Novel electrochemiluminescence sensing platform for ultrasensitive detection of malathion residue in tea based on SiO2NSs doped Luminol/AgNPs as a signal amplification strategy.

To address the potential hazards of organophosphorus pesticides (OPs) residues in tea, an electrochemiluminescence (ECL) aptasensor based on functionalized nanomaterials was constructed in this work. Firstly, gold nanoparticles (AuNPs) were attached on the surface of multi-walled carbon nanotubes (MWCNTs) by the constant potential electrodeposition to form a compound, and it was utilized to provide excellent immobilization sites for complementary DNA (cDNA). Subsequently, composite nanomaterials were synthesized by a one-pot method with aminated Luminol/silver nanoparticles@silica nanospheres (NH2-Luminol/Ag@SiO2NSs). Finally, NH2-Luminol/Ag@SiO2NSs was combined with a malathion aptamer (Apt) to obtain signal probes (SPs) for the construction of an aptasensor. The aptasensor had a wide linear range (1×10-3-1×103 ng/mL) and a low limit of detection (LOD) (0.3×10-3 ng/mL). It had the virtues of high sensitivity, wonderful stability and excellent specificity, which could be used for the detection of malathion residue in tea. The work provides a proven way for the construction of a rapid and ultrasensitive aptasensor with low-cost.

Combined metabolomics and proteomics to reveal the mechanism of S. oneidensis MR-1 degradation malathion enhanced by FeO/C.

Iron oxide @ biochar (FeO/C) promotes bacterial growth and facilitates electron transfer, thereby effectively promoting malathion degradation by Shewanella oneidensis MR-1 (S. oneidensis MR-1). This study elucidated the underlying mechanism of FeO/C-enhanced malathion degradation by S. oneidensis MR-1 through a combination of metabolomics and proteomics analysis. The kinetic fitting results from the degradation experiment indicated that 0.1 g/L FeO/C exerted the most significant enhancement effect on malathion degradation by S. oneidensis MR-1. Observations from Scanning Electron Microscopy and Laser Scanning Confocal Microscopy, along with physiological and biochemical analysis, showed that FeO/C enhanced the growth and oxidative response of S. oneidensis MR-1 under malathion stress. In addition, metabolomics and proteomics analysis revealed an increase in certain electron transfer related metabolites, such as coenzymes, and the upregulation of proteins, including coenzyme A, sdhD, and petC. Overall, spectroscopic analysis suggested that Fe2+, which was reduced from Fe3+ by S. oneidensis MR-1 in FeO/C, promoted electron transfer in S. oneidensis MR-1 to enhance the degradation of malathion. This study offers enhanced strategies for efficient removal of malathion contaminants.

Single-atom Zr-doped CoOOH with enhanced electrical conductivity as a signal amplifier and detection probe for the indirect non-enzymatic electrochemical determination of malathion in foods.

Herein, a novel electrochemical sensor based on zirconium-doped cobalt oxyhydroxide (ZrCoOOH) was proposed for highly sensitive non-enzymatic determination of malathion (MAL). The doping of Zr can improve the electrical conductivity of CoOOH, of which the transfer resistance was reduced from 241.1 Ω to 140.2 Ω. Furthermore, the X-ray photoelectron spectroscopy confirmed that part of Co2+ was converted to Co3+ due to the introduction of Zr. The Co3+ in ZrCoOOH could react with MAL to form Co2+, which enhanced the electrooxidation current of Co2+. Therefore, the peak current of Co2+ was served as detection probe for MAL. Under optimal conditions, the developed sensor established the linear relationship for MAL in the concentration range of 0.001-10.0 µM with a low limit of detection (0.64 nM). The constructed sensor was employed to detect MAL in food samples (peach, kiwi fruit, spinach and tomato), verifying the accuracy and practicability of the sensor.

Superior oxidase-mimetic activity of FeCo-NC dual-atom nanozyme for smartphone-based visually colorimetric assay of organophosphorus pesticides.

A colorimetric analysis platform has been successfully developed based on FeCo-NC dual-atom nanozyme (FeCo-NC DAzyme) for the detection of organophosphorus pesticides (OPPs). The FeCo-NC DAzyme exhibited exceptional oxidase-like activity (OXD), enabling the catalysis of colorless TMB to form blue oxidized TMB (oxTMB) without the need for H2O2 involvement. By combining acid phosphatase (ACP) hydrolase with FeCo-NC DAzyme, a "FeCo-NC DAzyme + TMB + ACP + SAP" colorimetric system was constructed, which facilitated the rapid detection of malathion. The chromogenic system was applied to detect malathion using a smartphone-based app and an auxiliary imaging interferogram device for colorimetric measurements, which have a linear range of 0.05-4.0 µM and a limit of detection (LOD) as low as 15 nM in real samples, comparable to UV-Vis and HPLC-DAD detection methods. Overall, these findings present a novel approach for convenient, rapid, and on-site monitoring of OPPs.

Evaluation of esterases hydrolyzing α-naphthyl acetate as markers for malathion resistance in Culex quinquefasciatus.

Early detection of insecticide resistance is essential to develop resistance countermeasures and depends on accurate and rapid biological and biochemical tests to monitor resistance and detect associated mechanisms. Many such studies have measured activities of esterases, enzymes associated with resistance to ester- containing insecticides, using the model substrate, α-naphthyl acetate (α-NA). However, in the field, pests are exposed to ester-containing insecticides such as malathion, that are structurally distinct from α-NA. In the current study, malathion resistance in C. quinquefasciatus (3.2- to 10.4-fold) was highly associated with esterase activity measured with either α-NA (R2 = 0.92) or malathion (R2 = 0.90). In addition, genes encoding two esterases (i.e., EST-2 and EST-3) were over-expressed in field- collected strains, but only one (EST-3) was correlated with malathion hydrolysis (R2 = 0.94) and resistance (Rs = 0.96). These results suggest that, in the strains studied, α-NA is a valid surrogate for measuring malathion hydrolysis, and that heightened expression of an esterase gene is not necessarily associated with metabolic resistance to insecticidal esters.

Comprehensive investigation of the mutagenic potential of six pesticides classified by IARC as probably carcinogenic to humans.

Pesticides are significant environmental pollutants, and many of them possess mutagenic potential, which is closely linked to carcinogenesis. Here we tested the mutagenicity of all six pesticides classified probably carcinogenic (Group 2A) by the International Agency of Research on Cancer: 4,4'-DDT, captafol, dieldrin, diazinon, glyphosate and malathion. Whole genome sequencing of TK6 human lymphoblastoid cell clones following 30-day exposure at subtoxic concentrations revealed a clear mutagenic effect of treatment with captafol or malathion when added at 200 nM or 100 µM initial concentrations, respectively. Each pesticide induced a specific base substitution mutational signature: captafol increased C to A mutations primarily, while malathion induced mostly C to T mutations. 4,4'-DDT, dieldrin, diazinon and glyphosate were not mutagenic. Whereas captafol induced chromosomal instability, H2A.X phosphorylation and cell cycle arrest in G2/M phase, all indicating DNA damage, malathion did not induce DNA damage markers or cell cycle alterations despite its mutagenic effect. Hypersensitivity of REV1 and XPA mutant DT40 chicken cell lines suggests that captafol induces DNA adducts that are bypassed by translesion DNA synthesis and are targets for nucleotide excision repair. The experimentally identified mutational signatures of captafol and malathion could shed light on the mechanism of action of these compounds. The signatures are potentially suitable for detecting past exposure in tumour samples, but the reanalysis of large cancer genome databases did not reveal any evidence of captafol or malathion exposure.

Towards solving the reproducibility crisis in surface-enhanced Raman spectroscopy-based pesticide detection.

Growing concerns about pesticide residues in agriculture are pushing the scientific community to develop innovative and efficient methods for detecting these substances at low concentrations down to the molecular level. In this context, surface-enhanced Raman spectroscopy (SERS) is a powerful analytical method that has so far already undergone some validation for its effectiveness in pesticide detection. However, despite its great potential, SERS faces significant difficulties obtaining reproducible and accurate pesticide spectra, particularly for some of the most widely used pesticides, such as malathion, chlorpyrifos, and imidacloprid. Those inconsistencies can be attributed to several factors, such as interactions between pesticides and SERS substrates and the variety of substrates and solvents used. In addition, differences in the equipment used to obtain SERS spectra and the lack of standards for control experiments further complicate the reproducibility and reliability of SERS data. This review systematically discusses the problems mentioned above, including a comprehensive analysis of the challenges in precisely evaluating SERS spectra for pesticide detection. We not only point out the existing limitations of the method, which can be traced in previous review works, but also offer practical recommendations to improve the quality and comparability of SERS spectra, thereby expanding the potential applications of the method in such an essential field as pesticide detection.

Metabolic Resistance and Not Voltage-Gated Sodium Channel Gene Mutation Is Associated with Pyrethroid Resistance of Aedes albopictus (Skuse, 1894) from Cambodia.

(1) Background: In Cambodia, Aedes albopictus is an important vector of the dengue virus. Vector control using insecticides is a major strategy implemented in managing mosquito-borne diseases. Resistance, however, threatens to undermine the use of insecticides. In this study, we present the levels of insecticide resistance of Ae. albopictus in Cambodia and the mechanisms involved. (2) Methods: Two Ae. albopictus populations were collected from the capital, Phnom Penh city, and from rural Pailin province. Adults were tested with diagnostic doses of malathion (0.8%), deltamethrin (0.03%), permethrin (0.25%), and DDT (4%) using WHO tube assays. Synergist assays using piperonyl butoxide (PBO) were implemented before the pyrethroid assays to detect the potential involvement of metabolic resistance mechanisms. Adult female mosquitoes collected from Phnom Penh and Pailin were tested for voltage-gated sodium channel (VGSC) kdr (knockdown resistance) mutations commonly found in Aedes sp.-resistant populations throughout Asia (S989P, V1016G, and F1534C), as well as for other mutations (V410L, L982W, A1007G, I1011M, T1520I, and D1763Y). (3) Results: The two populations showed resistance against all the insecticides tested (<90% mortality). The use of PBO (an inhibitor of P450s) strongly restored the efficacy of deltamethrin and permethrin against the two resistant populations. Sequences of regions of the vgsc gene showed a lack of kdr mutations known to be associated with pyrethroid resistance. However, four novel non-synonymous mutations (L412P/S, C983S, Q1554STOP, and R1718L) and twenty-nine synonymous mutations were detected. It remains to be determined whether these mutations contribute to pyrethroid resistance. (4) Conclusions: Pyrethroid resistance is occurring in two Ae. albopictus populations originating from urban and rural areas of Cambodia. The resistance is likely due to metabolic resistance specifically involving P450s monooxygenases. The levels of resistance against different insecticide classes are a cause for concern in Cambodia. Alternative tools and insecticides for controlling dengue vectors should be used to minimize disease prevalence in the country.

Malathion exposure may increase infertility risk among US Adults: Results from the 2015-2016 NHANES.

BACKGROUND AND PURPOSE: Organophosphate pesticides such as malathion are the most widely used pesticides. Despite endocrine-disrupting effects, there is a paucity of information regarding chronic exposure to non-persistent organopesticides such as malathion. The purpose of this study is to describe the exposure burden among U.S. residents as well as possible impacts on fertility. METHODS: Population-based data collected by the National Health and Nutrition Examination Survey (NHANES) between 2015 and 2016 were used to perform a retrospective analysis on urinary concentrations of malathion diacid. Samples were assessed from 1703 adult participants, statistically weighted to represent over 231 million individuals. General linear models were used to examine associations between exposure and reproductive health measures among pre-menopausal women. RESULTS: Detectable concentrations of malathion diacid were identified in 16.1 % (n = 254) of samples. Concentrations were higher among women who reported seeing a physician due to difficulties becoming pregnant (P < 0.001; r2 = 0.12) as well as among women who reported trying for at least a year to become pregnant (P < 0.001; r2 = 0.06). CONCLUSIONS: Exposure to malathion is associated with a history of reproductive health challenges among women.

Assessing malathion residue impact on poultry health, human safety, and production performance.

Over the past decade, food safety has become a major concern due to the intensive use of pesticides. Pesticide contamination has been observed in poultry products when seeds are coated with pesticides or when stored products are exposed to pesticides in warehouses. In this experiment, the residue levels of malathion transferred from corn grain to the different parts of the chicken product, its transfer factors (TFs) and the human dietary risk for consumers were evaluated. Growth performance and carcass parameters of the chicken samples were also determined after different doses of malathion exposure. Malathion residues from different parts of chicken meat (breast, thigh, wing, liver and skin) were extracted by the QuEChERS method and analyzed by liquid chromatography-mass spectrophotometry (LC-MS/MS). A deterministic approach was used to calculate the acute and chronic risk assessment. Body weight, feed conversion ratio and feed intake decreased with increasing malathion dose. In addition to reduced feed intake, cold carcass and liver weights of the chicks were also decreased. The highest residues were found in the skin of the chicken followed by the breast, thigh, wing and liver. The TFs of malathion varied between 0.00 and 0.05 according to the different doses applied (4 mg/kg, 8 mg/kg, 16 mg/kg, 32 mg/kg). The chronic exposure assessment (HQ) showed that consumers of all ages and genders consumed 0.008-0.604% of the acceptable daily intake (0.3 mg/kg body weight (bw)/day) of malathion from chicken products. The acute intake assessment (aHQ) of consumers ranged from 0.00015 to 0.0135% of the acute reference dose (0.3 mg/kg bw). In conclusion the results suggest that the risk associated with the malathion residues in chicken meat was found to be low but the residue levels in meat should not be ignored.

Lower malathion concentrations reduce testosterone biosynthesis by Leydig TM3 cells in vitro by altering cellular redox profile and inducing oxidative damage.

Malathion is an organophosphate pesticide used in agriculture and control of the Aedes aegypti mosquito. As previous reports have indicated the potential of malathion to compromise testosterone production in in vivo models, the objective of this study was to elucidate the mechanisms underlying the impairment of Leydig cell function, considering its critical role in male reproductive function. To this end, murine Leydig TM3 cells were exposed to concentrations of 1, 10, 100 or 1000 µM malathion for 24 h for evaluation of the compound on cell viability. Subsequently, concentrations of 1, 10, and 100 µM malathion were employed for a 24-h period to assess testosterone biosynthesis, levels of cytokines IL-1ß, IL-6, IL-10, and TNF-α, as well as the redox profile. Malathion exerted a concentration-dependent impact on cell viability. Notably, the lower concentrations of malathion (1 and 10 µM) were found to impair testosterone biosynthesis in TM3 cells. While there were changes in IL-1 and TNF-α levels at specific concentrations, no direct correlation with altered hormone production was established. Our investigation revealed that varied malathion concentrations induced oxidative stress by increase in superoxide anion and a compensatory rise in antioxidants. In conclusion, the observed changes in the oxidative profile of TM3 cells were linked to functional impairment, evidenced by reduced testosterone biosynthesis at lower malathion concentrations.

Bioenzyme-nanoenzyme-chromogen all-in-one test strip for convenient and sensitive detection of malathion in water environment.

The presence of pesticide residues in aquatic environments poses a significant threat to both aquatic ecosystems and human health. The presence of these residues can result in significant harm to aquatic ecosystems and can negatively impact the health of aquatic organisms. Consequently, this issue requires urgent attention and effective measures to mitigate its impact. However, developing sensitive and rapid detection methods remains a challenge. In this study, an all-in-one test strip, which integrated bioenzymes, nanoenzymes, and a chromogen, was developed in combination with an enzyme labeling instrument for a highly sensitive and convenient sensing of malathion residues. The oxidase activity of heme chloride (Hemin) in the strip can catalyze the oxidation of H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue-colored oxide. Simultaneously, the alkaline phosphatase (ALP) present in the strip can break down l-ascorbic acid-2-phosphate to produce ascorbic acid (AA). This AA then acts to reduce the oxidized form of TMB, turning it into a colorless substance and leading to the disappearance of its fluorescent signal. In the presence of a pesticide, the activity of ALP is inhibited and formation of AA is blocked, thereby preventing the reduction of oxidized TMB and producing a colored signal. According to this principle, the integrated test strip detected the target pesticide with high performance as per the optical density value determined via an enzyme marker. The detection limit of the test strip was 0.209 ng/mL with good sensitivity. The method was used for detecting malathion in actual river water samples, and the recoveries were in the range of 93.53 %-96.87 %. The newly devised technique effectively identified malathion in samples of natural water. This research has introduced a novel approach for the precise and convenient surveillance of pesticide remnants. Additionally, these discoveries could inspire the advancement of proficient multi-enzyme detection systems.

Metabolism of Tembotrione, a Triketone Herbicide, confers Differential Sensitivity in Winter Wheat (Triticum aestivum).

Tembotrione is a triketone herbicide widely used for broad-spectrum weed control in corn but not registered for use in wheat. A wide collection of spring, winter, and EMS-derived mutant lines of wheat was evaluated for their response to tembotrione treatment. Two winter wheat (WW) genotypes (WW-1 and WW-2) were found to be least sensitive to this herbicide, surviving >6 times the field recommended dose (92 g ai ha-1) compared to the most sensitive genotype (WW-24). Further, HPLC analysis using [14C] tembotrione suggested that both WW-1 and WW-2 metabolized tembotrione rapidly to nontoxic metabolites. Pretreatment with a P450 inhibitor (malathion) followed by tembotrione application increased the sensitivity of WW-1 and WW-2 genotypes to this herbicide, suggesting likely involvement of P450 enzymes in metabolizing tembotrione similar to corn. Overall, our results suggest that the genotypes WW-1 and WW-2 can potentially be used to develop tembotrione-resistant wheat varieties.

Odorant Binding Protein Expressed in Legs Enhances Malathion Tolerance in Bactrocera dorsalis (Hendel).

Bactrocera dorsalis is a highly invasive species and is one of the most destructive agricultural pests worldwide. Organophosphorus insecticides have been widely and chronically used to control it, leading to the escalating development of resistance. Recently, odorant binding proteins (OBPs) have been found to play a role in reducing insecticide susceptibility. In this study, we used RT-qPCR to measure the expression levels of four highly expressed OBP genes in the legs of B. dorsalis at different developmental stages and observed the effect of malathion exposure on their expression patterns. The results showed that OBP28a-2 had a high expression level in 5 day old adults of B. dorsalis, and its expression increased after exposure to malathion. By CRISPR/Cas9 mutagenesis, we generated OBP28a-2-/- null mutants and found that they were more susceptible to malathion than wild-type adults. Furthermore, in vitro direct affinity assays confirmed that OBP28a-2 has a strong affinity for malathion, suggesting that it plays a role in reducing the susceptibility of B. dorsalis to malathion. Our findings enriched our understanding of the function of OBPs. The results highlighted the potential role of OBPs as buffering proteins that help insects survive exposure to insecticides.

Mechanisms of oxidative response during biodegradation of malathion by S. oneidensis MR-1.

Malathion, an extensively used organophosphorus pesticide, poses a high potential risk of toxicity to humans and the environment. Shewanella (S.) oneidensis MR-1 has been proposed as a strain with excellent bioremediation capabilities, capable of efficiently removing a wide range of hard-to-degrade pollutants. However, the physiological and biochemical response of S. oneidensis MR-1 to malathion is unknown. Therefore, this study aimed to examine how S. oneidensis MR-1 responds physiologically and biochemically to malathion while also investigating the biodegradation properties of the pesticide. The results showed that the 7-day degradation rates of S. oneidensis MR-1 were 84.1, 91.6, and 94.0% at malathion concentrations of 10, 20, and 30 mg/L, respectively. As the concentration of malathion increased, superoxide dismutase and catalase activities were inhibited, leading to a significant rise in malondialdehyde content. This outcome can be attributed to the excessive production of reactive oxygen species (ROS) triggered by malathion stress. In addition, ROS production stimulates the secretion of soluble polysaccharides, which alleviates oxidative stress caused by malathion. Malathion-induced oxidative damage further exacerbated the changes in the cellular properties of S. oneidensis MR-1. During the initial stages of degradation, the cell density and total intracellular protein increased significantly with increasing malathion exposure. This can be attributed to the remarkable resistance of S. oneidensis MR-1 to malathion. Based on scanning electron microscopy observations, continuous exposure to contaminants led to a reduction in biomass and protein content, resulting in reduced cell activity and ultimately leading to cell rupture. In addition, this was accompanied by a decrease in Na+/K+- ATPase and Ca2+/Mg2+-ATPase levels, suggesting that malathion-mediated oxidative stress interfered with energy metabolism in S. oneidensis MR-1. The findings of this study provide new insights into the environmental risks associated with organophosphorus pesticides, specifically malathion, and their potential for bioremediation.

Alteration of haematological and biochemical biomarkers after sub-lethal chronic malathion (Elathion®) intoxication in freshwater fish, Labeo rohita (Hamilton, 1822).

The present investigation aimed to evaluate the long-term effects of malathion (Elathion®) at two sub-lethal concentrations (0.36 and 1.84 mgL-1) for 45 days after the determination of 96 h-LC50 value (18.35 mgL-1) in a commercially important aquaculture species, Labeo rohita by assaying multiple biomarker approaches. Total erythrocyte count (TEC), and haemoglobulin count (Hb) were found to be decreased while total leucocyte counts (TLC) were increased (p < 0.05) in malathion-intoxicated fish. Malathion exposure significantly reduced (p < 0.05) serum protein levels while significantly increased (p < 0.05) blood glucose levels. RNA activity in muscle was reduced (p < 0.05) while DNA activity increased (p < 0.05) in malathion-intoxicated fish. Acid phosphatase (ACP) activities in the brain; lacate dehydrogenase (LDH) activities in brain and liver were increased (p < 0.05), while alkaline phosphatase (ALP) activities in the brain; succinate dehydrogenase (SDH) activities in the brain, liver and kidney; acetylcholine esterase (AChE) activity in the brain; and ATPase activities in the brain, liver and kidney were reduced (p < 0.05) in comparison to control. Thus, the alteration in studied biomarkers was in a concentation-time dependent manner; however, it was more pronounced at the higher concentration at 45 days of exposure. The alteration in biomarker activity is probably a defensive mechanism/ adaptive response of fish to overcome the stress induced by malathion, which is a novel insight and possible impact on L.rohita. Our findings suggest malathion-induced stress, therefore, the use of malathion needs to be regulated to safeguard aquatic animals including fish and human health.

Evaluación de la sensibilidad a organofosforados en poblaciones de Aedes aegypti (L. ) (Diptera: Culicidae) del departamento de La Guajira, Colombia / Evaluation of susceptibility to organophosphates in populations of Aedes aegypti (L. ) (Diptera: Culicidae) in La Guajira, Colombia

Introducción. El dengue es un problema de salud pública para el departamento de La Guajira. El control se ha enfocado en el vector con el uso de insecticidas, entre ellos los organofosforados. Objetivo. Evaluar el estado de la sensibilidad a insecticidas organofosforados de quince poblaciones de Aedes aegypti (L.) en el departamento de La Guajira, Colombia. Materiales y métodos. Se realizaron bioensayos para temefos, malatión y pirimifos- metil en larvas de tercer estadio y mosquitos adultos de Ae. aegypti en los municipios de Albania, Barrancas, Dibulla, Distracción, El Molino, Fonseca, Hatonuevo, La Jagua del Pilar, Maicao, Manaure, Riohacha, San Juan del Cesar, Uribia, Urumita y Villanueva, siguiendo la metodología de la Organización Mundial de la Salud (OMS) y la técnica de botellas usando la guía de los de los Centers for Disease Control and Prevention, respectivamente. Se determinó la sensibilidad por medio de la relación de resistencia a CL50 y CL95 (RRCL50, RRCL95) para temefos y a dosis y tiempo diagnóstico para temefos, malatión y pirimifos-metil en las poblaciones de campo evaluadas, usando como control la cepa sensible Rockefeller. Resultados. Las 15 poblaciones del departamento de La Guajira son sensibles a: temefos (relación de la resistencia a CL50<5,0; relación de resistencia a CL95<5,0; 98 a 100 % de mortalidad); pirimifos-metil (99 a 100 % de mortalidad) y malatión (100 % de mortalidad). Conclusión. Con base en los resultados obtenidos, es factible el uso de temefos, malatión y pirimifos-metil para el control de Ae. aegypti en las poblaciones evaluadas.

Introduction. Dengue is a public health problem in La Guajira region. Control has focused on the vector using insecticides, including organophosphates. Objective. To evaluate the state of susceptibility to organophosphates insecticides in fifteen Aedes aegypti (L.) populations in La Guajira, Colombia. Materials and methods. We collected samples of third-instar larvae and adult mosquitoes of Ae. aegypti in the municipalities of Albania, Barrancas, Dibulla, Distracción, El Molino, Fonseca, Hatonuevo, La Jagua del Pilar, Maicao, Manaure, Riohacha, San Juan del Cesar, Uribia, Urumita, Villanueva. Bioassays for temefos, malathion, and pirimiphos-methyl were carried out following the methodology of the World Health Organization, and the bottle technique using the guidance of the Centers for Disease Control and Prevention. Susceptibility to temefos was determined through the resistance ratio between lethal concentration 50 and lethal concentration 95; for the compounds temefos, malathion and pirimiphos-methyl, susceptibility was calculated using diagnostic dose and diagnostic time in the populations evaluated. Rockefeller susceptible strain was used as a control. Results. All evaluated populations of Ae. aegypti from La Guajira were found to be susceptible to temefos (ratio resistance to CL50<5.0; ratio resistance to CL95<5.0; 98 - 100 % mortality); pirimiphosmethyl (99 - 100 % mortality), and malathion (100 % mortality). Conclusion. Based on the results, the use of temefos, malathion, and pirimiphosmethyl is feasible for the control of Ae. aegypti in the evaluated populations.

Efeitos do malathion no sistema nervoso central: uma revisão breve / Effects of malathion on the central nervous system: a brief review

O presente estudo tem como objetivo apresentar uma revisão bibliográfica sobre os efeitos do malathion no sistema nervoso central humano (SNC). Foram obtidas publicações do Google Scholar, SciElo, Pubmed, Lilacs e repositório CAPES no período de 2002 a 2020. Os seguintes descritores foram utilizados: "malathion", "SNC", "sistema nervoso", "intoxicação", "inseticidas" e "organofosforados". O inseticida malathion é um organofosforado com meia vida de 32 horas e conforme a via de administração pode ser considerado de Classe II (altamente tóxico). Um dos principais efeitos é a inibição enzimática de colinesterases acarretando o acúmulo de metabólitos e diversas síndromes neurológicas. Apesar do uso liberado e moderada toxicidade, o malathion causa danos significativos no SNC e desse modo deve ser utilizado com cautela para evitar intoxicações

The present study aims to describe neurotoxic effects of malathion on the human central nervous system (CNS). Methods ­ A bibliographic survey were performed using papers from Google Scholar, SciElo, Pubmed, Lilacs and Repositório CAPES, between 2002 to 2020. The following key words were used: "malathion", "CNS", "nervous system", "intoxication", "insecticides" and "organophosphate". Malathion is an organophosphorus with a short mid-life of only 32 hours, depending on their availability, the insecticide is classified as category "Class II" (highly toxic). One of the main effects is the enzymatic inhibition of cholinesterase's causing the accumulation of the metabolites and several neurological syndromes. Despite the liberated use and moderate toxicity, malathion causes significant damage to the CNS and should be used only with care and to avoid pesticide poisoning incidents

Susceptibility of Anopheles sinensis to insecticides in Puyang City, Henan Province / 中国血吸虫病防治杂志

Objective To investigate the susceptibility of Anopheles sinensis to malathion, deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province, so as to provide the scientific basis for local malaria vector control. Methods An. sinensis was captured from Puyang County, Puyang City of Henan Province in September 2018 and July 2020, and the susceptibility of field captured An. sinensis to malathion, deltamethrin and lambda-cyhalothrin was tested using the filter-paper bioassay recommended by WHO. The insecticide resistance level was assessed based on the WHO criteria. Results In 2018 and 2010, the half knock-down times (KT50) of malathion were 91.08 min and 40.95 min for An. sinensis, with knock-down rates of 37.50% and 60.87% 60 min post-exposure to malathion and 24-hour mortality rates of 90.91% and 100%, respectively, and the insecticide resistance levels were moderately resistant (M) and susceptible (S). The KT50 of deltamethrin were 415.56 min and 341.19 min for An. sinensis in 2018 and 2020, with knock-down rates of 22.92% and 16.98% 60 min post-exposure to malathion and 24-hour mortality rates of 22.92% and 16.98%, and the insecticide resistance levels were all resistant (R). The KT50 of lambda-cyhalothrin were 164.22 min and 236.22 min for An. sinensis in 2018 and 2020, with knock-down rates of 30.39% and 38.30% 60 min postexposure to malathion and 24 h mortality rates of 19.60% and 21.28%, respectively, and the insecticide resistance levels were all R. Conclusion An. sinensis is relatively susceptible to malathion but has developed high-level resistance to deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province..