Optimization and validation of high-performance liquid chromatography using modified QuEChERS to determine anthelmintic drugs in mutton.

The aim of this study was to rapidly determine the presence of anthelmintic drugs in sheep meat using the optimized high-performance liquid chromatography-ultraviolet (HPLC-UV) method with modified QuEChERS (quick, easy, cheap, effective, rugged, safe) technology. Fifty fresh sheep meat samples from different slaughterhouses were collected. A double extraction procedure (QuEChERS/HPLC-UV technology) was used to extract the target analytes. A multilevel calibration curve from 1 to 1000 g/kg was used to establish instrument linearity for rafoxanide, albendazole, and closantel, whereas 0.1-100 µg/kg was used for ivermectin, levamisole, and oxyclozanide to find the lowest concentration, maximum residue limit (MRL), and occupied range for targeted analytes. The concentration levels were used to investigate the linearity, whereas several certified reference materials were applied to determine accuracy. The process was linear for all combinations, from the limit of quantification (LOQ) to the maximum concentration. The LOQ was established at 0.5 µg/kg for ivermectin, levamisole, and oxyclozanide and 10 µg/kg for rafoxanide, albendazole, and closantel. Recovery values were 70%-120%, and repeatability/reproducibility stated in relative standard deviation was obtained at less than 20%. QuEChERS method revealed that most meat samples contained anthelmintic drug residues, of which the majority exceeded the MRLs. Thus, the drugs should be used correctly in animals to avoid residues in food for human consumption.

Eficácia da ivermectina e atazanavir no tempo de recuperação dos sintomas de covid-19: uma coorte prospectiva / Effectiveness of ivermectin and atazanavir on time to resolution from covid-19 symptoms: a prospective cohort / Eficacia de ivermectina y atazanavir en el tiempo hasta lá resolución de los síntomas de covid-19: una cohorte prospectiva

Objetivo: avaliar a eficácia da Ivermectina e do Atazanavir em comparação com placebo no tempo de resolução dos sintomas e no tempo de duração da doença por COVID-19. Método: estudo observacional, de coorte prospectivo, longitudinal, descritivo e analítico com pacientes sintomáticos ambulatoriais, acompanhados por 06 meses em duas Unidades Básicas de Saúde para atendimento de COVID-19 em Teresina- Piauí, Brasil, no período de novembro a abril de 2021 identificados por amostragem aleatória 1:1:1. Foram realizados exames Reverse transcription polymerase chain reaction (RT-PCR) para confirmação laboratorial da suspeita de infecção pelo novo coronavírus e avaliação sociodemográfica e clínica. Resultados: dos 87 pacientes randomizados, 62,1% (n=54) eram do sexo masculino, com média de idade de 35,1 anos, possuíam companheira (53,9%), baixa renda (50,6%), eutróficos (40,7%) e sem comorbidades de saúde (78,2%). Não houve diferença entre o tempo médio para resolução dos sintomas, que foi de 21 dias (IQR, 8-30) no grupo atazanavir, 30 dias (IQR, 5-90) no grupo ivermectina em comparação com 14 dias (IQR, 9-21) no grupo controle. No dia 180, houve resolução dos sintomas em 100% no grupo placebo, 93,9% no grupo atazanavir e 95% no grupo ivermectina. A duração mediana da doença foi de 08 dias em todos os braços do estudo. Conclusão: o tratamento com atazanavir (6 dias) e ivermectina (3 dias) não reduziu o tempo de resolução dos sintomas e nem o tempo de duração da doença entre os pacientes ambulatoriais com COVID-19 leve em comparação com o grupo placebo. Os resultados não suportam o uso de ivermectina e atazanavir para tratamento de COVID-19 leve a moderado.

Objective: to evaluate the effectiveness of Ivermectin and Atazanavir compared to placebo in the time to resolution of symptoms and duration of illness due to COVID-19. Method: observational, prospective, longitudinal, descriptive and analytical cohort study with symptomatic outpatients, followed for 06 months in two Basic Health Units for COVID-19 care in Teresina-Piauí, Brazil, from November to April 2021 identified by 1:1:1 random sampling. Reverse transcription polymerase chain reaction (RT-PCR) tests were performed for laboratory confirmation of suspected infection with the new coronavirus and sociodemographic and clinical evaluation. Results: of the 87 randomized patients, 62.1% (n=54) were male, with a mean age of 35.1 years, had a partner (53.9%), low income (50.6%), eutrophic (40.7%) and without health comorbidities (78.2%). There was no difference between the median time to resolution of symptoms, which was 21 days (IQR, 8-30) in the atazanavir group, 30 days (IQR, 5- 90) in the ivermectin group compared with 14 days (IQR, 9- 21) in the control group. At day 180, there was resolution of symptoms in 100% in the placebo group, 93.9% in the atazanavir group, and 95% in the ivermectin group. The median duration of illness was 8 days in all study arms. Conclusion: Treatment with atazanavir (6 days) and ivermectin (3 days) did not reduce the time to symptom resolution or the duration of illness among outpatients with mild COVID-19 compared to the placebo group. The results do not support the use of ivermectin and atazanavir for the treatment of mild to moderate COVID-19.

Objetivo: evaluar la efectividad de Ivermectina y Atazanavir en comparación con placebo en el tiempo de resolución de los síntomas y duración de la enfermedad por COVID-19. Método: estudio de cohorte observacional, prospectivo, longitudinal, descriptivo y analítico con pacientes ambulatorios sintomáticos, seguidos durante 06 meses en dos Unidades Básicas de Salud para atención de COVID-19 en Teresina-Piauí, Brasil, de noviembre a abril de 2021 identificados por 1:1:1 muestreo aleatorio. Se realizaron pruebas de reacción en cadena de la polimerasa con transcriptasa inversa (RT-PCR) para confirmación de laboratorio de sospecha de infección por el nuevo coronavirus y evaluación sociodemográfica y clínica. Resultados: de los 87 pacientes aleatorizados, 62,1% (n=54) eran del sexo masculino, con una edad media de 35,1 años, tenían pareja (53,9%), bajos ingresos (50,6%), eutróficos (40,7%) y sin comorbilidades de salud (78,2%). No hubo diferencia entre la mediana de tiempo hasta la resolución de los síntomas, que fue de 21 días (RIC, 8-30) en el grupo de atazanavir, 30 días (RIC, 5- 90) en el grupo de ivermectina en comparación con 14 días (RIC, 9 - 21) en el grupo control. En el día 180, hubo una resolución de los síntomas del 100 % en el grupo de placebo, del 93,9 % en el grupo de atazanavir y del 95 % en el grupo de ivermectina. La mediana de duración de la enfermedad fue de 8 días en todos los brazos del estudio. Conclusión: El tratamiento con atazanavir (6 días) e ivermectina (3 días) no redujo el tiempo de resolución de los síntomas ni la duración de la enfermedad entre los pacientes ambulatorios con COVID-19 leve en comparación con el grupo placebo. Los resultados no respaldan el uso de ivermectina y atazanavir para el tratamiento de la COVID-19 de leve a moderada.

Incorporating Bioaccessibility into Inhalation Exposure Assessment of Emamectin Benzoate from Field Spraying.

The inhalation exposure of pesticide applicators and residents who live close to pesticide-treated fields is a worldwide concern in public health. Quantitative assessment of exposure to pesticide inhalation health risk highlights the need to accurately assess the bioaccessibility rather than the total content in ambient air. Herein, we developed an in vitro method to estimate the inhalation bioaccessibility of emamectin benzoate and validated its applicability using a rat plasma pharmacokinetic bioassay. Emamectin benzoate was extracted using the Gamble solution, with an optimized solid-to-liquid ratio (1/250), extraction time (24 h), and agitation (200 rpm), which obtained in vitro inhalation bioaccessibility consistent with its inhalation bioavailability in vivo (32.33%). The margin of exposure (MOE) was used to assess inhalation exposure risk. The inhalation unit exposures to emamectin benzoate of applicators and residents were 11.05-28.04 and 0.02-0.04 ng/m3, respectively, varying markedly according to the methods of application, e.g., formulations and nozzles. The inhalation risk assessment using present application methods appeared to be acceptable; however, the MOE of emamectin benzoate might be overestimated by 32% without considering inhalation bioaccessibility. Collectively, our findings contribute insights into the assessment of pesticide inhalation exposure based on bioaccessibility and provide guidance for the safe application of pesticides.

Simultaneous quantitative determination of residues of abamectin, ivermectin, albendazole and its three metabolites in beef and chicken by HPLC-PDA.

Antimicrobial drugs are frequently used in a combination or shuttle way to cope with coinfection of bacteria or parasites and prevent drug resistance, thus the accurate quantification of multiple drug residues in animal-derived foods is crucial to ensure food safety. Here, a simple and efficient high-performance liquid chromatography-photodiode array (HPLC-PDA) method was established for the simultaneous quantitative screening of six common residues of antiparasitic drugs, including abamectin (ABM), ivermectin (IVM), albendazole (ABZ) and the three metabolites of ABZ in beef and chicken. The LODs and LOQs for six target compounds in beef and chicken are determined to be 3.2 to 12.5 µg/kg and 9.0 to 30.0 µg/kg, respectively. The calibration curves show good linearity (R2 ≥ 0.9990) between the peak area and concentration. The recoveries from the fortified blank samples are all above 85.10%. Finally, the applicability of the HPLC-PDA method is successfully demonstrated by the real sample analysis.

Ivermectin: A Critical Review on Characteristics, Properties, and Analytical Methods.

BACKGROUND: Ivermectin is one of the first, safe, broad-spectrum avermectin class of antiparasitic agent, widely used to control parasitic growth in livestock. Ivermectin being highly lipophilic accumulates in fat tissues, causing its long-term existence in the body. Accordingly, ivermectin residues are observed in various animal products such as milk and meat presenting several health hazards. Therefore, monitoring of ivermectin residue levels in the various food products of animal origin is greatly important to ensure the safety of consumers. This review could be of significant importance in the area of ivermectin analytical method development studies. OBJECTIVE: In this context, objective of the present work is to provide a critical review of analytical methods in the literature for detection and quantification of ivermectin in pharmaceutical formulations, and biological materials including animal tissues. METHODS: The data from analysis of accessible literature within the time span of 1980 to 2022 was selected. RESULTS: Several analytical methods based on HPLC-fluorescence detector, UV-diode array detector, HPLC-tandem mass spectrometry (MS/MS), ultra-performance liquid chromatography-MS/MS, and capillary electrophoresis techniques have been utilized for the simultaneous determination of ivermectin singly or in the presence of other drugs with realistic retention times. Several derivatization strategies were used to introduce a fluorophore followed by extraction into organic phase to remove the matrix interferences and enhance the sensitivity by pre-concentration. Methods such as HPLC linked to MS/MS were developed to lower the detection limit and quantification limit, with no requirement for derivatization. CONCLUSION: More simple, selective, fast, sensitive, and green chemistry-oriented methods for ivermectin analysis need to be developed. Novel analytical devices based on pulsed electrochemical methods, voltammetry, and amperometry can be developed for real-time analysis of ivermectin, in addition to biosensors based on nanotechnology including quantum dots and nanoparticles, etc. HIGHLIGHTS: Various methods are described in the review including HPLC techniques with UV or visible spectrophotometric, fluorescence, and mass spectrometric detection, capillary electrophoresis, and immunological methods.

Season-Long Simplification of Insect Communities in Dung From Cattle Treated With an Extended-Release Formulation of the Parasiticide Eprinomectin.

Cattle treated with LongRange®, an injectable formulation of the parasiticide eprinomectin, fecally excrete insecticidal residues for an extended period post application. We examined the nontarget effect of these residues by comparing insect communities developing in dung of untreated cattle (week 0) with those developing in dung of cattle treated 1, 2, 4, 8, 12, 16, 20, and 24 or 25 weeks previously. Chemical analyses of dung showed that eprinomectin concentrations peaked at 1 week post application and were still detectable at 25 weeks. Results from two separate experiments showed that dung of untreated cattle supported more total insects (beetles, flies, parasitoid wasps) and insect species than did dung of cattle treated for ≤12 weeks (Experiment 1) and ≤25 weeks (Experiment 2) previously. For the two experiments, an effect of residue on individual taxa was either not detected (nine cases) or was determined to suppress insect development in dung of cattle treated for 8-12 weeks (two cases), 12-16 weeks (three cases), 16-20 weeks (two cases), or 24 or 25 weeks (six cases) previously. Flies and their parasitoid wasps were particularly sensitive to residues with suppression often at or near 100%. These results show that cattle treated with LongRange in spring will fecally excrete residues for the entire grazing season with an associated simplification of the dung insect community. The effect of this simplification on the long-term health on dung-breeding populations of insects on pastures and dung degradation was not examined in the present study, but merits future research. Environ Toxicol Chem 2023;42:684-697. © 2023 His Majesty the King in Right of Canada. Environmental Toxicology and Chemistry © 2023 SETAC. Reproduced with the permission of the Minister of Agriculture and Agri-Food Canada.

Ivermectin and curcumin cause plasma membrane rigidity in Leishmania amazonensis due to oxidative stress.

Spin label electron paramagnetic resonance (EPR) spectroscopy was used to study the mechanisms of action of ivermectin and curcumin against Leishmania (L.) amazonensis promastigotes. EPR spectra showed that treatment of the parasites with both compounds results in plasma membrane rigidity due to oxidative processes. With the IC50 and EPR measurements for assays using different parasite concentrations, estimations could be made for the membrane-water partition coefficient (KM/W), and the concentration of the compound in the membrane (cm50) and in the aqueous phase (cw50), which inhibits cell growth by 50%. The KM/W values indicated that ivermectin has a greater affinity than curcumin for the parasite membrane. Therefore, the activity of ivermectin was higher for experiments with low cell concentrations, but for concentrations greater than 1.5 × 108 parasites/mL the compounds did not show significantly different results. The cm50 values indicated that the concentration of compound in the membrane leading to growth inhibition or membrane alteration is approximately 1 M for both ivermectin and curcumin. This high membrane concentration suggests that many ivermectin molecules per chlorine channel are needed to cause an increase in chlorine ion influx.

Quantitative Analysis of Abamectin, Albendazole, Levamisole HCl and Closantel in Q-DRENCH Oral Suspension Using a Stability-Indicating HPLC-DAD Method.

Combination therapy of many anthelmintic drugs has been used to achieve fast animal curing. Q-DRENCH is an oral suspension, containing four different active drugs against GIT worms in sheep, commonly used in Australia and New Zeeland. The anti-parasitic drugs are Albendazole (ALB), Levamisole HCl (LEV), Abamectin (ABA), and Closantel (CLO). The main purpose of this study is to present a new simultaneous stability-indicting HPLC-DAD method for the analysis of the four drugs. The recommended liquid system was 1 mL of Triethylamine/L water, adjusting the pH to 3.5 by glacial acetic acid: acetonitrile solvent (20:80, v/v). Isocratic elusion achieved the desired results of separation at a 2 mL/min flow rate using Zorbax C-18 as a stationary phase. Detection was performed at 210 nm. The linearity ranges were 15.15 to 93.75 µg/mL for ALB, 25 to 150 µg/mL for LEV, 30 to 150 µg/mL for ABA, and 11.7 to 140.63 µg/mL for CLO. Moreover, the final greenness score was 0.62 using the AGREE tool, which reflects the eco-friendly nature. Moreover, the four drugs were determined successfully in the presence of their stressful degradation products. This work presents the first chromatographic method for simultaneous analysis for Q-DRENCH oral suspension drugs in the presence of their stressful degradation products.

Study of the Effect of Antibiotics in Drinking Water on the Content of Antioxidant Compounds in Red Wines.

The presence of antibiotic residues in drinking water may be a source of contamination, which could affect the diffusion of polyphenols into the wine must during the traditional fermentation process. Antibiotic residues such as ivermectin, hydroxychloroquine, ciprofloxacin, and azithromycin on the diffusion of polyphenols and anthocyanins during wine fermentation were studied. Different samples were taken at different periods (0, 48, 96, and 168 h) to analyse the total polyphenols, anthocyanin content, and antioxidant capacity, which were correlated with Peleg's equation to establish the diffusion kinetics of these compounds. The results indicated that the presence of antibiotics reduced between 40 and 50% the diffusion of the total polyphenols and monomeric anthocyanins in red wine. The use of ivermectin showed the highest kinetic parameter k1 compared with the use of other antibiotics. This suggested that the chemical structure and molecular weight of the antibiotics could play an important role in inhibiting the metabolism of yeasts affecting the ethanol and CO2 production. Consequently, cell membranes would be impermeable and would not allow the release of polyphenols and anthocyanins. Therefore, it is necessary to establish strategies that allow future water quality control in wine production companies.

Pharmacokinetics and milk excretion pattern of eprinomectin at different dose rates in dairy cattle.

This study aimed at determining the plasma disposition kinetics of eprinomectin (EPM) and EPM excretion pattern through milk after topical administration to dairy cattle at the recommended dose of 0.5 mg/kg and at 1 and 1.5 mg/kg. A high variability in the plasma concentration profiles was observed among animals, particularly in the Cmax values, with a coefficient of variation between 39 and 53%. The Cmax and AUC values were significantly affected by the dose administered at 1.5 mg/kg. However, such differences did not seem to follow a linear pattern among treatments. These parameters did not differ among dose rates after dose normalization; nevertheless, the simulation of a linear kinetic disposition showed a mean plasma AUC value of 254 ng.d/ml instead of the observed value of 165 ng.d/ml. EPM concentration profiles in milk were significantly lower than those measured in plasma. The Cmax and AUC milk-to-plasma ratios ranged from 0.14 to 0.26 and 0.16 to 0.21, respectively (p>0.05). The low milk-to-plasma ratio of EPM accounted for a low percentage of the fraction of the administered dose excreted through milk, being significantly higher at a dose rate of 0.5 mg/kg (0.07%) of EPM than at 1.5 mg/kg (0.04%) (p<0.05). The topical administration of EPM to lactating dairy cows at higher doses than that recommended for gastrointestinal nematodes showed a milk excretion pattern with a zero milk withdrawal period. In conclusion, the administration of topical EPM formulation at 1 or 1.5 mg/kg may be a valuable tool to be used in regional strategic deworming programs aimed to control ectoparasite infections in dairy production systems.

Residue and dissipation of two formulations of emamectin benzoate in tender cowpea and old cowpea and a risk assessment of dietary intake.

The dissipation and residue levels of emamectin benzoate emulsifiable concentrate (EC) and microemulsion (ME) formulations in tender cowpeas and old cowpeas were investigated under field conditions. The decline curves of emamectin benzoate residues in cowpea corresponded to first-order kinetics. The dissipation rate of emamectin benzoate in tender cowpeas was faster than that in old cowpeas. The half-lives of the EC were 1.34-1.39 d and 1.74-2.31 d in tender cowpea and old cowpea, respectively. For the ME, the half-lives were 1.39-1.51 d and 2.08-2.67 d, respectively. The risk of adult intake of emamectin benzoate from cowpea is within the acceptable limits of the human body. Compared to tender cowpeas, the risk of eating old cowpeas is higher. Emamectin benzoate (EC) is recommended for cowpeas when the intention is to harvest tender cowpeas, while both formulations are acceptable for cowpeas when the intention is to harvest old cowpeas.

A qualitative analysis of seven ivermectin formulations in South Africa.

Some South African (SA) healthcare practitioners are promoting the prescription and use of products claiming to contain ivermectin for the treatment and/or prevention of COVID-19 in SA. This study qualitatively analysed seven samples of ivermectin formulations (5 tablet and 2 capsule formulations) being sold in SA for human use. The samples were analysed using a high-performance liquid chromatography instrument connected to a Sciex X500R quadrupole time-of-flight high-resolution mass spectrometer. The study found that all the samples had both the major homologues of ivermectin (B1a and B1b) and also that 4 out of the 5 tablet formulations tested had at least one additional undeclared active pharmaceutical ingredient.

Simultaneous Determination of Abamectin and Closantel in Veterinary Formulation by Validated HPLC Method.

A rapid and accurate high-performance liquid chromatographic method was developed for the determination of both abamectin and closantel in the veterinary formulation. The chromatographic separation was conducted on an Agilent 1200 with a UV detector using Waters C18 (4.6 mm × 50 mm; 2.7 µm). The mobile phase consisted of acetonitrile:water (80:20 v/v) adjusts pH 3.0 using diluted phosphoric acid. The flow rate of 1.5 mL min-1 was used. An injection volume of 10 µL was used The calibration curve of abamectin B1b was linear with a correlation coefficient (r2) = 0.9996; over a concentration range of 2.0-8.0 µg/mL, abamectin B1a was linear with a correlation coefficient (r2) = 0.9997; over a concentration range of 8.0-32.0 µg/mL; with a retention time of 2.18 and 3.72 minutes for avermectin B1b and avermectin B1a, respectively. While the calibration curve of closantel was linear with a correlation coefficient (r2) = 0.99929; over a concentration range of 250.0-1,000.0 µg/mL for; with a retention time of 5.84 minutes. Correlation coefficient was r2 ≥ 0.999. The relative standard deviation was found to be ≤ 2. The proposed method was validated and successfully applied for the simultaneous determination of abamectin and closantel in the veterinary formulation.

A highly sensitive octopus-like azobenzene fluorescent probe for determination of abamectin B1 in apples.

The development of detecting residual level of abamectin B1 in apples is of great importance to public health. Herein, we synthesized a octopus-like azobenzene fluorescent probe 1,3,5-tris (5'-[(E)-(p-phenoxyazo) diazenyl)] benzene-1,3-dicarboxylic acid) benzene (TPB) for preliminary detection of abamectin B1 in apples. The TPB molecule has been characterized by ultraviolet-visible absorption spectrometry, 1H-nuclear magnetic resonance, fourier-transform infrared (FT-IR), electrospray ionization mass spectroscopy (ESI-MS) and fluorescent spectra. A proper determination condition was optimized, with limit of detection and limit of quantification of 1.3 µg L-1 and 4.4 µg L-1, respectively. The mechanism of this probe to identify abamectin B1 was illustrated in terms of undergoing aromatic nucleophilic substitution, by comparing fluorescence changes, FT-IR and ESI-MS. Furthermore, a facile quantitative detection of the residual abamectin B1 in apples was achieved. Good reproducibility was present based on relative standard deviation of 2.2%. Six carboxyl recognition sites, three azo groups and unique fluorescence signal towards abamectin B1 of this fluorescent probe demonstrated reasonable sensitivity, specificity and selectivity. The results indicate that the octopus-like azobenzene fluorescent probe can be expected to be reliable for evaluating abamectin B1 in agricultural foods.

Acceptable risk of fenpropathrin and emamectin benzoate in the minor crop Mugua (Chaenomeles speciosa) after postharvest processing.

Production of minor crop varieties often requires intensive pesticide use, which raises serious concerns over food safety and human health. Chaenomeles speciosa (Sweet) Nakai as one of the representative of this kind of crops is therefore used for investigating the residue behavior of fenpropathrin and emamectin benzoate, a synthetic pyrethroid and macrocyclic lactone widely used as an insecticide, respectively, from cultivation to C. speciosa postharvest processing. Results showed that the degradation trends of those selected insecticides in C. speciosa followed first-order kinetics with an average half-life (t1/2) of 3.7-4.1 days and a dissipation rate of 97% over 14 days. The terminal residues of fenpropathrin and emamectin benzoate at 120 and 3 g a.i./ha were below the U.S Environmental Protection Agency (FAD, 1.00 mg/kg) and European Union (EU, 0.01 mg/kg) maximum residue limits (MRLs) in papaya species, respectively, when measured 14 days after the final application, which suggested that the use of these insecticides was safe for humans. Postharvest processing procedure resulted in a |90% reduction of the insecticides. Moreover, the hazard quotient (HQ) for C. speciosa decoction (with processing factors) indicated an acceptable risk for human consumption. These findings provide the scientific evidence of reasonable application and risk assessment of the selected pesticide residues in C. speciosa.

Implications of Endectocide Residues on the Survival of Aphodiine Dung Beetles: A Meta-Analysis.

It is often difficult to compare studies examining the effects of endectocides on dung fauna because of different experimental approaches, for example, active ingredients (eprinomectin, doramectin, ivermectin, moxidectin) and formulations (injectable, pour-on, spiked). To gain a better understanding, we performed a quantitative meta-analysis using 22 studies to assess the overall effect of endectocide residues on the occurrence (presence or absence) and abundance of aphodiine dung beetles. Our results document a positive effect on the occurrence of adult beetles, indicating that adults tend to be attracted to dung with residues. Conversely, larvae are less likely to occur in the presence of residues. Thus, either adults that colonize dung with residues do not lay eggs or, more likely, the larvae that hatch from these eggs die early in development. Abundance of adult and larval stages was shown to be significantly reduced in dung containing residues. When individual endectocides were compared, only ivermectin demonstrated a significantly negative effect on the abundance of both adults and larvae, possibly owing to a small sample size for other agents. In laboratory studies, only dung "spiked" with endectocides reduced the abundance of larvae, whereas during field research, only pour-on applications were shown to reduce the abundance of larvae. The present study further documents the nontarget effects of endectocide residues on dung-dwelling organisms, provides robust evidence on the consequences of different application methods, and emphasizes the need for standardized methodological techniques in future studies. Environ Toxicol Chem 2020;39:863-872. © 2020 SETAC.

Residues and dissipation kinetic of abamectin, chlorfenapyr and pyridaben acaricides in green beans (Phaseolus vulgaris L.) under field conditions using QuEChERS method and HPLC.

The current study estimated the dissipation rates of abamectin, chlorfenapyr and pyridaben acaricides in pods of green beans (Phaseolus vulgaris L.) under field conditions in Egypt. Pesticides were extracted and cleaned-up by QuEChERS method and were analyzed by HPLC. The dissipation of these acaricides followed the first order kinetics model with half-life (t1/2) values 1.00, 3.50 and 1.50 days for abamectin, chlorfenapyr and pyridaben, respectively. The lowest residues, at different time intervals of field application rate of each pesticide, were observed with abamectin followed by pyridaben and then chlorfenapyr. Pre-harvest intervals (PHIs) were 10.00, 13.50 and 6.00 days for abamectin, chlorfenapyr and pyridaben, respectively and were below the established European maximum residue limits (EU MRLs) 10-14, 14-21 and 7-10 days after application, respectively. If the fresh pods will be consumed after harvest, it is expected that the presence of these pesticides in the food will have a negative impact on human health. Therefore, the elimination of the residues of these harmful pesticides must be carried out.

Toxicological effect of ivermectin on the survival, reproduction, and feeding activity of four species of dung beetles (Coleoptera: Scarabaeidae and Geotrupidae) in Japan.

We investigated the effects of the antiparasitic drug ivermectin on the dung beetles Copris acutidens Motschulsky, Onthophagus bivertex Heyden, O. lenzii Harold and Phelotrupes auratus auratus Motschulsky in Japan. Ivermectin was detected in cattle dung from 1 to 3 or 7 days post-treatment, with a peak at 3 days post-treatment in two pour-on administrations (500 µg kg-1). In C. acutidens, adult survivals and numbers of brood balls were significantly reduced in dung collected at 3 and 7 days post-treatment, and adult emergence rates were significantly decreased in dung collected at 7 and 14 days post-treatment. Feeding activity of C. acutidens was inhibited in dung collected at 3 days post-treatment, but was not significantly different from that seen in control dung at 7 and 14 days post-treatment. In O. bivertex and O. lenzii, there were no effects of ivermectin on adult survival or feeding activities, but the numbers of brood balls of O. bivertex constructed in dung collected at 3 and 7 days post-treatment were significantly lower than observed with control dung. The adult emergence rates of O. bivertex and O. lenzii were significantly reduced in dung collected at 1 to 3 and 1 to 7 days post-treatment, respectively. In P. auratus, there were no effects of ivermectin on adult survival, oviposition, feeding activity, or larval survival (until the third instar) in dung at 3 days post-treatment. The environmental risks affecting the populations of dung beetles in Japan are discussed.

Aerobic dissipation of avermectins and moxidectin in subtropical soils and dissipation of abamectin in a field study.

Avermectins and moxidectin are antiparasitics widely used as active pharmaceutical ingredients in veterinary medicine, as well as in pesticide formulations for pest control in agriculture. Although the use of these compounds provides benefits to agribusiness, they can impact the environment, since a large part of these substances may reach the soil and water from the excreta of treated animals and following direct applications to crops. The present work had the objective of evaluating the dissipation behaviors of abamectin, doramectin, eprinomectin, ivermectin, and moxidectin in four native Brazilian soils of different textural classes (clay, sandy-clay, sandy, and sandy-clay-loam), following OECD Guideline 307. The studies were conducted in a climate chamber at 22 °C, 71% relative humidity, and protected from light. The dissipation studies were carried out with all drugs together, since no difference was verified when studies were done with each drug separately. The concentrations of the drugs in the soils were determined using an ultra-high performance liquid chromatograph coupled to a fluorescence detector or a tandem mass spectrometer. The dissipation half-life (DT50) values ranged from 9 to 16 days and the calculated GUS index values were in the range from -1.10 to 0.08, indicating low mobility of the drugs in the soils evaluated and low tendency for leaching. In addition, a field study was carried out to evaluate the dissipation of abamectin after application of a foliar pesticide in an orange crop. A DT50 of 9 days was determined, which was similar to that obtained under controlled conditions in the climate chamber (12 days), indicating that biotransformation was the primary process influencing the overall dissipation.

Pesticide Residues Identification by Optical Spectrum in the Time-Sequence of Enzyme Inhibitors Performed on Microfluidic Paper-Based Analytical Devices (µPADs).

Pesticides vary in the level of poisonousness, while a conventional rapid test card only provides a general "absence or not" solution, which cannot identify the various genera of pesticides. In order to solve this problem, we proposed a seven-layer paper-based microfluidic chip, integrating the enzyme acetylcholinesterase (AChE) and chromogenic reaction. It enables on-chip pesticide identification via a reflected light intensity spectrum in time-sequence according to the different reaction efficiencies of pesticide molecules and assures the optimum temperature for enzyme activity. After pretreatment of figures of reflected light intensity during the 15 min period, the figures mainly focused on the reflected light variations aroused by the enzyme inhibition assay, and thus, the linear discriminant analysis showed satisfying discrimination of imidacloprid (Y = -1.6525X - 139.7500), phorate (Y = -3.9689X - 483.0526), and avermectin (Y = -2.3617X - 28.3082). The correlation coefficients for these linearity curves were 0.9635, 0.8093, and 0.9094, respectively, with a 95% limit of agreement. Then, the avermectin class chemicals and real-world samples (i.e., lettuce and rice) were tested, which all showed feasible graphic results to distinguish all the chemicals. Therefore, it is feasible to distinguish the three tested kinds of pesticides by the changes in the reflected light spectrum in each min (15 min) via the proposed chip with a high level of automation and integration.