.26 ± 3.58 ppb) than individuals living on IP-Suisse (3.38 ± 0.86 ppb), and organic farms (2.59 ± 0.56 ppb). Our large-scale survey highlights how ubiquitous neonicotinoid insecticides have become in agricultural habitats, and reveals generalized exposure of house sparrows, and potentially other species inhabiting farmlands, to neonicotinoids.

Dose-related impacts of imidacloprid oral intoxication on brain and liver of rock pigeon (Columba livia domestica), residues analysis in different organs

Available data regarding Imidacloprid (IMI) insecticide hazards to birds are still being scare. Our study aimed to investigate toxic impacts of IMI oral gavage by different dose levels on the brain and liver of Rock pigeon (Columba livia domestica). Forty mature male birds were divided equally into four groups. A control group (C) was orally dosed Mazola corn oil and other three groups; the low dose (LD), the medium dose (MD), and the high dose (HD) groups were orally dosed IMI in Mazola corn oil by three dose levels corresponding to 1/15^th, 1/10^th, 1/5^th IMI oral LD₅₀ respectively. IMI exposure induced a significant decrease in serum levels of glutathione (GSH), superoxide dismutase (SOD) enzyme activity. On the other hand; malondialdehyde (MDA) levels were elevated. The levels of serum total protein, albumin, globulin, and A/G ratio showed a non-significant changes in all IMI dosed groups except levels of total protein in the HD IMI dosed group showed a significant decrease compared to the C group. Serum levels of alanine aminotransferase (ALT), lactate dehydrogenase (LDH), uric acid, plasma tumor necrosis factor α (TNFα) and plasma acetylcholinesterase (AChEs) enzyme activities showed a significant dose related increase in all IMI exposed groups compared to the C group; except the levels of ALT, LDH, and uric acid showed a non significant decrease in the LD IMI dosed group only. Residues of IMI were detected in the pectoral muscles, liver, brain, and kidney of all dosed rock pigeon. Moreover; pectoral muscles were the highest tissue for IMI residues detection. This is the first study reports accumulation of IMI in tissues other than crop, liver, and kidney of rock pigeon including brain and muscles. Moreover, the examined brain and liver tissues of all IMI dosed groups showed dosed related alterations in their structural and ultra-structural morphology. It is concluded that IMI oral administration to pigeon induced oxidative stress and detrimental effects in brain and liver of exposed pigeons. Additionally; IMI bio-accumulated in different organs being muscles is the highest tissues for IMI residues, thus monitoring of IMI residues in food is very essential.

Trends in neonicotinoid pesticide residues in food and water in the United States, 1999-2015

BACKGROUND

Neonicotinoids are a class of systemic insecticides widely used on food crops globally. These pesticides may be found in "off-target" food items and persist in the environment. Despite the potential for extensive human exposure, there are limited studies regarding the prevalence of neonicotinoid residues in foods sold and consumed in the United States.

METHODS

Residue data for seven neonicotinoid pesticides collected between 1999 and 2015 by the US Department of Agriculture's Pesticide Data Program (PDP) were collated and summarized by year across various food commodities, including fruit, vegetable, meat, dairy, grain, honey, and baby food, as well as water to qualitatively describe and examine trends in contamination frequency and residue concentrations.

RESULTS

The highest detection frequencies (DFs) for neonicotinoids by year on all commodities were generally below 20%. Average DFs over the entire study period, 1999-2015, for domestic and imported commodities were similar at 4.5%. For all the samples (both domestic and imported) imidacloprid was the neonicotinoid with the highest overall detection frequency at 12.0%. However, higher DFs were observed for specific food commodity-neonicotinoid combinations such as: cherries (45.9%), apples (29.5%), pears (24.1%) and strawberries (21.3%) for acetamiprid; and cauliflower (57.5%), celery (20.9%), cherries (26.3%), cilantro (30.6%), grapes (28.9%), collard greens (24.9%), kale (31.4%), lettuce (45.6%), potatoes (31.2%) and spinach (38.7%) for imidacloprid. Neonicotinoids were also detected in organic commodities, (DF < 6%). Individual commodities with at least 5% of samples testing positive for two or more neonicotinoids included apples, celery, and cherries. Generally, neonicotinoid residues on food commodities did not exceed US Environmental Protection Agency tolerance levels. Increases in detection trends for both finished and untreated water samples for imidacloprid were observed from 2004 to 2011.

CONCLUSIONS

Analysis of PDP data indicates that low levels of neonicotinoids are present in commonly-consumed fruits and vegetables sold in the US. Trends in detection frequencies suggest an increase in use of acetamiprid, clothianidin and thiamethoxam as replacements for imidacloprid. Given these findings, more extensive surveillance of the food and water supply is warranted, as well as biomonitoring studies and assessment of cumulative daily intake in high risk groups, including pregnant women and infants.

The metabolism distribution and effect of imidacloprid in chinese lizards (Eremias argus) following oral exposure

Systematically evaluation of the metabolism, distribution and effect of imidacloprid in Chinese lizards (Eremias argus) were carried out following oral exposure. Imidacloprid-olefin-guanidine was prone to accumulate in the brain and caused potential neurotoxicity. Percutaneous and excretory excretions were the primary ways for the elimination of imidacloprid and its metabolites. Liver was the main site for hydroxy reduction and nitro-reduction metabolism of imidacloprid. The metabolism of imidacloprid was a complex process in which many metabolic enzymes participated. Aldehyde oxidase and CYP2C9 were the key enzymes in nitro-reduction process. CYP3A4 dominated the process of hydroxylation and desaturation. The increase in Glutathione S-transferase expression may be related to the removal of imidacloprid, but also related to the oxidative stress reaction that imidacloprid may cause in tissues, especially in the kidney. The findings enrich and supplement the knowledge of the environmental fate of imidacloprid in reptiles.

Part-per-trillion LC-MS/MS determination of neonicotinoids in small volumes of songbird plasma

Neonicotinoids are the most widely used class of insecticides in the world, and there are increasing concerns about their effects on non-target organisms. Analytical methods to diagnose exposure to neonicotinoids in wildlife are still very limited, particularly for small animals such as songbirds. Blood can be used as a non-lethal sampling matrix, but the sample volume is limited by body size. Neonicotinoids have a low bioaccumulation potential and are rapidly metabolized, therefore, sensitive assays are critically needed to reliably detect their residues in blood samples. We developed an efficient LC-MS/MS method at a part-per-trillion (pg/ml) level to measure eight neonicotinoid related insecticides (acetamiprid, clothianidin, dinotefuran, flonicamid, imidacloprid, nitenpyram, thiacloprid and thiamethoxam) plus one metabolite (6-chloronicotinic acid) in small volumes (50 μL) of avian plasma. The average recovery of target compounds ranged from 95.7 to 101.3%, and relative standard deviations were between 0.82 and 2.13%. We applied the method to screen blood samples from 36 seed-eating songbirds (white-crowned sparrows; Zonotrichia leucophrys) at capture, and detected imidacloprid in 78% (28 of 36), thiamethoxam in 22% (8 of 36), thiacloprid in 11% (4 of 36), and acetamiprid in 11% (4 of 36) of wild-caught sparrows. 6 h after capture, birds were orally dosed with 0 (control), 1.2 or 3.9 mg of imidacloprid/kg bw, test results using this method indicated that plasma imidacloprid was significantly elevated (low 26-times, high 316-times) in exposed groups. This is the first study to confirm neonicotinoid exposure in small free-living songbirds through non-lethal blood sampling, and to demonstrate that environmentally realistic doses significantly elevate circulating imidacloprid concentrations. This sensitive method could be applied to characterize exposure to neonicotinoids in free-living wildlife and in toxicological studies.

First evidence of neonicotinoid residues in a long-distance migratory raptor, the European honey buzzard (Pernis apivorus)

The evidence of negative impacts of agricultural pesticides on non-target organisms is constantly growing. One of the most widely used group of pesticides are neonicotinoids, used in treatments of various plants, e.g. oilseed crops, corn and apples, to prevent crop damage by agricultural insect pests. Treatment effects have been found to spill over to non-target insects, such as bees, and more recently also to other animal groups, among them passerine birds. Very little is known, however, on the presence of neonicotinoids in other wild species at higher trophic levels. We present results on the presence of neonicotinoid residues in blood samples of a long-distant migratory food-specialist raptor, the European honey buzzard. Further, we investigate the spatial relationship between neonicotinoid residue prevalence in honey buzzards with that of crop fields where neonicotinoids are typically used. A majority of all blood samples contained neonicotinoids, thiacloprid accounting for most of the prevalence. While neonicotinoid residues were detected in both adults and nestlings, the methodological limit of quantification was exceeded only in nestlings. Neonicotinoids were present in all sampled nests. Neonicotinoid presence in honey buzzard nestlings' blood matched spatially with the presence of oilseed plant fields. These are the first observations of neonicotinoids in a diurnal raptor. For better understanding the potential negative sub-lethal of neonicotinoids in wild vertebrates, new (experimental) studies are needed.

Effect of imidacloprid ingestion on immune responses to porcine reproductive and respiratory syndrome virus

Nicotine and acetylcholine cause immunosuppresion by signaling to the α7 nicotinic acetylcholine receptor (α7 nAChR) on immune cells. Neonicotinoids are nAChR agonists and widly used insecticides. We aimed to define the immunosuppressive potential of dietary exposure to the neonicotinoid imidacloprid (IMI) on the generation of innate and adaptive immune responses to porcine reproductive and respiratory syndrome virus (PRRSV). Piglets were randomized into groups based on diet and infection. Behavioral signs of illness were recorded. Urine IMI levels were measured by high performance liquid chromatography-mass spectrometry. Flow cytometry was used to determine the expression pattern of the α7 nAChR on porcine leukocytes as well as the effects of infection and treatment on circulating leukocyte populations. Serum cytokines and PRRSV-specific antibody levels were determined by ELISA. Viral RNA in lung, spleen and plasma was determined by RT-qPCR. Pigs in the treatment group had elevated urine levels of IMI. Treatment with IMI reduced body weight, caused bouts of hypothermia, increased serum IL-10 and elevated levels of virus-specific antibodies. Viral RNA levels in the spleen showed a trend toward being increased in pigs fed IMI. Our data indicates that IMI injection may modulate virus specific immune function during PRRSV infection.

Teratogenic effects of the neonicotinoid thiacloprid on chick embryos (Gallus gallus domesticus)

Thiacloprid is an insecticide belonging to the family of neonicotinoids, substances initially underestimated for their potential adverse effects, that they may manifest in the long term leading to an extensive use. The objective of this study was to evaluate the effect at increasing concentrations of thiacloprid on chick embryos development. The research was carried out on 75 fertile eggs of Gallus gallus domesticus. The eggs were opened after 10, 15 and 20 days of incubation and in treated embryos were observed developmental alterations, growth retardation, limbs defects and ectopia viscerale. The histological analysis showed hepatic steatosis and haemorrhages both in the liver and in the lungs. Moreover, the immunohistochemical analysis performed on the liver sections showed a strong positivity only for the erythrocytes to the anti-CYP1A antibody. Thiacloprid exposure increases the risks of teratogenic effects especially at the higher doses tested, therefore its use should be more controlled and limited. Since the literature on the topic is lacking, then the human health impacts resulting from neonicotinoids exposure is not yet fully understood, and, our data will be helpful to allow the assessment of an oral reference dose and health risk characterization.

Effects of co-exposure to imidacloprid and gibberellic acid on redox status, kidney variables and histopathology in adult rats

Data on the individual nephrotoxic effects of imidacloprid (IMI) and gibberellic acid (GA₃) are scarce. Moreover, there is a lack of information about their combined effects on the renal tissue. Our study investigated the effects of IMI and GA₃ separately or together on rats kidney. IMI (64 mg/kg bw) was given for 3 weeks by gavage either individually or in combination with GA₃ (200 mg/L) via drinking water. IMI associated or no with GA₃ increased the levels of kidney malondialdehyde, advanced oxidation protein products, protein carbonyls and metallothionein, plasma creatinine, urea, blood urea nitrogen and lactate dehydrogenase activity. A decline of kidney uric acid level and antioxidant status was also observed. All these changes were supported by histopathological observations. Our results highlighted the role of IMI and/or GA₃-induced nephrotoxicity. Co-exposure to IMI and GA₃ exhibited synergism in biochemical kidney variables and histopathology and antagonism in physical and morphological parameters.

Imidacloprid affects rat liver mitochondrial bioenergetics by inhibiting FoF1-ATP synthase activity

Imidacloprid (IMD) is a neonicotinoid insecticide widely used in crops, pets, and on farm animals for pest control. Several studies were conducted examining the adverse effects of IMD on animals often exhibiting hepatic damage. The aim of this study was to determine the effects of IMD on bioenergetics of mitochondria isolated from rat liver. Imidacloprid (50-200 µM) produced a concentration-dependent decrease in oxygen consumption and ATP production without markedly affecting mitochondrial membrane potential (MMP). Oxygen consumption experiments showed that IMD did not significantly affect the respiratory chain, and this was similar to findings with oligomycin and carboxyatractyloside, suggesting a direct action on F_oF₁-ATP synthase and/or the adenine nucleotide translocator (ANT). Imidacloprid inhibited F_oF₁-ATP synthase activity only in disrupted mitochondria and induced a partial inhibition of ADP-stimulated depolarization of the MMP. Our results indicate that IMD interacts specifically with F_oF₁-ATP synthase resulting in functional inhibition of the enzyme with consequent impairment of mitochondrial bioenergetics. These effects of IMD on mitochondrial bioenergetics may be related to adverse effects of this insecticide on the liver.

Human exposure to neonicotinoid insecticides and the evaluation of their potential toxicity: An overview

Neonicotinoid insecticides have become the fastest growing class of insecticides over the past few decades. The insecticidal activity of neonicotinoids is attributed to their agonist action on nicotinic acetylcholine receptors (nAChRs). Because of the special selective action on nAChRs in central nervous system of insects, and versatility in application methods, neonicotinoids are used to protect crops and pets from insect attacks globally. Although neonicotinoids are considered low toxicity to mammals and humans in comparison with traditional insecticides, more and more studies show exposure to neonicotinoids pose potential risk to mammals and even humans. In recent years, neonicotinoids and their metabolites have been successfully detected in various human biological samples. Meanwhile, many studies have focused on the health effects of neonicotinoids on humans. Our aims here are to review studies on human neonicotinoid exposure levels, health effect, evaluation of potential toxicity and to suggest possible directions for future research.

Mechanism of Neonicotinoid Toxicity: Impact on Oxidative Stress and Metabolism

Thousands of tons of neonicotinoids are widely used around the world as broad-spectrum systemic insecticides and veterinary drugs. Researchers originally thought that neonicotinoids exhibited low mammalian toxicity. However, following their widespread use, it became increasingly evident that neonicotinoids could have various toxic effects on vertebrates and invertebrates. The primary focus of this review is to summarize the research progress associated with oxidative stress as a plausible mechanism for neonicotinoid-induced toxicity as well as neonicotinoid metabolism. This review summarizes the research conducted over the past decade into the production of reactive oxygen species, reactive nitrogen species, and oxidative stress as aresult of neonicotinoid treatments, along with their correlation with the toxicity and metabolism of neonicotinoids. The metabolism of neonicotinoids and protection of various compounds against neonicotinoid-induced toxicity based on their antioxidative effects is also discussed. This review sheds new light on the critical roles of oxidative stress in neonicotinoid-induced toxicity to nontarget species.

Validation of a QuECheRS method for analysis of neonicotinoids in small volumes of blood and assessment of exposure in Eurasian eagle owl (Bubo bubo) nestlings

Neonicotinoid pesticides have gained great interest in the last years both for agricultural and domestic use. Since the information on their environmental distribution or the effects derived from exposure to ecosystems and biota is scarce, new analytical techniques are being developed for monitoring studies. In this sense, two extraction techniques based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) methodology to detect the neonicotinoids authorised in Spain (acetamiprid, clothianidin, dinotefuran, imidacloprid, thiacloprid, nitenpyram and thiamethoxam) were adapted and compared: a) using acetate buffer (AB); and b) using citrate buffer (CB). For detection and quantification, high performance liquid chromatography coupled with time of flight mass spectrometry (HPLC/TOF-MS) was used. The CB method provided a wide range of recoveries (68-134%) and accuracy (4-9%). The AB method provided good recoveries (59-76%, 59% corresponded to clothianidin) precision (4-11%) linearity (0.987-0.998%) and limit of quantification (2-10ng/mL) for all the compounds. To test the effectiveness of the technique, we analysed 30 blood samples of free-ranging nestlings of Eurasian eagle owl (Bubo bubo). The only compound detected, in one nestling from a dry land farming area, was imidacloprid, with a concentration of 3.28ng/mL. To our knowledge, this is the first study of neonicotinoid pesticides in free-ranging birds of prey using non-destructive samples, providing the first insight for biomonitoring studies. Further studies, including toxicokinetics and toxicodynamics, are recommended to assess the risk for these species.

Toxic Effects of Bromothalonil and Flutolanil on Multiple Developmental Stages in Zebrafish

In this study, we applied various developmental stages of zebrafish to address the potential environmental risk and aquatic toxicity of bromothalonil and flutolanil. This results demonstrated that the acute toxicity of bromothalonil to the three phases of zebrafish were 4.34 (embryo) < 3.27 (12 h old larvae) < 2.52 mg/L (adult fish) and that of flutolanil were 5.47 (embryo) < 4.09 (72 h old larvae) < 3.91 (12 h old larvae) < 2.70 mg/L (adult). Sublethal effects induced by both bromothalonil and flutolanil on zebrafish embryos were noted, including growth inhibition, abnormal spontaneous movement, slower heart rate, complete hatching failure, and morphological deformities. In addition, both bromothalonil and flutolanil could cause notochord deformation and short body length of larvae. This study provides a foundation for future investigation into the mechanism of bromothalonil and flutolanil toxicity in zebrafish.

Metabolomics to Explore Imidacloprid-Induced Toxicity in the Central Nervous System of the Freshwater Snail Lymnaea stagnalis

Modern toxicology is seeking new testing methods to better understand toxicological effects. One of the most concerning chemicals is the neonicotinoid pesticide imidacloprid. Although imidacloprid is designed to target insects, recent studies have shown adverse effects on nontarget species. Metabolomics was applied to investigate imidacloprid-induced sublethal toxicity in the central nervous system of the freshwater snail Lymnaea stagnalis. The snails (n = 10 snails) were exposed for 10 days to increasing imidacloprid concentrations (0.1, 1, 10, and 100 μg/L). The comparison between control and exposure groups highlighted the involvement and perturbation of many biological pathways. The levels of several metabolites belonging to different metabolite classes were significantly changed by imidacloprid exposure. A change in the amino acids and nucleotide metabolites like tryptophan, proline, phenylalanine, uridine, and guanosine was found. Many fatty acids were down-regulated, and the levels of the polyamines, spermidine and putrescine, were found to be increased which is an indication of neuron cell injury. A turnover increase between choline and acetylcholine led us to hypothesize an increase in cholinergic gene expression to overcome imidacloprid binding to the nicotinic acetylcholine receptors. Metabolomics revealed imidacloprid induced metabolic changes at low and environmentally relevant concentration in a nontarget species and generated a novel mechanistic hypothesis.

Imidacloprid-treated seed ingestion has lethal effect on adult partridges and reduces both breeding investment and offspring immunity

The ingestion of imidacloprid treated seeds by farmland birds may result in exposure to toxic amounts of this insecticide. Here we report on the effects that the exposure to the recommended application rate and to 20% of that rate may produce on birds feeding on treated seeds. Experimental exposure to imidacloprid treated seeds was performed on red-legged partridges (Alectoris rufa) (n=15 pairs per treatment group: control, 20% or 100% of the recommended application rate) during two periods that corresponded to the autumn (duration of exposure: 25 days) and late winter (10 days) cereal sowing times in Spanish farmlands. We studied effects on the survival, body condition, oxidative stress biomarkers, plasma biochemistry, carotenoid-based coloration, T-cell mediated immune response and reproduction of exposed adult partridges, and on the survival and T-cell immune response of their chicks. The high dose (recommended application rate) killed all partridges, with mortality occurring faster in females than in males. The low dose (20% the recommended application rate) had no effect on mortality, but reduced levels of plasma biochemistry parameters (glucose, magnesium and lactate dehydrogenase), increased blood superoxide dismutase activity, produced changes in carotenoid-based integument coloration, reduced the clutch size, delayed the first egg lay date, increased egg yolk vitamins and carotenoids and depressed T-cell immune response of chicks. Moreover, the analysis of the livers of dead partridges revealed an accumulation of imidacloprid during exposure time. Despite the moratorium on the use of neonicotinoids in the European Union, birds may still be at high risk of poisoning by these pesticides through direct sources of exposure to coated seeds in autumn and winter.

Differential protein expression in the susceptible and resistant Myzus persicae (Sulzer) to imidacloprid

Myzus persicae, a serious economic agricultural pest, has developed resistance to imidacloprid (IMI), which was widely used to control this aphid worldwide. To gain a better understanding of the mechanisms of IMI resistance in M. persicae, we carried out a comparative proteomic analysis. Total proteins of the IMI-susceptible and resistant strains were extracted and separated by two-dimensional gel electrophoresis. More than 1300 protein spots were reproducibly detected, including 14 that were more abundant and 14 less abundant. Mass spectrometry analysis and database searching helped us to identify 25 differentially abundant proteins. The identified proteins were categorized into several functional groups including signal transduction, RNA processing, protein processing, transport processing, stress response, metabolisms, and cytoskeleton structure, etc. This study is the first analysis of differentially expressed proteins in IMI-susceptible and resistant M. Persicae, and gives new insights into the mechanisms of IMI resistance in M. persicae.

Effect of imidacloprid on hepatotoxicity and nephrotoxicity in male albino mice

Imidacloprid (IC) is a systemic insecticide related to the tobacco toxin nicotine. IC is a toxic substance frequently used into combat insects, rodents and plants pests and other creatures that can pose problems for agriculture. We, therefore, planned this study to assess risk factors, biochemical and histological alterations associated with hepatotoxicity and nephrotoxicity. Forty-eight adult male albino mice were divided into four groups of 12 animals each. All the animals were given standard synthetic pellet diet. One group served as control, and the other three were served as experimental groups. Decrease in the body weight of the high dose group was observed at 15 mg/kg/day, and no mortality occurred during the treatment period. High dose of imidacloprid caused a significant elevation of serum clinical chemistry parameters, serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvate kinase (SGPT), alkaline phosphatase (ALP) and total bilirubin (TBIL). Histology of liver and kidney indicates hepatotoxicity and nephrotoxicity at a high dose of imidacloprid. Based on the morphological, biochemical and histopathological analysis, it is evident that imidacloprid induced toxicological effects at 15 mg/kg/day to mice. The results of the present study demonstrate that IC had significant effects on body weight, liver functions and kidney (p < 0.05) at a dose of 15 mg/kg body weight. IC treatment 5 and 10 mg/kg/day may be considered as no observed adverse effect level (NOAEL) for mice. It was concluded that IC can cause hepatotoxicity and nephrotoxicity at a dose much lower than the LD₅₀ (131 mg/kg body weight) in mice.