Cyfluthrin Research Articles

Assessment of reproductive toxicity of Cyfluthrin and Pestban either individually or combined in adult male albino rats

Many studies on individual pesticide risk assessments are available, but the toxicity of combined usage is still to estimate. So, the current study investigated reproductive toxicity induced by exposure to cyfluthrin (CYF) and pestban (PES) and their mixture in adult male albino rats. Forty adult male albino rats were randomized into four groups. All treatments were given daily by oral gavage for 60 days. Group I (control group): this group included 16 rats, divided into two equal subgroups: subgroup Ia (negative control) and subgroup Ib (a vehicle control), in which each rat received 2 ml of corn oil. Group II: CYF group (15.6 mg/kg). Group III; PES group (7.45 mg/kg). Group IV: CYF + PES. Individual CYF and PES exposure significantly decreased testicular weight, serum testosterone level, and epididymal sperm count when compared to the control group. These biochemical changes were confirmed by histological and ultra-structural disarray and reduced immunoreactions of Melan-A (also known as MART-1, Melanoma Antigen Recognized by T-cells), but mutual exposure to both pesticides resulted in a highly significant difference compared to other treated groups. Co-administration of CYF and PES aggravated testicular toxicity, exhausting the endogenous antioxidant status, and down-regulating the immune expression of Melan-A. So, mixing both components can intensify the damaging effects of each compound on testes.

New approach methodologies (NAM) to characterize neurotoxic chemicals for use in risk assessment: case study of four neurotoxic pesticides

Neurotoxic pesticides: Cyfluthrin (CYF), βCYF, endosulfan (ENDO) and chlorpyrifos-oxon (CPFO) were examined using new approach methodologies (NAM) to assess ToxCast in vitro neurotoxic assay activities (50% concentration–AC50s), chemical-target specificity (Z-Scores) and in vitro to in vivo extrapolation with ToxCast assay AC50s as inputs to calculate human Administered Equivalent Dose (AEDHuman mg/kg) through Integrated Chemical Environment (ICE) models. Fold differences (FD) between AEDHuman NAM predictions and adjusted (animal to human interspecies extrapolation) in vivo regulatory neurotoxicity points of departure (POD) were calculated to assess modeled predictions against measured in vivo data. Interspecies (animal to human) in vivo adjusted PODs were 0.147 mg/kg/d (CYF/βCYF), 0.180 mg/kg/d (ENDO) and 0.106 mg/kg/d (CPFO). ToxCast neurotoxicity assay results supported in vivo observations: CYF, βCYF and CPFO showed depressed neuroactivity, while ENDO showed increased neuroactivity. βCYF is known to have twice the toxicity of CYF in vivo but was less toxic in the in vitro assays. Percent assays with Z-Scores greater than 3 for CYF, βCYF, ENDO and CPFO were 100%, 100%, 67% and 71% respectively. Most AEDHuman were less than 10-FD indicating good predictivity of the in vivo adjusted PODs with ICE models. The NAMs were useful for characterizing the main neurotoxic activities and the ICE models were highly predictive of in vivo PODs to support mechanisms in risk assessment.

Mixture effects of thiamethoxam and seven pesticides with different modes of action on honey bees (Aplis mellifera)

Even though honey bees in the field are routinely exposed to a complex mixture of many different agrochemicals, few studies have surveyed toxic effects of pesticide mixtures on bees. To elucidate the interactive actions of pesticides on crop pollinators, we determined the individual and joint toxicities of thiamethoxam (THI) and other seven pesticides [dimethoate (DIM), methomyl (MET), zeta-cypermethrin (ZCY), cyfluthrin (CYF), permethrin (PER), esfenvalerate (ESF) and tetraconazole (TET)] to honey bees (Aplis mellifera) with feeding toxicity test. Results from the 7-days toxicity test implied that THI elicited the highest toxicity with a LC50 data of 0.25 (0.20–0.29) μg mL−1, followed by MET and DIM with LC50 data of 4.19 (3.58–4.88) and 5.30 (4.65–6.03) μg mL−1, respectively. By comparison, pyrethroids and TET possessed relatively low toxicities with their LC50 data from the range of 33.78 (29.12–38.39) to 1125 (922.4–1,442) μg mL−1. Among 98 evaluated THI-containing binary to octonary mixtures, 29.59% of combinations exhibited synergistic effects. In contrast, 18.37% of combinations exhibited antagonistic effects on A. mellifera. Moreover, 54.8% pesticide combinations incorporating THI and TET displayed synergistic toxicities to the insects. Our findings emphasized that the coexistence of several pesticides might induce enhanced toxicity to honey bees. Overall, our results afforded worthful toxicological information on the combined actions of neonicotinoids and current-use pesticides on honey bees, which could accelerate farther comprehend on the possible detriments of other pesticide mixtures in agro-environment.

Consolidation of temperature-dependent toxicity and thermoregulatory behavior into risk assessments of insecticides under thermal scenarios: A prospective study on Eremias argus

In this study, the temperature-dependent chemical toxicity of three insecticides and the resulting thermoregulatory (TR) behavior of the lizard Eremias argus have been consolidated into the current risk assessment framework. According to acute dermal toxicity assays, an increase of ambient temperature from 15 °C to 35 °C decreased the acute dermal toxicity of beta-cyfluthrin (BC) but increased the toxicity of chlorpyrifos (CPF). The toxicity of avermectin (AVM) did not show significant temperature-dependent responses. Based on thermal preference trials, lizards changed their body temperature via TR behavior to adaptively reduce toxicity under sub-lethal doses, which can be understood as a “self-rescue” behavior attenuating lethal effects. However, the risk quotient indicated that the effectiveness of this “self-rescue” behavior is limited. Metabolomics analysis showed that six different metabolites (i.e., creatine, glutamate, succinate, N-acetylaspartate, acetylcholine, and lactate) contributed to TR behavior changes. Biochemical assays and insecticide residue results demonstrated that the temperature-dependent toxicity of BC, CPF, and AVM affected lizards in the three aspects of biotransformation, oxidative stress, and neurometabolic interference. This work clarifies the ecotoxicological impacts of representative insecticides on reptiles from toxicological understanding to risk relevance. This knowledge may improve ecological predictions of agrochemical applications in the context of global climate change.

Chlorpyrifos, permethrin and cyfluthrin effect on cell survival, permeability, and tight junction in an in-vitro model of the human blood-brain barrier (BBB)

The blood-brain barrier (BBB) is a structural and functional interface between the plasma and the human brain. Predictive BBB in-vitro models like immortalized human capillary microvascular endothelial cells (HCMEC/D3) can be used to explore the BBB disruption potential of daily exposed chemicals. The present study was focused on investigating the human BBB permeation potential of one organophosphate pesticide, chlorpyrifos (CPF), and two pyrethroids, permethrin (PMT) and cyfluthrin (CFT). HCMEC/D3 cells were exposed to the chemical and the time-dependent pass across BBB along with permeation coefficient (Papp) was calculated. Transendothelial electrical resistance (TEER) was measured for the cells to check the monolayer formation and later to check the reduction in integrity after chemical exposure. Real time PCR was conducted to investigate the effect of chemicals on the expression BBB´s tight and adherens junction proteins. Calculated Papp value for three chemicals was in the following order: CPF>CFT>PMT, where CPF showed the highest permeation coefficient. TEER calculation showed that the integrity decreased after CPF exposure which was in concordance with Papp value whereas for other chemicals, no change in TEER after exposure was observed. In addition, the transwell study showed a higher efflux ratio (ER) (>2) of CFT indicating that CFT could be a substrate for active transport. For CPF and PMT, ER was less than 2, so no active transport seems to be involved. The evaluation of the mRNA expression analysis revealed a statistically significant decrease in Occludin (OCLN) gene expression for CPF, VE-Cadherin (CDH5) for PMT and Zonula Occludens (ZO1) expression for CFT. Our study showed that CPF has the highest potential for inducing cell death, higher permeation, and capability to induce BBB dysfunction than among the above-mentioned chemicals. Additionally, the results of the permeation study could be useful to build a human PBPK model using in vitro-to-in vivo extrapolation approach.

Identification of two ABCC transporters involved in malathion detoxification in the red flour beetle, Tribolium castaneum.

ABC transporters have been suggested to be involved in insecticide detoxification in different insect species mainly based on the indirect observation of transcriptional upregulation of ABC gene expression in response to insecticide exposure. Previous studies performed by us and others in the red flour beetle, Tribolium castaneum, have analyzed the function of TcABCA-C and TcABCG-H genes using RNA interference (RNAi) and demonstrated that specific TcABCA and TcABCC genes are involved in the elimination of the pyrethroid tefluthrin and the benzoylurea diflubenzuron, because gene silencing increased the beetle's susceptibility to the insecticides. In this study, we focused on the potential functions of TcABCA-C genes in detoxification of the pyrethroid cyfluthrin (CF), the organophosphate malathion (MAL) and the diacylhdyazine tebufenozide (TBF). Analysis of transcript levels of selected TcABCA-C genes in response to treatment with these three chemically unrelated insecticides revealed that some genes were particularly upregulated after insecticide treatment. In addition, the ABC inhibitor verapamil synergized significantly the toxicity of MAL but only negligibly CF and TBF toxicities. Finally, silencing of two TcABCC genes by RNAi revealed a significant increase in susceptibility to MAL. In contrast, we did not observe a significant increase in insecticide-induced mortalities when knocking down TcABC genes in larvae treated with CF or TBF, although they were upregulated in response to insecticide treatment. Our results suggest that two pleiotropic ABCC transporters expressed in metabolic and excretory tissues contribute to the elimination of MAL.

Targeted Multiresidue Method for the Analysis of Different Classes of Pesticides in Agro-Food Industrial Sludge by Liquid Chromatography Tandem Mass Spectrometry.

Sludge generated after washing of fruits and vegetables during agro-food processes is a complex matrix and selective methods for the identification and quantification of pesticides’ residues are necessary in order to achieve a sustainable and effective management of the total sewage. The present work describes the development and validation of a reliable, simple and fast analytical method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of 47 pesticides of different chemical classes, including organosphosphates, pyrethroids, neonicotinoids, triazoles and others, in sludge samples after QuEChERS sample preparation. The necessity of the individual steps of QuEChERS was investigated and the LC-ESI-MS/MS conditions were optimized to achieve maximum sensitivity of the target analytes. The method limits of detection (LODs) ranged between 0.0005 mg/kg (imidacloprid) and 0.05 mg/kg (beta cyfluthrin). The recoveries ranged between 71–120% and the repeatability of the method was ≤25% expressed as relative standard deviation. The method was applied to sludge samples generated after washing of fruits in an agro-fruit-packaging unit in Greece. The results showed the presence of 37 pesticides’ active substances with concentrations ranging from low ppbs, such as fludioxinil (5 μg/kg) up to low ppms such as beta cyfluthrin (3.5 mg/kg) and with their sum concentration reaching up to 19 mg/kg.

Thermoregulation of Eremias argus alters temperature-dependent toxicity of beta-cyfluthrin: Ecotoxicological effects considering ectotherm behavior traits

Risk assessments of the ecotoxicological effects insecticides impose on ectotherms have increasingly considered temperature. However, the changes toxicants induce in thermoregulatory behavioral traits may lead to a divergence of thermal selection and temperature-dependent changes of contaminant toxicity. This study demonstrated the interaction of behavioral thermoregulation and temperature-dependent toxicity of beta-cyfluthrin (BC) in the lizard Eremias argus. Based on the negative relationship between temperature and BC toxicity, seeking a warming environment was assumed to represent a self-rescue behavior (and vice versa). The results showed that BC-treated lizards (0–20 μg/g body weight (bw)) showed such self-rescue behavior, while lizards exposed to an extremely high BC dose (200 μg/g bw) sought a cooler environment. Biochemical assays showed that BC affected neurotransmitter systems, caused oxidative stress, and interfered with ion-transport in the central nervous system. Biomarkers of the cholinergic and glutamatergic system, ion-transport function, and oxidative stress were identified as potential biochemical variables related to thermoregulatory behavior. Apparently, seeking a warmer environment is a survival strategy with the aim to neutralize BC toxicity, while seeking a cooler environment aims to attenuate the harmful effects of metabolic and oxidative stress, and to decelerate internal BC diffusion. This phenomenon could be also explained by the concept of the “cooling trap”, i.e., a behavior where cooler temperatures are sought. This impairs survival after exposure to BC at it has a negative temperature coefficient, derived from a dysfunction of the central nervous system regarding thermoregulation caused by the high dosage of neurotoxicant and resulting temperature maladaptation. Implications of the interaction between thermoregulatory behavior and temperature-dependent toxicity are presented, which may aid further temperature-dependent risk assessments.

Binary and ternary toxicological interactions of clothianidin and eight commonly used pesticides on honey bees (Apis mellifera)

Although many toxicological evaluations have been conducted for honey bees (Apis mellifera), most of these studies have only focused on the effects of individual chemicals. However, honey bees are usually exposed to pesticide mixtures under field conditions. In this study, we examined the effects of individual pesticides and mixtures of clothianidin (CLO) with eight other pesticides [carbaryl (CAR), thiodicarb (THI), chlorpyrifos (CHL), beta-cyfluthrin (BCY), gamma-cyhalothrin (GCY), tetraconazole (TET), spinosad (SPI) and indoxacarb (IND)] on honey bees using a feeding method. Toxicity tests of a 4-day exposure to individual pesticides revealed that CLO had the highest toxicity to A. mellifera, with an LC50 value of 0.24 μg a.i. mL-1, followed by IND and CHL with LC50 values of 3.40 and 3.56 μg a.i. mL-1, respectively. SPI and CAR had relatively low toxicities, with LC50 values of 7.19 and 8.42 μg a.i. mL-1, respectively. In contrast, TET exhibited the least toxicity, with an LC50 value of 258.7 μg a.i. mL-1. Most binary mixtures of CLO with other pesticides exerted additive and antagonistic effects. However, all the ternary mixtures containing CLO and TET (except for CLO+TET+THD) elicited synergistic responses to bees. Either increased numbers of components in the mixture or/and a unique mode of action appeared to be responsible for the higher toxicity of mixtures. Our findings emphasized the need for risk assessment of pesticide mixtures rather than the individual chemicals. Our data also provided information that might help growers avoid increased toxicity and unnecessary injury to pollinators.

Cyfluthrin Pestisitinin Zebra Midyesi (Dreissena polymorpha) Üzerindeki Etkisinin Bazı Antioksidan Enzim Aktiviteleriyle Belirlenmesi

In this study, some biochemical responses of Cyfluthrin (CFT), a commercial insecticide in Dreissena polymorpha, were investigated. The 96 hour LC50 value of CFT on D. polymorpha was calculated as 553.22 ± 27.3 µg / L. D. polymorpha was exposed to subletal concentrations (1/20, 1/10 and 1/5 of LC50 value) of CFT for 24 and 96 hours. The enzyme activities of superoxide dismustase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were determined in D. polymorpha individuals. In D. polymorpha exposed to CFT, SOD activity increased compared to control. It was determined that CAT and GPx activities were inhibited compared to the control.
 As a result, D. polymorpha individuals exposed to CFT were found to cause increased oxidative damage.

Whole-Body Acute Contact Toxicity of Formulated Insecticide Mixtures to Blue Orchard Bees (Osmia lignaria).

Blue orchard bees, [Osmia lignaria (Say) (Hymenoptera: Megachilidae)], have been developed as an important pollinator for orchard crops in North America over the last 40 years. The toxicity of several pesticides to O. lignaria and other Osmia species has been previously reported. However, the field-realistic toxicity of formulated premix insecticides comprised of multiple active ingredients (each with a different mode of action) to O. lignaria has not been assessed. Here, we use a customized spray tower in a laboratory setting to assess adult male and female whole-body direct contact exposure to four formulated pesticide mixtures: thiamethoxam + lambda-cyhalothrin (TLC), imidacloprid + beta-cyfluthrin (IBC), chlorantraniliprole + lambda-cyhalothrin (CLC) and methoxyfenozide + spinetoram (MS) by directly spraying anesthetized bees in Petri dishes. Separately, adult male and female whole-body direct contact exposure to formulated imidacloprid (I), beta-cyfluthrin (BC) and their 1:1 binary combination (IBC) was assessed using the same experimental method. Resulting mortality in each study was screened up to 96 h post-treatment to determine acute whole-body contact toxicity. In the first study, TLC and IBC resulted in statistically higher mortality at 24 and 48 h than the two other insecticide combinations tested. The CLC and MS combinations were slower acting and the highest mortality for O. lignaria exposed to these mixtures was recorded at 96 h. We did observe significant differences in toxicity between CLC and MS. In the second study, exposure to the 1:1 binary combination of IBC caused overall significantly higher mortality than exposure to I or BC alone. Both active ingredients alone, however, demonstrated equivalent levels of mortality to the 1:1 binary combination treatment at the 96 h observation reading, indicating increased speed of kill, but not necessarily increased toxicity. Significant differences in the onset of mortality following acute contact whole-body exposure to the formulated insecticide mixtures and individual active ingredients tested were consistently observed across all experiments in both studies.

Dummy-surface molecularly imprinted polymers based on magnetic graphene oxide for selective extraction and quantification of pyrethroids pesticides in fruit juices

A highly binding dummy template molecularly imprinted polymers (Fe3O4-NH2@GO@MIPs) was synthesized used Fe3O4-NH2@GO as carrier by dummy surface molecular imprinting technique (DSMIT) for the first time. Fe3O4-NH2@GO@MIPs were characterized by fourier transform infrared (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA), brunauer emmett teller (BET) and vibrating specimen magnetometer (VSM). Adsorption and selectivity experiments of Fe3O4-NH2@GO@MIPs and non-imprinted polymers (Fe3O4-NH2@GO@NIPs) verified that the Fe3O4-NH2@GO@MIPs had a better selectivity and adsorption properties for five pyrethroids pesticides. Adsorption test results revealed that the adsorption behaviors of pyrethroids onto Fe3O4-NH2@GO@MIPs followed Langmuir equation adsorption isotherm and pseudo-second-order kinetic models. Fe3O4-NH2@GO@MIPs were used as sorbent in magnetic solid phase extraction (MSPE) to extract five pyrethroids from fruit juice samples, following desorption with acidified ethyl acetate, the pyrethroids were quantified by gas chromatography with electron capture detection (GC-ECD). The developed method MSPE coupled with GC-ECD achieved satisfactory recovery (72.1–106.8%) with RSD less than 10.8%, and the detection limits (LOD) for fenpropathrin (FENP), lambda-cyhalothrin (LC), cyfluthrin (CYF), fenvalerate (FEN) and deltamethrin (DEL) ranged from 0.007 to 0.015 μg/L. Compared to other methods, the procedure MSPE-GC-ECD based on Fe3O4-NH2@GO@MIPs in this work demonstrated to be a more convenient and practical method for the separation, enrichment, and detection of pyrethroids pesticides from fruit juice samples.

Immunotoxicological Investigation of The Intracranial Auditory Centers In Pyrethroids Formulation Treated Wistar Rat

Purpose: The use of pesticides and their potential impact on public health are of great concern. Recent studies on the pathophysiology of neurodegenerative diseases have suggested that chronic exposure to pyrethroids could be associated with alterations in the central auditory pathways. This study was therefore aimed at evaluating the neurotoxicity of pyrethroids on the intracranial auditory relay-centers in adult wistar rats. Methods: Forty adult wistar rats of both sexes with average weight of 180g were assigned into five groups (n=8). Groups A, B, and C were treated with known pyrethroids formulation containing Cyfluthrin, Imiprothrin, and Prallethrin, diluted with olive oil to form 25%, 50% and 75% concentrations. Groups D and E were administered distilled water and olive oil once treatment negative and positive controls, respectively. The treatment lasted for duration of forty days. At the end of the duration, all animals were sacrificed by cervical dislocation, after which the inferior colliculi (IC), medial geniculate bodies (MGB) and cerebellum were harvested for histology and immuno histochemistry using calbindin and palvalbumin antibodies. Results: Histologically, there was slight degeneration of neuronal cells and vacuolated cytoplasm, dispersed distribution of nissl bodies in several cells of MGB and IC of the treated groups compared to the controls. In the cerebellum, there was abnormal proliferation of cells in the purkinje layer with poor distribution of nissl bodies when compared to control groups. Immuno histochemistry further revealed decreased immuno-reactivity of Calbindin2 and Parvalbumin in the treated tissues compared to the control groups. Conclusion: Pyrethroids influences motor coordination and balance of rats, and also the function of the auditory relay-centres.

Thermal effects on tissue distribution, liver biotransformation, metabolism and toxic responses in Mongolia racerunner (Eremias argus) after oral administration of beta-cyfluthrin

Effects of temperature on metabolism/biotransformation and toxicokinetics to lizards are significant, but frequently ignored in toxicology studies. Beta-cyfluthrin (BC) is a pyrethroid insecticide and has been widely used globally. The study aimed to understand the diverse adverse effects of BC to the lizard (Eremias argus) at different temperature regimes. We carried out a single oral BC treatment (20 mg/kg bw) for toxicokinetic study and a 7-day BC (10 mg/kg bw) gavage to look at toxicology by monitoring changes in the biomarkers HSP70, SOD, MDA, CarE, UDPGT, GST, cyp genes, and other metabolic responses. Results showed that BC was lethal to lizards, showing oxidative damages in the liver at ambient temperature (25 °C). Heat stress (35 °C) could exacerbate the oxidative damage (MDA increased) caused by BC, due to the disorder of the antioxidant defense system. The result of tissue distribution and toxicokinetic study also showed that temperature affected the BC biotransformation in lizards. The biotransformation of BC maybe relates to the activation of CarE and UDGPT by heat stress. However, the cyp system and GST didn't increase under BC or/and heat treatments. 1H-NMR metabolomics analysis showed that BC or/and heat stress interfered with energy and amino acid metabolism of the liver. Unlike acute lethal toxicity, the occurrence of the BC and heat stresses has detrimental effects on lizard individuals and populations on sub-lethal levels. Our results indicate that pollution and global warming (or some other extremely weather) may generate significant and harmful effects on lizards.

Highly Selective Electrochemiluminescence Sensor Based on Molecularly Imprinted-quantum Dots for the Sensitive Detection of Cyfluthrin.

A highly selective and sensitive molecularly imprinted electrochemiluminescence (MIECL) sensor was developed based on the multiwall carbon nanotube (MWCNT)-enhanced molecularly imprinted quantum dots (MIP-QDs) for the rapid determination of cyfluthrin (CYF). The MIP-QDs fabricated by surface grafting technique exhibited excellent selective recognition to CYF, resulting in a specific decrease of ECL signal at the MWCNT/MIP-QD modified electrode. Under optimal conditions, the MIECL signal was proportional to the logarithm of the CYF concentration in the range of 0.2 µg/L to 1.0 × 103 µg/L with a determination coefficient of 0.9983. The detection limit of CYF was 0.05 µg/L, and good recoveries ranging from 86.0% to 98.6% were obtained in practical samples. The proposed MIECL sensor provides a novel, rapid, high sensitivity detection strategy for successfully analyzing CYF in fish and seawater samples.

Effective mycoremediation coupled with bioaugmentation studies: An advanced study on newly isolated Aspergillus sp. in Type-II pyrethroid-contaminated soil

The intensive application of type-II pyrethroid worldwide in agricultural and residential practices potentially contributes to soil and water pollution, raising various concerns about environmental and public health. In the present study, robust fungus (strain PYR-P2) with high pyrethroids degradation potential was isolated from pesticide-contaminated soil. The strain was identified based on morphology and molecular characteristics, as Aspergillus sp. The screening of the transforming ability of strain PYR-P2 was evaluated in minimal salt media (MSM), where the fungus utilized up to 500 mg L−1 of pyrethroid mixture (cypermethrin (CYP), cyfluthrin (CYF), cyhalothrin (CYH)). With this in view, central composite design (CCD) with three independent variables (pH, temperature, and initial concentration) was employed to identify the optimal conditions for achieving maximum pyrethroid removal. Under optimal conditions, strain PYR-P2 was implemented for the bioaugmentation studies in natural and sterile soil (NS/SS) systems spiked with pyrethroid (single and mixture) at a concentration of 100 mg kg−1. The highest pyrethroid removal percentages were observed in fungally augmented NS, accompanied by a decrease in pyrethroid half-life (t1/2). Herein, the observed half-life (t1/2) of pyrethroids in the fungally augmented NS varied between 1.48 and 2.69 d, with equally good values recorded in SS as 1.65–3.10 d. Taken together, the mycoremediation study employing fungal (strain PYR-P2) augmentation under optimized conditions represents an efficient strategy to restore pyrethroid-contaminated soil.

Assessment of matrix effect in quantitative milk analysis for pyrethroids based on GC-MS/MS

In chromatographic analysis of complex samples, the chromatographic responses attributed to pesticides may undergo changes caused by matrix components. These variations can be due by the phenomenon named matrix effect. Cyfluthrin (CYF), cypermethrin (CYP), deltamethrin (DEL), and permethrin (PER) were extracted from raw milk and analysis carried out using a Gas Chromatography coupled to mass spectrometry (GC-MS/MS) technique. The aim of the present work was to investigate the variations of chromatographic response when milk samples are diluted with different solvents (acetone, acetonitrile or hexane) in final dilution immediately after the extraction. Results showed differences between solvents (p<0.05) and acetonitrile showed more appropriate results for all pyrethroids.

Prevalence and stability of insecticide resistances in field population of Spodoptera litura (Lepidoptera: Noctuidae) from Huizhou, Guangdong Province, China

Abstract The field population of Spodoptera litura from Huizhou, Guangdong Province, China was evaluated for resistance to 21 insecticides, including conventional and new chemistry insecticides. Extreme levels of resistance were observed to metaflumizone and emamectin benzoate with resistance factors of 234.1 and 183.3, respectively. Resistance to abamectin was also high (perhaps extremely high) and over 71.9-fold. The Huizhou population of S. litura possessed high resistance to deltamethrin (96.5-fold) and moderate resistance to beta cyfluthrin and lambda cyhalothrin but remained susceptible to bifenthrin. Moderate resistance to chlorantraniliprole (22.3-fold), endosulfan (22.2-fold), tebufenozide (10.7-fold) and thiodicarb (14.3-fold), and low-level resistance to fipronil, indoxacarb and spinosad were also reported in this population. This field population remained susceptible to acetamiprid, chlorfenapyr, chlorfluazuron, hexaflumuron, chlorpyrifos, pyridalyl and spinetoram. The stabilities of resistance to metaflumizone, emamectin benzoate, deltamethrin, chlorantraniliprole and endosulfan were evaluated, the resistance level decreased when the insecticide stress was removed, suggesting stop of the application of insecticides with high level resistance could be implemented into the resistance management. Because S. litura from Huizhou developed resistance to multiple insecticides, integration of different control practices, especially the rotation of insecticides with biocontrol agents, should be performed in the management of this pest. The results suggested the suspension of the application of insecticide to which S. litura had developed high level of resistance in order to mitigate the resistance status, and the use of the insecticides to which this pest remained sensitive, including spinetoram, pyridalyl, indoxacarb, hexaflumuron, chlorfluazuron, chlorfenapyr and bifenthrin, could be incorporated into the alternating application for resistance management.

Susceptibility of Euschistus heros (Fabr 1794.) (Heteroptera: Pentatomidae) to insecticides in Mato Grosso

The stink bug Euschistus heros attacks several crops of grains and fiber the state of Mato Grosso, which may cause severe damage to the productivity and quality of the seeds/plume. The repeated use of molecules with the same mode of action to control this insect favors selecting individual resistant individuals to insecticides. Aiming to evaluate the susceptibility of E. heros to the insecticides molecules thiamethoxan, imidacloprid, betacyfluthrin and lambdacyhalothrin populations from Sinop, Nova Mutum and Rondonopolis were collected. Susceptibility curve in a laboratory susceptible population was determined in order to establish diagnostic doses (CL95) to monitor the susceptibility of populations of E. heros to the insecticides molecules. Regarding the toxicity of the assayed molecules, thiamethoxam was the most toxic to E. heros , while the betacyfluthrin had the lowest toxicity (68 fold lower than thiametoxam). As result of the bioassays, we concluded that all populations tested behaved as susceptible to the tested molecules.

Development and application of a novel fluorescent nanosensor based on FeSe quantum dots embedded silica molecularly imprinted polymer for the rapid optosensing of cyfluthrin

A novel molecularly imprinted silica layer appended to FeSe quantum dots (MIP-FeSe-QDs) was fabricated and utilized as a recognition element to develop a selective and sensitive fluorescent nanosensor for cyfluthrin (CYF) determination. The MIP-FeSe-QDs were characterized by fluorescence spectrometry, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. Excellent selectivity and high sensitivity of MIP-FeSe-QDs to CYF molecules were observed based on the fluorescence quenching of FeSe-QDs. Under optimal conditions, a good linear relationship was found between fluorescence quenching effect and increased CYF concentration within 0.010–0.20mg/L, with a correlation coefficient of 0.9911. The practicality of the developed sensor method for CYF detection in fish and sediment samples was further validated. Good recoveries ranging from 88.0% to 113.9% with<6.8% relative standard deviations were obtained. The detection limits of CYF in sediment and fish samples were 1.3 and 1.0µg/kg, respectively. This study established a novel, rapid fluorescent nanosensor detection method based on MIP-QDs for successfully analyzing CYF in fish and sediment samples.