Pyrethroid Lambda-cyhalothrin Research Articles

Lethal and sublethal effects of insecticides on Bathycoelia distincta (Heteroptera: Pentatomidae)

Bathycoelia distincta is one of the most dominant stink bug pests associated with macadamia orchards in South Africa. Understanding the toxicity and sublethal effects of insecticides on this pest is essential for its effective management. This study tested four commercial insecticide formulations, consisting of one organophosphate (acephate) and three pyrethroids (lambda-cyhalothrin, beta-cyfluthrin and tau-fluvalinate). The toxicity of these insecticides and their behavioural effects on mobility were assessed. The sublethal effects of lambda-cyhalothrin on the biological parameters of parent B. distincta (F0) and offspring generations (F1) were also determined by treating B. distincta adults with sublethal concentrations (LC10 and LC30). In toxicity bioassays, acephate was more toxic to B. distincta than lambda-cyhalothrin, beta-cyfluthrin and tau-fluvalinate. Behavioural changes were only observed in bugs exposed to pyrethroids, resulting in an increase in the distance walked and decrease of angular velocity. In the F0 generation, LC30 reduced the fecundity whereas the LC10 and LC30 accelerated development of the F1 generation. These results suggest that pyrethroids may enhance the dispersal of this pest and stimulate the growth of offspring populations. Further experiments should be conducted to confirm these results and understand the mechanism of action of pyrethroids on B. distincta.

Determination of Pesticide Residues in Vine Leaves Using the QuEChERS Method and Liquid Chromatography-Tandem Mass Spectrometry.

Commercial viticulture necessitates regular pesticide applications to manage diseases and pests, raising significant concerns regarding pesticide residues among stakeholders. Due to health risks associated with these residues in Turkish vine leaves, the European Commission has increased the frequency of official control from 20% to 50%. Thus, the aim of this study was to determine multi-class pesticide residues in brined vine leaves from Turkey. A total of 766 samples of vine leaves were collected between May 2022 and June 2023. More than 500 residues were analyzed using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method, followed by liquid chromatography-tandem mass spectrometry. In-house validation data demonstrated that the analytical method exhibits fit-for-purpose performance in terms of linearity, accuracy, precision, and measurement uncertainty. Out of 766 samples analyzed, 180 samples (23.5%) contained one (131, 17.1%) or multiple (49, 6.4%) pesticides. Both the frequencies of occurrence and the rate of maximum residue level (MRL) exceedance increased in 2023 compared to 2022, with the MRL exceedance rate rising from 9.5% to 25.2%. Forty-three different residues were found in quantifiable concentrations and eight of them were non-approved. Among the residues, the non-systemic pyrethroid insecticides, lambda-cyhalothrin (8.0%) and cypermethrin (7.2%), were the two most frequently detected, with concentrations ranging from 0.010 to 0.248 mg kg-1 and from 0.011 to 0.533 mg kg-1, respectively. Turkey is a major exporter of vine leaves and these results provide crucial information regarding pesticide occurrence and quality assessment of vine leaves. The significant increase in both pesticide occurrence and MRL exceedance rates between 2022 and 2023 underscores the urgency for regulatory bodies to reassess current pesticide usage and monitoring practices. The findings emphasize the importance of implementing more stringent rules and improving enforcement methods in order to reduce the spread of unapproved pesticides and ensure adherence to global food safety standards.

Alfalfa weevils (Coleoptera: Curculionidae) in the western United States are resistant to multiple type II pyrethroid insecticides.

The alfalfa weevil (Hypera postica Gyllenhal (Coleoptera: Curculionidae)), a key pest of alfalfa (Medicago sativa L. (Fabales: Fabacae)) across the US, has developed resistance to pyrethroids lambda-cyhalothrin and zeta-cypermethrin in at least 6 western US states. Unfortunately, 6 pyrethroid active ingredients represent most commercial insecticides registered for alfalfa weevil control in forage alfalfa systems. Thus, the loss of efficacy of this mode of action group due to multiple resistance represents a significant agricultural challenge because of a limited registered alternative mode of actions. To evaluate the extent and severity of resistance among pyrethroids around the United States, laboratory bioassays using larvae from Arizona, California, Montana, Oregon, Washington, and Wyoming, including both the Egyptian and western strains, were conducted. Results indicated that similar degrees of resistance among type II pyrethroids as determined by both laboratory bioassays and field trials exist. The LC50 values of alpha-cypermethrin, beta-cyfluthrin and zeta-cypermethrin produced significant correlations with the LC50 values of lambda-cyhalothrin. In contrast, resistance did not include type I pyrethroid, bifenthrin (registered for seed alfalfa production), whose LC50 values yielded a slope not significantly different from zero when correlated with lambda-cyhalothrin. Field trials conducted in Arizona, Montana, and Washington corroborated laboratory results, as commercial formulations with type II pyrethroid active ingredients failed to adequately control alfalfa weevils resistant to lambda-cyhalothrin. Integrated resistance management recommendations are discussed.

Magnetic effervescence-assisted switchable solvent dispersive liquid-liquid microextraction for the determination of pyrethroids in edible fungi

A simple, rapid, effective, and environmental friendly analytical procedure for determining three pyrethroids (tetramethrin, lambda-cyhalothrin and fenvalerate) in edible fungi was developed by high-performance liquid chromatography-diode array detection after magnetic effervescence-assisted switchable solvent dispersive liquid-liquid microextraction (MEA-SHS-DLLME). In the extraction procedure, hexanoic acid and carbon dioxide were used as the extraction and dispersion solvents. The magnetic Fe3O4 @ graphene with large specific surface area were used to adsorb the extraction solvent and the target analytes. The optimized conditions were as follows: sodium hexanoate 45 mg, citric acid 90 mg, sodium bicarbonate 60 mg, Fe3O4 @ graphene mixing ratio 1:6, and dosage of Fe3O4 @ graphene 25 mg. Under these conditions, accuracy and precision were demonstrated at the concentration range of 1.25-125 mg/kg, and the correlation coefficients were between 0.9903-0.9998. The limits of detection and quantification were 0.0067-0.0329 mg/kg and 0.0224-0.1096 mg/kg, and the extraction recovery was 81.0-97.4% with relative standard deviations < 5.1%. The technique had been successfully proven to be valuable for the ultrasensitive detection of tetramethrin, lambda-cyhalothrin and fenvalerate in 5 kinds of edible fungi, and only magnetic effervescent tablets containing switchable solvent were needed without dispersing solvent, centrifugation, and complex instruments. Moreover, the extraction recovery was better than other reported methods. This novel approach has a favorable potential to be applied for detection of pyrethroid residues in other samples.

Assessing the impact of coexposure on the measurement of biomarkers of exposure to the pyrethroid lambda-cyhalothrin in agricultural workers.

There are few published data on the impact of combined exposure to multiple pesticides (coexposure) on levels of biomarkers of exposure in workers, which may alter their toxicokinetics and thus the interpretation of biomonitoring data. This study aimed to assess the impact of coexposure to two pesticides with shared metabolism pathways on levels of biomarkers of exposure to pyrethroid pesticides in agricultural workers. The pyrethroid lambda-cyhalothrin (LCT) and the fungicide captan were used as sentinel pesticides, since they are widely sprayed concomitantly in agricultural crops. Eighty-seven (87) workers assigned to different tasks (application, weeding, picking) were recruited. The recruited workers provided two-consecutive 24-h urine collections following an episode of lambda-cyhalothrin application alone or in combination with captan or following tasks in the treated fields, as well as a control collection. Concentrations of lambda-cyhalothrin metabolites - 3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethyl-cyclopropanecarboxylic acid (CFMP) and 3-phenoxybenzoic acid (3-PBA) - were measured in the samples. Potential determinants of exposure established in a previous study, including the task performed and personal factors were documented by questionnaire. Multivariate analyses showed that coexposure did not have a statistically significant effect on the observed urinary levels of 3-PBA (Exp(β) (95% confidence interval (95% CI)): 0.94 (0.78-1.13)) and CFMP (1.10 (0.93-1.30). The repeated biological measurements ("time variable") - defined as the within-subjects variable - was a significant predictor of observed biological levels of 3-PBA and CFMP; the within-subjects variance (Exp(β) (95% (95% CI)) for 3-PBA and CFMP was 1.11 (1.09-3.49) and 1.25 (1.20-1.31). Only the main occupational task was associated with urinary levels of 3-PBA and CFMP. Compared to the weeding or picking task, the pesticide application task was associated with higher urinary 3-PBA and CFMP concentrations. In sum, coexposure to agricultural pesticides in the strawberry fields did not increase pyrethroid biomarker concentrations at the exposure levels observed in the studied workers. The study also confirmed previous data suggesting that applicators were more exposed than workers assigned to field tasks such as weeding and picking.

Assessment of piscicidal effect of five toxicants for the eradication of weed fish Nile tilapia (Oreochromis niloticus)

Unwanted or weed fish in aquaculture pond may affect the growth and development of cultured fish species. The current investigation aimed to assess the piscicidal effect of five commercial toxicants on weed fish, Nile tilapia (Oreochromis niloticus) for a short period. The fish was exposed to four concentrations (0.5, 1.0, 1.5, and 2.0 ppm) of dimethoate, pyrethroid lambda-cyhalothrin, cypermethrin, malathion, and Chillas along with control (without any toxicants) during a 48-hour static bioassay. Fish mortality and physicochemical parameters i.e., pH and dissolved oxygen (DO) of water were checked after every 8 hours. The pH of water varied from 3.46to 6.5 and DO range 2.70-5.66 during all experiments. After 48 hours of exposure, the maximum fish mortality was achieved by dimethoate (4.15, 8.30%), cypermethrin (4.16, 8.32%), malathion (4.0, 8.00%), and Chillas (4.0, 8.00%) at the highest applied concentration (2.0 ppm). While pyrethroid lambda-cyhalothrin showed the highest mortality at 1.5 ppm (4.16) with 8.32% as well as on 2.0 ppm (4.16, 8.32%). In conclusion, pyrethroid lambda-cyhalothrin was observed as the best toxicant as piscicide causing overall higher mortality on all applied concentrations. However, the long-term experiment is further needed to clarify the mortality trend and optimization of toxicants in a long-term experiment.

Evaluating how occupational exposure to organophosphates and pyrethroids impacts ADHD severity in Egyptian male adolescents

BackgroundAttention Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder characterized by deficits in attention and hyperactivity/impulsivity that cause impairments to daily living. An area of long-standing concern is understanding links between environmental toxicants, including pesticides, and the development or worsening of ADHD. ObjectivesThe present study evaluated associations between occupational pesticide exposure, specifically organophosphate (OP) pesticides, chlorpyrifos (CPF) and the pyrethroids (PYR) alpha-cypermethrin (αCM) and lambda-cyhalothrin (λCH), and symptoms of ADHD in a longitudinal study among Egyptian adolescent males. MethodsParticipants (N = 226, mean age = 17) were Egyptian adolescent males who either applied pesticides or were non-applicators. Urinary trichloro-2-pyridinol (TCPy) was measured as a specific metabolite biomarker of exposure to chlorpyrifos. Urinary 3-phenoxybenzoic acid (3-PBA) was measured as a general metabolite biomarker of exposure to pyrethroids, while urinary cis-3-(2,2- dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DCCA) was measured as a specific biomarker of exposure to αCM and lambda cyhalothric acid (λCH acid) measured as a specific biomarker of exposure to λCH. Ordinal logistic regression models controlling for age were used to determine the likelihood of ADHD development (measured via parent-reported ADHD symptoms) as the level of biomarkers of pesticide exposure increased. ResultsCis-DCCA was the only biomarker associated with higher likelihood ADHD symptoms (> 0.60 vs. 0–0.17 μg/g creatinine; OR = 2.82, 95% CI: 1.29–6.14). All participants reported clinical levels of ADHD symptoms when compared to national norms used in the United States. TCPy, trans-DCCA and λCH acid were not associated with risk of ADHD symptoms after controlling for levels of cis-DCCA. No other metabolites were associated with the number of ADHD symptoms. There were no interaction effects found for exposure to both OPs and Pyrethroids. DiscussionThe results suggest that exposure to the pyrethroid αCM is associated with more ADHD symptoms. Methodological and cultural considerations in need of further study are discussed.

Foliar Residual Toxicity of Insecticides to Brassica Pests and Their Natural Enemies.

Overuse of pesticides can result in the development of resistance, secondary pest outbreaks, and pest resurgence due to a reduction in natural enemies. The present study compares the residual toxicity of lambda-cyhalothrin, a relatively nonselective insecticide, with abamectin, indoxacarb, and spinosad, compounds which have been reported to be less harmful to arthropod natural enemies. Two key cosmopolitan pests of crucifer crops, (Plutella xylostella) and (Myzus persicae), and two of their respective hymenopteran parasitoids, (Cotesia vestalis) and (Aphidius colemani) were used as representative pests and natural enemies. The pyrethroid lambda-cyhalothrin was found to be the most persistent toxicant against both pest and both parasitoid species tested, while the lactones abamectin and spinosad were the least persistent toxicants. A leaf wax stripping technique was used to compare the contact toxicity of insecticide residues against adult C. vestalis and A. colemani in the epicuticular wax layer. For each compound, removal of epicuticular wax reduced the 24 h residual toxicity (LC50) of fresh deposits (day 0) by about an order of magnitude against C. vestalis. A second residual toxicity experiment showed that removal of epicuticular wax significantly reduced the residual toxicity of each compound against A. colemani at 0, 7, and 14 d after application, with little or no detectable residual activity for the oxadiazine indoxacarb or abamectin/spinosad respectively after 14 d. The present data supports the view that in addition to the intrinsic toxicity of insecticides to natural enemies, differences in their persistence as foliar residues should also be considered in IPM systems.

Insecticide resistance status of malaria vectors in the malaria endemic states of India: implications and way forward for malaria elimination

BackgroundIn 2012, the World Health Organization (WHO) released the Global Plan for Insecticide Resistance Management in malaria vectors to stress the need to address insecticide resistance. In a prospective multi-centric study commissioned by the Indian Council of Medical Research (ICMR), we assessed the insecticide susceptibility status of the primary malaria vectors in India from 2017 through 2019. MethodsThe insecticide susceptibility status of the prevalent primary malaria vectors – An. culicifacies, An. fluviatilis, An. stephensi, An. minimus and An. baimaii and secondary malaria vectors - An. aconitus, An. annularis and An. philippinensis/nivepes from 328 villages in 79 districts of 15 states of India were assessed following the WHO method mainly to insecticides used in vector control, organochlorine (DDT), organophosphate (malathion), and other pyrethroids (alpha-cypermethrin, cyfluthrin, lambda-cyhalothrin and permethrin). The study sites were selected as suggested by the National Vector Borne Disease Control Programme. ResultsThe primary malaria vector An. culicifacies showed resistance to DDT (50/50 districts including two districts of Northeastern India), malathion (27/44 districts), and deltamethrin (17/44 districts). This species was resistant to DDT alone in 19 districts, double resistant to DDT-malathion in 16 districts, double resistant to DDT-deltamethrin in 6 districts, and triple resistant to DDT-malathion-deltamethrin in 9 districts. An. minimus and An. baimaii were susceptible in Northeastern India while An. fluviatilis and the secondary malaria vector An. annularis was resistant to DDT in Jharkhand. ConclusionIn this study we report that among the primary vectors An. culicifacies is predominantly resistant to multiple insecticides. Our data suggest that periodic monitoring of insecticide susceptibility is vital. The national malaria program can take proactive steps for insecticide resistance management to continue its push toward malaria elimination in India.

Neurotoxicity induced by the pyrethroid lambda-cyhalothrin: Alterations in monoaminergic systems and dopaminergic and serotoninergic pathways in the rat brain.

The effects of Type II pyrethroid lambda-cyhalothrin on dopamine (DA) and serotonin (5-HT) synthesis in rat brain regions (striatum, hippocampus, prefrontal cortex, hypothalamus and midbrain) were studied. Lambda-cyhalothrin (1, 4 and 8mg/kg bw, oral gavage, 6 days) induced a decrease of DA, 5-HT and metabolites contents, in a brain regional- and dose-related manner. The major decreases in DA and 5-HT contents were observed in hippocampus and prefrontal cortex tissues. This research study also showed in hippocampus and prefrontal cortex, that lambda-cyhalothrin modified the mRNA levels of DA transporter gene (Dat1 up-regulation), 5-HT transporter gene (SERT down-regulation), DA receptor genes (Drd1and Drd2 down-regulation), 5-HT receptor genes (5-HT1A and 5-HT2A down-regulation/up-regulation), DA synthesis gene (TH down-regulation), 5-HT synthesis gene (TPH2 down-regulation), DA and 5-HT degradation genes (MAOA and MAOB up-regulation). These results reveal that lambda-cyhalothrin altered central nervous system (CNS) monoaminergic neurotransmitters. Lambda-cyhalothrin evoked a selective neurotoxic injury to dopaminergic and serotoninergic pathways. These findings may clarify on the pyrethroids-induced neurotoxicity mechanisms and could involve pyrethroids as environmental risk factors leading to the development of neurodegenerative diseases.

Association of Midgut Bacteria and Their Metabolic Pathways with Zika Infection and Insecticide Resistance in Colombian Aedes aegypti Populations.

Introduction: Aedes aegypti is the vector of several arboviruses such as dengue, Zika, and chikungunya. In 2015–16, Zika virus (ZIKV) had an outbreak in South America associated with prenatal microcephaly and Guillain-Barré syndrome. This mosquito’s viral transmission is influenced by microbiota abundance and diversity and its interactions with the vector. The conditions of cocirculation of these three arboviruses, failure in vector control due to insecticide resistance, limitations in dengue management during the COVID-19 pandemic, and lack of effective treatment or vaccines make it necessary to identify changes in mosquito midgut bacterial composition and predict its functions through the infection. Its study is fundamental because it generates knowledge for surveillance of transmission and the risk of outbreaks of these diseases at the local level. Methods: Midgut bacterial compositions of females of Colombian Ae. aegypti populations were analyzed using DADA2 Pipeline, and their functions were predicted with PICRUSt2 analysis. These analyses were done under the condition of natural ZIKV infection and resistance to lambda–cyhalothrin, alone and in combination. One-step RT-PCR determined the percentage of ZIKV-infected females. We also measured the susceptibility to the pyrethroid lambda–cyhalothrin and evaluated the presence of the V1016I mutation in the sodium channel gene. Results: We found high ZIKV infection rates in Ae. aegypti females from Colombian rural municipalities with deficient water supply, such as Honda with 63.6%. In the face of natural infection with an arbovirus such as Zika, the diversity between an infective and non-infective form was significantly different. Bacteria associated with a state of infection with ZIKV and lambda–cyhalothrin resistance were detected, such as the genus Bacteroides, which was related to functions of pathogenicity, antimicrobial resistance, and bioremediation of insecticides. We hypothesize that it is a vehicle for virus entry, as it is in human intestinal infections. On the other hand, Bello, the only mosquito population classified as susceptible to lambda–cyhalothrin, was associated with bacteria related to mucin degradation functions in the intestine, belonging to the Lachnospiraceae family, with the genus Dorea being increased in ZIKV-infected females. The Serratia genus presented significantly decreased functions related to phenazine production, potentially associated with infection control, and control mechanism functions for host defense and quorum sensing. Additionally, Pseudomonas was the genus principally associated with functions of the degradation of insecticides related to tryptophan metabolism, ABC transporters with a two-component system, efflux pumps, and alginate synthesis. Conclusions: Microbiota composition may be modulated by ZIKV infection and insecticide resistance in Ae. aegypti Colombian populations. The condition of resistance to lambda–cyhalothrin could be inducing a phenome of dysbiosis in field Ae. aegypti affecting the transmission of arboviruses.

Field applications of granular and liquid pyrethroids, carbaryl, and IGRs to control the asian longhorned tick (Haemaphysalis longicornis) and impacts on nontarget invertebrates

Few documented control strategies exist for the invasive tick, Haemaphysalis longicornis, despite its potential to reach extremely high numbers and vector human and animal pathogens. In 2020, we evaluated the effects of single applications of five granular and liquid acaricides on H. longicornis in a public park in northern New Jersey. Acaricides tested included pyrethroids (lambda-cyhalothrin, bifenthrin), a carbamate (carbaryl), and the insect growth regulators (IGRs) pyriproxyfen and novaluron. We also monitored the impact of each treatment on non-target soil and above-ground invertebrate species using pitfall and sticky traps, respectively. We recorded over 70,000 H. longicornis ticks in the study area from July to October 2020. An average of 99% control was achieved with lambda-cyhalothrin spray and 95% with granular bifenthrin. In contrast, granular carbaryl did not significantly reduce any life stages of H. longicornis. The IGR (pyriproxyfen/novaluron) resulted in a significant 45% reduction of the larval stage following treatments in July. No other stages were significantly impacted by pyriproxyfen alone or in combination with novaluron. Analysis of non-target species revealed that the community composition of soil-dwelling arthropods was strongly impacted by pyrethroid treatments and, to a lesser extent, by the carbamate treatment. The granular pyrethroid bifenthrin had more pronounced effects and impacted a broader range of non-target groups in the pitfall traps than the liquid pyrethroid lambda-cyhalothrin. Arthropod groups that were negatively impacted included Isopoda, Formicidae, Coleoptera, Araneae, Acari, and Grylloidea. Collembola numbers, however, were elevated in both pyrethroid treatments. The community composition of arthropods collected on the above-ground sticky traps was strongly impacted only in the liquid lambda-cyhalothrin treatment. The primary groups impacted in the sticky trap analysis were Collembola and Hemiptera. Community composition in traps remained distinct in the pyrethroid treatments through the entire survey period up to 62 days post-treatment. The results of this study indicate that pyrethroid acaricides were highly effective at controlling H. longicornis, while other compounds, including carbaryl and IGRs, did not achieve consistent levels of control. Further research is needed to find effective and environmentally sustainable alternatives. Integrated management programs can include the judicious use of pyrethroids to control H. longicornis.

Structure and release properties of pyrethroid/sulfobutyl ether β-cyclodextrin intercalated into layered double hydroxide and layered hydroxide salt.

The aim of this study was to realize the intercalation of the pyrethroid pesticides beta-cypermethrin (BCT) and lambda-cyhalothrin (LCT) into ZnAl-layered double hydroxides (LDH) and NiZn-layered hydroxide salt (LHS). BCT (LCT)/SBECD-LDH and BCT (LCT)/SBECD-LHS hybrids were obtained with the aid of sulfobutyl ether β-cyclodextrin (SBECD) through one step method. The hybrids were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetry and differential thermal analysis (TGA/DTA). The hybrids based on LHS had larger basal spacing than those on LDH. The LDH-hybrids prepared in N-methylpyrrolidone (NMP) had larger basal spacing than those in ethanol. These results were discussed in terms of the matrix structure and solvent properties. The supramolecular structure of the hybrid was reasonably proposed. Furthermore, the release properties of BCT (LCT) from the hybrids were investigated and discussed in two media. The release rate in pH = 5.0 was slower than that in pH = 6.8. The accumulated release amount of pesticide in pH = 5.0 was lower than that in pH = 6.8. LHS-hybrids synthesized in ethanol exhibit a sustainable release property. These depend on the inclusion complexes’ arrangement and release medium. The release kinetic processes could be described by pseudo-second order and parabolic diffusion models. The release behavior can be controlled by adjusting the synthesis conditions and the releasing media. This provides the guidance for the application of SBECD and LDH (LHS) in pesticide formulation.

Characterization of Insecticide Resistance in Aedes aegypti from the Zoological Garden of Havana, Cuba.

Chemical control of Aedes aegypti continues to be an indispensable alternative to preventing dengue, Zika, and chikungunya outbreaks. The Havana Zoological Garden requires constant vigilance because its special characteristics help in the spread of the causal agents of diseases transmitted by mosquitoes, which put the health of visitors at risk. The goals of this study were to determine the level of susceptibility and insecticide resistance mechanisms in the Ae. aegypti population. Temephos susceptibility in larvae was evaluated with bioassays using the World Health Organization's methodology, and susceptibility of adult mosquitoes was determined by the impregnated bottle bioassay, recommended by the Centers for Disease Control and Prevention. Resistance mechanisms were determined with biochemical assays. Mosquito larvae from the Havana Zoo were found resistant to temephos, which was associated with the activity of the enzymes α- and β-esterases and mixed function oxidases but not glutathione-S-transferase. Adult mosquitoes were susceptible to pyrethroid (lambda-cyhalothrin, deltamethrin, and cypermethrin), organophosphate (chlorpyrifos), and carbamate (bendiocarb). Temephos resistance detected in the mosquito population from the Havana Zoo is an alert for the Vector Control Program, which must take measures to manage their resistance, relying on the surveillance carried out by Cuba's medical entomology laboratories.

Momordica foetida (Cucurbitaceae) prevents behavioral impairment, motor incoordination and brain oxidative stress induced by subchronic exposure to Parastar pesticide formulation

Background: Parastar is an agricultural insecticide formulation composed of two active ingredients; a pyrethroid lambda-cyhalothrin and a neonicotinoid imidachloprid used in Cameroon for vegetable protection. Previous studies showed reprotoxicity and neurotoxicity of this pesticide formulation. Momordica foetida Schumach. Et Thonn is a medicinal plant with potent antioxidant properties used traditionally in Cameroon for the treatment of several aliments. As farmers are currently exposed to Parastar pesticide formulation, this study was designed to evaluate the protective effect of M. foetida on behavioral impairment, motor incoordination and brain oxidative stress induced by subchronic administration of Parastar. Methods: The study was carried out using 40 Wistar male rats, divided into 5 groups of 8 rats each. The groups received a vehicle (distilled water; 10 mL/kg), Parastar alone (6.23 mg/kg), or concomitantly with M. foetida methanol extract (50, 100 and 200 mg/kg) for 60 days. The animals were submitted to behavioural tests including, beam walking test, open field test and forced swimming test. At end of the treatment, oxidative stress parameters and acetylcholinesterase activity were assessed in brain of each animal. Results: Parastar induced motor dysfunctions, anxiogenic like and depressive-like behaviours in the animals. The Parastar -induced alterations in behavior were all prevented by M. foetida extract. The plant extract alleviated Parstar-induced oxidative stress and alteration of cholinesterase activity, especially at the dose 100mk/kg. Conclusion: Results from this study suggest that, M. feotida methanol extract may prevent anxiety-like behavior, depressive-like behavior, motor incoordination induced by Parastar, possibly through it antioxidant properties and the preservation of acetylcholinesterase activity.&#x0D; Keywords: acetylcholinesterase, Momordica foetida, neurotoxicity, oxidative stress, Parastar, rats

Excretion time courses of lambda-cyhalothrin metabolites in the urine of strawberry farmworkers and effect of coexposure withcaptan.

There are limited literature data on the impact of coexposure on the toxicokinetics of pesticides in agricultural workers. Using the largely employed pyrethroid lambda-cyhalothrin (LCT) and fungicide captan as sentinel pesticides, we compared individual temporal profiles of biomarkers of exposure to LCT in strawberry field workers following an application episode of LCT alone or in coexposure with captan. Participants provided all urine voided over a 3-day period after an application of a pesticide formulation containing LCT alone (E1) or LCT mixed with captan (E2), and in some cases following re-entry in treated field (E3). Pyrethroid metabolites were measured in all urine samples, in particular 3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethyl-cyclopropanecarboxylic acid (CFMP), 3-phenoxybenzoic acid (3-PBA), and 4-hydroxy-3-phenoxybenzoic acid (4-OH3PBA). There were no obvious differences in individual concentration-time profiles and cumulative excretion of metabolites (CFMP, 3-PBA, 4-OH3BPA) after exposure to LCT alone or in combination with captan. For most workers and exposure scenarios, CFMP was the main metabolite excreted, but time courses of CFMP in urine did not always follow that of 3-PBA and 4-OH3BPA. Given that the latter metabolites are common to other pyrethroids, this suggests that some workers were coexposed to pyrethroids other than LCT. For several workers and exposure scenarios E1 and E2, values of CFMP increased in the hours following spraying. However, for many pesticide operators, other peaks of CFMP were observed at later times, indicating that tasks other than spraying of LCT-containing formulations contributed to this increased exposure. These tasks were mainly handling/cleaning of equipment used for spraying (tractor or sprayer) or work/inspection in LCT-treated field according to questionnaire responses. Overall, this study provided novel excretion time course data for LCT metabolites valuable for interpretation of biomonitoring data in workers, but also showed that coexposure was not a major determinant of variability in exposure biomarker levels. Our analysis also pointed out the importance of measuring specific metabolites.

Ultrasound-assisted QuEChERS-based extraction using EDTA for determination of currently-used pesticides at trace levels in soil.

It is essential to monitor pesticides in soils as their presence at trace levels and their bioavailability can induce adverse effects on soil's ecosystems, animals, and human health. In this study, we developed an analytical method for the quantification of traces of multi-class pesticides in soil using liquid chromatography-tandem mass spectrometry. In this way, 31 pesticides were selected, including 12 herbicides, 9 insecticides, and 10 fungicides. Two extraction techniques were first evaluated, namely, the pressurized liquid extraction and the QuEChERS procedure. The latest one was finally selected and optimized, allowing extraction recoveries of 55 to 118%. The role of the chelating agent EDTA, which binds preferentially to soil cations that complex some pesticides, was highlighted. Coupled with liquid chromatography-tandem mass spectrometry, the procedure displayed very high sensitivity, with limits of quantification (LOQ) in the range 0.01-5.5ng/g. A good linearity (R2 > 0.992) was observed over two orders of magnitude (LOQ-100 [Formula: see text] LOQ) with good accuracy (80-120%) for all compounds except the two pyrethroids lambda-cyhalothrin and tau-fluvalinate (accuracy comprised between 50 and 175%) and the cyclohexanedione cycloxydim (accuracy < 35%). Good repeatability and reproducibility were also achieved. The method was finally successfully applied to 12 soil samples collected from 3 land-use types. Among the 31-targeted pesticides, 24 were detected at least once, with concentration levels varying from LOQ to 722ng/g. Many values were below 0.5ng/g, indicating that the developed method could provide new knowledge on the extremely low residual contents of some pesticides.

Inert agricultural spray adjuvants may increase the adverse effects of selected insecticides on honey bees (Apis mellifera L.) under laboratory conditions

Currently, more than 360 spray adjuvants are registered in Germany (September 2021). Unlike plant protection products (PPPs), adjuvants are not subjected to regulatory risk assessment. In practice, numerous combinations of PPPs and adjuvants are therefore possible. Thus, tank mixtures containing insecticides that are classified as non-hazardous to bees up to the highest approved application rate or concentration may raise pollinator safety concerns when mixed with efficacy increasing adjuvants and applied in bee-attractive crops. This study analyzes whether selected “PPP–adjuvant” combinations result in increased contact mortality and pose an elevated risk to honey bees. To answer this question, we chose six common spray adjuvants of different classes for laboratory screening. These were then tested in a total of 30 tank mixtures, each with a neonicotinoid (acetamiprid), pyrethroid (lambda-cyhalothrin), diamide (chlorantraniliprole), carbamate (pirimicarb), and butenolide (flupyradifurone) formulation. We adapted an acute contact test (OECD Test Guideline 214) to our needs, e.g., by using a professional spray chamber for more realistic exposures. Our results showed that, in total, 50% of all combinations significantly increased the mortality of caged honey bees in comparison with individual application of insecticides. In contrast, none of the adjuvants alone affected bee mortality (Cox proportional hazard model, p > 0.05). With four of the five insecticide formulations, the organosilicone surfactant Break-Thru® S 301 significantly increased bee mortality within 72 h (for all insecticides except chlorantraniliprole). Furthermore, acetamiprid yielded the highest and second highest mortality increases from a tank mixture with the crop oil surfactant LI 700® (hazard ratio = 28.84, p < 0.05) and the organosilicone Break-Thru® S 301 (hazard ratio = 14.66, p < 0.05), respectively. To assess risk in a more field-realistic setting, field trials should be performed to provide a more realistic exposure scenario under colony conditions.

Current Status of Pyrethroids Resistance in Aedes aegypti (Culicidae: Diptera) in Lahore District, Pakistan: A Novel Mechanistic Insight.

Aedes aegypti (Linnaeus, 1762) is a major vector responsible for dengue transmission. Insecticides are being used as the most effective tool to control vector populations in Lahore, Pakistan. Control of Ae. aegypti is threatened by the development of resistance against insecticides. The current status of insecticide resistance was evaluated against pyrethroids (deltamethrin, cypermethrin, and lambda-cyhalothrin) in different populations of Lahore (Model Town, Mishri Shah, Sadar Cantt, Walton, and Valencia). The susceptibility of the larval and adult populations was tested following the standard WHO guidelines. Moderate to high levels of resistance were found against pyrethroids in the larval (RR50: 3.6-27.2 and RR90: 5-90) and adult populations (percentage mortality < 98%). Biochemical assays revealed a statistically significant increase in the enzyme level in all field populations compared to the laboratory strain. The value of esterase was one-fold higher, monooxygenase was 3.9- to 4.7-fold higher, and glutathione S-transferases was 1.9- to 2.6-fold higher in field populations compared to the laboratory strain. These results depict the presence of resistance against deltamethrin, cypermethrin, and lambda-cyhalothrin in field populations of Lahore mediated by metabolic enzymes i.e. esterases, monooxygenases, and glutathione S-transferase.

Assessment of Toxicity Risk of Selected Insecticides Used in Pistachio Ecosystem on Two Egg Parasitoids (Hymenoptera: Scelionidae) of Stink Bugs (Hemiptera: Pentatomidae).

Psix saccharicola (Mani) and Trissolcus semistriatus (Nees) are the most abundant eggs parasitoids of the stink bug, Acrosternum arabicum Wagner, in pistachio orchards and have the potential to contribute to their suppression. However, treatment of orchards with broad-spectrum insecticides may greatly reduce populations of these beneficial natural enemies. Therefore, we conducted risk assessments and evaluated sublethal impacts of two insecticides routinely used in pistachio orchards: the organophosphate fenitrothion and a formulated mixture of the neonicotinoid thiamethoxam and the pyrethroid lambda-cyhalothrin on parasitism success, emergence and sex ratio of P. saccharicola and T. semistriatus. Based on the values of their risk quotients (RQ), which are derived from toxicity data, the two insecticide products would be classified as slightly-to-moderately toxic although an alternative metric, the safety factor (SF), showed them to be highly risky. Assessments of sublethal effects on adult wasps showed that insecticide exposure significantly reduced their ability to successfully parasitize stink bug eggs, and exposure of adult females reduced the emergence, survival, and proportion of females of their progeny, which could disrupt biological control for an extended period of time. Analysis of the decreased emergence and parasitism for P. saccharicola and T. semistriatus in accordance with the standards of the International Organization for Biological Control (IOBC) indicate that fenitrothion is slightly harmful to both parasitoid species whereas the mixture of thiamethoxam + lambda-cyhalothrin is moderately harmful. These findings will be useful for integrating insecticides and egg parasitoids into a comprehensive integrated pest management program for managing stink bugs populations in pistachio orchards.