Concentrations Of Chlorpyrifos Research Articles

CHLORPYRIFOS TOXICITY STUDIES ON FISH SCALES OF ANABAS TESTUDINEUS

Indiscriminate use of organophosphorus compounds as pesticides is causing a threat to non-target organisms, especially in aquatic environments.The present investigation was to find the chlorpyrifos toxicity effects in scales ofthe edible freshwater fish, Anabastestudineus. The structural morphology, melanophore index, and decalcification effects were selected for elucidating the toxicity effects in the scales of Anabas. The fish was subjected for a period of 18 days to low dosages (12.5 ppm& 25 ppm) of chlorpyrifosand the changes were observed.The study revealed that exposureto 12.5 ppm and 25 ppm concentrations of chlorpyrifosaltered the scale morphology. The circuli of the scalesof treated fish were observed to be faint, degraded and loosely attached to the underlying skin. A remarkable change observed was the change in color of Anabas testudineus, it became too pale. Chlorpyrifos was found to induce the dispersion of melanophores. The study also revealed an increase in decalcification of the scaleswith the increasing concentration of chlorpyrifos. From the results of the parameters studied it is evident thatchlorpyrifos cause acute toxic effects on Anabastestitudens as early as 18 days of exposure.

Combining Passive Sampling and Dosing to Unravel the Contribution of Hydrophobic Organic Contaminants to Sediment Ecotoxicity.

Contaminated sediments are ubiquitous repositories of pollutants and cause substantial environmental risks. Results of sediment bioassays remain difficult to interpret, however, as observed effects may be caused by a variety of (un)known stressors. This study aimed therefore to isolate the effects of hydrophobic organic contaminants from other (non)chemical stressors present in contaminated sediments, by employing a newly developed passive sampling-passive dosing (PSPD) test. The results showed that equilibrium partitioning between pesticides or polyaromatic hydrocarbons (PAHs) in contaminated sediments and a silicone rubber (SR) passive sampler was achieved after 1-3 days. Chlorpyrifos concentrations in pore water of spiked sediment matched very well with concentrations released from the SR into an aqueous test medium, showing that SR can serve as a passive dosing device. Subjecting the 96 h PSPD laboratory bioassay with nonbiting midge (Chironomus riparius) larvae to field-collected sediments showed that at two locations, concentrations of the hydrophobic organic contaminant mixtures were high enough to affect the test organisms. In conclusion, the developed PSPD test was able to isolate the effects of hydrophobic organic contaminants and provides a promising simplified building block for a suite of PSPD tests that after further validation could be used to unravel the contribution of hydrophobic organic chemicals to sediment ecotoxicity.

Chlorpyrifos and diazinon elimination through pAAm-g-XG/HKUST-1@Fe3O4 biopolymer nanoadsorbent hydrogel from wastewater: Preparation, characterization, kinetics and isotherm

In this study, a MOF-functionalized biopolymer nanoadsorbent hydrogel was developed to effectively eliminate chlorpyrifos (CPF) and diazinon (DZ) from aquatic areas. The adsorbent system was prepared through a multi-step process, such as graft copolymer preparation of xanthan gum (XG) with acrylamide (Aam) and cross-linking with N,N'-Methylenebisacrylamide (MBA) to obtain (pAAm-g-XG), synthesis of Fe3O4 MNPs through ex-situ co-precipitation method, and covalent attachment onto the pAAm-g-XG. Finally, in-situ HKUST-1 was attached to pAAm-g-XG@Fe3O4 to obtain the pAAm-g-XG/HKUST-1@Fe3O4 biopolymer nanocomposite hydrogel. They are characterized by a variety of characteristic methods for example, FTIR, VSM, SEM, TGA, EDX, XRD, and BET confirmed the adequate preparation of pAAm-g-XG/HKUST-1@Fe3O4 biopolymer nanocomposite hydrogel. CPF and DZ, both organophosphorus pesticides (OPPs), were studied for their removal from aqueous solutions using the developed adsorbent system. The most efficient adsorption conditions were achieved by doing batch adsorption tests with varying values of solution pH, adsorbent dose, contact duration, and beginning concentrations of CPF and DZ. Additionally, model fitting was excellent for the Freundlich isotherm model, and by using the pAAm-g-XG/HKUST-1@Fe3O4 biopolymer nanocomposite hydrogel, the maximal adsorption capacity of DZ and CPF was achieved about 4525.102 and 1708.735 mg.g−1, consequently. The pseudo-second-order (PSO) model, according to the findings, is an excellent fit for the experimental data in this research on adsorption kinetics. The hypothesized process suggests that intermolecularly by hydrogen bonding, diffusion, and entrapment in the polymeric lattice of biopolymer nanocomposite hydrogel all contribute to the adsorption of CPF and DZ onto the biopolymer nanocomposite hydrogel. The two OPPs under study responded best to regeneration studies lasting up to four cycles.

Investigating the Residue of Diazinon, Chlorpyrifos, and Dichlorvos in Urban Drinking Water Supply Sources and Determining the Water Quality Index in Tirano-Korun in 2020

Introduction: Contamination of water sources with toxins is an environmental problem and a serious threat to the health of societies. This study aimed to ascertain the remaining levels of toxins in urban drinking water networks and compute the water quality index.
 Materials and Methods: To examine the residual concentration of diazinon, chlorpyrifos, and dichlorvos in urban drinking water distribution networks, 35 underground and surface water sources were sampled in Tiran-o-Korun in Isfahan province, Iran. GC-ECD device was used to analyze the samples.
 Results: Diazinon was not observed in any of the sampling seasons. The maximum concentration of chlorpyrifos and dichlorvos was 61 and 100 ppb, respectively. Although chlorpyrifos was seen more in the hot season and dichlorvos in the cold season, the mean concentration of these toxins in different seasons was lower than the guidelines of Iran and the World Health Organization (WHO). The mean concentration of nitrate, and hardness, in wet and dry seasons was 46.23 and 46.42, and 343.7 and 338.8 mg/l, respectively.
 Conclusion: The mean and standard deviation of quality index of Iran's water resources (IRWQI) in wet and dry seasons were 52.16 ± 45.3 and 50.69 ± 15.8, respectively. The residual concentration of toxins in some water sources of this city exceeded the guidelines of Iran and the WHO in summer and spring.

Insecticide contamination in organic agriculture: Evidence from a long-term farming systems comparisons trial

Synthetic pesticides applied in conventional agriculture to control pests tend to compromise ecosystem services, and their residues may contaminate organic agriculture. To understand the significance of this contamination, also in small-scale farming systems in sub-Saharan Africa, quantitative data is required. Therefore, we compared synthetic insecticide and botanical/biopesticide residues in conventional and organic agricultural production systems after nine years of continuous cultivation of a maize-based crop rotation system at two sites in Kenya. Our results show high detectable concentrations of synthetic insecticide residues (imidacloprid, acetamiprid, chlorpyrifos, and chlorantraniliprole) in conventional plant produce and soil. Furthermore, the organophosphate chlorpyrifos was detected at concentrations above European Union Maximum Residue Limits (MRL) for plant produce, indicating potential risks for human health. Additionally, we detected imidacloprid, acetamiprid, chlorpyrifos, and chlorantraniliprole concentrations in the soil, indicating potential environmental harm. No residues of biopesticide/botanicals were detected in any of the production systems. However, we detected imidacloprid and chlorantraniliprole in organic plots. The findings indicate that the MRLs can be crossed even if synthetic insecticides are applied according to or below the recommended rates on the conventional plots. Thus, synthetic insecticides potentially risk human health and the environment, while botanicals and bio-pesticides represent a safe alternative.

A Laser-Induced Graphene-Based Sensor Modified with CeO2 for Determination of Organophosphorus Pesticides with Improved Performance

In this work, a flexible electrochemical sensor was developed for the detection of organophosphorus pesticides (OPs). To fabricate the sensor, graphene was generated in situ by laser-induced graphene (LIG) technology on a flexible substrate of polyimide (PI) film to form a three-electrode array, and pralidoxime (PAM) chloride was used as the probe molecule. CeO2 was used to modify the working electrode to improve the sensitivity of the sensor because of its electrocatalytic effect on the oxidation of PAM, and the Ag/AgCl reference electrode was prepared by the drop coating method. The effects of the laser power, laser scanning speed, and CeO2 modification on the electrochemical properties of the sensor were studied in detail. The results prove that the sensor has good repeatability, stability, and anti-interference ability, and it shows an excellent linear response in the chlorpyrifos concentration range from 1.4 × 10−8 M to 1.12 × 10−7 M with the detection limit of 7.01 × 10−10 M.

Effects of chlorpyrifos on histopathological biomarkers of the freshwater teleost Oreochromis niloticus

Abstract An attempt was made to evaluate histopathological changes in the gills, liver, and kidney tissues of the freshwater teleost Oreochromis niloticus as biomarkers of chlorpyrifos toxicity. An experiment was conducted in glass aquaria with O. niloticus exposed for 28 days to sub-lethal concentrations of chlorpyrifos of 0.0 µg L−1 (control), 10 µg L−1, and 20 µg L−1. Chlorpyrifos caused distortions of the primary gill lamellae structure, the curling of secondary lamellae, desquamation, and epithelial hyperplasia on secondary gill filaments. Hepatocyte vacuolation and nuclear membrane necrosis were found in the liver. Additionally, the shrinkage of the glomeruli, thickening of Bowman’s capsule, glomerular and tubular necrosis, intracytoplasmic vacuoles, and hyaline degeneration in the renal tubule were seen in the kidney of O. niloticus exposed to chlorpyrifos. No remarkable lesions were observed in the control group. The severity of lesions in the fish tissues was assessed using the standard semi-quantitative grading system. The degree of histopathological lesions in various fish tissues was found to increase with chlorpyrifos concentrations. Histopathological lesions appeared to be good biomarkers of chlorpyrifos toxicity.

A sustainable approach for the removal of chlorpyrifos pesticide from aqueous phase using novel nano magnetized biochar

In last two decades, organophosphate pesticides have become a prominent class of toxic water pollutants. Besides, these are not only poisonous for living beings, but their decomposition is also a time-taking process. For the first time, our study reports the application of nano-magnetized and carbonaceous adsorbents, obtained from orange peels (bio-waste), for the removal of chlorpyrifos from water resources. The -nano magnetized orange peels (NMOPs) were synthesized by the co-precipitation method with the use of iron salts. The competency of orange peels for chlorpyrifos adsorption was further enhanced by converting untreated orange peels (UOPs) into carbonaceous orange peels (COPs). The adsorbents were analyzed with FT-IR, SEM, EDX, XRD and VSM. The peak at 540 cm−1 in FTIR spectra corresponded to the Fe-O bond and confirmed the successful doping of iron salts on orange peels. Biosorption studies carried out by varying different parameters showed that these adsorbents are efficient for the uptake of chlorpyrifos. The effects of adsorbent dose, contact time, chlorpyrifos initial concentration, and pH were investigated to assess the adsorbents’ efficiency via biosorption studies. It was noted that the adsorbents showed maximum adsorption with adsorbent dose = 0.4 g, contact time = 50 mins, chlorpyrifos concentration = 150 ppm, pH = 4 and temperature = 30 °C. The adsorption maximum values (qmax) were found to be 68, 108 & 100 mg g−1 for the UOPs, COPs and NMOPs, respectively. Kinetic studies indicate that the removal of chlorpyrifos followed the pseudo-second-order model of adsorption. The adsorption results were effectively described by the Langmuir isotherm and Freundlich isotherm models.

Sublethal effect of chlorpyrifos on predatory behavior and physiology of Eocanthecona furcellata (Hemiptera: Pentatomidae).

Insecticides have been known to reduce the predation efficacy of natural enemies. However, the mechanism of the sublethal effect of insecticides on the functional response of predators remains unclear. This study investigated the sublethal effects of the broad-spectrum insecticide chlorpyrifos on the predatory bug Eocanthecona furcellata (Wolff), which is a potential biological control agent against pests in integrated pest management (IPM) programs. After exposure to a sublethal concentration of chlorpyrifos, the predation capacity and the maximum predatory number of E. furcellata increased by 11.27 and 15.26%, respectively, with prey handling time decreased by 15.07%, and the searching efficiency increased by 5.88-12.61%. Additionally, the intraspecific interference effect was enhanced. Glutathione S-transferase (GST) activity was significantly decreased after 12- to 60-h treatment. At 12 h after treatment, the expression levels of GST gene (GST3), acetylcholinesterase gene (AChE), and cytochrome P450 monooxygenasegene (cyp6B1) were significantly up-regulated by 1.47-, 1.48-, and 2.05-fold, respectively, while GST gene (GST1) was significantly down-regulated by 16.67-fold. These results indicated that a sublethal chlorpyrifos concentration inhibited the GST activity and stimulated the predatory behavior of E. furcellata. The results will advance our understanding of the toxicological mechanism of predatory stink bug responses to insecticides and predict chlorpyrifos' effects on predators in an IPM program.

HISTOPATHOLOGICAL EFFECT OF CHLORPYRIFOS PESTICIDE ON LIVER AND KIDNEY OF FRESH WATER FISH CATLA CATLA

All the natural water bodies are continuously being contaminated with toxic chemicals from industrial, agricultural and domestic activities. Chlorpyrifos is one of the most widely used organophosphate pesticides. Excessive application of pesticides from agricultural fields contaminate aquatic medium, resulting in serious damage to non-target species, including fish. The fish as a bioindicator of aquatic medium plays an important role in the monitoring of water pollution. Histopathology is an important tool for evaluating the action of any toxicant at tissue level. The focus of the present study is to measure the histological changes in liver and kidney of the fresh water fish Catla catla exposed to sub lethal concentrations of chlorpyrifos 1/15th of the 96 hour LC50 values for the period of 10 and 20 days. The fish exposed to chlorpyrifos showed mild vacuolar hepatocytes, dilation of central vein, vaculor degenerative changes, mild hyperaemia and severe hyperaemia of central vein in the liver tissue slide. The changes observed in kidney slide due to the impact of chlorpyrifos toxicity are hemorrhage, degenerative changes in between tubules, constriction of primary tubule, vacuolardegenerative changes, necrosis in epithelial lining of proximal tubules, chlorpyrifos compound induced.

Quantification, distribution and cancer risk assessment of pesticides in mango orchards of Kerala, India

ABSTRACT Muthalamada in the Western Ghats has been a prominent mango-cultivating region of Asia for the last three decades. In the present study, soil samples from Muthalamada mango orchards were analysed for pesticide contents and estimated associated cancer risk indices. Sixteen pesticides, including organochlorines, organophosphates, synthetic pyrethroids, and carbamates were detected in the region. The concentration of chlorpyrifos (2.05–720.27 mg/kg) was the highest level reported from any agroecosystem in India. Community health risk assessment indicates high carcinogenic risk and greater susceptibility in children. The study demonstrates the need for immediate interventions to reduce the ecological and human cancer risks in the mango orchards.

Assessing phytotoxicity and cyto-genotoxicity of two insecticides using a battery of in-vitro biological assays.

Intensive use of chemical pesticides in agriculture poses environmental risks and may have negative impacts on agricultural productivity. The potential phytotoxicity of two chemical pesticides, chlorpyrifos (CPS) and fensulfothion (FSN), were evaluated using Cicer arietinum and Allium cepa as model crops. Different concentrations (0-100 μgmL-1) of both CPS and FSN decreased germination and biological attributes of C. arietinum. High pesticide doses significantly (p≤0.05) caused membrane damage by producing thiobarbituric acid reactive substances (TBARS) and increasing proline (Pro) content. Pesticides elevated ROS levels and substantially increased the superoxide anions and H2O2 concentrations, thus aggravating cell injury. Plants exposed to high pesticide dosages displayed significantly higher antioxidant levels to combat pesticide-induced oxidative stress. Ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) increased by 48%, 93%, 71%, 52% and 94%, respectively, in C. arietinum roots exposed to 100 µgFSNmL-1. Under CLSM, pesticide-exposed C. arietinum and 2',7'-dichlorodihydrofluorescein diacetate (2'7'-DCF) and 3,3'-diaminobenzidine stained roots exhibited increased ROS production in a concentration-dependent manner. Additionally, enhanced Rhodamine 123 (Rhd 123) and Evan's blue fluorescence in roots, as well as changes in mitochondrial membrane potential (ΔΨm) and cellular apoptosis, were both associated with high pesticide dose. Allium cepa chromosomal aberration (CAs) assay showed a clear reduction in mitotic index (MI) and numerous chromosomal anomalies in root meristematic cells. Additionally, a-dose-dependent increase in DNA damage in root meristematic cells of A. cepa and conversion of the super-coiled form of DNA to open circular in pBR322 plasmid revealed the genotoxic potential of pesticides. The application of CPS and FSN suggests phytotoxic and cyto-genotoxic effects that emphasize the importance of careful monitoring of current pesticide level in soil before application and addition at optimal levels to soil-plant system. It is appropriate to prepare both target-specific and slow-release agrochemical formulations for crop protection with concurrent safeguarding of agroecosystems.

Occurrence of chlorpyrifos and organochlorine pesticides in a native bumblebee (Bombus pauloensis) living under different land uses in the southeastern Pampas, Argentina

Pollinators such as Apidae bees are vital for ecosystems and food security. Unfortunately, their populations have declined due to several factors including pesticide use. Among them, the organophosphate insecticide chlorpyrifos, poses a global threat, while legacy compounds like organochlorine pesticides (OCPs) easily bioaccumulate, increasing the concern. Bombus pauloensis, a widely distributed native bee in Argentina, is used for commercial pollination; however, information regarding their health status is scarce. This study assessed chlorpyrifos and OCP levels in B. pauloensis (workers and males) and related environmental matrices living from three different land uses schemes, by means of GC-ECD and GC–MS. The ornamental horticulture field (OP) showed the highest total pesticide concentrations in workers (13.1 ng/g), flowers and soils, whereas the organic agriculture field (OA) exhibited the lowest. Chlorpyrifos was the most abundant compound, accounting for at least 20 % of pesticide load across all matrices. The food production horticulture field (FH) had the highest chlorpyrifos concentration in workers, males and soils (5.0, 4.4 and 3.3 ng/g, respectively), suggesting a local greater usage, whereas OA showed the lowest. Regarding OCPs groups, Drins and DDTs were predominant in most matrices, with FH males registering the highest levels (4.0 and 2.5 ng/g, respectively), closely followed by OP. However, metabolites' contribution indicated historical use and atmospheric inputs in all sites. Multivariate analyses confirmed the significance of site and bumblebee sex to explain pesticide composition. Males from all sites exhibited higher chlorpyrifos levels than workers and this trend was similar for some OCP groups. Overall, OA differed from FH and OP, indicating a correlation between production modes and pesticide profiles. This study demonstrates the value of B. pauloensis as a pesticide biomonitor but also offers insights into its populations' health in the area. In this sense, this information could be useful towards the preservation of this crucial pollinator.

Enhanced remediation of chlorpyrifos-contaminated soil by immobilized strain Bacillus H27

Chlorpyrifos is a pesticide widely used in agricultural production with a relatively long residual half-life in soil. Addressing the problem of residual chlorpyrifos is of universal concern. In this study, rice hull biochar was used as an immobilized carrier to prepare the immobilized strain H27 for the remediation of chlorpyrifos-contamination soil. Soil microorganisms after remediation were investigated by ecotoxicological methods. The immobilized strain H27 had the highest removal rate of chlorpyrifos when 10% bacterial solution was added to the liquid medium containing 0.075-0.109 mm diameter biochar cultured for 22 hr. This study on the removal of chlorpyrifos by immobilized strain H27 showed that the initial concentration of chlorpyrifos in solution was 25 mg/L, and the removal rate reached 97.4% after 7 days of culture. In the soil, the removal rate of the immobilized bacteria group increased throughout the experiment, which was significantly higher than that of the free bacteria and biochar treatment groups. The Biolog-ECO test, T-RFLP and RT-RCR were used to study the effects of the soil microbial community and nitrogen cycling functional genes during chlorpyrifos degradation. It was found that ICP group had the highest diversity index among the four treatment groups. The microflora of segment containing 114 bp was the dominant bacterial community, and the dominant microflora of the immobilized bacteria group was more evenly distributed. The influence of each treatment group on ammonia-oxidizing bacteria (AOB) was greater than on ammonia-oxidizing archaea (AOA). This study offers a sound scientific basis for the practical application of immobilized bacteria to reduce residual soil pesticides.

Study on the effective removal of chlorpyrifos from water by dielectric barrier discharge (DBD) plasma: The influence of reactive species and different water components

Chlorpyrifos is a widely used organophosphorus pesticide with a significant impact on water. Although non-thermal plasma is a promising technology for removing organic pollutants from water, there is still a limited understanding of how plasma degradation of pesticides works as well as the influence of various water components on pesticide degradation. In this paper, the effects of different influencing factors (different power, different initial concentration of chlorpyrifos, different environmental components) on the degradation of chlorpyrifos in water were investigated, and the relevant mechanism of plasma for the degradation of chlorpyrifos was explored. The experimental results show that the plasma power is 22.2 W and treatment for 10 min, 20 mg/L chlorpyrifos is almost completely degraded and its toxicity is greatly reduced. it was found that Cl− can effectively promote the degradation of chlorpyrifos, while CO32–, HCO3– and HA can inhibit the degradation of chlorpyrifos, SO42− and NO3– have no obvious effect on the removal efficiency of chlorpyrifos. ESR and quenching experiments confirmed that O2–, OH, and 1O2 were effective reactive species in the degradation of chlorpyrifos, and the effect of O2– was more obvious. The long-lived reactive species H2O2, O3 also have a certain promoting effect in the degradation process. The intermediate degradation production and possible degradation path of chlorpyrifos were inferred by UPLC-MS.

Chlorpyrifos Mediated Amendment in Protein Profiling of Bacillus spp.

Chlorpyrifos is a popularly used organophosphate and has immense agricultural applications. It is one of the major causes of soil contamination due to its higher adsorption coefficient, hydrophobicity and relatively longer persistence. Conducted study was attempted to monitor responses of Bacillus megaterium, isolated from the paddy growing agricultural field towards different doses of chlorpyrifos. The results highlighted the tolerance of this bacterium to higher concentration (800 mg L-1) of chlorpyrifos. However, protein is an important macromolecule in any living cells and is representative of all the important functions going inside the cell. Thus, quantification and profiling of protein of this bacterium in response to different doses of chlorpyrifos would probably decipher expression, if any, of stress responsive gene(s). The overall findings revealed that Bacillus megaterium expressed a few enzymes/ or proteins in order to show adaptation towards surrounding environment. It can be an efficient degrader of chlorpyrifos, hence, could be exploited for remediation of chlorpyrifos contaminated sites.

Pesticides residues determination and probabilistic health risk assessment in the soil and cantaloupe by Monte Carlo simulation: A case study in Kashan and Aran-Bidgol, Iran

Cantaloupe is a popular agricultural product in the hot season of Iran. On the other hand, the frequent use of pesticides in cantaloupe fields is the most important threat to the health of farmers and consumers. Therefore, the present study aims to measure the concentration of diazinon (DZN), chlorpyrifos (CPF), and malathion (MLT) in cantaloupe cultivated in Kashan and Aran-Bidgol (Iran) and to estimate the possible oral and dermal risk of these pesticides by Monte Carlo simulation (MCS). 36 cantaloupe samples, 18 samples before, and 18 samples after the latent period were collected from different places of cantaloupe cultivation from April to May 2021. After measuring the pesticides using the QuEChERS approach, oral and dermal risk assessments were calculated.The mean and standard deviation of the concentrations of chlorpyrifos, malathion, and diazinon in 18 cantaloupe samples, after the latent period, were (30.39 ± 13.85), (18.361 ± 1.8), and (21.97 ± 0.86) μg kg-1, respectively. Concentration of Malathion, diazinon, and Chlorpyrifos in the soil were 0.22, 0.25, and 0.3 mg kg-1, respectively, and pesticide cumulative risk assessment in soil was obtained 0.011 for Malathion, 0.05 for diazinon and 0.03 for Chlorpyrifos. Target Hazard Quotient (THQ) according to the cantaloupe consumption and dermal exposure in children and adults, was safe range. Although non-cancerous dermal and oral risk of cantaloupe is low, constant exposure can be harmful. Therefore, the findings of this study play an important role in increasing the understanding of the negative health consequences of pesticide contamination in cantaloupe for consumers, especially local residents, and can help by adopting remedial strategies to reduce environmental concerns.

Environmental fate of chlorpyrifos in Rhodic Ferralsol grown with corn during summer and winter seasons under high-intensity rainfall

The interactions between pesticides' physicochemical properties and edaphoclimatic factors influence their distribution into the environment. Understanding how those factors interact in a changing environment is crucial for mitigating environmental and agronomic problems. Thus, a percolation lysimeter with undisturbed soil and suction lysimeters were used to conduct a field study to evaluate the distribution of chlorpyrifos sprayed in a corn crop cultivated in a Rhodic Ferralsol in simulated extreme rainfall conditions. The mobility of chlorpyrifos was evaluated under simulated precipitation (150 mm h−1), 24 h and 48 h after applying the chlorpyrifos in different phenological stages of corn during the summer and winter crops in two agricultural years. In addition, GC-ECD determined the residual concentration of chlorpyrifos in the runoff and leached samples. Finally, a laboratory adsorption study was conducted with Rhodic Ferralsol to find the chlorpyrifos adsorption capacity in different temperatures, with and without soil organic matter. Our results show that soil organic matter is essential in chlorpyrifos adsorption, responsible for approximately 5% pesticide retention, which could be 25% higher during winter. High-intensity rainfalls positively affect runoff and leaching; nevertheless, these are responsible for only 0.2% of all chlorpyrifos amounts, as the soil is the major reservoir of chlorpyrifos by retention into clays and organic matter. Furthermore, the corn growth stages directly affect chlorpyrifos transportation, with higher amounts observed in runoff and leaching during the first and last corn growth stages. Therefore, in the conditions such as high-intensity rainfall, exposed soil, shallow soil profile, and temperatures below 20 °C, attention should be paid to chlorpyrifos spray with special regard to the weather forecast, avoiding its spray near rainfall events. Further studies should be conducted in other soil classes and rainfall conditions to validate our observations.

Population-level variation in insecticide tolerance across three life stages of the trematode Echinostoma trivolvis

Ecotoxicological studies using single test populations may miss the inherent variation of natural systems and limit our understanding of how contaminants affect focal species. Though population-level variation in pesticide tolerance is commonly observed in host taxa, few studies have assessed population-level differences in the tolerance of parasites to different contaminants. We investigated population-level variation in insecticide tolerance of three Echinostoma trivolvis life stages (egg, miracidium, and cercaria) to three insecticides (carbaryl, chlorpyrifos, and diazinon). We tested two relevant metrics of insecticide tolerance—baseline and induced—across up to eight different parasite populations per life stage. Across all life stages, the insecticide treatments tended to reduce survival, but the magnitude of their effects often varied significantly among populations. Surprisingly, we found that exposure to chlorpyrifos increased the hatching success of echinostome eggs relative to the control treatment in three of six tested populations. We also found that cercariae shed from snails previously exposed to a sublethal concentration of chlorpyrifos had a significantly lower mortality rate when subsequently exposed to a lethal concentration of chlorpyrifos relative to individuals from snails that were not previously exposed; this suggests inducible tolerance in cercariae. We found no evidence that insecticide tolerance is correlated across parasite life stages within a population. Together the findings of our study demonstrate that single-population toxicity assays may greatly over- or underestimate the effects of pesticides on the survival of free-living parasite stages, insecticide tolerance levels may not be predictable from one parasite life stage to the next, and insecticides can have both expected and counterintuitive effects on non-target taxa.

Isolation and characterization of chlorpyrifos-degrading bacteria in tea-growing soils

The excess use of pesticides in the agricultural sector has caused environmental pollution and affected the complete ecosystem. Among the various commonly used pesticides, chlorpyrifos (CPF) is widely used against multiple agrarian pests due to its effectiveness and higher insecticidal activities. However, along with its beneficial usage, CPF has various residual effects on the environment, causing multiple negative impacts on aquatic organisms and human health. Consequently, methods for eliminating CPF in the background are essential. Among the currently available approaches to CPF remediation, biological methods using microorganisms are eco-friendly and cost-effective. Therefore, this study was conducted to isolate and characterize chlorpyrifos-degrading bacteria from the tea-growing soil of Vietnam. For this, soil samples were collected from the 20 tea-growing areas of Vietnam. From the collected samples, three bacterial strains viz., Methylobacterium populi CNN2, Ensifer adhaerens VNN3, and Acinetobacter pittii CNN4 have been isolated by using streak plate method and identified based on 16S rRNA gene analysis. The study results showed that under laboratory conditions, E. adhaerens VNN3 had the highest CPF degradation ability and was followed by the strain M. populi CNN2. In liquid medium, CPF concentration (100 mg/L) was reduced by 95.2% and 81.4% by E.adhaerens VNN3 and M. populi CNN2, respectively, after 72 h. Further, under in-vitro conditions, the concentration of CPF was reduced from 500 mg/kg to 112 ± 1.73 (77.6%) and 197 ± 2.08 mg/kg (60.6%) by E. adhaerens VNN3 and M. populi CNN2, respectively. Based on the obtained results, it can be concluded that E. adhaerens VNN3 and M. populi CNN2 can be used for CPF-contaminated agricultural soil remediation.