Pyrethroid Research Articles

Effectiveness of long-lasting insecticidal nets with pyriproxyfen–pyrethroid, chlorfenapyr–pyrethroid, or piperonyl butoxide–pyrethroid versus pyrethroid only against malaria in Tanzania: final-year results of a four-arm, single-blind, cluster-randomised trial

New classes of long-lasting insecticidal nets (LLINs) containing two active ingredients have been recently recommended by WHO in areas where malaria vectors are resistant to pyrethroids. This policy was based on evidence generated by the first 2 years of our recently published trial in Tanzania. In this Article, we report the final third-year trial findings, which are necessary for assessing the long-term effectiveness of new classes of LLIN in the community and the replacement intervals required. A third year of follow-up of a four-arm, single-blind, cluster-randomised controlled trial of dual active ingredient LLINs was conducted between July 14, 2021, and Feb 10, 2022, in Misungwi, Tanzania. Restricted randomisation was used to assign 84 clusters to the four LLIN groups (1:1:1:1) to receive either standard pyrethroid (PY) LLINs (reference), chlorfenapyr-PY LLINs, pyriproxyfen-PY LLINs, or piperonyl butoxide (PBO)-PY LLINs. All households received one LLIN for every two people. Data collection was done in consenting households in the cluster core area with at least one child between 6 months and 15 years of age who permanently resided in the selected household. Exclusion criteria were householders absent during the visit, living in the cluster buffer area, no adult caregiver capable of giving informed consent, or eligible children who were severely ill. Field staff and study participants were masked to allocation, and those analysing data were not. The primary 24-month endpoint was reported previously; here, we present the secondary outcome, malaria infection prevalence in children at 36 months post LLIN distribution, reported in the intention-to-treat analysis. The trial was registered with ClinicalTrials.gov (NCT03554616) and is now complete. Overall usage of study nets was 1023 (22·3%) of 4587 people at 36 months post distribution. In the standard PY LLIN group, malaria infection was prevalent in 407 (37·4%) of 1088 participants, compared with 261 (22·8%) of 1145 in the chlorfenapyr-PY LLIN group (odds ratio 0·57, 95% CI 0·38-0·86; p=0·0069), 338 (32·2%) of 1048 in the PBO-PY LLIN group (0·95, 0·64-1·42; p=0·80), and 302 (28·8%) of 1050 in the pyriproxyfen-PY LLIN group (0·82, 0·55-1·23; p=0·34). None of the participants or caregivers reported side-effects. Despite low coverage, the protective efficacy against malaria offered by chlorfenapyr-PY LLINs was superior to that provided by standard PY LLINs over a 3-year LLIN lifespan. Appropriate LLIN replacement strategies to maintain adequate usage of nets will be necessary to maximise the full potential of these nets. Department for International Development, UK Medical Research Council, Wellcome Trust, Department of Health and Social Care, and Bill & Melinda Gates Foundation via the Innovative Vector Control Consortium.

Studies of Interactions between Beta-Cyfluthrin and BSA Based on Fluorescence Spectrometry and Ultraviolet Degradation

Pesticides play a pivotal role in modern agriculture, but their potential environmental and health impacts necessitate a comprehensive understanding of their interactions with biological molecules. Beta-cyfluthrin, a widely used synthetic pyrethroid insecticide, is known for its efficiency in pest control. However, its interaction with bovine serum albumin (BSA), a crucial transport protein in living organisms, has not been extensively studied. The interaction between beta-cyfluthrin, a prominent synthetic pyrethroid insecticide, and bovine serum albumin (BSA) was comprehensively investigated using fluorescence spectrometry. Furthermore, the influence of ultraviolet (UV) degradation on the interaction parameters was explored, enhancing our understanding of the impact of environmental conditions on this interaction. The Stern–Volmer equation was employed to determine quenching constants, revealing that the fluorescence quenching mechanism primarily involved static quenching. The temperature variations were studied, showing an increase in the binding constant with rising temperature prior to degradation, while post-UV degradation, an inverse correlation between the binding constant and temperature was observed. The thermodynamic parameters were derived through appropriate equations, unveiling the underlying reaction forces. In the absence of degradation, hydrophobic interactions dominated, whereas after UV degradation, interactions shifted to hydrogen bonding and van der Waals forces. The findings elucidate the nuanced effects of UV degradation on the interaction between beta-cyfluthrin and BSA. This study furnishes critical insights that serve as a scientific foundation for pesticide production and application strategies, accounting for the influence of UV degradation on the intricate interplay between pesticides and BSA.

Adverse effects of bifenthrin exposure on neurobehavior and neurodevelopment in a zebrafish embryo/larvae model

Bifenthrin, a third-generation synthetic pyrethroid, is widely used as an agricultural insecticide. However, it can flow into surface and groundwater, leading to adverse consequences such as immunotoxicity, hepatotoxicity, hormone dysregulation, or neurotoxicity. Nevertheless, the entire range of its neurotoxic consequences, particularly in aquatic organisms, remains unclear. In this study, we conducted an extensive examination of how exposure to bifenthrin affects the behavior and nervous system function of aquatic vertebrates, using a zebrafish model and multiple-layered assays. We exposed wild-type and transgenic lines [tg(elavl3:eGFP) and tg(mbp:mGFP)] to bifenthrin from <3 h post-fertilization (hpf) to 120 hpf. Our findings indicate that bifenthrin exposure concentrations of 103.9 and 362.1 μg/L significantly affects the tail-coiling response at 24 hpf and the touch-evoked responses at 72 hpf. Moreover, it has a significant effect on various aspects of behavior such as body contact, distance between subjects, distance moved, and turn angle. We attribute these effects to changes in acetylcholinesterase and dopamine levels, which decrease in a concentration-dependent manner. Furthermore, neuroimaging revealed neurogenesis defects, e.g., shortened brain and axon widths, and demyelination of oligodendrocytes and Schwann cells. Additionally, the transcription of genes related to neurodevelopment (e.g., gap43, manf, gfap, nestin, sox2) were significantly upregulated and neurotransmitters (e.g., nlgn1, drd1, slc6a4a, ache) was significantly downregulated. In summary, our data shows that bifenthrin exposure has detrimental effects on neurodevelopmental and neurotransmission systems in the zebrafish embryo/larvae model.

A single-fluorophore-based self-calibrating supramolecular sensor for the fast and ratiometric detection of permethrin

Permethrin (PMT) is a broad-spectrum synthetic pyrethroid insecticide widely used for treatment of insects in agriculture. Yet the massive use of PMT comes at the cost of its residue ubiquitous in the environment thereby causing a significant risk to human health. Therefore, development of an analytical method for accurate detection of PMT at the point-of-care is of great importance. In this study, we report a novel single-fluorophore-based supramolecular sensor with dual emissions as ratiometric output signals, successfully realizing the fast detection of PMT with the self-calibrating feature. This sensor exhibited several advantages for PMT detection, such as fast response, high sensitivity, high specificity, and excellent anti-interference property. Notably, this sensor could be used for on-site monitoring of PMT residues on the food surface without the help of complicated testing facilities. To our best knowledge, this is the first promising fluorescent method for the fast and ratiometric determination of PMT.

Deltamethrin Toxicity: Impacts on Non-Target Organisms and the Environment

Deltamethrin is a synthetic pyrethroid insecticide widely used for controlling pests in agriculture and public health programs. However, its toxicity towards non-target organisms, including humans, has raised concerns over its safe use. This review paper aims to summarize the current knowledge of deltamethrin toxicity, including its mechanism of action, acute and chronic toxicity, genotoxicity, and ecotoxicity. The findings suggest that deltamethrin can cause acute toxicity in humans and animals, leading to symptoms such as convulsions, respiratory distress, and even death. Chronic exposure to deltamethrin has been associated with various adverse health effects, including neurotoxicity, reproductive toxicity, and carcinogenicity. Furthermore, deltamethrin has been shown to have toxic effects on non-target organisms, such as bees and aquatic organisms, which can have significant ecological consequences. Therefore, there is a need to regulate and monitor the use of deltamethrin to ensure its safe use and protect the environment and human health.

Navigating the resistance: Current perspectives on ectoparasite control in veterinary medicine

Ectoparasites present a global challenge to animal health, affecting a wide range of species. These parasites can infect both animals and humans, leading to significant health issues. The impact of ectoparasites extends beyond health, as they can also reduce the productivity of livestock. Moreover, many ectoparasite species act as vectors for bacterial, viral, or parasitic pathogens, thereby posing significant risks to human and animal health. Historically, agents such as organochlorides, organophosphates, carbamates, insect growth regulators, neonicotinoids, spinosad, fipronil, avermectins, isoxazolines, and synthetic pyrethroids have been extensively used to treat and prevent ectoparasitic infestations. However, the extensive use of these chemicals has resulted in the development of resistance among many target species, potentially reducing the effectiveness of these treatments. This article aims to survey the current status of resistance in ectoparasites to active pharmaceutical ingredients used in veterinary medicine. It also seeks to update the understanding of resistance mechanisms and explore measures that can be implemented to prevent the development of resistance.

Rapid Elimination of Aedes aegypti and Culex quinquefasciatus Mosquitoes from Puerco Island, Palawan, Philippines with Odor-Baited Traps.

Globalization and climate change are key drivers for arboviral and parasitic infectious diseases to expand geographically, posing a growing threat to human health and biodiversity. New non-pesticidal approaches are urgently needed because of increasing insecticide resistance and the negative human and environmental health impacts of synthetic pyrethroids used for fogging. Here, we report the complete and rapid removal of two mosquito species (Aedes aegypti L. and Culex quinquefasciatus Say), both arboviral disease vectors, with odor-baited mosquito traps (at a density of 10 traps/hectare) from a 7.2-hectare island in the Philippines in just 5 months. This rapid elimination of mosquitoes from an island is remarkable and provides further proof that high-density mosquito trapping can play a significant role in mosquito- and vector-borne disease elimination in small islands around the world.

Knockdown resistance mutations are common and widely distributed in Xenopsylla cheopis fleas that transmit plague in Madagascar.

Plague, caused by the bacterium Yersinia pestis, remains an important disease in Madagascar, where the oriental rat flea, Xenopsylla cheopis, is a primary vector. To control fleas, synthetic pyrethroids (SPs) have been used for >20 years, resulting in resistance in many X. cheopis populations. The most common mechanisms of SP resistance are target site mutations in the voltage-gated sodium channel (VGSC) gene. We obtained 25 collections of X. cheopis from 22 locations across Madagascar and performed phenotypic tests to determine resistance to deltamethrin, permethrin, and/or dichlorodiphenyltrichloroethane (DDT). Most populations were resistant to all these insecticides. We sequenced a 535 bp segment of the VGSC gene and identified two different mutations encoding distinct substitutions at amino acid position 1014, which is associated with knockdown resistance (kdr) to SPs in insects. Kdr mutation L1014F occurred in all 25 collections; a rarer mutation, L1014H, was found in 12 collections. There was a significant positive relationship between the frequency of kdr alleles and the proportion of individuals surviving exposure to deltamethrin. Phylogenetic comparisons of 12 VGSC alleles in Madagascar suggested resistant alleles arose from susceptible lineages at least three times. Because genotype can reasonably predict resistance phenotype, we developed a TaqMan PCR assay for the rapid detection of kdr resistance alleles. Our study provides new insights into VGSC mutations in Malagasy populations of X. cheopis and is the first to report a positive correlation between VGSC genotypes and SP resistance phenotypes in fleas. Widespread occurrence of these two SP resistance mutations in X. cheopis populations in Madagascar reduces the viability of these insecticides for flea control. However, the TaqMan assay described here facilitates rapid detection of kdr mutations to inform when use of these insecticides is still warranted to reduce transmission of plague.

Online solid phase extraction high-performance liquid chromatography – Isotope dilution – Tandem mass spectrometry quantification of organophosphate pesticides, synthetic pyrethroids, and selected herbicide metabolites in human urine

Analytical methods to quantify pesticide biomarkers in human population studies are critical for exposure assessment given the widespread use of pesticides for pest and weed control and their potential for affecting human health. We developed a method to quantify, in 0.2 mL of urine, concentrations of 10 pesticide biomarkers: four organophosphate insecticide metabolites (3,5,6-trichloro-2-pyridinol (TCPy), 2-isopropyl-6-methyl-4-pyrimidinol, para-nitrophenol, malathion dicarboxylic acid); five synthetic pyrethroid insecticide metabolites (4-fluoro-3-phenoxybenzoic acid, 3-phenoxybenzoic acid, cis and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (DCCA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid); and the herbicide 2,4-dichlorophenoxyacetic acid.he method is based on enzymatic hydrolysis of conjugated urinary metabolites, extraction and pre-concentration of the deconjugated metabolites using automated online solid-phase extraction, and separation and quantification using liquid chromatography-isotope dilution tandem mass spectrometry.Depending on the analyte, method detection limits were 0.1–0.6 ng/mL; mean accuracy, calculated as spike recoveries, was 91–102%, and total precision, given as percent variation coefficient, was 5.9–11.5%. Percent differences associated with three freeze-thaw cycles, 24-h benchtop storage, and short-term processed sample stability were <14%.Method suitability was assessed by recurring successful participation in external quality assessment schemes and by analyzing samples from subjects with suspected exposure to pesticides (n = 40) or who self-reported consuming an organic diet (n = 50). Interquartile ranges were considerably lower for people consuming an organic diet than for those potentially exposed for cis-DCCA (0.37 ng/mL vs 0.75 ng/mL), trans-DCCA (0.88 ng/mL vs 1.78 ng/mL) and TCPy (1.81 ng/mL vs 2.48 ng/mL). This method requires one-fifth of the sample used in our previous method and is suitable for assessing background exposures to select pesticides in large human populations and for studies with limited sample volumes.

The protective effect of caffeic acid phenethyl ester in the nephrotoxicity induced by α-cypermethrin.

Alpha cypermethrin (α-CYP) is an insecticide, a member of the group of synthetic pyrethroid pesticides. This study aims to assess the histopathological and biochemical subacute effects of α-CYP on the renal tissues of 48 male Spraque-Dawley adult rats. In this study, the rats were divided into six groups: control, α-CYP (10 mg kg-1), α-CYP (20 mg kg-1), caffeic acid phenethyl ester (CAPE) (10 µmol kg-1), α-CYP + CAPE (10 mg kg-1), and α-CYP + CAPE (20 mg kg-1) groups. The percentage of weight gain was found to be dose-dependent on α-CYP in all groups. As a result of exposure, the normal histological structure of renal tissue was also observed in the control and CAPE groups, while glomerular atrophy and haemorrhage, enlargement of Bowman capsule, glomerular lobulation, and degeneration in distal and proximal tubules were noted in the α-CYP-treated groups with an increased frequency and severity in parallel with the dose increase. Although the severity and intensity of lesions decreased in the α-CYP + CAPE groups, they were statistically insignificant (p > 0.05). A decrease in the antioxidant parameter levels and an increase in oxidant parameters were observed in parallel with the negative effects of the antioxidant system in the α-CYP-treated groups. The groups exposed to CAPE in combination with α-CYP exhibited a therapeutic trend towards normalization in biochemical parameters due to the antioxidant character of CAPE. However, considering the statistical difference between the groups treated with α-CYP alone and CAPE alone, it was observed that the therapeutic features of those chemicals were not robust.

Autophagy perturbation upon acute pyrethroid treatment impacts adipogenic commitment of mesenchymal stem cells

Environmental chemical exposure can cause dysregulation in adipogenesis that can result in metabolic syndrome, which includes insulin resistance, type 2 diabetes, cardiovascular disease, as well as excessive body weight. The role of autophagy in adipocyte differentiation is debatable since both positive and negative effects have been reported. Type-I and type-II synthetic pyrethroids α-cypermethrin (CPM) and permethrin (PER), respectively, are reported to increase adipogenesis in vitro and in vivo. However, it is not known how these pyrethroids affect mesenchymal stem cells (MSCs). Thus, this study focused on evaluating the effect of pyrethroids (CPM and PER) pre-treatment (24 h) on MSC commitment and the regulatory role of autophagy in adipogenic lineage commitment. The formation of adipocytes was observed through nile red staining, perilipin expression by immunoflourescence, and adipogenic markers PPARγ, C/EBPα, and FABP4 by western blotting. It was found that the adipogenic differentiation ability of MSCs was significantly increased upon CPM or PER pre-treatment at 100 μM concentration as evident by lipid accumulation and enhanced expression of adipogenic markers. To assess the involvement of autophagy, the expression of p62 and LC3II were evaluated following pre-treatment. Immunoblotting results revealed an increased expression of p62 and LC3II in CPM or PER pretreated MSCs suggesting CPM and PER mediated inhibition of autophagy at 24 h. Further, an increase was observed in adipogenesis upon CPM or PER pre-treatment in combination with chloroquine, while use of rapamycin during pre-treatment abrogated the effect of CPM and PER. Thus, this study concludes that CPM or PER pre-treatment increases the adipogenic differentiation of MSCs. Since chloroquine also demonstrated similar adipogenic response, it further highlights that 24 h pre-treatment with autophagy modulators to inhibit basal autophagy primes MSCs towards adipogenic lineage.

Endocrine disruptive toxicity of cypermethrin in Labeo catla: Involvement of genes and proteins related to the HPG axis

Cypermethrin (CYP) is a synthetic pyrethroid abundantly used in agriculture and aquaculture. It is an established potent endocrine disruptor to fish, yet the molecular mechanism behind its reproductive toxicity remains unclear. In this study, fish Labeo catla (Catla) was exposed to environmentally relevant concentration of CYP (0.7 μg/L) and 0.14 μg/L for 30 days. The changes in circulating sex steroids, genes, and hormones linked to the hypothalamic-pituitary-gonadal (HPG) axis, stress response and associated histological alterations were studied. Significant decline (P < 0.05) in serum 17 beta (β) estradiol (E2), 11 ketotestosterone (11-KT), and brain (FSH and GnRH) were observed in 0.7 μg/L dose of CYP. These effects may be due to the down-regulated expression of the upstream genes of the HPG axis i.e. Kiss 1 and Kiss 2, which further downregulates the expression of the GnRH gene. The decreased level of E2 and 11-KT also affects the vitellogenin (Vtg) gene expression, reducing the production of Vtg, a crucial protein for ovarian development. Principal component analysis (PCA) revealed the relationship between CYP and the biosynthesis of sex steroids. The toxic effect of CYP was also visible in antioxidant enzyme assay and related histological alterations. Overall, the study elucidated that long-term exposure to CYP, even at an environmentally relevant dose, may affect reproductive potential and fish recruitment. The study provides important insights into molecular mechanisms underlying CYP-induced endocrine disruption in fish, and it also raises questions about CYP's potential toxicity at environmentally relevant concentration in terms of understanding ecological risk.

Effects of next-generation, dual-active-ingredient, long-lasting insecticidal net deployment on insecticide resistance in malaria vectors in Tanzania: an analysis of a 3-year, cluster-randomised controlled trial

Insecticide resistance among malaria-vector species is a pervasive problem that might jeopardise global disease-control efforts. Novel vector-control tools with different modes of action, including long-lasting insecticidal nets (LLINs) incorporating new active ingredients, are urgently needed to delay the evolution and spread of insecticide resistance. We aimed to measure phenotypic and genotypic insecticide-resistance profiles among wild Anopheles collected over 3 years to assess the longitudinal effects of dual-active-ingredient LLINs on insecticide resistance. For this analysis, data nested in a 3-year, four parallel-arm, superiority cluster-randomised controlled trial (cRCT) in Tanzania, collected from 84 clusters (39 307 households) formed of 72 villages in the Misungwi district, were used to measure insecticide-resistance profiles among female Anopheles mosquitoes via insecticide-resistance bioassays and quantitative RT-PCR of metabolic-resistance genes. Wild, blood-fed, indoor-resting mosquitoes were collected annually during the rainy seasons from house walls in clusters from all four trial groups. Mosquitoes were morphologically identified as An gambiae sensu lato (SL) or An funestus SL before separate bioassay testing. The primary outcomes were lethal-dose values for α-cypermethrin, permethrin, and piperonyl butoxide pre-exposure plus permethrin-resistance intensity bioassays, mortality 72 h after insecticidal exposure for chlorfenapyr bioassays, fertility reduction 72 h after insecticidal exposure for pyriproxyfen bioassays, and fold change in metabolic-enzyme expression relative to an insecticide-susceptible laboratory strain. All primary outcomes were measured in An funestus SL 1 year, 2 years, and 3 years after LLIN distribution. Primary outcomes were also assessed in An gambiae SL if enough mosquitoes were collected. The cRCT is registered with ClinicalTrials.gov (NCT03554616). Between May 24, 2019, and Oct 25, 2021, 47 224 female Anopheles were collected for resistance monitoring. In the pyrethroid (PY)-LLIN group, there were significant increases in α-cypermethrin-resistance intensity (year 1 LD50=9·52 vs year 2 76·20, p<0·0001) and permethrin-resistance intensity (year 1 13·27 vs year 2 35·83, p=0·0019) in An funestus SL. In the pyriproxyfen PY-LLIN group, there was similar increase in α-cypermethrin-resistance intensity (year 1 0·71 vs year 2 81·56, p<0·0001) and permethrin-resistance intensity (year 1 5·68 vs year 2 50·14, p<0·0001). In the piperonyl butoxide PY-LLIN group, α-cypermethrin-resistance intensity (year 1 33·26 vs year 3 70·22, p=0·0071) and permethrin-resistance intensity (year 1 47·09 vs year 3 2635·29, p<0·0001) also increased over time. In the chlorfenapyr PY-LLIN group, there were no effects on α-cypermethrin-resistance intensity (year 1 0·42 vs year 3 0·99, p=0·54) or permethrin-resistance intensity (data were not estimable due to nearly 100% mortality). There were also minimal reductions in chlorfenapyr susceptibility. However, in the chlorfenapyr PY-LLIN group, a significant decline in piperonyl-butoxide synergy was seen by year 3 (year 1 0·02 vs year 3 0·26, p=0·020). Highly over-expressed detoxification enzymes showed dynamic patterns of selection throughout the trial. Our phenotypic data supports trial epidemiological findings; chlorfenapyr PY-LLINs provided superior protection from malaria across multiple transmission seasons, with few effects on insecticide-resistance selection. Rapid pyrethroid-resistance intensification in the piperonyl butoxide PY-LLIN group and pre-existing tolerance of pyriproxyfen in vector populations might explain the poorer performance of these two interventions regarding malaria outcomes. Further work is required to elucidate the potential mechanisms driving cross-resistance between pyrethroids and novel active ingredients to better inform the design of pre-emptive resistance-management strategies. UK Department for International Development; UK Medical Research Council; Wellcome Trust; UK Department of Health and Social Care; UK Foreign, Commonwealth and Development Office; and The Bill and Melinda Gates Foundation via the Innovative Vector Control Consortium.

Isolation, Characterization and Screening of Potential Lambda-Cyhalothrin-Degrading Bacteria from Cultivated Soil in Moro, Kwara State, Nigeria

The indiscriminate use of Lambda Cyhalothrin (LC), one of the commonly used synthetic pyrethroids (SPs) insecticides in agriculture, has led to the contamination of different environments with potentially serious impacts on the health of humans and animals. This study investigated the presence of LC-degrading bacteria in cultivated soils. Bacteria were isolated from agricultural soil on mineral salt medium (MSM) using an enrichment technique. They were characterized and identified. Their growth in different concentrations (50 mg/L, 75 mg/L, 100 mg/L, and 125 mg/L) of LC was studied, Potential to degrade LC was assessed by the growth of the bacteria in a mineral salts medium containing LC as the sole carbon source over 14 days. Five bacteria able to grow in MSM with LC as the sole source of carbon and on nutrient agar enriched with 100mg/L of LC were isolated. Their growth (turbidity and viable counts of the bacterial cells) increased from the third day till the sixth day, after which it declined till the 14th day. The Lambda Cyhalothrin-degrading bacterial isolates (LCDB) were tentatively identified as Bacillus species, Klebsiella species, Pseudomonas species, and Lysinibacillusspecies. These results indicated that these bacterial isolates are potentially able to degrade LC and can be useful for the remediation of SPs-contaminated agricultural soils.

The Acute Toxicity of Fenvalerate on the Larval Stage of the Mediterranean Flour Moth, Ephestia kuehniella (Lepidoptera: Pyralidae)

The Mediterranean flour moth or mill moth (Ephestia kuehniella Zeller) from the family Pyralidae is a common pest of cereal grains, especially flour. This moth is found throughout the world, especially in countries with temperate climates. Fenvalerate is a synthetic pyrethroid insecticide which is a mixture of four optical isomers with different insecticidal activities. In this research, the acute toxicity of this insecticide was investigated on the larval stage of E. kuehniella during 24h and 48h, in two replications. Accordingly, the LC30 in 24h and 48h were determined as 389.67 and 271.30 mg.a.i/ L. During these times, LC50 values being 690.71 and 502.91 mg.a.i/ L, respectively. Finally, LC90 was determined as 2797.94 and 2272.71 mg.a.i/ L for 24h and 48h. The results showed that this insecticide has suitable toxicity on this pest and can be recommended against it.

Tralomethrin causes cardiovascular toxicity in zebrafish (Danio rerio) embryos.

Tralomethrin, a synthetic pyrethroid insecticide used to control a wide range of pests in agriculture and public health, is highly toxic to aquatic organisms. However, data regarding the toxicity and underlying mechanisms of tralomethrin in aquatic organisms are limited. Thus, this study aimed to investigate the toxicity of tralomethrin in zebrafish. Zebrafish embryos were exposed to tralomethrin at different concentrations (16.63, 33.25, and 49.88 μg/L). Results showed that tralomethrin exposure caused cardiovascular dysplasia and dysfunction, including developmental abnormalities (pericardial edema, delayed yolk absorption, and uninflated swim bladder), elevated heart rate, and erythrogenesis disorders. Moreover, the expression patterns of crucial genes responsible for cardiovascular development (alas2, gata1a, hbbe2, nkx2.5, myl7, and myh6) also exhibited dysregulation in response to tralomethrin exposure. Oxidative stress occurred in embryos after exposure to tralomethrin. Collectively, our data suggest that exposure to tralomethrin induces cardiovascular and developmental toxicity in zebrafish. These findings are instrumental for evaluations of the environmental risk of tralomethrin in aquatic ecosystems in the future.

Myzus persicae (Sulzer, 1776) (Hemiptera: Aphididae) popülasyonlarında neonikotinoid ve sentetik piretroid insektisitlerin tekli ve karışımlarına karşı direnç durumu

The peach potato aphid, Myzus persicae (Sulzer, 1776) (Hemiptera: Aphididae), a vector of many plant virus diseases, causes damage to its wide range of hosts by direct feeding. Chemical control has been the primary method to control this species, and the intensive use of insecticides has led to the development of resistance. In this study, conducted between the years 2017-2019, firstly resistance ratio of five M. persicae populations from Antalya, Türkiye were determined by leaf-dip bioassay method. The field populations showed significant resistance to thiamethoxam (between 201-332 fold) and lambda-cyhalothrin (between 50-103 fold) when compared to susceptible population. To identify whether resistance mediated by mutations in sodium channel and nicotinic acetylcholine receptor, DNA regions that encompass “mutation hot-spot” were sequenced. This revealed no population contained R81T mutation that has been previously linked with neonicotinoid resistance. As to synthetic pyrethroid resistance, the L1014F kdr mutation was fixed in all field populations. This study is the first description of kdr mutation in M. persicae populations from Türkiye. Bioassay results also indicated that the toxicity of thiamethoxam and lambda-cyhalothrin mixture was higher than that of lambda-cyhalothrin alone. Our findings can make significant contributions to M. persicae resistance management.

Comprehensive insights into the occurrence, distribution, risk assessment of typical pesticides and their environmental driving effects in a large drinking water reservoir

The problem of pesticide pollution in large drinking water reservoirs is becoming increasingly prominent due to agricultural production. To systematically evaluate the distribution characteristics, seasonal fluctuations, environmental behaviors, and ecological risks of pesticides in the Fengshuba Reservoir (China), we conducted a comprehensive investigation of the seasonal changes in the concentrations of 31 pesticides, including 8 organochlorine pesticides (OCPs), 16 organophosphates pesticides (OPPs), and 7 synthetic pyrethroids (SPs). The results showed the concentrations of OCPs, OPPs, and SPs in the water phase were 121.98–321.64 ng/L, 279.28–371.75 ng/L, and 118.96–186.65 ng/L, respectively. The concentrations in the porewater phase were 3363.34–7105.00 ng/L, 8648.98–14,265.95 ng/L, and 2740.83–7738.28 ng/L, respectively. The concentrations in the sediment phase were 47.92–88.28 μg/kg, 159.87–446.64 μg/kg, and 29.43–99.62 μg/kg, respectively. The concentrations in the soil phase were 23.62–50.76 μg/kg, 96.85–184.19 μg/kg, and 21.02–37.02 μg/kg, respectively. Seasonal hydrology, hydraulic retention time, precipitation, temperature, and biological metabolism all impacted the concentration and composition of pesticides, but no apparent environmental gradient effect was found within the reservoir. Redundancy analysis indicated that NO3-, Dissolved oxygen (DO), Dissolved organic carbon (DOC), Organic nitrogen (ON), and Inorganic carbon (IC) were the main environmental parameters affecting pesticide concentrations. The pseudo-partitioning values in water and porewater ranged from 1.2 to 3.3 × 104 and 22.0–61.7 L/kg, respectively. The ecological risk was low for OCPs, moderate for OPPs, and high for SPs in the water phase. SPs should be considered a priority indicator for risk assessment. Future conservation efforts for reservoir system should focus on pollution prevention in the soil phase.

Molecular imprinted polymer capped luminescent metal -organic framework for the determination of pyrethroids and its metabolite

Monitoring the pyrethroids and its metabolite is of importance to estimate the potential risk of human exposure. Herein, a lanthanide luminescent metal of framework (Ln-MOF) was employed to construct fluorescent molecular imprinted polymer probe for the detection of pyrethroids metabolite, 3-phenoxybenzaldehyde (3-PBALD). Through a typical sol–gel imprinting process, the imprinted layer capped Ln-MOFs exhibited specific fluorescence quenching at 615 nm upon adding 3-PBALD. Under the optimum condition, a linear relationship was obtained in the range from 0.01 to 5 μg mL−1 and the limit of detection was 8 ng mL−1, which is superior to bare Ln-MOFs. In addition, the obtained probe showed good stability and repeatability as well as anti-interference. Furthermore, coupling with esterase hydrolysis strategy, the proposed fluorescent probe can be extended for the determination of various synthetic pyrethroids. In spiked apple and spinach samples, the recoveries ranged from 80.2% ∼116.7% and 80.8% ∼113.2%, respectively. Therefore, this fluorescent molecular imprinted polymer probe has potential for a broad-spectrum pyrethroids residue screening.

Docking Analysis of Deltamethrin Pesticide with MHC I and MHC II Molecules to Establish Immunomodulation Effects

Background: Deltamethrin is a class II synthetic pyrethroid pesticide extensively used to control pests and vectors in the agriculture sector and health management programme. Due to excessive applications of this pesticide in the environment, it is harming many organisms other than the target organisms. Higher organisms like human beings are also affected by this pesticide because it instigates the impairment of the central nervous system and also distresses the immune system of vertebrates. Methods: In the current research study, MHC I and MHC II molecules of human origin have been targeted to evaluate the interaction with deltamethrin molecules by the AutoDock tool to establish the immunomodulatory effect. MHC I receptor molecule is presented on every nucleated cell, and MHC II receptors are located specifically on cell surfaces of antigen-presenting cells. These receptors play a role in cell-mediated and humoral immune responses. The binding affinity of deltamethrin with MHC receptors can affect the immune response, specifically the acquired immunity of an individual. Results: Findings of the current research study support that deltamethrin causes the suppression of the immune system by interaction with MHC I and MHC II molecules and may cause the organisms to be more prone towards antigen and disease development. Conclusion: The autoDock tool can be utilized to analyse other pesticides’ effects on the immune system and in the drug development process to minimize the toxic effects due to several types of pesticides.