Acetamiprid Concentration Research Articles

A fluorescence and localized surface plasmon resonance dual-readout sensing strategy for detection of acetamiprid and organophosphorus pesticides

In this work, a fluorescence/localized surface plasmon resonance (Fluorescence/LSPR) dual-readout sensing system that using DNA functionalized gold nanoparticles (AuNPs) as nanoprobe was designed for acetamiprid (ACE) and organophosphorus pesticides (OPs) detection. The ACE detection was based on the fluorescence resonance energy transfer (FRET) between fluorochrome Cy3-labeled aptamer and AuNPs of nanoprobe. The high specificity of ACE allowed Cy3-labeled aptamer to release from nanoprobe, resulting in a significantly fluorescence recovery related to the concentration of ACE. On the other hand, the strategy for OPs detection relied on the acetylcholinesterase (AChE)-mediated oxidative polymerization blocking of dopamine on AuNPs surface and the inhibition of OPs toward AChE. The degree of polymerization of dopamine depended on the concentration of OPs, which led to a tremendous LSPR spectral shift and scattering color change of nanoprobe. The dual-readout sensing system showed great sensitivity and selectivity for ACE and OPs (used chlorpyrifos as model) with a detection limit of 166.7 pg mL−1 and 0.17fgmL−1, respectively. Moreover, two distinct color changes could be visual recognized to indicate the content of ACE and OPs, which was considered to be a conceivable way for pesticides residues assay. Therefore, this work paved a new avenue for rapid detection of multi-pesticides via a Fluorescence/LSPR dual signal response and visual screening, and hold great potential for noxious substance monitoring.

Associations of neonicotinoids with insulin and glucose homeostasis parameters in US adults: NHANES 2015-2016

BACKGROUND AND AIM: Neonicotinoids are replacement insecticides increasingly used for organophosphates, methylcarbamates, and pyrethroids. Experimental evidence suggests neonicotinoid may affect glucose metabolism and insulin secretion as a result of pancreatic β cell dysfunction, oxidative stress, and inflammation. However, no epidemiologic study has investigated neonicotinoids as potential diabetogens. We examined associations between neonicotinoids with insulin and glucose homeostasis parameters among 1381 non-diabetic, US adults in the National Health and Nutrition Examination Survey (2015-2016). METHODS: Urinary concentrations of acetamiprid, clothianidin, imidacloprid, N-desmethyl-acetamiprid, and 5-hydroxy-imidacloprid were quantified. Fasting plasma glucose, insulin, and hemoglobin A1c (HbA1c) were assessed. Insulin resistance was defined as a homeostatic model assessment of insulin resistance (HOMA-IR) ≥2.5. We used weighted linear and logistic regression models to estimate associations between detectable neonicotinoids with insulin and glucose homeostasis parameters. RESULTS:Weighted detection frequencies for imidacloprid, 5-hydroxy-imidacloprid, and N-desmethyl-acetamiprid were 4.4%, 21.5%, and 32.8%, respectively. Detectable imidacloprid (β=-4.7 µIU/mL, 95% CI -8.5, -0.8) and 5-hydroxy-imidacloprid (β=-2.4 µIU/mL, 95% CI -4.6, -0.2) were associated with lower fasting plasma insulin levels. Individuals with detectable 5-hydroxy-imidacloprid had lower odds of insulin resistance (OR=0.3, 95% CI 0.2, 0.7). We observed evidence of sexually dimorphic associations between N-desmethyl-acetamiprid with glucose (pint=0.079) and 5-hydroxy-imidacloprid with HbA1c (pint=0.038), with patterns suggesting positive associations in males and negative associations in females. Associations between 5-hydroxy-imidacloprid and insulin were modified by BMI (pint=0.013), with significant inverse associations among those overweight/obese and null associations for those under/normal weight. We additionally observed age modified associations between 5-hydyroxy-imidacloprid and glucose (pint=0.048). Detectability of 5-hydroxy-imidacloprid among individuals aged 20-45 years were associated with higher glucose levels, while lower levels were noted among those 46+ years. CONCLUSIONS:Results suggest neonicotinoids may be associated with insulin and glucose homeostasis indices and call for prospective studies to examine the metabolic impact of these replacement insecticides in humans. KEYWORDS: Neonicotinoids, glucose, insulin, HbA1c, HOMA-IR, insulin resistance

Associations of neonicotinoids with insulin and glucose homeostasis parameters in US adults: NHANES 2015–2016

Neonicotinoids are replacement insecticides increasingly used for organophosphates, methylcarbamates, and pyrethroids. Experimental evidence suggests neonicotinoids may affect glucose metabolism and insulin secretion through pancreatic β cell dysfunction, oxidative stress, and inflammation. However, no epidemiologic study has investigated neonicotinoids as potential diabetogens. We examined associations between neonicotinoids with insulin and glucose homeostasis parameters among 1381 non-diabetic adults in the National Health and Nutrition Examination Survey (2015–2016). Urinary concentrations of acetamiprid, clothianidin, imidacloprid, N-desmethyl-acetamiprid, and 5-hydroxy-imidacloprid were quantified. Fasting plasma glucose, insulin, and hemoglobin A1c (HbA1c) were assessed. Insulin resistance was defined as a homeostatic model assessment of insulin resistance ≥2.5. We used weighted linear and logistic regression to estimate associations between detectable neonicotinoids with insulin and glucose homeostasis parameters compared to non-detectable neonicotinoid concentrations. Weighted detection frequencies for imidacloprid, 5-hydroxy-imidacloprid, and N-desmethyl-acetamiprid were 4.4 %, 21.5 %, and 32.8 %, respectively. Detectable imidacloprid (β = −4.7 μIU/mL, 95 % confidence interval [CI] -8.5, −0.8) and 5-hydroxy-imidacloprid (β = −2.4 μIU/mL, 95 % CI -4.6, −0.2) were associated with lower fasting plasma insulin levels. Individuals with detectable 5-hydroxy-imidacloprid had lower odds of insulin resistance (odds ratio [OR] = 0.3, 95 % CI 0.2, 0.7). We observed evidence of sexually dimorphic associations between N-desmethyl-acetamiprid with glucose (pint = 0.079) and 5-hydroxy-imidacloprid with HbA1c (pint = 0.038), with patterns suggesting positive associations in males and negative associations in females. Associations between 5-hydroxy-imidacloprid and insulin were modified by body mass index (BMI) (pint = 0.013). We additionally observed age modified associations between 5-hydyroxy-imidacloprid and glucose (pint = 0.048). Results suggest neonicotinoids may be associated with insulin and glucose homeostasis indices and call for prospective studies to examine the metabolic impact of these replacement insecticides in humans.

A green approach to remove acetamiprid insecticide using pistachio shell-based modified activated carbon; economical groundwater treatment

This study deals with an economical and green approach for the successful removal of acetamiprid (ATP) from groundwater samples using pistachio shell-based modified activated carbon (MAC). The prepared MAC has an apparent surface area (SBET) of 1158.7 m2 g−1, total pore (Vtotal) of 0.982 cm3 g−1, and micropore (Vmicro) volumes of 0.841 cm3 g−1, and pore diameter (Pdia) of 11.18 nm. The maximum removal efficiency of 98.6% was obtained at the optimal condition of the ATP concentration of 10 mg L−1, solution pH of 6.5, the contact time of 23 min, and adsorbent dosage of 300 mg L−1. It was in good accordance with the predicted removal efficiency of 99.3% by the developed model. According to the analysis of variance (ANOVA), the high F-value of 797.5 and the very low P-value of <0.0001 confirm that the proposed model is highly significant. The ATP concentration of the groundwater sample was reduced to zero after applying the proposed process. The obtained results confirmed that modifying the activated carbon by ferric chloride increased the surface area, total pore volume, and the adsorption capacity as compared to the commercial activated carbon (CAC) and raw activated carbon (RAC). ATP adsorption followed the pseudo-second-order kinetics model with the Akaike information criterion (AIC) of 0.101 and 0.114 for the synthetic and real samples that suggest the treatment process controlled under the chemisorption mechanism. The equilibrium studies were well fitted to the Langmuir isotherm with the AIC of 1.38, which indicates that the ATP adsorption is monolayer and homogeneous. The maximum adsorption capacity (qm) of 86.1 and 83.6 mg g−1, and RL of 0.0312 and 0.055 were found for synthetic and real samples, respectively.

Integrated non-targeted lipidomics and metabolomics analyses for fluctuations of neonicotinoids imidacloprid and acetamiprid on Neuro-2a cells

Neonicotinoid insecticides are widely used for pest control. However, they are highly water-soluble and easily ingested by organisms, posing potential health risks. In this study, cytotoxicity evaluations of imidacloprid and acetamiprid were conducted in Neuro-2a cells by obtaining their half maximal inhibitory concentration (IC50 values) (1152.1 and 936.5 μM, respectively). The toxic effects at the IC10 and IC20 on cell metabolism were determined by integrated non-targeted lipidomics and metabolomics analyses. Changes in the concentration of acetamiprid caused the most drastic perturbations of metabolism in Neuro-2a cells. Altogether, the detected lipids were mainly attributed to triglyceride, phosphatidylcholine (PC), and diglyceride. These three categories of lipids accounted for more than 67% of the sum in Neuro-2a cells. A total of 14 lipids and other 40 metabolites were screened as differential metabolites based on multivariate data analysis, and PCs were most frequently observed with a proportion of 25.9%. The results demonstrated that lipid metabolism should be paid considerable attention after imidacloprid and acetamiprid exposure. Pathway analysis showed that the metabolisms of glycerophospholipid, sphingolipid, and glutathione were the dominant pathways that were interfered. The present study is the first to investigate the cellular toxic mechanisms after separate imidacloprid and acetamiprid exposure by using lipidomics and metabolomics simultaneously. This research also provides novel insights into the evaluation of the ecological risk of imidacloprid and acetamiprid and contribute to the study of toxicity mechanism of these neonicotinoid insecticides to animals and humans in the future.

A Photoelectrochemical Aptasensor for Acetamiprid Determination Based on λ Exonuclease-Assisted Recycling Amplification and DNAzyme-Catalyzed Precipitation

In the present work, we developed a selective and sensitive photoelectrochemical (PEC) aptasensor for acetamiprid determination. Due to specific recognition ability of the aptamer, acetamiprid could combine with its aptamer, leading to the release of the primer from the aptamer-primer hybrid duplex and the formation of 5′-phosphorylated double-stranded DNAs on the nanocomposite of graphitic carbon nitride and titanium dioxide nanotube array (TNA/g-C3N4), which could be catalytically recycling-digested by λ exonuclease, leading to the amplification of the signal, and the generated DNAzymes could catalyze the in situ production of benzo-4-chlorohexadienone (4-CD) precipitate in the presence of H2O2, causing the significant decrease of photocurrent response of TNA/g-C3N4. Under the optimal experimental conditions, the logarithm of decrease value of photocurrent was linear proportional to the logarithm of acetamiprid concentration from 0.1 pM to 1.0 nM. And the constructed PEC aptasensor exhibited a low limit of detection (0.025 pM) and good selectivity towards acetamiprid determination, which has been successfully applied for the analysis of real vegetable samples with good precision of RSD less than 4.3% and good accuracy of the recoveries ranged from 96.4% to 104.3%.

Self-Assembled MoS2/ssDNA Nanostructures for the Capacitive Aptasensing of Acetamiprid Insecticide

The aim of this work is to detect acetamiprid using electrochemical capacitance spectroscopy, which is widely used as a pesticide in agriculture and is harmful to humans. We have designed aptasensing platform based on the adsorption of a DNA aptamer on lipoic acid-modified MoS2 nano-sheets. The biosensor takes advantage of the high affinity of single-stranded DNA sequences to MoS2 nano-sheets. The stability of DNA on MoS2 nano-sheets is assured by covalent attachment to lipoic acid that forms self-assembled layer on MoS2 surface. The biosensor exhibits excellent capacitance performances owing to its large effective surface area making it interesting material for capacitive transduction system. The impedance-derived capacitance varies with the increasing concentrations of acetamiprid that can be attributed to the aptamer desorption from the MoS2 nanosheets facilitating ion diffusion into MoS2 interlayers. The developed device showed high analytical performances for acetamiprid detection on electrochemical impedance spectroscopy EIS- derived capacitance variation and high selectivity toward the target in presence of other pesticides. Real sample analysis of food stuff such as tomatoes is demonstrated which open the way to their use for monitoring of food contaminants by tailoring the aptamer.

Determination of acetamiprid using electrochemiluminescent aptasensor modified by MoS2QDs-PATP/PTCA and NH2-UiO-66.

A novel aptasensor has been fabricated based on the resonance energy transform (RET) system from MoS2QDs-PATP/PTCA (donor) to NH2-UiO-66 (acceptor). The electrochemiluminescence (ECL) signal of PTCA was greatly amplified due to the decoration of MoS2QDs-PATP, and the NH2-UiO-66 was utilized to label the signal probe DNA (pDNA), which hybridizes with the exposed aptamer anchored on the surface of MoS2QDs-PATP/PTCA. With the target acetamiprid, the specific binding of acetamiprid to aptamer causes the connection between the donor and the acceptor to be interrupted and produce an "on" ECL signal. Thus, an "off-on" ECL sensing platform for sensitive and selective acetamiprid assay was designed. Under the optimal condition, the ECL signal of theaptasensor was found to be linearly related to the logarithm of the acetamiprid concentration ranging from 0.1fM to 0.1μM with a detection limit of 0.064fM. More importantly, the recovery rate of the ECL aptasensor was calculated to be 98.7 ~ 106% with aRSD lower 5.1% for the residual acetamiprid assay in real food samples, which indicated that the aptasensor has high potential for practical applications.

Inner filter effect-based immunoassay for the detection of acetamiprid using upconversion nanoparticles and gold nanoparticles

ABSTRACTIn this study, we present an inner filter effect-based immunoassay (IFE-IA) for the detection of acetamiprid with a turn off–on model. In the IFE-IA, the monoclonal antibody (mAb) conjugated with upconversion nanoparticles (UCNPs) were set as a fluorescence source, and the antigen conjugated with gold nanoparticles (AuNPs) were set as the fluorescence switch off reagent, while acetamiprid acts as the fluorescence turn-on reagent. After optimization, the concentration of acetamiprid producing 50% saturation of the signal (SC50) was 0.04 µg/L, and the detection range (SC10–SC90) was 0.002–0.58 µg/L. The IFE-IA showed no cross-reactivity with the analogues of acetamiprid except for thiacloprid (36.4%). The average recoveries of the immunoassay for spiked samples were in the range of 75.1–104.7%. In addition, the assay showed good correlation with high-performance liquid chromatography in the detection of blind samples.

Label-free hairpin-like aptamer and EIS-based practical, biostable sensor for acetamiprid detection

Acetamiprid (ACE) is a kind of broad-spectrum pesticide that has potential health risk to human beings. Aptamers (Ap-DNA (1)) have a great potential as analytical tools for pesticide detection. In this work, a label-free electrochemical sensing assay for ACE determination is presented by electrochemical impedance spectroscopy (EIS). And the specific binding model between ACE and Ap-DNA (1) was further investigated for the first time. Circular dichroism (CD) spectroscopy and EIS demonstrated that the single strand AP-DNA (1) first formed a loosely secondary structure in Tris-HClO4 (20 mM, pH = 7.4), and then transformed into a more stable hairpin-like structure when incubated in binding buffer (B-buffer). The formed stem-loop bulge provides the specific capturing sites for ACE, forming ACE/AP-DNA (1) complex, and induced the RCT (charge transfer resistance) increase between the solution-based redox probe [Fe(CN)6]3−/4− and the electrode surface. The change of ΔRCT (charge transfer resistance change, ΔRCT = RCT(after)-RCT(before)) is positively related to the ACE level. As a result, the AP-DNA (1) biosensor showed a high sensitivity with the ACE concentration range spanning from 5 nM to 200 mM and a detection limit of 1 nM. The impedimetric AP-DNA (1) sensor also showed good selectivity to ACE over other selected pesticides and exhbited excellent performance in environmental water and orange juice samples analysis, with spiked recoveries in the range of 85.8% to 93.4% in lake water and 83.7% to 89.4% in orange juice. With good performance characteristics of practicality, sensitivity and selectivity, the AP-DNA (1) sensor holds a promising application for the on-site ACE detection.

A syringe-aided apta-nanosensing method for colorimetric determination of acetamiprid

A syringe-aided apta-nanosensing method is reported for the colorimetric determination of acetamiprid. The method employs double-stranded (ds) DNA-conjugated gold nanoparticle@magnetic agarose beads, i.e., dsDNA-AuNP@MABs as peroxidase-mimicking composite probes, in which the aptamer is indirectly attached to the AuNP surface through its hybridization with complementary DNA (cDNA). Upon contact with the acetamiprid target, the probes can give perceptible color change due to the possible conformation switch from dsDNA’s brush-like to cDNA’s ‘pancake’ regime. An “air-spaced pumping” procedure using a syringe equipped with ring magnets as the operation platform was proposed to facilitate the magnetic separation of the sensing probes. Therefore, the analytical steps can be easily accomplished in a syringe, including probe loading, acetamiprid capture and magnetic separation from crude samples, chromogenic reagent loading and colorimetric visualization. Acetamiprid concentration down to 3.3 ppb can be easily identified by the naked eye. The final solution also can be transferred for quantitative measurement. Under spectrometer, the ratio of the absorbance at 652 nm in the presence and absence of acetamiprid (A/A0) is linearly related to the acetamiprid concentration in the 0.4–4.5 ppb range. The limit of detection is calculated to be 0.24 ppb. Moreover, satisfactory recoveries ranging from 90.90 to 91.82% with relative standard deviations of ≤2.96% were obtained in analyzing real spiked samples.

Acute neurotoxicity evaluation of two anticholinesterasic insecticides, independently and in mixtures, and a neonicotinoid on a freshwater gastropod

Neurotoxic insecticides are ubiquitous in aquatic ecosystems, frequently as part of complex mixtures. Freshwater gastropods are generally underrepresented in neurotoxicity evaluations and cumulative toxicity testing. This study investigates the behavioural and biochemical effects of acute exposures to the carbamate carbaryl, the organophosphate chlorpyrifos, and the neonicotinoid acetamiprid on the freshwater gastropod Chilina gibbosa. First, we evaluated behavioural neurotoxicity and cholinesterase (ChE), carboxylesterase (CE), and glutathione S-transferase (GST) activities in acute (48h) single-chemical exposures to increasing concentrations of carbaryl (0.5–500 μg L−1), chlorpyrifos (10–7500 μg L−1), and acetamiprid (1–10000 μg L−1). We then studied the effects of acute (48h) exposures to binary mixtures of carbaryl and chlorpyrifos equivalent to 0.5, 1, and 1.5 ChE 48h-IC50. None of the insecticides caused severe behavioural neurotoxicity, except for a significant lack of adherence by 5000 μg L−1 chlorpyrifos. Carbaryl caused concentration-dependent inhibition of ChEs (NOEC 5 μg L−1; 48h-IC50 45 μg L−1) and CEs with p-nitrophenyl butyrate as substrate (NOEC 5 μg L−1; 48h-IC50 37 μg L−1). Chlorpyrifos caused concentration-dependent inhibition of ChEs (NOEC 50 μg L−1; 48h-IC50 946 μg L−1) but did not affect CEs (NOEC ≥7500 μg L−1). Carbaryl-chlorpyrifos mixtures inhibited ChEs additively, inhibited CEs with p-nitrophenyl butyrate, and did not affect behaviour. GST activity was not affected by single or mixture exposures. Acute exposure to acetamiprid did not affect any of the endpoints evaluated. This study provides new information on carbaryl, chlorpyrifos, and acetamiprid toxicity on C. gibbosa, relevant to improve gastropod representation in ecotoxicological risk assessment.

Effects of the Neonicotinoid Acetamiprid in Pollen on Bombus impatiens Microcolony Development.

Honey bees and other wild bee species including bumble bees have experienced population declines in recent decades. Although many stressors are implicated in bee population declines, much attention has focused on neonicotinoid pesticides, which are widely used and known to be toxic to pollinators. One neonicotinoid, acetamiprid, has been studied very little in bumble bees, despite its use on bumble bee-pollinated crops. We assessed the impacts of acetamiprid to the North American bumble bee Bombus impatiens using the microcolony model. We examined nest growth, development, and subsequent nest productivity as measured by drone production. We found that high concentrations of acetamiprid in pollen (4520 µg/kg) significantly impacted nest growth, development, and, ultimately, reproduction (drone production). We found the no-observable-adverse effect level to be 45.2 µg/kg. Overall, acetamiprid has the potential to negatively impact reproductive endpoints for B. impatiens. However, effects occurred at concentrations substantially higher than expected environmental concentrations that would be achieved when following label rates. Further work is required to assess the effects of this pesticide on B. impatiens via alternate routes of exposure and on queenright colonies. Environ Toxicol Chem 2020;39:2560-2569. © 2020 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Effects of the neonicotinoid acetamiprid in syrup on Bombus impatiens (Hymenoptera: Apidae) microcolony development.

Worldwide, many pollinator populations are in decline. Population reductions have been documented for the agriculturally important honey bee (Apis mellifera), and other bee species such as bumble bees that are also critical for pollinating crops and natural landscapes. A variety of factors contribute to the observed population reductions, including exposure to agrochemicals. In recent decades, neonicotinoid pesticide use has dramatically increased, as have concerns regarding the safety of these chemicals for pollinator health. Here we assessed the toxicity of the neonicotinoid acetamiprid to the bumble bee Bombus impatiens, a species commercially available for use in agricultural settings in North America. Using the microcolony model, we examined nest growth, development and subsequent nest productivity as measured by drone production. We found that high concentrations of acetamiprid in syrup (11,300 μg/L) significantly impacted nest growth and development, and ultimately drone production, and exposure to 1,130 μg/L acetamiprid also significantly decreased drone production. The no observable adverse effect level was 113 μg/L. Overall, acetamiprid delivered in syrup can negatively impact B. impatiens nest development and productivity, however only at concentrations above which would be expected in the environment when used according to label rates.

Neonicotinoids suppress contact chemoreception in a common farmland spider

Neonicotinoid insecticides are increasingly recognized for their role as information disruptors by modifying the chemical communication system of insects and therefore decreasing the chances of reproduction in target insects. However, data from spiders are lacking. In the present study, we tested the responses of males of a common agrobiont spider, Pardosa agrestis, to the application of field-realistic concentration of acetamiprid, which was formulated as Mospilan, and trace amounts of thiacloprid, which was formulated as Biscaya. We applied fresh or 24-h-old residues of Mospilan or Biscaya to the males just prior to the experiment or treated only the surface of a tunnel containing female draglines. We evaluated the ability of the males to recognize female cues from female dragline silk in a Y-maze. The field-realistic, sublethal doses of Mospilan altered pheromone-guided behavior. The choice of the tunnel with female draglines by males was hampered by tarsal treatment of the males with 24 h-old residues of Mospilan. The mating dance display was commonly initiated in control males that came into contact with female draglines and was suppressed by the Mospilan treatments in all three experimental settings. Some males only initiated the mating dance but did not manage to complete it; this was particularly true for males that were treated tarsally with fresh Mospilan residues, as none of these males managed to complete the mating dance. All three experimental settings with Mospilan decreased the frequency of males that managed to both select the tunnel with female draglines and complete the mating dance. The responses to the low-dose Biscaya were much milder and the study was not sufficiently powered to confirm the effects of Biscaya; however, the surprisingly observed trends in responses to very low Biscaya concentrations call for further analyses of long-term effects of trace amounts of neonicotinoids on the pheromone-guided behavior of spiders. These are the first conclusive data regarding the effects of commercially available formulations of neonicotinoid insecticides on the intraspecific chemical communication of spiders.

Neonicotinoid insecticides hinder the pupation and metamorphosis into adults in a crabronid wasp

Neonicotinoid insecticides are associated with a decline in the diversity and distribution of bees and wasps (Hymenoptera: Aculeata). The effects of neonicotinoids on the metamorphosis of aculeates have never been addressed in detail; however, recent evidence suggests that neonicotinoids induce wing abnormalities. We hypothesized that the metamorphosis success of bees and wasps differs in response to contact exposure to field-realistic concentrations of neonicotinoid insecticides or in response to combined exposure to neonicotinoid insecticides and benzimidazole fungicides. We treated prepupae of the model crabronid wasp Pemphredon fabricii with field-realistic concentrations of four neonicotinoids, acetamiprid, imidacloprid, thiacloprid and thiamethoxam, and/or with the benzimidazole fungicide thiabendazole. Treatment with acetamiprid or imidacloprid decreased the pupation rates to only 39% and 32%, respectively. Treatment with thiacloprid or thiamethoxam did not affect the pupation rate when applied alone, but the subsequent treatment of thiacloprid- or thiamethoxam-treated prepupae with thiabendazole led to significant decreases in pupation rates. A high concentration of acetamiprid, which severely affected the pupation rates, had moderate effects on metamorphosis into adults, resulting in 53% metamorphosis success (as opposed to 95% metamorphosis success in the water-treated group). However, imidacloprid or thiamethoxam treatment resulted in only 5%-10% metamorphosis success into adults. Overall survival decreased in response to treatment with any of the neonicotinoids or benzimidazoles or their combinations, with extremely low survival (<2%) following combined treatment with imidacloprid and thiabendazole or thiamethoxam and thiabendazole. In conclusion, neonicotinoids alter insect metamorphosis success, which can be further potentiated by their combination with other agrochemicals, such as benzimidazoles.

Evaluation of the biochemical effects of an acetamiprid‐based insecticide on a non‐target species, Gambusia holbrooki

AbstractThe toxic effects of an acetamiprid‐based insecticide (ABI) on Gambusia holbrooki were evaluated after 24 and 96‐h exposure periods. The 24 and 96‐h median lethal concentration (LC50) values of ABI were determined as 75.9 and 42.2 mg/L active ingredient (AI)/L, respectively. In addition, the activity of five biochemical marker enzymes, including glutathione S‐transferase (GST), glutathione reductase (GR), carboxylesterase (CaE), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) was measured after 24 and 96‐h exposure to three different concentrations of the ABI to evaluate its sublethal effects. The acetamiprid concentrations in the exposure media were measured using liquid chromatography‐tandem mass spectrometry. Our results showed that GST and LDH activities were increased and there were concentration‐dependent changes in the integrated biomarker response (IBR) indexes after 24‐h ABI exposure. However, the examined biomarkers were not useful for examining the effects of the ABI exposure for 96‐h exposure periods, even at the highest concentration.

Dual amplification in a fluorometric acetamiprid assay by using an aptamer, G-quadruplex/hemin DNAzyme, and graphene quantum dots functionalized with D-penicillamine and histidine.

D-penicillamine and histidine-functionalized graphene quantum dot (DPA-GQD-His) was synthesized and applied in a fluorometric method for determination of acetamiprid using a G-quadruplex DNAzyme. At first DNA probe (probe 1) consists of a target-specific aptamer with two arms of DNA segments. Probe 1 was hybridized with DNA probe 2 composed of a single DNA sequence with two split G-rich DNA sequences. This leads to the formation of a triplex-to-G-quadruplex (TPGQ). Next, acetamiprid was hybridized with the aptamer in the TPGQ to release free DNA probe 2. The released probe 2, in the presence of of K+, undergoes a structural change into a stem-loop structure (by self-complementary hybridization and Hoogsteen hydrogen bonding) that bears a G-quadruplex structure. This is followed by conjugation with hemin to form the G-quadruplex/hemin DNAzyme. The DNAzyme catalyzes the oxidation of o-phenylenediamine by H2O2 to produce a yellow fluorescent product with excitation/emission maxima at 420/560nm. The oxidation product interacts with DPA-GQD-His to achieve a rapid energy transfer between DPA-GQD-His and oxidation product. This increases the fluorescence of the oxidation product and quenches the fluorescence of DPA-GQD-His. DPA-GQD-His also improves the catalytic activity of DNAzyme towards oxidation of ophenylenediamine oxidization and enhances fluorometric response to acetamiprid. The assay works in the 1.0 fM to 1.0nM acetamiprid concentration range and has a 0.38 fM detection limit. It was successfully applied to the determination of acetamiprid in tea. Graphical abstractThe study reported one double amplification strategy for ultrasensitive fluorescence detection of acetamiprid in tea with D-penicillamine and histidine-functionalized graphene quantum dots and G-quadruplex/heminDNAzyme. The analtyical method exhibits ultra high sensitivity, selectivity and rapidity of fluorescenceresponse to acetamiprid.

Facile strategy for synthesis of silver-graphene hybrid with controllable size and excellent dispersion for ultrasensitive electrochemical detection of acetamiprid

Electrochemical properties of metal-graphene hybrid depend on size and dispersion of metal nanoparticles on graphene sheets. The study reports a facile synthesis of silver-graphene hybrid with controllable size and excellent dispersion. Histidine-functionalized graphene quantum dots (His-GQDs) are firmly bound on graphene sheets of graphite oxide (GO) and then combined with Ag+ to form stable Ag/His-GQD/GO complex. Followed by heating in N2 to produce Ag/His-GQD/G. The resulting hybrid offers well-defined three-dimensional structure, in which all Ag nanoparticles are uniformly dispersed on the surface of graphene sheets. Interestingly, the size and density of Ag nanoparticles can be effectively adjusted by varying mass ratio of His-GQD/GO or Ag+/GO. To construct on the aptasensor, aptamer of acetamiprid was connected to Ag nanoparticles via Ag-S bond in the hybrid immobilized on surface of glass carbon electrode. The architecture creates an excellent catalytic activity. The aptasensor based on Ag/His-GQD/G exhibits ultrahigh sensitivity, specificity and stability for electrochemical detection of acetamiprid. A linear relationship between the peak current of differential pulse voltammetry and logarithm value of acetamiprid concentration was obtained in the range from 1.0 × 10−16 to 5.0 × 10−12 M with a detection limit of 4.0 × 10−17 M. The method has been successfully applied in detection of acetamiprid in tea.

Improved efficacy of neonicotinoid in tablet formulation on the control of\xa0tomato chlorosis virus by controlling the vector Bemisia tabaci

Neonicotinoid insecticides are used for preventing insects from transmitting plant viruses. This group of chemicals are easily taken up by plants and translocated to different tissues and are applicable for soil treatment in sustained-release tablets, which greatly reduces environmental contamination compared to foliar spray. The goal of this study was to examine the efficacy of thiamethoxam, acetamiprid and nitenpyram in tablet formulation against whitefly, Bemisia tabaci, the vector of tomato chlorosis virus (ToCV) under laboratory and greenhouse conditions. Effective 50% lethal concentration (LC50) of thiamethoxam, acetamiprid, and nitenpyram on B. tabaci were 2.18, 0.46 and 0.18 μg/g plant tissue, respectively. In vitro test showed that tablets of 10 mg nitenpyram applied in seedbed with thiamethoxam transplanting treatment showed 80.9% control of B. tabaci on tomato and 75.5% of ToCV after 32 days of transplanting. Therefore, neonicotinoid tablets were an effective strategy of soil treatment in controlling viruliferous insects and ToCV with reduced environmental contamination.