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Kuttanad is a unique wetland agriculture system featuring polder-based rice cultivation below sea level. Facing increasing pollution threats from agrochemicals, this FAO-recognized Globally Important Agricultural Heritage System (GIAHS) needs constant monitoring and risk assessment. The present study investigated the seasonal dynamics of agricultural pesticide residues in fish cultured in the wetland system. A total of 217 fish samples were analyzed, spanning three different sampling stations of Kuttanad, viz., Vaikom, Ramankari, and Edathua, during pre-monsoon, monsoon, and post-monsoon seasons. The results revealed the presence of 14 pesticides across locations and seasons. The pesticides found in the highest concentrations were propetamphos (54.64 mg L−1), thiacloprid (46.78 mg L−1), and diphenylamine (24.70 mg L−1). The most frequently detected pesticides were propoxur, fenuron, and thiacloprid. Contaminants were detected more frequently during the post-monsoon season (49%) compared to the monsoon (38%) and pre-monsoon (13%) seasons, with imidacloprid being present in all three seasons. The target hazard quotients (THQ) for propetamphos, thiacloprid, and diphenylamine were determined to be 0.04, 0.004, and 0.0002, respectively. The hazard index (HI) calculated as the sum of THQ of quantified pesticides was 0.056, indicating a low to moderate risk. However, consistent monitoring of pesticides in the Kuttanad wetland agriculture system is important to ensure timely intervention to protect biodiversity and human health. [ABSTRACT FROM AUTHOR]

The widespread use of fenobucarb and propoxur insecticides for agricultural and non-agricultural purposes causes undesirable effects on human health and environment due to their residues in surface and ground water resources. In view of this, two new, simple, accurate, sensitive, economical and reproducible optical methods have been investigated for the determination of fenobucarb and propoxur insecticides in pure form, in their commercial formulations, and agricultural samples viz. water, grains and vegetables. The methods are based on the alkaline hydrolysis of the insecticides to methyl amine and the reaction of the latter to give colored products. In the spectrophotometric method, the methyl amine formed, in presence of carbon disulfide (CS2) and Ni(II) acetate gives a yellow colored complex, which was measured at 370 nm. Beer's law is valid in the concentration range of 0.41–8.29 and 0.42–8.37 µg mL−1 for fenobucarb and propoxur, respectively. The spectrofluorimetric method is based on the study of yellow-colored product, formed by the condensation of methyl amine with acetylacetone and formaldehyde (Hantzsch reaction), at pH 5.5. The reaction product exhibits fluorescence intensity at an emission wavelength of 470 nm after excitation at a wavelength of 390 nm for both fenobucarb and propoxur insecticides. The method has linearity range of 0.14–5.53 and 0.14–5.58 µg mL−1 for fenobucarb and propoxur, respectively. The different factors which affect the reactions were thoroughly studied and optimized. The proposed methods have been successfully applied to assay both insecticides in their commercial formulations and for recovery study from spiked environmental samples. The good results of recoveries of both insecticides demonstrate the accuracy and precision of both methods. [ABSTRACT FROM AUTHOR]

Background. The evidence linking the use of household pesticides and the risk of lymphoma is scanty. Methods. We explored the hypothesis in a population-based case-control study on lymphoma conducted in Sardinia, Italy, in 1998–2004, including 325 cases and 465 population controls and data on lifetime frequency, seasonality, and years of use of household insecticides and potential confounders. We calculated the risk of lymphoma (all subtypes) and its major subtypes associated with using household insecticides in three time windows (up to 1978, from 1979–2001, and 2002 onwards) with unconditional logistic regression adjusting by age, sex, education, and occupational exposure to pesticides. Results. Household insecticides did not increase risk of lymphoma (all subtypes), Hodgkin's lymphoma, B-cell lymphoma, and the major B-cell lymphoma subtypes. The risk of multiple myeloma (MM) but not the other subtypes showed a non-significant upward trend (p = 0.203) with increasing quartiles of days of use in the time window when propoxur was the most popular household insecticide. Conclusions. Our results suggest no association between the household use of insecticides and the risk of lymphoma. Further studies are warranted to confirm or discard an association between MM risk and the use of propoxur. [ABSTRACT FROM AUTHOR]

Background. The evidence linking the use of household pesticides and the risk of lymphoma is scanty. Methods. We explored the hypothesis in a population-based case-control study on lymphoma conducted in Sardinia, Italy, in 1998–2004, including 325 cases and 465 population controls and data on lifetime frequency, seasonality, and years of use of household insecticides and potential confounders. We calculated the risk of lymphoma (all subtypes) and its major subtypes associated with using household insecticides in three time windows (up to 1978, from 1979–2001, and 2002 onwards) with unconditional logistic regression adjusting by age, sex, education, and occupational exposure to pesticides. Results. Household insecticides did not increase risk of lymphoma (all subtypes), Hodgkin’s lymphoma, B-cell lymphoma, and the major B-cell lymphoma subtypes. The risk of multiple myeloma (MM) but not the other subtypes showed a non-significant upward trend (p = 0.203) with increasing quartiles of days of use in the time window when propoxur was the most popular household insecticide. Conclusions. Our results suggest no association between the household use of insecticides and the risk of lymphoma. Further studies are warranted to confirm or discard an association between MM risk and the use of propoxur.

Background: The house fly is a public health pest due to its ability to transmit various pathogens worldwide. The suppression of house flies is frequently controlled by organophosphate and carbamate insecticides, but recurrent selection has led to the mutated target. To understand the spread and evolution of Mdace mutations in house flies, we sampled flies in eight different China provinces, sequenced, and then estimated the frequencies of mutations., Results: The inhibition of AChE towards propoxur varied geographically and was lowest in the Heilongjiang field population, and highest in Jiangsu population. The overall frequencies of the different Mdace mutations (V260L, G342A, G342V, F407Y) varied considerably between populations. Strong positive correlations were found between acetylcholinesterase (AChE) insensitivity and the frequencies of G342V allele, 342A/V genotype and combination (260V/L-342A/V-407Y/Y) for the field populations. Eighteen combinations of Mdace at three sites (V260L, G342A/V, F407Y) were observed, with the majority of flies being categorized into the combination (260V/L-342A/V-407Y/Y), ranging in frequency from 24% (in field populations in Hubei and Hainan) to 96% (Jiangsu)., Conclusion: Based on comparison with historical data, the mutations responsible for the extremely high resistance to the level of insecticide resistance spread widely, propoxur should be limited to use for house fly control in China. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

BackgroundNorthern fowl mites (Ornithonyssus sylviarum) are obligate hematophagous ectoparasites of both feral birds and poultry, particularly chicken layers and breeders. They complete their entire life-cycle on infested birds while feeding on blood. Infestations of O. sylviarum are difficult to control and resistance to some chemical classes of acaricides is a growing concern. The contact susceptibility of O. sylviarum to a new active ingredient, fluralaner, was evaluated, as well as other compounds representative of the main chemical classes commonly used to control poultry mite infestations in Europe and the USA.MethodsSix acaricides (fluralaner, spinosad, phoxim, propoxur, permethrin, deltamethrin) were dissolved and serially diluted in butanol:olive oil (1:1) to obtain test solutions used for impregnation of filter paper packets. A carrier-only control was included. Thirty adult northern fowl mites, freshly collected from untreated host chickens, were inserted into each packet for continuous compound exposure. Mite mortality was assessed after incubation of the test packets for 48 h at 75% relative humidity and a temperature of 22 °C.ResultsAdult mite LC50 /LC99 values were 2.95/8.09 ppm for fluralaner, 1587/3123 ppm for spinosad, 420/750 ppm for phoxim and 86/181 ppm for propoxur. Permethrin and deltamethrin LC values could not be calculated due to lack of mortality observed even at 1000 ppm.ConclusionsNorthern fowl mites were highly sensitive to fluralaner after contact exposure. They were moderately sensitive to phoxim and propoxur, and less sensitive to spinosad. Furthermore, the tested mite population appeared to be resistant to the pyrethroids, permethrin and deltamethrin, despite not being exposed to acaricides for at least 10 years.

ObjectiveTo investigate the resistance dynamics of Blattella germanica to commonly used insecticides in Yangpu District of Shanghai during 2014‒2020， and to provide the basis for the rational use of insecticides against cockroaches.MethodsBlattella germanica was captured in two farmer’s markets in 2014， 2017 and 2020. The residual film method recommended by WHO was used to test resistance of Blattella germanica to the insecticides.ResultsIn 2014， 2017 and 2020， the resistance ratio of Blattella germanica in Yangpu District was 6.96， 4.39， 7.26 to beta-cypermethrin， 10.41， 6.71， 5.24 to permethrin， and 2.28， 3.16， 1.01 to propoxur.ConclusionThe resistance of Blattella germanica to permethrin and propoxur decreases， and the resistance to beta-cypermethrin keeps at low level. Comprehensive management and rotation of insecticides should be implemented to delay the increase of resistance.

Acute direct ocular exposure to insecticides is rare and can present as a chemical injury. We present a case of a 21-year-old male patient who had an accidental exposure to chlorpyrifos and propoxur while spraying it as an insecticide. He presented with severe conjunctival ischemia and necrosis involving the inferior fornix. He underwent amniotic membrane transplantation to preserve the ocular surface. The case report highlights the chemical effects of organophosphorus compounds on the ocular surface.

Propoxur, an insecticide used to control opportunistic fleas and flies, is mainly ingested with meat. Considering that the common methods of propoxur determination in meat are time-consuming, employ toxic extraction solvents, and generate large amounts of waste, we herein established greener, faster, and cheaper alternatives. Two methods were developed: flow solid-liquid extraction or solid-liquid microextraction with low-temperature partitioning. Increasing the sensitivity and decreasing the limit of detection were accomplished by employing cloud point preconcentration of the intensely colored reaction product and long pathlength spectrophotometry. The method shows a linear response range within 0.01–1.0 µmol L−1 and coefficient of variation = 5.0%, n = 15. The limits of detection and quantification were estimated at 7.9 and 26.2 µg kg−1 at the 99.7% confidence level, respectively. The parameters were lower than the maximum residue limit of propoxur in meat (50.0 μg kg−1), and the recoveries were obtained for spiked meat samples (75–112%). The proposed methods for propoxur extraction are practical, easy to implement, and simple to perform, in addition to requiring low amounts of solvents and low waste generation. • Greener, faster, and cheaper alternatives for propoxur extraction. • Easy SLME-LTP or FIA for the propoxur extraction. • Requiring low amounts of solvents and low waste generation. [ABSTRACT FROM AUTHOR]

Abstract In accordance with Article 43 of Regulation (EC) No 396/2005, the European Commission requested EFSA to prepare a reasoned opinion on the toxicological properties and the existing maximum residue levels (MRLs) set for propoxur. EFSA was requested to assess the toxicological properties of propoxur and derive toxicological reference values, based on the toxicological assessment performed by Health Canada. EFSA was also requested to review the information provided by Member States and the UK on the metabolism of propoxur in plants and animals and on the current MRLs, as well as the limit of quantification (LOQ) that can be achieved with analytical methods used in MRL enforcement. Based on the information available to EFSA, toxicological reference values could not be derived for propoxur. No evidence was provided by Member States and UK that the existing EU MRLs need to be maintained as import tolerances. Information to support the current MRLs or alternative MRLs have not been provided by Member States and the UK. Codex MRLs are not in place. EFSA therefore recommended lowering of all existing EU MRLs for propoxur to the LOQ. According to the EU Reference Laboratories, sufficiently validated analytical methods are available to analyse for propoxur residues in all plant and animal commodities. Lacking toxicological reference values derived at EU level, a conclusion cannot be derived whether the setting of MRLs at the LOQs is sufficiently protective for the European consumers.

In accordance with Article 43 of Regulation (EC) No 396/2005, the European Commission requested EFSA to prepare a reasoned opinion on the toxicological properties and the existing maximum residue levels (MRLs) set for propoxur. EFSA was requested to assess the toxicological properties of propoxur and derive toxicological reference values, based on the toxicological assessment performed by Health Canada. EFSA was also requested to review the information provided by Member States and the UK on the metabolism of propoxur in plants and animals and on the current MRLs, as well as the limit of quantification (LOQ) that can be achieved with analytical methods used in MRL enforcement. Based on the information available to EFSA, toxicological reference values could not be derived for propoxur. No evidence was provided by Member States and UK that the existing EU MRLs need to be maintained as import tolerances. Information to support the current MRLs or alternative MRLs have not been provided by Member States and the UK. Codex MRLs are not in place. EFSA therefore recommended lowering of all existing EU MRLs for propoxur to the LOQ. According to the EU Reference Laboratories, sufficiently validated analytical methods are available to analyse for propoxur residues in all plant and animal commodities. Lacking toxicological reference values derived at EU level, a conclusion cannot be derived whether the setting of MRLs at the LOQs is sufficiently protective for the European consumers. [ABSTRACT FROM AUTHOR]

Controlling housefly populations relies on the use of insecticides, which inevitably leads to the development of resistance. A better and more comprehensive understanding of the spatial and temporal distribution of resistance could guide the control of houseflies. However, most studies on housefly resistance in China are scattered and poorly coordinated. We collected resistance data from houseflies in the published literature and from the vector biomonitoring system of the Chinese Center for Disease Control and Prevention. A 5- or 10-year resolution was used to study the temporal dynamics of resistance to five commonly used insecticides: deltamethrin, permethrin, beta-cypermethrin, dichlorvos, and propoxur. ArcGIS was used to visualize their spatial distributions. The correlation between year and resistance coefficient was determined using SPSS 26.0 and RStudio to explore the changes in resistance over the years. A total of 2128 data were included in this study, ranging from 1982 to 2022, based on which we found significant increases in resistance over the past forty years for the five studied insecticides. Among them, pyrethroids had the most strikingly elevated resistance level and were mainly distributed in the northern and southeastern coastal areas. Dichlorvos and propoxur had intermediate increases in resistance, and most of these increases were identified in North China and the Yangtze River. Housefly resistance to commonly used insecticides in China is increasing and spatially heterogeneous. This finding also highlights the necessity of continuous routine surveillance of housefly resistance, which could guide future housefly control operations and slow the development of resistance., (Copyright © 2024. Published by Elsevier Inc.)

Abstract Background Residual efficacy of indoor residual spray may vary with different spray quality and wall surfaces types. This study evaluated the impact of spray quality and wall surface types on residual efficacy of propoxur against wild Anopheles gambiae sensu lato (s.l.) in southwest Ethiopia. Methods Thirty houses of different mud wall surfaces (10 smooth, 10 rough, 10 painted) were selected and randomly allocated into routine and standard spray. The routine spray was conducted by district health office as usual, while the standard spray was done by strictly following guidelines. Three control houses were selected from unsprayed nearby semi-urban. Wild An. gambiae s.l. were used for wall bioassay tests. Two-way mixed model analysis of variance was used to analyse the data. The mean variation between wall and spray types was compared by post hoc analysis of IBM SPSS version 20. Results On standard spray, knockdown rate was 95.3% on painted, 82% on smooth and 72.5% on rough surface at week 17 of post-spray, whereas on routine spray it was 82.7% on painted, 48.7% on smooth and 60% on rough surface. On standard spray, mortality rate of An. gambiae s.l. was 99.3% on painted surface, 90% on smooth and 80% on rough surface. On routine spray, it was 89.3% on painted, 61.3% on smooth and 65% on rough surface at week 17 of post-spray. The painted wall surface showed the highest knockdown rate (86.4–100%) on standard and (73.8–91.5%) routine spray; mortality rate was more than 80% on both spray types during the 17 weeks of follow-up regardless of spray types. The lower mortality rate and residual effect was observed on routine smooth and rough wall surfaces. The residual efficacy of propoxur was > 80% at week 17 on standard spray regardless of the wall types and it was

Background: Pesticide toxicity is one of the major environmental health problems for the modern societies, as some of the effects may last long time after exposure. Propoxur is one of the Carbamate pesticide largely used in agriculture in the Western region of Cameroon. Methods: In order to evaluate the post-exposure effects of propoxur, 48 male rats (12 animals per group) aged 30 d were orally gavaged with 0.00, 1.73, 2.60 and 5.20 mg.kg-1 body weight of propoxur for 90 d. At the end of treatment, 6 rats per group were sacrificed and others were followed up for 90 additional days and submitted to a fertility test before sacrifice. Results: At the end of exposure propoxur significantly increased (P

Abstract Background Indoor residual spraying is one of the key vector control interventions for malaria control in Ethiopia. As malaria transmission is seasonal in most parts of Ethiopia, a single round of spraying can usually provide effective protection against malaria, provided the insecticide remains effective over the entire malaria transmission season. This experiment was designed to evaluate the residual efficacy of bendiocarb, pirimiphos-methyl, and two doses of propoxur on four different wall surfaces (rough mud, smooth mud, dung, and paint). Filter papers affixed to wall surfaces prior to spraying were analyzed to determine the actual concentration applied. Cone bioassays using a susceptible Anopheles arabiensis strain were done monthly to determine the time for which insecticides were effective in killing mosquitoes. Results The mean insecticide dosage of bendiocarb applied to walls was 486 mg/m2 (target 400/mg). This treatment lasted 1 month or less on rough mud, smooth mud, and dung, but 4 months on painted surfaces. Pirimiphos-methyl was applied at 1854 mg/m2 (target 1000 mg/m2), and lasted between 4 and 6 months on all wall surfaces. Propoxur with a target dose of 1000 mg/m2 was applied at 320 mg/m2, and lasted 2 months or less on all surfaces, except painted surfaces (4 months). Propoxur with a target dose of 2000 mg/m2, was applied at 638 mg/m2, and lasted 3 months on rough mud, but considerably longer (5–7 months) on the other substrates. Conclusions It would appear that the higher dose of propoxur and pirimiphos-methyl correspond best to the Ethiopian transmission season, although interactions between insecticide and the substrate should be taken into account as well. However, the insecticide quantification revealed that the dosages actually applied differed considerably from the target dosages, even though care was taken in the mixing of insecticide formulations and spraying of the walls. It is unclear whether this variability is due to initial concentrations of insecticides, poor application, or other factors. Further work is needed to ensure that target doses are correctly applied, both operationally and in insecticide evaluations.

The application of pyrethroids and carbamates represents an environmental risk and may exert adverse effects on beneficial microorganisms such as Trichoderma, which contribute to the biocontrol of several fungal phytopathogens. This research evaluated the tolerance of several strains of Trichoderma to a selected culture medium contaminated with a commercial insecticide (H24®) composed of pyrethroids, permethrin and prallethrin, and carbamate propoxur, and determined the influence of this insecticide on the release of enzymes such as chitinases, peroxidases, and endoglucanases by a consortium of selected Trichoderma strains grown in liquid culture medium. Four out of 10 Trichoderma strains showed tolerance to 200ppm (∼48.3% of growth) of the commercial insecticide after 96h of exposure to a contaminated solid medium. After eight days of growth in liquid culture, the insecticide enhanced extracellular protein content and peroxidase activities in the Trichoderma consortium but decreased both chitinase and glucanase activities. These fungal responses should be considered when implementing strategies that combine alternative pesticides and fungal biocontrollers for managing fungal phytopathogens., (Copyright © 2023. Publicado por Elsevier España, S.L.U.)

Background: Culex pipiens is a mosquito species distributed in different parts of Iran. It is known as vector of some diseases as well as a nuisance insect. A successful control campaign needs to study the biology, ecology and suscep­tibility status of the target pest. The aim of this study was to investigate the susceptibility status of Culex pipiens to some insecticides recommended by WHO in north of Iran. Methods: Larvae were collected from different breeding places in Sari County by standard dipping method. They were reared to adult stage in an under standard condition. World Health Organization (WHO) standard test kits and the diagnostic dose of 12 imagicides were used for adults, while two larvicides were used against larvae. Results: The least and highest mortality rates after exposure to insecticides were 4.7% (Propoxur 0.1%) and 76.4% (Etofenprox 0.5%), respectively. Larvae showed high resistance to temephos (19.19%) and malathion (54.63%). Culex pipiens was found to be resistant to all used insecticides/larvicides at diagnostic dose. Conclusion: Intensive use of pesticides against agriculture and urban pests increased the resistance level of this spe­cies to different insecticides, although currently there is no control program against it. Study on the mechanisms of resistant in this species to different insecticides is recommended.

Objective: To analyze the density, distribution and insecticide resistance of Aedes albopictus in Ningbo City in 2021, so as to provide insights into formulation of dengue fever control strategies., Methods: Four administrative villages were randomly selected from each county (district) in Ningbo City from April to November, 2021, to investigate the indoor population density of Aedes larvae, and the Breteau index (BI) was calculated. The population density of adult mosquitoes was investigated in residential areas, parks/bamboo forests, waste tire stacking sites/waste stations/construction sites in each county (district). On June 2021, larvae of the natural strain A. albopictus were collected from epidemic sites of dengue fever in Ningbo City in 2018, and raised in laboratory. Then, larvae and female mosquitoes without blood feeding were selected for insecticide resistance bioassays, while insecticide-sensitive strains of A. albopictus served as controls. The resistance of A. albopictus larvae to deltamethrin, beta-cypermethrin, propoxur, temephos and dichlorvos using the impregnation method, and the medium lethal concentration (LC 50 ) and resistance ratio (RR) were calculated. The resistance of adult A. albopictus to beta-cypermethrin, permethrin, deltamethrin, propoxur and malathion was determined using the tube bioassay, and the mosquito mortality was calculated., Results: A total of 10 072 small water containers from 9 935 households were investigated in Ningbo City in 2021, and there were 1 276 containers with Aedes larvae detected, with an average BI of 12.89. Totally 1 422 mosquito nets were allocated and 954 female A. albopictus were captured, with an average net trapping index of 1.34 mosquitoes/(net·hour). Both larval and adult A. albopictus mosquitoes were found from April to November, and the density of larval A. albopictus peaked in September (BI = 21.21), while the density of adult A. albopictus peaked in August, with a net trapping index of 2.38 mosquitoes/(net·hour). The LC 50 values of delta-methrin, beta-cypermethrin, propoxur, temephos and dichlorvos were 0.017 4, 0.000 9, 0.364 1, 0.038 1 mg/L and 0.001 6 mg/L against larvae of natural strains of A. albopicchus , with RRs of 49.66, 25.53, 9.65, 2.24 and 6.06, and the mortality rates of adult mosquitoes were 66.00% (66/100), 69.39% (68/98), 25.00% (25/100), 98.97% (96/97) and 100.00% (98/98) 24 hours post-treatment with 0.08% beta-cypermethrin, 0.03% deltamethrin, 0.4% permethrin, 0.05% propoxur, and 0.5% malathion for 24 h, respectively., Conclusions: A. albopictus is widely distributed in Ningbo City, with a high population density and presents high-level resistance to common pyrethroid insecticides. The population density and insecticide resistance of A. albopictus requires to be reinforced.

Background: Pesticide toxicity is one of the major environmental health problems for the modern societies, as some of the effects may last long time after exposure. Propoxur is one of the Carbamate pesticide largely used in agriculture in the Western region of Cameroon. Methods: In order to evaluate the post-exposure effects of propoxur, 48 male rats (12 animals per group) aged 30 d were orally gavaged with 0.00, 1.73, 2.60 and 5.20 mg.kg-1 body weight of propoxur for 90 d. At the end of treatment, 6 rats per group were sacrificed and others were followed up for 90 additional days and submitted to a fertility test before sacrifice. Results: At the end of exposure propoxur significantly increased (P<0.05) the testis weight while it decreased (P<0.05) the cauda epididymal sperm motility in rat. Propoxur treatment and posttreatment exposure showed variable effect on the fertility rate with an increase and decrease at 2.60 and 5.20 mg.kg-1, respectively. At the 90th day post treatment, there was a significant decrease (P<0.05) in epididymis weight and sperm count and motility (P<0.05). In addition, post-exposure treatment with propoxur reduced (P<0.05) the pup litter size and the sex ratio at all doses. Histopathological examination revealed a high vacuity of germinal epithelia in treated rats that persisted after post-exposure time. Conclusion: Propoxur negatively affected male rats' reproductive parameters with more significant adverse effects observed 90 d after the end of exposure. [ABSTRACT FROM AUTHOR]

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The present study enumerates the attenuating effects of curcumin and α-tocopherol against propoxur induced oxidative DNA damage in human peripheral blood mononuclear cells (PBMC). Cultured cells were isolated from peripheral blood of healthy volunteers, and were exposed to varying concentrations of propoxur (0–21 μg/ml) for 6, 12, and 24 h, and in combination with curcumin (9.2 μg/ml) or α-tocopherol (4.3 μg/ml) or both. Cytotoxic effect of propoxur was examined by MTT assay. The role of oxidative stress beneath the cytotoxicity of propoxur was evaluated by the measurement of reduced glutathione (GSH), malondialdehyde (MDA) and 8-hydroxy-2′-deoxyguanosine (8-OH-dG) levels in cell lysate. A concentration-dependent cell death, depletion of GSH, an increase in the level of both MDA and 8-OH-dG were observed. Co-treatment with curcumin or α-tocopherol significantly attenuates depleted GSH, decrease in MDA and 8-OH-dG levels in propoxur exposed cells (p < 0.05). The results of the present study provide experimental evidence of involvement of oxidative stress in propoxur-mediated genotoxicity in human PBMC and highlight the antioxidant role of curcumin and α-tocopherol following propoxur exposure. [ABSTRACT FROM PUBLISHER]

Water quality assessment was conducted on the Ruiru River, a tributary of an important tropical river system in Kenya, to determine baseline river conditions for studies on the aquatic fate of N-methyl carbamate (NMC) pesticides. Measurements were taken at the end of the long rainy season in early June 2013. Concentrations of copper (0.21-1.51 ppm), nitrates (2.28-4.89 ppm) and phosphates (0.01-0.50 ppm) were detected at higher values than in uncontaminated waters, and attributed to surface runoff from agricultural activity in the surrounding area. Concentrations of dissolved oxygen (8-10 ppm), ammonia (0.02-0.22 ppm) and phenols (0.19-0.83 ppm) were found to lie within normal ranges. The Ruiru River was found to be slightly basic (pH 7.08-7.70) with a temperature of 17.8-21.2°C. The half-life values for hydrolysis of three NMC pesticides (carbofuran, carbaryl and propoxur) used in the area were measured under laboratory conditions, revealing that rates of decay were influenced by the electronic nature of the NMCs. The hydrolysis half-lives at pH 9 and 18°C decreased in the order carbofuran (57.8 h) > propoxur (38.5 h) > carbaryl (19.3 h). In general, a decrease in the electron density of the NMC aromatic ring increases the acidity of the N-bound proton removed in the rate-limiting step of the hydrolysis mechanism. Our results are consistent with this prediction, and the most electron-poor NMC (carbaryl) hydrolyzed fastest, while the most electron-rich NMC (carbofuran) hydrolyzed slowest. Results from this study should provide baseline data for future studies on NMC pesticide chemical fate in the Ruiru River and similar tropical water systems. [ABSTRACT FROM AUTHOR]

Background: Culex pipiens is a mosquito species distributed in different parts of Iran. It is known as vector of some diseases as well as a nuisance insect. A successful control campaign needs to study the biology, ecology and susceptibility status of the target pest. The aim of this study was to investigate the susceptibility status of Culex pipiens to some insecticides recommended by WHO in north of Iran. Methods: Larvae were collected from different breeding places in Sari County by standard dipping method. They were reared to adult stage in an under standard condition. World Health Organization (WHO) standard test kits and the diagnostic dose of 12 imagicides were used for adults, while two larvicides were used against larvae. Results: The least and highest mortality rates after exposure to insecticides were 4.7% (Propoxur 0.1%) and 76.4% (Etofenprox 0.5%), respectively. Larvae showed high resistance to temephos (19.19%) and malathion (54.63%). Culex pipiens was found to be resistant to all used insecticides/larvicides at diagnostic dose. Conclusion: Intensive use of pesticides against agriculture and urban pests increased the resistance level of this species to different insecticides, although currently there is no control program against it. Study on the mechanisms of resistant in this species to different insecticides is recommended. [ABSTRACT FROM AUTHOR]

Mục tiêu của nghiên cứu nhằm đánh giá hiệu quả của bã cà phê làm chất mang thay thế biochar cố định vi khuẩn Paracoccus sp. P23-7 giúp gia tăng tốc độ phân hủy propoxur trong đất trồng hành tím ở Vĩnh Châu, Sóc Trăng. Biochar và bã cà phê (BCP) là chất mang trong thí nghiệm. Phân bò, bèo hoa dâu, vỏ trứng và xỉ than tổ ong là vật liệu bổ sung vào đất. Mật số vi khuẩn, nấm và nồng độ propoxur trong đất ở các thời điểm 0, 1, 3, 5, 7, và 11 ngày được thu thập. Kết quả cho thấy dòng vi khuẩn Paracoccus sp. P23-7 cố định trong bã cà phê cho hiệu quả cao hơn so với biochar trong phân hủy propoxur trong đất. Ngoài ra, nghiệm thức bón vỏ trứng (1%) hoặc hỗn hợp phân bò, bèo hoa dâu, vỏ trứng và xỉ than (1%) giúp gia tăng hiệu quả và tốc độ phân hủy propoxur bởi dòng Paracoccus sp. P23-7 cố định trong bã cà phê so với các nghiệm thức khác. Tóm lại, bã cà phê có thể sử dụng để cố định vi khuẩn Paracocus sp. P23-7, giúp gia tăng tốc độ phân hủy propoxur trong đất và kết hợp bón vỏ trứng (1%) hoặc hỗn hợp hữu cơ gồm phân bò, bèo hoa dâu, vỏ trứng và xỉ than (1%) là một trong những biện pháp tác động nhằm gia tăng tốc độ phân hủy propoxur trong đất.

Propoxur-sel strains of Culex pipiens quinquefasciatus were derived from a lab-bred strain following 16 generations of propoxur exposure under sublethal concentrations of LC25 (lethal concentration of 25%) and LC50 (lethal concentration of 50%), respectively. This resulted in resistance development in F16 with ratios of 8.8× and 6.3×, respectively, compared with F0. The fecundity, longevity, sex ratio (F/M), and hatchability of the propoxur-exposed Cx. quinquefasciatus adult survivors and their offspring were decreased, with no effect on the emergence ratio and pupa survival rate. In addition, the intrinsic rates of increase (r), the net reproduction (R0), and the finite rate of increase (λ) of the Cx. quinquefasciatus offspring generations were also decreased significantly compared to F0. Correspondingly, the mean generation time (T) and the population double time (DT) in propoxur-sels were increased. Enhanced activities of cytochrome P450 monooxygenase and esterase were also observed in propoxur-sels, indicating that a detoxification mechanism might be responsible for resistance development in Cx. quinquefasciatus. Except for the three genes cyp4d42v1, cyp4c52v1, and cyp6aa9 which displayed a coincidence in some degree in different treatments, induction by different doses of propoxur and constitutive expression in different generations of propoxur-sel strains resulted in an inconsistent identification of the P450 genes probably related with resistance.

Recent studies suggest that organophosphates and carbamates affect human fetal development, resulting in neurological and growth impairment. However, these studies are conflicting and the extent of adverse effects due to pesticide exposure warrants further investigation. In the present study, we examined the impact of the carbamate insecticide propoxur on zebrafish development. We found that propoxur exposure delays embryonic development, resulting in three distinct developmental stages: no delay, mild delay, or severe delay. Interestingly, the delayed embryos all physically recovered 5 days after exposure, but behavioral analysis revealed persistent cognitive deficits at later stages. Microarray analysis identified 59 genes significantly changed by propoxur treatment, and Ingenuity Pathway Analysis revealed that these genes are involved in cancer, organismal abnormalities, neurological disease, and hematological system development. We further examined hspb9 and hspb11 due to their potential roles in zebrafish development and found that propoxur increases expression of these small heat shock proteins in all of the exposed animals. However, we discovered that less significant increases were associated with the more severely delayed phenotype. This raises the possibility that a decreased ability to upregulate these small heat shock proteins in response to propoxur exposure may cause embryos to be more severely delayed.

Background: Indoor residual spraying is one of the key vector control interventions for malaria control in Ethiopia. As malaria transmission is seasonal in most parts of Ethiopia, a single round of spraying can usually provide effective protection against malaria, provided the insecticide remains effective over the entire malaria transmission season. This experiment was designed to evaluate the residual efficacy of bendiocarb, pirimiphos-methyl and two doses of propoxur on four different wall surfaces (rough mud, smooth mud, dung and paint). Filter papers affixed to wall surfaces prior to spraying were analyzed to determine the actual concentration applied. Cone bioassays using a susceptible Anopheles arabiensis strain were done monthly to determine the time for which insecticides were effective in killing mosquitoes. Results: The mean insecticide dosage of bendiocarb applied to walls was 486 mg/m2 (target 400/mg). This treatment lasted 1 month or less on rough mud, smooth mud and dung, but 4 months on painted surfaces. Pirimiphosmethyl was applied at 1854 mg/m2 (target 1000 mg/m2) and lasted between 4 and 6 months on all wall surfaces. Propoxur with a target dose of 1000 mg/m2 was applied at 320 mg/m2 and lasted 2months or less on all surfaces, except painted surfaces (4 months). Propoxur with a target dose of 2000 mg/m2, was applied at 638 mg/m2 and lasted 3 months on rough mud, but considerably longer (5-7 months) on the other substrates. Conclusions: It would appear that the higher dose of propoxur and pirimiphos-methyl correspond best to the Ethiopian transmission season, although interactions between insecticide and the substrate should be taken into account as well. However, the insecticide quantification revealed that the dosages actually applied differed considerably from the target dosages, even though care was taken in the mixing of insecticide formulations and spraying of the walls. It is unclear whether this variability is due to initial concentrations of insecticides, poor application, or other factors. Further work is needed to ensure that target doses are correctly applied, both operationally and in insecticide evaluations. [ABSTRACT FROM AUTHOR]

Three pairs of syntrophic bacteria involved in degradation of the N -methylcarbamate insecticide propoxur were isolated from agricultural soils. All pairs were able to use propoxur as a sole carbon and energy source. Among these pairs, SP1 degraded propoxur most rapidly and was chosen for further studies. Based on 16S rRNA gene sequence analysis, the members of SP1 were related to members of genera Pseudaminobacter and Nocardioides . SP1 completely degraded propoxur through syntrophic interaction without any identifiable products. The syntrophic strain SP1a appeared to convert propoxur to 2-isopropoxyphenol (2-IPP), which was subsequently degraded by strain SP1b, as observed by gas chromatography-mass spectrometry (GC-MS). When analyzed by PCR for previously reported carbamate hydrolase genes, strain SP1a showed homology with a cehA gene encoding carbaryl hydrolase. This is the first study to report that syntrophic metabolism by two bacterial strains completely degraded propoxur. [ABSTRACT FROM AUTHOR]

A solution with 0.38 mM of the pesticide propoxur (PX) at pH 3.0 has been comparatively treated by electrochemical oxidation with electrogenerated HO (EO-HO), electro-Fenton (EF), and photoelectro-Fenton (PEF). The trials were carried out with a 100-mL boron-doped diamond (BDD)/air-diffusion cell. The EO-HO process had the lowest oxidation ability due to the slow reaction of intermediates with OH produced from water discharge at the BDD anode. The EF treatment yielded quicker mineralization due to the additional OH formed between added Fe and electrogenerated HO. The PEF process was the most powerful since it led to total mineralization by the combined oxidative action of hydroxyl radicals and UVA irradiation. The PX decay agreed with a pseudo-first-order kinetics in EO-HO, whereas in EF and PEF, it obeyed a much faster pseudo-first-order kinetics followed by a much slower one, which are related to the oxidation of its Fe(II) and Fe(III) complexes, respectively. EO-HO showed similar oxidation ability within the pH range 3.0-9.0. The effect of current density and Fe and substrate contents on the performance of the EF process was examined. Two primary aromatic products were identified by LC-MS during PX degradation. [ABSTRACT FROM AUTHOR]

Background: Historically, malaria due to Plasmodium vivax has been epidemic in Henan Province, China, with Anopheles sinensis as the main vector. The most effective measures to prevent malaria transmission are based on vector control through the use of insecticides. However, insecticides exert a strong selective pressure on mosquito populations for insecticide resistance. The aim of this study was to investigate the susceptibility profile and population genetic characteristics of An. sinensis to provide basic data and scientific guidance for the study of resistance mechanisms and the control of An. sinensis in Henan Province., Methods: Adult Anopheles mosquitoes were collected at sites near local farmers' sheepfolds, pigsties and/or cowsheds located in Pingqiao, Xiangfu, Xiangcheng and Tanghe counties/districts of Henan Province during July-September 2021 for insecticide susceptibility testing. Molecular identification of collected mosquitoes as belonging to genus Anopheles was by PCR, and the frequencies of mutations in the knockdown resistance gene (kdr) and acetylcholinesterase-1 gene (ace-1) were detected using gene amplification. The mitochondrial DNA cytochrome oxidase subunit I (COI) gene was amplified in deltamethrin-resistant and deltamethrin-sensitive mosquitoes to analyze the genetic evolutionary relationship., Results: A total of 1409 Anopheles mosquitoes were identified by molecular identification, of which 1334 (94.68%) were An. sinensis, 28 (1.99%) were An. yatsushiroensis, 43 (3.05%) were An. anthropophagus and four (0.28%) were An. belenrae. The 24-h mortality rates of An. sinensis in Pingqiao, Tanghe, Xiangcheng and Xiangfu counties/districts exposed to deltamethrin were 85.85%, 25.38%, 29.73% and 7.66%, respectively; to beta-cyfluthrin, 36.24%, 70.91%, 34.33% and 3.28%, respectively; to propoxur, 68.39%, 80.60%, 37.62% and 9.29%, respectively; and to malathion, 97.43%, 97.67%, 99.21% and 64.23%, respectively. One mutation, G119S, was detected in the ace-1 gene. The frequencies of the main genotypes were 84.21% of specimens collected in Xiangfu (G/S), 90.63% of speciments collected in Xiangcheng (G/G) and 2.44% of speciments collected in Tanghe (S/S). Significantly higher G119S allele frequencies were observed in both propoxur- and malathion-resistant mosquitoes than in their sensitive counterparts in the Tanghe population (P < 0.05). Three mutations, L1014F (41.38%), L1014C (9.15%) and L1014W (0.12%), were detected in the kdr gene. The genotypes with the highest frequency in the populations of An. sinensis in Xiangfu and Tanghe were the mutant TTT (F/F) and wild-type TTG (L/L), at 67.86% (57/84) and 74.29% (52/70), respectively. In Pingqiao and Xiangfu, higher frequencies of the L1014F allele and lower frequencies of the L1014C allele were observed in mosquitoes resistant for beta-cyfluthrin than in those which were sensitive for this insecticide (P < 0.05). The results of Tajima's D and of Fu and Li's D and F were not significantly negative (P > 0.10), and each haplotype was interlaced and did not form two distinct branches., Conclusions: High resistance to pyrethroids and propoxur was observed at four sites, but the resistance to malathion varied according to the location. Anopheles belenrae and the L1014W (TGG) mutation in An. sinensis were first discovered in Henan Province. The deltamethrin-resistant and deltamethrin-sensitive mosquito populations showed no genetic differentiation. The generation of resistance might be the result of the combination of multiple factors., (© 2023. The Author(s).)

Reverse osmosis is used as a tertiary treatment for wastewater reclamation. However, sustainable management of the concentrate (ROC) is challenging, due to the need for treatment and/or disposal. The objective of this research was to investigate the efficiency of homogeneous and heterogeneous Fenton-like oxidation processes in removing propoxur (PR), a micro-pollutant compound, from synthetic ROC solution in a submerged ceramic membrane reactor operated in a continuous mode. A freshly prepared amorphous heterogeneous catalyst was synthesized and characterized, revealing a layered porous structure of 5-16 nm nanoparticles that formed aggregates (33-49 μm) known as ferrihydrite (Fh). The membrane exhibited a rejection of >99.6% for Fh. The homogeneous catalysis (Fe 3+ ) exhibited better catalytic activity than the Fh in terms of PR removal efficiencies. However, by increasing the H 2 O 2 and Fh concentrations at a constant molar ratio, the PR oxidation efficiencies were equal to those catalyzed by the Fe 3+ . The ionic composition of the ROC solution had an inhibitory effect on the PR oxidation, whereas increased residence time improved it up to 87% at a residence time of 88 min. Overall, the study highlights the potential of heterogeneous Fenton-like processes catalyzed by Fh in a continuous mode of operation.