Synthetic Pyrethroid Insecticide Research Articles

Removal of cyfluthrin by fine bubble technology in oranges (Citrus reticulata Blanco)

Cyfluthrin, a synthetic pyrethroid insecticide, is used widely for orange cultivation. Prolong exposure to cyfluthrin causes several human health issues such as kidney inflammation, weight loss and diarrhoea. This study aimed to investigate the fate of cyfluthrin residue in oranges after treatment with fine bubble produced with air or ozone. Micro-bubbles produced from different types of gas (air, oxygen and ozone) were used to treat oranges contaminated with cyfluthrin. Cyfluthrin residue was tested using GPO-TM kit. The pesticide residue was not detected after micro-bubble treatments. An air micro-bubble technology was chosen for further analysis by HPLC. HPLC analysis confirmed that more than 90% of contaminated cyfluthrin was removed by air micro-bubble treatment. Moreover, the insecticide residue was not detected in washing water.

A label-free optical whole-cell Escherichia coli biosensor for the detection of pyrethroid insecticide exposure

There is a growing need for low-cost, portable technologies for the detection of threats to the environment and human health. Here we propose a label-free, optical whole-cell Escherichia coli biosensor for the detection of 3-phenoxybenzoic acid (3-PBA), a biomarker for monitoring human exposure to synthetic pyrethroid insecticides. The biosensor functions like a competitive ELISA but uses whole-cells surface displaying an anti-3-PBA VHH as the detection element. When the engineered cells are mixed with 3-PBA-protein conjugate crosslinking that can be visually detected occurs. Free 3-PBA in samples competes with these crosslinks, leading to a detectable change in the output. The assay performance was improved by coloring the cells via expression of the purple-blue amilCP chromoprotein and the VHH expression level was reduced to obtain a limit of detection of 3 ng/mL. The optimized biosensor exhibited robust function in complex sample backgrounds such as synthetic urine and plasma. Furthermore, lyophilization enabled storage of biosensor cells for at least 90 days without loss of functionality. Our whole-cell biosensor is simple and low-cost and therefore has potential to be further developed as a screening tool for monitoring exposure to pyrethroids in low-resource environments.

Cypermethrin exposure reduces the ovarian reserve by causing mitochondrial dysfunction in granulosa cells

Cypermethrin (CYP) is one of the most highly effective synthetic pyrethroid insecticides and is recommended for insect control because it is considered to be relatively non-toxic to humans in all stages of life. However, recent data have shown that CYP has adverse effects on fertility, immune system, cardiovascular, hepatic metabolism and enzyme activity in vertebrates. Our objective was to investigate the toxicity of CYP to the ovary and to elucidate the underlying molecular mechanisms. Twenty 8-week-old CD-1 female mice were randomly assigned to four groups, that were separately exposed to CYP at doses of 12.5, 25 and 50 mg/kg/day or to corn oil (vehicle) for 28 days by intragastric administration. Moreover, human granulosa KGN cells were treated with CYP for 24 h at concentrations of 100 μM and 200 μM or to anhydrous ethanol (vehicle). This study clearly demonstrated that, compared to vehicle exposure, CYP exposure caused abnormal estrous cyclicity and decreased follicle numbers in all stages of mice with a dose-dependent manner. Interestingly, the apoptosis signals were mainly located in granulosa cells, and the expression levels of Caspase 3, Bax and Bcl-2 were increased in the 25 and 50 mg/kg/d groups. In KGN cells, CYP (100 and 200 μM) clearly induced apoptosis together with mitochondrial membrane potential depolarization and abnormal ROS generation compared to the control group. Altogether, these results suggest that CYP exposure reduced the ovarian reserve in mice by inducing apoptosis in granulosa cells via mitochondrial-related pathways.

Tracking genetic invasions: Genome-wide single nucleotide polymorphisms reveal the source of pyrethroid-resistant Aedes aegypti (yellow fever mosquito) incursions at international ports.

Biological invasions are increasing globally in number and extent despite efforts to restrict their spread. Knowledge of incursion pathways is necessary to prevent new invasions and to design effective biosecurity protocols at source and recipient locations. This study uses genome‐wide single nucleotide polymorphisms (SNPs) to determine the origin of 115 incursive Aedes aegypti(yellow fever mosquito) detected at international ports in Australia and New Zealand. We also genotyped mosquitoes at three point mutations in the voltage‐sensitive sodium channel (Vssc) gene: V1016G, F1534C and S989P. These mutations confer knockdown resistance to synthetic pyrethroid insecticides, widely used for controlling invertebrate pests. We first delineated reference populations using Ae. aegypti sampled from 15 locations in Asia, South America, Australia and the Pacific Islands. Incursives were assigned to these populations using discriminant analysis of principal components (DAPC) and an assignment test with a support vector machine predictive model. Bali, Indonesia, was the most common origin of Ae. aegypti detected in Australia, while Ae. aegypti detected in New Zealand originated from Pacific Islands such as Fiji. Most incursives had the same allelic genotype across the three Vsscgene point mutations, which confers strong resistance to synthetic pyrethroids, the only insecticide class used in current, widely implemented aircraft disinsection protocols endorsed by the World Health Organization (WHO). Additionally, all internationally assigned Ae. aegypti had Vssc point mutations linked to pyrethroid resistance that are not found in Australian populations. These findings demonstrate that protocols for preventing introductions of invertebrates must consider insecticide resistance, and highlight the usefulness of genomic data sets for managing global biosecurity objectives.

Derivation of combined species sensitivity distributions for acute toxicity of pyrethroids to aquatic animals

The aquatic toxicity profiles of synthetic pyrethroid insecticides are remarkably similar, and results for a large number of species can be combined across compounds in Species Sensitivity Distributions (SSDs). Normalizing acute toxicity values (median lethal concentrations, LC50s) for each species and each pyrethroid to the LC50 of the same pyrethroid to the freshwater amphipod Hyalella azteca (the most sensitive species to all pyrethroids tested) enabled expression of LC50s as Hyalella equivalents that can be pooled across pyrethroids. The resulting normalized LC50s (geometric means for each species across pyrethroids) were analyzed using SSDs. Based on tests with measured exposure concentrations, the fifth percentiles (Hazard Concentrations, HC5s) of the SSDs were 4.8 Hyalella equivalents for arthropods (36 species) and 256 Hyalella equivalents for fish (24 species). HC5 values are useful as effects metrics for screening-level risk assessments, and the full SSDs can be integrated with estimated exposure distributions for higher-level risk characterization. The combined pyrethroid SSDs provide a more taxonomically representative and statistically robust basis for risk characterization than data for the most sensitive single species or SSDs based on data for a single pyrethroid alone, and are especially useful for pyrethroids that have been tested with smaller numbers of species.

Cypermethrin induction of DNA damage and oxidative stress in zebrafish gill cells

Cypermethrin (CYP) is a synthetic pyrethroid insecticide, used to control pests in domestic, industrial and agricultural environments. According to recent reports, it is one of the most common contaminants in freshwater aquatic systems. The aim of this study was to evaluate its potential genotoxic effect and the activation of the superoxide dismutase (SOD) and catalase (CAT) systems of adult zebrafish gill cells after in vivo exposure. The comet assay (CA) demonstrated that gill cells are sensitive to DNA damage after in vitro exposure to hydrogen peroxide (H2O2), showing a dose-dependent response. We also found an increase in DNA damage of gill cells following a dose- and time-dependent treatment with CYP. Moreover, it was verified that SOD and CAT activities significantly increased after exposure to 0.6 µg/L CYP, both during six and nine days. The same treatment caused a significant up-regulation of the mRNA levels of Mn-sod and cat genes. These data indicate that CYP causes gill cell's DNA damage and oxidative stress, modifying the activities of the enzymes responsible for maintaining ROS balance, as well as in their corresponding gene expression levels.

Exposure of consumers and farmers to organophosphate and synthetic pyrethroid insecticides in Northern Thailand

Organophosphate and pyrethroid insecticides are used for controlling residential and agricultural insect pests and disease-carrying vectors in Thailand especially in the northern region. Chiang Rai and Nan Provinces are well known for agricultural production. The aim of the present study was to assess the level of exposure to organophosphate and pyrethroid insecticides in 51 consumers and 49 farmers living in Chiang Rai and Nan Provinces by monitoring the urinary metabolites 6-dialkylphosphates (DAPs) and 3-phenoxybenzoic acid (3-PBA) as biomarkers of exposure to organophosphates and pyrethroids. The results showed at least one metabolite was present in all subjects indicating that consumers and farmers were exposed to these pesticides. Concentrations of organophosphate and pyrethroid metabolites in consumers and farmers were similar except diethylthiophosphate which was significantly higher in farmers. Diethyldithiophosphate and 3-PBA concentrations were significantly different between the group who had reported using and not using pesticide in their house.

Chromogenic spray reagent for the detection and identification of amitraz in biological materials

In the present study, we developed a simple, sensitive, and selective thin-layer chromatographic method for the detection and identification of amitraz using chloranil as chromogenic spray. In the first step, amitraz was hydrolized by using 10% sodium hydroxide solution in water to give dimethylaniline (DMA) and N-2,4-dimethylphenyl- N-methyl formamidine (DMPMF). The dimethylaniline further treated with chloranil in acetone gives blue spot. This spray reagent does not react with other organophosphorous, organochloro, carbamate, and synthetic pyrethroid insecticides. This reagent is sensitive and selective only to amitraz. The constituents of viscera (amino acids, peptides, and proteins) do not interfere with the test. The detection limit for amitraz is about 0.7 µg.

Resistance of Aedes as a Vectors Potential for Dengue Hemorrhagic Fever (DHF) in Semarang City, Indonesia

Dengue Hemorrhagic Fever (DHF) is a significant health problem in Semarang, Indonesia. A Certain type of insecticides has been widely applied beginning in the last decade as an effort to control the mosquito vectors of dengue virus. This practice could lead to increased resistance in mosquito populations toward these types of insecticides. This research aimed to describe the resistance status of Aedes sp. populations in Semarang. A cross-sectional design study was conducted in 2015, with Aedes sp. populations sampled in several villages of Semarang. Field strains of Aedes sp. eggs were collected using ovitraps and larvae from entomological surveys. Mosquito adults were raised from the collected eggs and larvae under standard conditions and used for biochemical assays. ELISA examined Aedes sp . resistance status. The results showed that there was monooxygenase activity in Aedes sp. populations. In quantitative terms, 77.8% of mosquito samples showed an Optical Density (OD) more than the cut-off point (0.165). Resistance to synthetic pyrethroid insecticide in Aedes sp. mosquitoes population in Semarang may be caused by the mechanism of monooxygenase detoxification enzymes in particular. This case indicated that Aedes sp. has a high capacity as a vector to transmit the dengue virus in Semarang.

Proteasome inhibition by MG-132 protects against deltamethrin-induced apoptosis in rat hippocampus

AimsDeltamethrin (DM), a type II synthetic pyrethroid insecticide, is widely used in agriculture and home pest control. The evaluation of their toxic effects is of major concern to public health. However, the molecular mechanism of DM-induced neurodegenerative disease is still far from clear. This study was designed to investigate the potential role of ubiquitin proteasome system (UPS) in DM-induced neurotoxicity where the proteasome inhibitor MG-132 could mitigate the neurotoxic effects. Main methodsMale Sprague-Dawley rats were divided into two batches. The first batch of rats was administrated with a single dose of DM (12.5 mg/kg) by intraperitoneal injections (i.p.) and the animals were then euthanized at 5, 24, and 48 h post injection. The second batch was treated as follow: control group, DM (12.5 mg/kg) groups for 24 h, MG-132 (0.5 mg/kg, i.p.) 2 h plus DM 24 h group, and MG-132 alone group. Ubiqutinatied proteins, DNA damage and apoptosis were investigated. Key findingsDM treatment induced the ubiquitinated proteins expression with the peaks at 5 h. Moreover, DM increased DNA damage, early apoptotic rate, the expression level of Cleaved Caspase-3, caspase-3 activity and decreased the expression level of Bcl-2 at DM 24 h group. Compared to DM 24 h group, MG-132 pretreatment significantly down-regulated ubiquitinated proteins, lowered the DNA damage and apoptosis by decreasing Caspase-3 and increasing Bcl-2 expression. SignificanceThese results indicate that MG-132 effectively alleviates DM-induced DNA damage and apoptosis by inhibiting ubiquitinated proteins. UPS may play a role in DM-induced neurodegenerative disorders.

The response of three species of phytoseiid mite (Acari: Phytoseiidae) to synthetic pyrethroid pesticides in the laboratory and the field.

The Kanzawa spider mite, Tetranychus kanzawai Kishida, is a major pest in tea fields [Camellia sinensis (L.) O. Kuntze] in Japan. However, recently, there have been some instances where acaricides are no longer applied as a result of the low occurrence of T. kanzawai in tea fields in Japan. In the period of 2015-2017, surveys of predatory mites in the study tea field detected Amblyseius eharai Amitai and Swirski, Phytoseiulus persimilis Athias-Henriot, Euseius sojaensis (Ehara), Amblyseius obtuserellus Wainstein and Begljarov, and Typhlodromus vulgaris Ehara in tea fields, but not Neoseiulus womersleyi (Schicha), indicating that a major change in the composition of the phytoseiid mite population had occurred. In laboratory studies, we confirmed the ability to avoid synthetic pyrethroid insecticides of the major beneficial mites in tea fields, A. eharai and P. persimilis, but not of E. sojaensis, a predatory mite whose population declined heavily after pesticide application. Attempts are made in this study to associate the decrease in T. kanzawai frequency in Japan with changes in pesticide used, method of spraying, and composition of the phytoseiid mite population. By continuing the method of pesticide spraying ('partial surface'), which leaves refugia in the leaf layer with sub-lethal dosages of pesticide, phytoseiid mites are aided to evade pesticides, resulting in maintenance of the composition of the phytoseiid mite populations in terms of diversity and abundance. Maintaining the diversity and abundance of Phytoseiidae may have contributed to the stabilization of the T. kanzawai population at low densities in Japanese tea fields.

Toxicity to, oviposition and population growth impairments of Callosobruchus maculatus exposed to clove and cinnamon essential oils.

The use of plant essential oils has been shown to efficiently control insect pests of stored beans, significantly reducing the threats associated with synthetic insecticides. Here, we evaluated the potential of applications of essential oils of clove, Syzygium aromaticum L., and cinnamon, Cinnamomum zeylanicum L., to control Callosobruchus maculatus, considered as one of the most cosmopolitan pests of stored beans. Using four combinations of couples (i.e., unexposed couples, exposed females, exposed males, and exposed couples), we also evaluated how sublethal exposure to these essential oils impacted C. maculatus oviposition. Bioassays results revealed that both essential oils exhibited insecticidal activities similar to the synthetic pyrethroid insecticide deltamethrin. Furthermore, oil dosage increments proportionately decreased the growth rate and reduced the losses in bean weight caused by cowpea weevils, and offspring emergence was almost abolished when parents were exposed to the LD20 of each essential oil. Finally, significant oviposition impairments were perceived only in couples where females were exposed (i.e., females exposed and exposed couples) to the LD20 of cinnamon and clove essential oils. Thus, by exhibiting similar insecticidal activities as synthetic insecticides and by significantly affecting the oviposition of sublethally exposed C. maculatus females, the cinnamon and clove essential oils represent valuable tools with potential of integration into the management of C. maculatus infestations.

Insecticide-treated nets for preventing malaria.

A previous version of this Cochrane Review identified that insecticide-treated nets (ITNs) are effective at reducing child mortality, parasite prevalence, and uncomplicated and severe malaria episodes. Insecticide-treated nets have since become a core intervention for malaria control and have contributed greatly to the dramatic decline in disease incidence and malaria-related deaths seen since the turn of the millennium. However, this time period has also seen a rise in resistance to pyrethroids (the insecticide used in ITNs), raising questions over whether the evidence from trials conducted before resistance became widespread can be applied to estimate the impact of ITNs on malaria transmission today. The primary objective of this review was to assess the impact of ITNs on mortality and malaria morbidity, incorporating any evidence published since the previous update into new and existing analyses, and assessing the certainty of the resulting evidence using GRADE. We searched the Cochrane Infectious Diseases Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL) published in the Cochrane Library, MEDLINE, Embase, LILACS, the World Health Organization (WHO) International Clinical Trials Registry Platform, ClinicalTrials.gov, and the ISRCTN registry for new trials published since 2004 and up to 18 April 2018. We included individual randomized controlled trials (RCTs) and cluster RCTs comparing bed nets or curtains treated with a synthetic pyrethroid insecticide at a minimum target impregnation dose recommended by the WHO with no nets or untreated nets. One review author assessed the identified trials for eligibility and risk of bias, and extracted data. We compared intervention and control data using risk ratios (RRs), rate ratios, and mean differences, and presented all results with their associated 95% confidence intervals (CIs). We assessed the certainty of evidence using the GRADE approach. We drew on evidence from a meta-analysis of entomological outcomes stratified by insecticide resistance from 2014 to inform the GRADE assessments. Our updated search identified three new trials. A total of 23 trials met the inclusion criteria, enrolling more than 275,793 adults and children. The included studies were conducted between 1987 and 2001.ITN versus no netsInsecticide-treated nets reduce child mortality from all causes by 17% compared to no nets (rate ratio 0.83, 95% CI 0.77 to 0.89; 5 trials, 200,833 participants, high-certainty evidence). This corresponds to a saving of 5.6 lives (95% CI 3.6 to 7.6) each year for every 1000 children protected with ITNs. Insecticide-treated nets also reduce the incidence of uncomplicated episodes of Plasmodium falciparum malaria by almost a half (rate ratio 0.55, 95% CI 0.48 to 0.64; 5 trials, 35,551 participants, high-certainty evidence) and probably reduce the incidence of uncomplicated episodes of Plasmodium vivax malaria (risk ratio (RR) 0.61, 95% CI 0.48 to 0.77; 2 trials, 10,967 participants, moderate-certainty evidence).Insecticide-treated nets were also shown to reduce the prevalence of P falciparum malaria by 17% compared to no nets (RR 0.83, 95% CI 0.71 to 0.98; 6 trials, 18,809 participants, high-certainty evidence) but may have little or no effect on the prevalence of P vivax malaria (RR 1.00, 95% CI 0.75 to 1.34; 2 trials, 10,967 participants, low-certainty evidence). A 44% reduction in the incidence of severe malaria episodes was seen in the ITN group (rate ratio 0.56, 95% CI 0.38 to 0.82; 2 trials, 31,173 participants, high-certainty evidence), as well as an increase in mean haemoglobin (expressed as mean packed cell volume) compared to the no-net group (mean difference 1.29, 95% CI 0.42 to 2.16; 5 trials, 11,489 participants, high-certainty evidence).ITN versus untreated netsInsecticide-treated nets probably reduce child mortality from all causes by a third compared to untreated nets (rate ratio 0.67, 95% CI 0.36 to 1.23; 2 trials, 25,389 participants, moderate-certainty evidence). This corresponds to a saving of 3.5 lives (95% CI -2.4 to 6.8) each year for every 1000 children protected with ITNs. Insecticide-treated nets also reduce the incidence of uncomplicated P falciparum malaria episodes (rate ratio 0.58, 95% CI 0.44 to 0.78; 5 trials, 2036 participants, high-certainty evidence) and may also reduce the incidence of uncomplicated P vixax malaria episodes (rate ratio 0.73, 95% CI 0.51 to 1.05; 3 trials, 1535 participants, low-certainty evidence).Use of an ITN probably reduces P falciparum prevalence by one-tenth in comparison to use of untreated nets (RR 0.91, 95% CI 0.78 to 1.05; 3 trials, 2,259 participants, moderate-certainty evidence). However, based on the current evidence it is unclear whether or not ITNs impact on P vivax prevalence (1 trial, 350 participants, very low certainty evidence) or mean packed cell volume (2 trials, 1,909 participants, low certainty evidence). Although there is some evidence that insecticide resistance frequency has some effects on mosquito mortality, it is unclear how quantitatively important this is. It appeared insufficient to downgrade the strong evidence of benefit on mortality and malaria illness from the trials conducted earlier.

Mass Spectrometry-Compatible Enantiomeric Separations of 100 Pesticides Using Core–Shell Chiral Stationary Phases and Evaluation of Iterative Curve Fitting Models for Overlapping Peaks

Pesticides are often chiral, and their isomers have different activity, toxicity, metabolism, and degradation properties. Perhaps, the most complex are the synthetic pyrethroid insecticides that have up to 8 stereoisomers, but not all are active. Pyrethroids are toxic to aquatic invertebrates and non-targeted species like honey bees since they persist in the environment. Extensive biological studies of the pyrethroid enantiomers are limited. Possibly, this is because liquid chromatography enantiomeric methods for these studies often have limitations with mass spectrometry (MS) compatibility. In this study, an effective methodology was developed with MS compatible solvents to evaluate several core–shell (superficially porous particle, SPP) chiral stationary phases (CSPs) for the enantiomeric separation of several classes of chiral pesticides. The CSP with the broadest selectivity or spectrum amongst all pesticide classes was the hydroxypropyl-β-cyclodextrin. The other CSPs (cyclofructan, macrocyclic glycopeptide, and quinine-based selectors) had more selective applications including separations of the pesticides with amine or acid functionalities. Overall, 74 of 100 pesticides were baseline-separated. Most of the remaining ones had multiple stereogenic centers and had only one overlapping pair. Such cases were evaluated with a convenient peak area extraction protocol by iterative curve fitting. This approach will lead to more facile enantiomeric analyses where MS is needed to overcome complex matrices and reduce extensive method optimization.

Current Resistance Status to Synthetic Pyrethroid Insecticides in Aedes aegypti (Diptera: Culicidae) Populations from Different regions of Bogor City, Indonesia

Current Resistance Status to Synthetic Pyrethroid Insecticides in Aedes aegypti (Diptera: Culicidae) Populations from Different regions of Bogor City, Indonesia

Differential expression of carboxylesterases in larva and adult of Culex quinquefasciatus Say (Diptera: Culicidae) from sub-Himalayan West Bengal, India

AbstractCulex quinquefasciatusSay, a widely distributed mosquito in tropical and subtropical areas, is the most important vector of the filarial parasiteWuchereria bancrofti, the causative agent of lymphatic filariasis. In India, filariasis is endemic in 17 States and six Union Territories, putting about 553 million people at risk of infection. Vector control, which aims to prevent pathogen transmission through interventions targeting adult mosquito vectors, is a significant component of control of the disease. Chemical-based control represents a chief strategy in the management of mosquito vectors; however, continuous application of insecticides has led to the development of resistance in many mosquito vectors around the world. The current study aims to observe the variability of expression of carboxylesterase isozymes that play a role in detoxifying insecticides into non-toxic compounds, in different life stages ofCulexmosquitoes, to understand levels of insecticide susceptibility that may be used in integrated mosquito management for efficient vector control.C. quinquefasciatus werecollected from different localities of sub-Himalayan West Bengal, India, and adult and larval bioassays were performed against one organophosphate insecticide (chlorpyrifos) and two synthetic pyrethroid insecticides (deltamethrin and lambda-cyhalothrin). The activity of α- and β-carboxylesterases (quantitative assay) were measured in larvae and adults ofC. quinquefasciatususing a microplate assay, and measured qualitative expression by native polyacrylamide gel electrophoresis. The study shows a differential activity of α- and β-carboxylesterases both in quantitative and qualitative assays. The quantitative assay reveals that larvae exhibit a 12.2-fold higher level activity of α-carboxylesterase and about 5.0-fold higher level of activity of β-carboxylesterase than adults. Some carboxylesterase isozymes, i.e., α-Est I-IV, α-Est VII and α-Est XI-XV were exclusively expressed in larvae, whereas α-Est V-VI and α-Est IX were expressed only in adults. In larvae, all β-Est I-IX were expressed, while in adults only β-Est IV-V was expressed. The results of adult and larval insecticide bioassay are also as per the above findings showing an LC90value of 0.017 ppm, 0.097 ppm and 0.072 ppm in the larva, and LC90value of 0.0015 ppm, 0.721 ppm, 0.364 ppm in adults against chlorpyrifos, deltamethrin and lambda-cyhalothrin, respectively.

Red clover casebearer moth (Coleophora deauratella) is widespread throughout New Zealand

Coleophora deauratella (red-clover casebearer moth, RCCB) was first confirmed as present in New Zealand during late 2016. It devastated red-clover seed crops throughout the mid-Canterbury region during the 2016/17 growing season but its distribution and control options were unknown. Therefore, traps containing a male pheromone specific to RCCB were located inside either red-clover seed crops or hay crops at 27 sites throughout the South Island and lower North Island during summer 2017/18. Moth numbers were monitored at 7—14-day intervals between November and February. RCCB was confirmed as present at all 27 sites (from Invercargill to Masterton). Peak flights occurred during December with mean moth catch well correlated in thermal time, with half of adult emergence occurring 285˚C days from 1 July (baseline temperature=12oC). Laboratory-based trials were conducted against live moths to evaluate the effectiveness of various organophosphate and synthetic pyrethroid insecticides. Tau-fluvalinate, lambda cyhalothrin and chlorpyrifos each provided >90% control of moths so chemical control is possible, if required. However, an integrated pest-management control strategy needs to be tested and evaluated.

Fenvalerate decreases semen quality in puberty rat through germ cell apoptosis.

Fenvalerate, a widely used synthetic pyrethroid insecticide, may adversely affect semen quality in males, but the possible mechanism remains unclear. In our study, forty male SD rats were randomly divided into one control group and three treatment groups administered with fenvalerate (0.02, 1 and 50mgkg-1 day-1 ) by gavage from post-natal day 28 (PND 28) to PND 88. Semen quality parameters were measured by computer-assisted sperm analysis, histological changes in testes were observed by hematoxylin-eosin (HE) staining, germ cell apoptosis was measured by TdT-mediated dUTP Nick-End Labeling (TUNEL) and caspases protein levels were measured by western blotting. Results showed that the increased body weight, the relative testis weight, the sperm concentration and the sperm motility were all significantly reduced in the 50mgkg-1 day-1 fenvalerate group. Increased inner diameter of seminiferous tubules and disturbed array of spermatogenic cells in testicular were observed in fenvalerate exposure groups. Meanwhile, TUNEL-positive germ cells significantly increased in 1 and 50mgkg-1 day-1 fenvalerate exposure groups, and the expression of caspase-8 and caspase-3 in rat testes were also significantly up-regulated. Taken together, our results indicate that fenvalerate has an adverse effect on semen quality, which may be related to germ cell apoptosis.

Toxicity of the pyrethroid bifenthrin insecticide

Bifenthrin is a chiral synthetic pyrethroid insecticide that has been commonly used for agricultural and domestic pest control over the past decades. Due to its widespread application, residues of bifenthrin has been frequently detected in environmental media, residential areas and biota, thus posing potential risks to the health of wildlife and humans. In particular, bifenthrin exhibits high acute lethal toxicity to aquatic species, and it is the primary contributor to the toxicity of insecticides in waters. Additionally, bifenthrin can also cause sublethal toxic effects on various non-target organisms, including developmental toxicity, neurobehavioral toxicity, oxidative damage, immune toxicity and endocrine disrupting effects. Here we review recent studies about the fate of bifenthrin in the environment and biological systems, the toxicity of the chiral parent compound bifenthrin and the toxic effects of main metabolites. The adverse effects of bifenthrin, identified from both in vitro and in vivo studies, and the potential underlying mechanisms are presented. We discuss the enantiomeric difference in the toxicological effects of bifenthrin, since enantiomers of chiral compounds show different interactions with biological systems. Pyrethroid insecticides metabolites are not acutely toxic, but they have sublethal toxicity, such as endocrine disrupting effects and immunotoxicity. We provide emerging evidence for toxic effects of several main metabolites.

Assessment of the inhibitory activity of the pyrethroid pesticide deltamethrin against human placental glutathione transferase P1-1: A combined kinetic and docking study

Deltamethrin (DEL), which is a synthetic pyrethroid insecticide, has been used successfully all over the world to treat mosquito nets for the control of malaria. Glutathione S-transferases (GSTs; EC 2.5.1.18) catalyze the conjugation of reduced glutathione (GSH) to a variety of xenobiotics and are normally recognized as detoxification enzymes. Here, we used a colorimetric assay based on the human placental GSTP1-1 (hpGSTP1-1)-catalyzed reaction between GSH and the model substrate 1-chloro-2,4-dinitrobenzene (CDNB) as well as molecular docking to investigate the mechanistic and structural aspects of hpGSTP1-1 inhibition by DEL. We show that DEL is a potent, noncompetitive inhibitor of hpGSTP1-1 with an IC50 value of 6.1 μM and Ki values of 5.61 ± 0.32 μM and 7.96 ± 0.97 μM at fixed [CDNB]–varied [GSH] and fixed [GSH]–varied [CDNB], respectively. DEL appears to be accommodated well in an eccentric cavity located at the interface of the hpGSTP1-1 homodimer, presumably causing conformational changes to the enzyme’s substrate-binding sites such that the enzyme is no longer able to transform GSH and CDNB effectively. Correspondingly, considerable maternal exposure to and subsequent accumulation of DEL may interfere with the proper development of the vulnerable fetus, possibly increasing the risk of developing congenital defects.