Characterisation of Neonicotinoid and Pymetrozine Resistance in Strains of Bemisia tabaci(Hemiptera:Aleyrodidae)from China

Four strains of the Q biotype and one of the B biotype of the whitefly Bemisia tabaci collected from China were characterised for resistance to four neonicotinoid insecticides and pymetrozine.Q biotype strains showed moderate to strong resistance to imidacloprid,thiamethoxam and acetamiprid,but little or no cross-resistance to dinotefuron.Resistance to neonicotinoids was consistently associated with resistance to pymetrozine,despite the latter having a distinct（though unresolved）mode of action.The single B biotype strain proved largely susceptible to all the insecticides investigated.Resistance in the Q biotype strains was associated with over-expression of a cytochrome P450 monooxygenase gene,CYP6CM1,whose substrate specificity presumably accounts for the observed cross-resistance profiles.

Pharmacophore model for neonicotinoid insecticides

An effective prediction pharmacophore model （RMS = 0.634, Correl = 0.893, Weight = 1.463, Config = 11.940） was successfully obtained by 3D-QSAR based on a series of nAChR （nicotinic acetylcholine receptors） agonists, which consists of a hydrogen- bonding acceptor, a hydrogen-bond donor, a hydrophobic aliphatic and a hydrophobic aromatic centre. This pharmacophore model may provide theoretical basis for designation and development of higher active insecticides.

Synthesis, Crystal Structure and Insecticidal Activities of Novel Neonicotinoid Derivatives

Ten new N-oxalyl derivatives of neonicotinoid compound were designed and synthesized. Their structures were confirmed by ^1H NMR spectra, elemental analysis and X-ray diffraction. The preliminary insecticidal activities of the new compounds were evaluated. The results of bioassays indicate that the title Compounds exhibit moderate insecticidal activities. Surprisingly, the insecticidal activity of compound 7b against bean aphids at 200 mg/kg is 100%, which is comoarable to that of the commercialized imidacloprid.

Synthesis and Crystal Structure of the Optical Activity of (Z)-Nitromethylene Neonicotinoid Analogue

A novel （Z）-nitromethylene neonicotinoid analogue （C23H27Cl2N5O4·2H2O） （II） with optical activity has been synthesized, the structure was characterized by elemental analysis, IR and 1H NMR spectra, and the （Z）-configuration was confirmed by single-crystal X-ray diffraction. The crystal belongs to triclinic, space group P1 with a = 7.4638（3）, b = 12.6232（5）, c = 15.2990（6）, α = 71.907（1）, β = 89.397（2）, γ = 80.314（1）°, V = 1349.28（9）3, Z = 2, Dc = 1.340 g/cm3, μ = 0.286 mm-1, Mr = 544.43, F（000） = 572, S = 1.056, R = 0.0801 and wR = 0.2366 for 4998 unique reflections with 3012 observed ones （I 〉 2σ（I））. In the crystal, the dihedral angle between the pyridine and 4-Cl-phenyl rings is 58.13°. Intermolecular O-H···O, C-H···O and C-H···Cl hydrogen bonds involving water molecules stabilize the crystal structure.

Comparing the Impact of a Neonicotinoid and Biorational Agroneem on Herbivorous and Beneficial Arthropods on Cowpea and Tomato

Cowpea （Vigna unguiculata L. Walp.） and tomato （Lycopersicum esculentum L. Karst） are attacked by a wide range of insect pests worldwide. In many cases, pesticides are used to control the pests. In 2010 and 2011, we conducted field experiments to evaluate and compare the effectiveness of a biorational （Agroneem~） and conventional pesticide （imidacloprid or thiamethoxam） on insect pests of these crops. In the first year, two varieties of cowpea （Mississippi Silver and Pinkeye Purple Hull） and two of tomato （Mariana and German Johnson） were used; in the second year, the better performing of each group （Mississippi Silver and Mariana） were used for the study. A split-plot design with four replications in Year 1, and a randomized complete block design with six treatment combinations in Year 2. In the first year, both pesticide groups were applied following manufacturer＇s recommendation （10-14 d cycles）; and in the second year, the application of the pesticides was driven by economic thresholds level （ETL） of insect pests. The most prevalent species of insects recorded in both crops were in the families： Chrysomelidae, Pentatomidae, Cicadellidae, Vespidae, Sarcophagidae, Thripidae and Sphingidae. In both years, the diversity of insects on cowpea was greater than on tomato and more insects were observed in the second year compared to the first, despite the absence of significant difference （P 〉 0.05） between varieties in the treated plots. The yield of cowpea and tomato was comparable in all sprayed plots.

Energy Metabolism Pattern in Cotton Aphid, Aphis gossypii Glover （Hem.： Aphididae） Exposure to Neonicotinoids

This study was mainly made on the role of energy revisers in cotton aphid, Aphis gossypii Glover （Hemiptera： Aphididae） countered with imidacloprid and thiametoxam. We measured used energy, available energy and the content of total energy in three strains of cotton aphid which were from very resistant to neonicotinoid, sup to semi-sensitive and sensitive speccies, respectively. It was observed changes in energy resources rate in all of the aphid strains at which each substrate was metabolized under stress. Our findings indicated among energy sources, total lipid in susceptible strain was increased in counter of spraying and it was decreased in resistance and semi sensitive strains. Whereas, total protein was decreased in all of the strains encountering with neonicotiniod stress. Total glycogen was increased significantly in different aphid strains and sugar was decreased in countered of spraying.

Energy Intensity and Fitness Cost of Cotton aphid Exposure to Neonicotinoids

Three populations of Aphis gossypii of distinct susceptibility to neonicotinoids show differences in the accumulation and mobilization of energy reserves, what may allow the production of their defensive tools against two neonicotinoid insecticides without impairing their reproductive performance. Bioassays were also carried out for these aphid populations. According to the results obtained, the Ag-R population showed resistant rate significantly higher than the other two populations. Levels of some biochemical characteristics were determined in the resistant, susceptible and semi susceptible populations of cotton aphid. The results obtained in the assays with biochemical parameters indicated significant differences in activity among the populations, with higher activity in using glycogen in the Ag-R population. The inverse activity trends oft （generation time） and DT （doubling time） in both resistant and susceptible populations, one showing fitness disadvantage without insecticide exposure and the other not showing it, may underlay the mitigation of insecticide resistance physiological costs observed in the Ag-R population.

Adverse Effects of the Neonicotinoid Thiacloprid Assessed on an Ant Used as a Biological Model*

Thiacloprid has been banned in many European countries for its toxicity, but is nevertheless still used outside the EU. Using the ant Myrmica sabuleti as a model organism, we sought a concentration of thiacloprid that would be low in environmental impact, but nonetheless harmful to an insect. Assessed on ten biological traits, a sub-lethal 2 μg/L concentration in the sugar water diet of the ants impacted their locomotion and other motor-linked behavioral traits such as orientation, moving on an unfamiliar device, moving on a rough surface, brood caring and progressing along a twist and turns path. Sensory perception appeared unaffected. Behaviors involving cognition or related in some way to it, such as social relationships, ability to leave an enclosure, learning and memory also appeared unaffected, but their outcomes could be entangled with those of locomotor impairment. The effect of thiacloprid on locomotion vanished in about 30 hours. Adverse effects were still present with the 0.1 and 0.01 μg/L concentrations, but at a lower level. Partial physiological adaptation at the individual level occurred for the 2 μg/L concentration, less so for 0.1 μg/L and not for 0.01 μg/L. Thiacloprid should thus be used at the lowest still active concentration producing a significant damaging behavioral effect with no physiological adaptation. This concentration remains to be specifically defined for targeted pest species.

Developmental toxicity assessment of neonicotinoids and organophosphate esters with a human embryonic stem cell-and metabolism-based fast-screening model

In recent years,neonicotinoids(NEOs)and organophosphate esters(OPEs)have been widely used as substitutes for traditional pesticides and brominated fame-retardants,respectively.Previous studies have shown that those compounds can be frequently detected in environmental and human samples,are able to penetrate the placental barrier,and are toxic to animals.Thus,it is reasonable to speculate that NEOs and OPEs may have potential adverse effects in humans,especially during development.We employed a human embryonic stem cell differentiation-and liver S9 fraction metabolism-based fast screening model to assess the potential embryonic toxicity of those two types of chemicals.We show that four NEO and five OPE prototypes targeted mostly ectoderm specification,as neural ectoderm and neural crest genes were down-regulated,and surface ectoderm and placode markers up-regulated.Human liver S9 fraction's treatment could generally reduce the effects of the chemicals,except in a few specific instances,indicating the liver may detoxify NEOs and OPEs.Our findings suggest that NEOs and OPEs interfere with human early embryonic development.

Two aquaporins,PIP1;1 and PIP2;1,mediate the uptake of neonicotinoid pesticides in plants

Neonicotinoids(NEOs),a large class of organic compounds,are a type of commonly used pesticide for crop protection.Their uptake and accumulation in plants are prerequisites for their intra-and intercellular move-ments,transformation,and function.Understanding the molecular mechanisms that underpin NEO uptake by plants is crucial for effective application,which remains elusive.Here,we demonstrate that NEOs enter plant cells primarily through the transmembrane symplastic pathway and accumulate mainly in the cytosol.Two plasma membrane intrinsic proteins discovered in Brassica rapa,BraPIP1;1 and BraPIP2;1,were found to encode aquaporins(AQPs)that are highly permeable to NEOs in different plant species and facilitate NEO subcellular diffusion and accumulation.Their conserved transport function was further demonstrated in Xenopus laevis oocyte and yeast assays.BraPIP1;1 and BraPIP2;1 gene knockouts and interaction as-says suggested that their proteins can form functional heterotetramers.Assessment of the potential of mean force indicated a negative correlation between NEO uptake and the energy barrier of BraPIP1;1 chan-nels.This study shows that AQPs transport organic compounds with greater osmolarity than previously thought,providing new insight into the molecular mechanisms of organic compound uptake and facilitating innovations in systemic pesticides.

Degradation of neonicotinoids with different molecular structures in heterogeneous peroxymonosulfate activation system through different oxidation pathways

The elimination of neonicotinoids(NEOs)from water has been a research priority due to their threats to human health and ecosystems.In this study,we established the heterogeneous peroxymonosulfate(PMS)activation system using manganese catalyst(Mn NC)and cobalt catalyst(Co NC)to trigger the nonradical oxidation and synergistic oxidation pathway,respectively to remove NEOs.The results showed that the nonradical oxidation system exhibited superior NEOs degradation capability.The composition of organic pollutants in wastewater significantly impacted subsequent degradation processes.The charge distribution and reaction sites of various NEOs were analyzed using density functional theory(DFT)calculations,and it demonstrated the electron distribution and activity of NEOs were significantly influenced by the type and number of substituents.Nitro group(–NO_(2))and cyanide group(–C≡N)were identified as strong electron-withdrawing groups and prone to be attacked by negatively charged radicals.The transformation of NEOs was analyzed,and result showed that the C and N sites adjacent to the nitro group and cyanide group were more susceptible to oxidation attacks.S and N atoms,which possess strong electronegativity and high electron cloud density,were identified as key active sites in the degradation pathway.The outcomes of this study provide valuable guidance for the oriented regulation of oxidation pathways towards efficient removal of NEOs in water.

The alarming link between neonicotinoid insecticides and kidney injury

Neonicotinoid insecticides(NEOs)have been extensively approved for application in agricultural production both in China and globally.Previous studies indicated that human exposure to NEOs would have adverse health effects.However,studies on occurrences of NEOs in kidney injury patients and their association with nephrotoxicity are limited.This study investigates the potential correlation between exposure to NEOs and kidney injury within a subset(n=224)of the population residing in South China.Levels of 8 NEOs and 5 metabolites were quantified in blood samples obtained from both the 110 healthy and 114 kidney injury cohorts in South China.We found that target analytes were frequently detected in samples from the healthy and kidney injury cohorts(61%-100%).Dinotefuran is the predominant NEO in the healthy(42.3%)and kidney injury cohort(49.6%).Significantly positive(p<0.05)associations between blood NEO concentrations and kidney injury were found,indicating that these pollutants may increase the odds of human kidney injury prevalence.Through multilinear regression analysis,it was observed that the concentrations of various NEOs exhibited a significant association(p<0.05)with hematological parameters linked to nephrotoxicity.Our study represents the pioneering investigation examining the relationships between NEOs and kidney injury,thereby offering novel insights into the nephrotoxicity associated with these pollutants.This discovery carries significant implications for public health policies and environmental conservation practices.

Design,synthesis and insecticidal activity of spiro heterocycle containing neonicotinoid analogs

Spiro heterocycles frequently occur in bioactive molecules. In the pursuit of neonicotinoids with spiro hererocycles, three types of novel neonicotinoids with spirobenzofuranone, spirooxindole or spiroacenaphythylenone framework were designed and synthesized. Insecticidal evaluation showed that some of spirobenzofuranone containing neonicotinoids exhibited moderate activity against cowpea aphid, armyworm or brown planthopper.

Lethal, sublethal and transgenerational effects of the novel chiral neonicotinoid pesticide cycloxaprid on demographic and behavioral traits of Aphis gossypii （Hemiptera： Aphididae）

Aphis gossypii Glover （Hemiptera： Aphididae） is a key pest in cotton crops, notably owing to its increasing resistance to commonly used pesticides. Such resistance prompts for the development of integrated pest management （IPM） programs that include novel pesticides being effective against the aphid. In the present study, we assessed lethal and sublethal effects of cycloxaprid, a novel chiral neonicotinoid pesticide developed in China, on A. gossypii. The lethal concentration at 50% （LCs0） value of cycloxaprid on A. gossypii was estimated, using the dipping method, at 7.73 mg/L. The impact of a sublethal concentration （LC10） and a lethal concentration （LC40） of cycloxaprid on A. gossypii population growth and feeding behavior （using electrical penetration graph technique [EPG]）, and its transgenerational effect were further assessed. Adult longevity and fecundity significantly decreased after exposure to LEa0 or LC10 of cycloxaprid. Cycloxaprid with sublethal concentrations （especially LC40） had negative effects on phloem ingestion by A. gossypii. Additionally, the offspring of the adults exposed to LC40 of cycloxaprid had shorter nymphal development duration and adult longevity than the control, and those from LC10 and LC40 treatments had lower adult fecundity and net productive rate. We demonstrated that cycloxaprid is a pesticide showing both lethal and sublethal activities, and transgenerational effects on,4. gossypii; it may be useful for implementation in IPM programs against this aphid pest.

Induction of P450 genes in Nilaparvata lugens and Sogatella furcifera by two neonicotinoid insecticides

Nilaparvata lugens and Sogatella furcifera are two primary planthoppers on rice throughout Asian countries and areas. Neonicotinoid insecticides, such as imidaclo- prid （IMI）, have been extensively used to control rice planthoppers and IMI resistance consequently occurred with an important mechanism from the over-expression of P450 genes. The induction of P450 genes by IMI may increase the ability to metabolize this insecticide in planthoppers and increase the resistance risk. In this study, the induction of P450 genes was compared in S. furcifera treated with IM] and nitromethyleneimidazole （NMI）, in two planthopper species by IMI lethal dose that kills 85% of the population （LD85）, and in N. lugens among three IMI doses （LD15, LD50 and LD85）. When IMI and NMI at the LD85 dose were applied to S. furcifera, the expression changes in most P450 genes were similar, including the up-regulation of nine genes and down-regulation of three genes. In terms of the expression changes in 12 homologous P450 genes between N. lugens and S. furcifera treated with IMI at the LD85 dose, 10 genes had very similar patterns, such as up-regulation in seven genes, down-regulation in one gene and no significant changes in two genes. When three different IMI doses were applied to N. lugens, the changes in P450 gene expression were much different, such as up-regulation in four genes at all doses and dose-dependent regulation of the other nine genes. For example, CYP6AY1 could be induced by all IMI doses, while CYP6ER1 was only up-regulated by the LDs0 dose, although both genes were reported important in IMI resistance. In conclusion, P450 genes in two planthopper species showed similar regulation patterns in responding to IMI, and the two neonicotinoid insecticides had similar effects on P450 gene expression, although the regulation was often dose-dependent.

Occurrence, variations, and risk assessment of neonicotinoid insecticides in Harbin section of the Songhua River, northeast China

Neonicotinoid insecticides(NNIs)have been intensively used and exploited,resulting in their presence and accumulation in multiple environmental media.We herein investigated the current levels of eight major NNIs in the Harbin section of the Songhua River in northeast China,providing the first systematic report on NNIs in this region.At least four NNIs in water and three in sediment were detected,with total concentrations ranging from 30.8 to 135 ng L^(-1) and from 0.61 to 14.7 ng g^(-1) dw,respectively.Larger spatial variations in surface water NNIs concentrations were observed in tributary than mainstream(p<0.05)due to the intensive human activities(e.g.,horticulture,urban landscaping,and household pet flea control)and the discharge of wastewater from many treatment plants.There was a significant positive correlation(p<0.05)between the concentrations of residual imidacloprid(IMI),clothianidin(CLO),and S4NNIs in the sediment and total organic carbon(TOC).Due to its high solubility and low octanol-water partition coefficient(Kow),the sediment-water exchange behavior shows that NNIs in sediments can re-enter into the water body.Human exposure risk was assessed using the relative potency factor(RPF),which showed that infants have the highest exposure risk(estimated daily intake(SIMIeq EDI):31.9 ng kg^(-1) bw$d^(-1)).The concentration thresholds of NNIs for aquatic organisms in the Harbin section of the Songhua River were determined using the species sensitivity distribution(SSD)approach,resulting in a value of 355 ng L^(-1) for acute hazardous concentration for 5%of species(HC5)and 165 ng L^(-1) for chronic HC5.Aquatic organisms at low trophic levels were more vulnerable to potential harm from NNIs.

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

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

Design,synthesis,and insecticidal bioactivities evaluation of pyrrole-and dihydropyrrole-fused neonicotinoid analogs containing chlorothiazole ring

Chlorothiazole ring, as a substituted heterocycle, frequently occurred in structures of various insecticides, and brought positive effect on bioactivity. In purpose to find novel neonicotinoids, a series of pyrrole- and dihydropyrrole-fused neonicotinoid analogs containing chlorothiazole ring were synthesized for the first time. Results of the following biological assays showed that compounds Sa-c achieved good insecticidal activity against Aphis craccivora, and compound Sh exhibited good activity against Nilaparvata lugens.

Insights into Free and Conjugated Forms of Neonicotinoid Insecticides in Human Serum and Their Association with Oxidative Stress

Following exposure,neonicotinoid insecticides(NEOs)can be metabolized by both Phase Ⅰ and Phase Ⅱ reactions catalyzed by human cytochrome P450 enzymes.However,toxicities of parent NEOs and their metabolites are still unclear,and little is known about biotransformation rates and pathways of NEOs in humans.In this study,98 serum samples collected in China were analyzed for free,conjugated and total forms of six parent NEOs(i.e.,acetamiprid(ACE),imidacloprid(IMI),clothianidin(CLO),thiacloprid(THD),thiamethoxam(THM),and dinotefuran(DIN))and four metabolites(i.e.,N-desmethyl-acetamiprid(N-dm-ACE),1-methyl-3-(tetrahydro-3-furylmethyl)(DIN-U),5-hydroxy-imidacloprid(5-OH-IMI),olefin-imidacloprid(Of-IMI)).NEOs and their metabolites were detected in all serum samples,and the total median concentrations of free,conjugated,and total forms of 10 NEOs were 2.04,2.01,and 5.12 ng/mL,respectively.Conjugated forms of NEOs accounted for only half(53%)of the total forms of NEOs.Based on the profiles of Phase Ⅰ and Phase Ⅱ metabolites of NEOs in serum,it was found that age is a determinant in Phase Ⅰmetabolism of DIN and Phase Ⅱ metabolism of IMI.The Phase Ⅱmetabolites of NEOs are associated with oxidative DNA damage,and the conjugated forms of IMI,DIN,and 5-OH-IMI in serum were significantly positively correlated with oxidative stress.Overall,the amount of NEOs present in conjugated forms in human serum was determined to document the existence of a considerable proportion of free forms of these insecticides.

超高效液相色谱-串联质谱法测定水体沉积物中17种新烟碱类杀虫剂及代谢物的残留量

建立了基于全自动加速溶剂萃取-超高效液相色谱-串联质谱法检测水体沉积物中17种新烟碱类杀虫剂及代谢物残留的分析方法,17种目标物的质量浓度在一定范围内与对应的峰面积呈线性关系,该方法的检出限(3.143s)为0.0007~0.0022μg/kg。在0.02、0.2、1.5μg/kg加标水平下的平均回收率为82.70%~114.30%,日内精密度和日间精密度的相对标准偏差分别为1.4%~9.4%和3.8%~9.7%。