Toxicological effects of dimethomorph on soil enzymatic activity and soil earthworm (Eisenia fetida)

Photoaged Tire Wear Particles Leading to the Oxidative Damage on Earthworms (Eisenia fetida) by Disrupting the Antioxidant Defense System: The Definitive Role of Environmental Free Radicals

Tire wear particles (TWPs) have caused increasing concerns due to their detrimental effects on the soil ecosystem. However, the role of weathering in altering the toxicity of TWP to soil organisms is poorly understood. In this study, the toxicity of original and photoaged TWP was compared using earthworms (Eisenia fetida) as soil model organisms. The obtained results indicated that photoaging of TWP resulted in an increase of environmentally persistent free radicals (EPFRs) from 3.69 × 1017 to 5.20 × 1017 spin/g. Meanwhile, photoaged TWP induced the changes of toxic endpoint in E. fetide, i.e., the increase of the weight loss and death ratio from 0.0425 to 0.0756 g/worm and 23.3 to 50% compared to original TWP under a 10% concentration, respectively. Analyses of transcriptomics, antioxidant enzyme activity, and histopathology demonstrated that the enhanced toxicity was mainly due to oxidative damage, which was induced by disruption in the antioxidant defense system. Free-radical quenching and correlation analysis further suggested that the excessive production of ex vivo reactive oxygen species, induced by EPFRs, led to the exhaustion of the antioxidant defense system. Overall, this work provides new insights into the potential hazard of the weathered TWP in a soil environment and has significant implications for the recycling and proper disposal of spent tire particles.

Co-exposure of dimethomorph and imidacloprid: effects on soil bacterial communities in vineyard soil

In Taiwan, the pesticides dimethomorph and imidacloprid are recommended for pest control in vineyards. Therefore, tank-mixing of these two pesticides is usually a routine practice before application. This study analyzed the influence of vineyard soil microbial flora under the recommended and high dosages (100 times the recommended dosage) of dimethomorph and imidacloprid. Individual and combined applications of pesticides were also tested through batches of soil incubation experiments. Four treatments-control (C), dimethomorph (DT), imidacloprid (IM), and mixed application of dimethomorph and imidacloprid (ID)-were used in the experimental design. From the soil metabolism, no significant reaction was observed after 2 months in the recommended dosage group, regardless of whether the pesticides were being applied individually or combined. For the high dosage, imidacloprid showed a higher effect than the co-exposure treatments, showing a possible prolonged effect after its repetitive application. From PCoA analysis, pesticide treatments altered the soil ecology after 2 months, and the effect of imidacloprid can be explicitly observed at high dosages. At the phylum level, Acidobacteria can indicate pesticide application around the recommended dosage. It was inhibited by ID on day 7 and was augmented by all pesticides on day 63. The effect of the recommended dosage of pesticide mixtures after 2 months of incubation was revealed in the minor families Gemmataceae and Pirellulaceae, while the high dosage treatments affected both the core and the minor families. Our findings verified the changes in the composition of microbial communities upon pesticide application, which would affect carbon, nitrogen, sulfur, phosphorous cycles, and contaminant removal ability within the vineyard.

Pesticide residues in common fruits and vegetables in Henan Province, China

In this study 3307 samples of 24 vegetables and fruits from 18 regions of Henan Province, China, were collected in 2021 with the aim of assessing the levels of pesticide residues and analysing the differences between different sources in Henan Province. Thirteen kinds of pesticides were analysed by gas chromatography-mass spectrometry (GC-MS) and detection rates were compared by the chi-square test. In all samples, except ginger, pimento, edible fungi and yam, pesticide residues were detected. The detection rates of difenoconazole, acetamiprid, carbendazim, procymidone, emamectin benzoate, lambda-cyhalothrin, cypermethrin and dimethomorph in supermarkets and traditional farmers' markets were different. The difenoconazole group and the dimethomorph group were both statistically different (P < 0.05). This study showed common vegetables and fruits to contain pesticide residues in Henan Province and provided a scientific basis for their evaluation. Different sources take different regulatory measures to control pesticide residues to ensure food safety.

Empirical model to assess leaching of pesticides in soil under a steady-state flow and tropical conditions

Abstract

An empirical model of leaching of pesticides was developed to simulate the concentration of fungicides throughout unsaturated soil. The model was based on chemical reactions and the travel time of a conservative tracer to represent the travel time required for water to flow between soil layers. The model's performance was then tested using experimental data from dimethomorph and pyrimethanil applied to the soil under field and laboratory conditions. The empirical model simulated fungicide concentration on soil solids and in soil solution at different depths over time (mean square error between 2.9 mg2 kg-2 and 61mg2 kg-2) using sorption percentages and degradation rates under laboratory conditions. The sorption process was affected by the organic carbon, clay, and the effective cation exchange capacity of the soil. The degradation rate values of dimethomorph (0.039 d-1-0.009 d-1) and pyrimethanil (0.053 d-1-0.004 d-1) decreased from 0 to 40 cm and then remained constant in deeper soil layers (60-80 cm). Fungicide degradation was a critical input in the model at subsurface layers. The model was determined to be a reliable mathematical tool to estimate the leachability of pesticides in tropical soil under a steady-state flow. It may be extended to other substances and soils for environmental risk assessment projects.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13762-023-05038-w.

Comparative Transcriptome Analysis to Investigate the Immunotoxicity Mechanism Triggered by Dimethomorph on Human Jurkat T Cell Lines

Dimethomorph (DMM) is a broad-spectrum fungicide used globally in agricultural production, but little is known regarding the immunotoxicity of DMM in humans. In this study, the immunotoxicity of DMM on human Jurkat T cells was evaluated in vitro. The results indicated that the half-effective concentration (EC₅₀) of DMM for Jurkat cells was 126.01 mg/L (0.32 mM). To further elucidate the underlying mechanism, transcriptomics based on RNA sequencing for exposure doses of EC₂₅ (M21) and EC₁₀ (L4) was performed. The results indicated that compared to untreated samples (Ctr), 121 genes (81 upregulated, 40 downregulated) and 30 genes (17 upregulated, 13 downregulated) were significantly differentially regulated in the L4 and M21 samples, respectively. A gene ontology analysis indicated that the significantly differentially expressed genes (DEGs) were mostly enriched in the negative regulation of cell activities, and a KEGG pathway analysis indicated that the DEGs were mainly enriched in the immune regulation and signal transduction pathways. A quantitative real-time PCR for the selected genes showed that compared to the high-dose exposure (M21), the effect of the low-dose DMM exposure (L4) on gene expression was more significant. The results indicated that DMM has potential immunotoxicity for humans, and this toxicity cannot be ignored even at low concentrations.

Use of cover crops in vineyards to prevent groundwater pollution by copper and organic fungicides. Soil column studies

Several fungicides, such as copper and organic products (synthetic or natural), are currently being used in vineyards to control downy mildew (Plasmopara viticola) resulting in soil, surface water, and groundwater pollution. This study aims to assess the effectiveness of using cover crops as an agricultural practice in vineyards to protect soil and groundwater pollution. For that purpose, we performed different soil column studies to quantify soil leaching of selected fungicides (copper, dimethomorph, oxathiapiprolin, zoxamide, acibenzolar-s-methyl, and laminarin) following a rainfall event after a conventional fungicide vineyard application. Two types of vineyard soils (loam and sandy-loam soil textures) and three ground covers (bare ground, monoculture cover, and polyculture cover) were assessed. These studies were completed with hydroponic assays to check the effectiveness of cover roots in the fungicide degradation. Mass balance results show that whereas 3 fungicides (Cu, zoxamide, and dimethomorph) were leached through sandy soil columns, only copper was leached from loam soil columns. The effect of cover crops was only significant for Cu and zoxamide when fungicides were applied 24 h before the rain event, reducing the fungicide leaching by 30%. Hydroponic studies showed that cover roots enhanced the kinetic rates of almost all tested fungicides by 5-467%, suggesting that they are relevant to improving the degradation of fungicides in the soil column. These results are relevant to drawing up recommendations on the use of cover crops to protect soil and groundwater pollution by fungicides.

A pH- and redox-stimulated responsive hollow mesoporous silica for triggered delivery of fungicides to control downy mildew of Luffa cylindrica

BACKGROUND

Downy mildew, a devastating disease of cucurbitaceous crops caused by Pseudoperonospora cubensis. Although a variety of fungicides are used to control downy mildew, choosing an effective product can be challenging. Environmental stimulus-responsive pesticide delivery systems have great potential to improve the effectiveness of disease and pest control and reduce the impact on environmentally beneficial organisms.

RESULTS

In this work, a disulfide bond (SS)-modified and chitosan oligosaccharide (COS)-capped hollow mesoporous silica (HMS) pesticide delivery system was synthesized using a hard template method for the control of downy mildew in cucurbit crops. The synthesized nanoparticles were loaded with dimethomorph (DMM), denoted as DMM@HMS-SS-COS, and the developmental toxicity of these nanoparticles to zebrafish embryos were evaluated. The results showed that the prepared DMM@HMS-SS-COS exhibited excellent dual response properties to pH and glutathione (GSH), with an encapsulation rate of up to 24.36%. DMM@HMS-SS-COS has good ultraviolet (UV) radiation stability and adhesion properties. Compared with dimethomorph suspension concentrate (SC), DMM@HMS-SS-COS was more effective against downy mildew for up to 21 days. Toxicity tests showed that DMM@HMS-SS-COS significantly reduced the effect of DMM on the hatching rate and survival rate of zebrafish embryos.

CONCLUSIONS

This work not only demonstrates that DMM@HMS-SS-COS could be used as a nanodelivery system for intelligent control of downy mildew but also emphasizes the necessity of increasing the acute toxicity of nanoformulations to non-target organisms in environmental risk assessment. © 2022 Society of Chemical Industry.

Toxicological effects of different ionic liquids on growth, photosynthetic pigments, oxidative stress, and ultrastructure of Nostoc punctiforme and the combined toxicity with heavy metals

Ionic liquids (ILs¹) are used widely because of their excellent properties. However, their ecotoxicity for environment has aroused great concern. Here we studied, the toxicity of three ILs with different numbers of methyl substituents and anions as well as the combined effect of heavy metals to edible algae Nostoc punctiforme. The results show that fresh weight and chlorophyll content decreased, indicating that the growth and photosynthesis were adversely affected. Polysaccharides and soluble protein contents decreased, resulting in a reduced nutritional value of Nostoc punctiforme. ILs can produce many reactive oxygen species (ROS), which lead to increased the malondialdehyde (MDA) content. In order to remove excessive ROS, antioxidant enzymes activity is increased, but decreases under high IL concentration, because the structure and function of the enzymes became damaged. ILs cause stress to algae, as the cell ultrastructure is indicating by increased amounts of starch and osmiophilic globules. The combined action of heavy metals with ILs decreases the antioxidant enzymes activity and chlorophyll content, and increases the MDA content. The results show that the order of toxicity is [C₈MIM]Cl >[C₈MIM]Br> [C₈DMIM]Br. The combination of heavy metals and ILs cause an increase of the toxicity to Nostoc punctiforme.

Human cytochrome P450 3A-mediated two-step oxidation metabolism of dimethomorph: Implications in the mechanism-based enzyme inactivation

Dimethomorph (DMM), an effective and broad-spectrum fungicide applied in agriculture, is toxic to environments and living organisms due to the hazardous nature of its toxic residues. This study aims to investigate the human cytochrome P450 enzyme (CYP)-mediated oxidative metabolism of DMM by combining experimental and computational approaches. Dimethomorph was metabolized predominantly through a two-step oxidation process mediated by CYPs, and CYP3A was identified as the major contributor to DMM sequential oxidative metabolism. Meanwhile, DMM elicited the mechanism-based inactivation (MBI) of CYP3A in a suicide manner, and the iminium ion and epoxide reactive intermediates generated in DMM metabolism were identified as the culprits of MBI. Furthermore, three common pesticides, prochloraz (PCZ), difenoconazole (DFZ) and chlorothalonil (CTL), could significantly inhibit CYP3A-mediated DMM metabolism, and consequently trigger elevated exposure to DMM in vivo. Computational studies elucidated that the differentiation effects in charge distribution and the interaction pattern played crucial roles in DMM-induced MBI of CYP3A4 during sequential oxidative metabolism. Collectively, this study provided a global view of the two-step metabolic activation process of DMM mediated by CYP3A, which was beneficial for elucidating the environmental fate and toxicological mechanism of DMM in humans from a new perspective.

The protective layer formed by soil particles on plastics decreases the toxicity of polystyrene microplastics to earthworms (Eisenia fetida)

The recent discovery of microplastics contaminants in most ecosystems has raised major health issues, yet knowledge on their impact on soil organisms is limited, especially their toxicity evolution with aging. Herein, the toxicity of polystyrene microplastic (PS-MP) to earthworm (Eisenia fetida) along with aging was investigated. Results showed that the 28 d-LC₅₀ (50% lethal concentration) of PS-MP was 25.67 g kg^-1, whereas that increased to 96.47 g kg^-1 after PS-MP initially aged in soil for 28 days, indicating the toxicity of PS-MP decreased with aging. Laser scanning confocal microscope and scanning electron microscope (SEM) found that the toxicity of PS-MP to earthworm may be due to the ingestion of PS-MP by earthworms and the physical damage (e.g., epidermis abrasion and setae loss) of PS-MP to earthworms. Similarly, the levels of reactive oxygen species, antioxidant enzyme activities and malondialdehyde content increased with PS-MP concentrations from 0.1 to 1.5 g kg^-1, but decreased with aging from 7 to 28 days. The integrated biomarker response index also confirmed that the toxicity of PS-MP decreased with aging. SEM found that PS-MP were progressively covered by soil particles during soil aging, inducing the formation of protective layer and increasing the particle size of PS-MP, which prevented direct contact with earthworms and decreased the ingestion of PS-MP, in turn decreased PS-MP toxicity. Overall, our study provides valuable insights for elucidating the effect of aging on the toxicity of microplastics.

Ecotoxicity of herbicide carfentrazone-ethyl towards earthworm Eisenia fetida in soil

Herbicides pose a potential threat to the soil biodiversity and health. Carfentrazone-ethyl (CE), a triazolinones herbicide, is increasingly used in agricultural production. Its non-target toxic effects on soil microorganisms and soil enzymes are reported recently. However, the sublethal toxicity of CE on soil invertebrates like earthworms is not yet known. Therefore, in this work, the sublethal toxic effects of CE (0.05, 0.5, and 5.0 μg/g in soil) on the soil earthworm (Eisenia fetida) were evaluated using a battery of biomarkers including reactive oxygen species (ROS), enzyme (superoxide dismutase-SOD, catalase-CAT, peroxidase-POD, and glutathione S-transferase-GST) activities, malondialdehyde (MDA) contents, histopathological and DNA damage. Results indicated that CE increased ROS contents, enzyme activities, and MDA contents in the short-time (14 d), thus, causing a slight oxidative stress to E. fetida. However, the toxic effects of CE on earthworms gradually disappeared after 14 days. The CE did not cause histopathological and DNA damage in earthworms. Integrated Biological Response index (IBR) indicated that both concentration and exposure time of CE regulated its sublethal toxicity on earthworms. In conclusion, herbicide CE is safe to soil invertebrate earthworms when applied at the recommended doses. Our results contribute to the current understanding of CE effects on soil earthworms, and can be useful in developing soil health strategies under agrochemical use.

Interactive effects of polymethyl methacrylate (PMMA) microplastics and salinity variation on a marine diatom Phaeodactylum tricornutum

Until now, knowledge about the interactive effects of microplastics and environmental factors on primary producers is quite limited. In this work, a marine diatom (Phaeodactylum tricornutum) was exposed to polymethyl methacrylate (PMMA) microplastics at different salinities (25, 35, and 45‰) for 10 days in order to study their interactive effects. Results showed that growth of P. tricornutum was negatively affected by PMMA microplastics and salinity variation with a minimum EC₅₀ value of 91.75 mg L^-1. Photosynthetic activity of P. tricornutum was also inhibited by the two factors, and their interactive effects on chlorophyll fluorescence parameters (F_v/F_m and Φ_PSII) were significant. In the algal cells, soluble protein accumulated, activities of two antioxidant enzymes changed, and malondialdehyde (MDA) content increased when this diatom was exposed to the microplastics at different salinities. These data would help to evaluate the risks of microplastics to primary producers under different environmental factors.

Gold-based immunochromatographic strip assay for detecting dimethomorph in vegetables

Gold-based immunochromatographic strip assay for detecting dimethomorph in vegetables.

Enantioselective bioaccumulation and detoxification mechanisms of earthworms (Eisenia fetida) exposed to mandipropamid

As a novel chiral amide fungicide, the enantioselective behaviors of mandipropamid in the soil environment are unclear. Furthermore, there is a need to understand the stress response mechanisms of soil organisms exposed to mandipropamid isomers. Therefore, the selective bioaccumulation of mandipropamid isomers and detoxification mechanisms of earthworms (Eisenia fetida) were investigated in this study. Our results suggested that the enantioselective bioaccumulation of mandipropamid in earthworms occurred with the preferential enrichment of S-(+)-isomer. The activities of detoxification enzymes, such as cytochrome P450 (CYP450), glutathione-S-transferases (GST), and carboxylesterase (CarE), changed significantly upon exposure to S-(+)- and R-(-)-mandipropamid (particularly for CYP450 and GST). A transcriptome analysis revealed that more differentially expressed genes (DEGs) were observed under S-(+)-isomer exposure (15,798) than those under R-(-)-isomer exposure (12,222), as compared to the control group. These DEGs were mainly enriched in bile secretion and thyroid hormone signaling pathways, which were related to the detoxification process in earthworms. Moreover, the 20 DEGs, which exhibited the most profound changes (such as CYP2 and CYP3A4) in these pathways, were screened, clustered, and observed to be mainly involved in regulating the detoxification function of earthworm cells. These results indicated that detoxification systems played an essential role in the stress response to mandipropamid exposure. Additionally, earthworms were more sensitive to the stress induced by S-(+)-mandipropamid than that induced by R-(-)-mandipropamid. This is the first study to elucidate the mandipropamid detoxification mechanism of earthworms at the enantiomer level, which can be beneficial for remediating chiral pollutants.

Multiresidue procedure to assess the occurrence and dissipation of fungicides and insecticides in vineyard soils from Northwest Spain

The presence of fungicide and insecticide residues in wine has been largely investigated. However, few studies have addressed the persistence of these compounds in vineyard soils. In this research, we investigate the residues of a relevant number of fungicides and insecticides in vineyard soils, obtained in the Northwest of Spain, at the beginning of each agriculture campaign. Moreover, the dissipation of species showing high concentrations were monitored during the non-vegetative period of vines, in order to understand their soil evolution between application campaigns. To this end, a multiresidue analytical procedure based on pressurized liquid extraction (PLE) followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) determination was first optimized. Under final working conditions, absolute recoveries in the range from 70 to 130% were achieved for 44 out of 51 selected compounds. The method LOQs remained at the low ng g^-1 level (0.2-13 ng g^-1) with a linear response range up to 500 ng g^-1. Analysis of vineyard soils, collected during a 2-year period, from a geographic area with a high incidence of fungal diseases, demonstrated the presence of relevant concentrations of several fungicides and the insecticide imidacloprid (IMI) in this compartment. Most compounds detected at the end of the application season remained in soil at the beginning of the next year campaign. Among them, six fungicides (dimethomorph, boscalid, myclobutanil, penconazole, pyraclostrobin and pyrimethanil) and IMI showed average dissipation efficiencies below 50%, so they pose a potential to accumulate in this kind of soils.

Rapid degradation of dimethomorph in polluted water and soil by Bacillus cereus WL08 immobilized on bamboo charcoal-sodium alginate

The presence of hazardous dimethomorph residues in the environment poses a threat to birds, aquatic organisms and mammals. The novel pure strain Bacillus cereus WL08 responsible for detoxifying dimethomorph was isolated from dimethomorph-polluted soils. The immobilized system of WL08 was developed using bamboo charcoal (BC) and sodium alginate (SA). Immobilization significantly improved tolerance and stability of strain WL08. Under optimal conditions of pH 7.0 and 30 ℃, free and immobilized WL08 degraded 66.95% and 96.88% of 50 mg/L dimethomorph within 72 h, respectively. Moreover, strain WL08 effectively degraded dimethomorph to simple products which were lower toxic than dimethomorph. In a continuous reactor system, immobilized WL08 removed 85.61% of dimethomorph for 30 d at an influent concentration of 50-100 mg/L. In the field soil sprayed with 4.20 kg a.i./ha 80% dimethomorph water dispersible granule (WDG) was treated by immobilized WL08, the lower half-life (1.93 d) was observed, as compared with free WL08 (4.28 d) and natural dissipation (23.82 d). Immobilized WL08 can be considered as a tool for the removal of dimethomorph in water-soil systems. This study provides a feasible microbe-based strategy for bioremediation of dimethomorph-polluted environments.

Benzotriazole alleviates copper mediated lysosomal membrane damage and antioxidant defense system responses in earthworms (Eisenia fetida)

Benzotriazole (BTR) is a common corrosion inhibitor used to protect copper (Cu) and Cu alloys. To reveal the combined subacute toxicity of BTR and Cu at environmental levels on terrestrial animals, the activity of antioxidative enzymes and the glutathione levels in earthworms (Eisenia fetida) of the single or co-exposure treatments were determined. The activity of both antioxidant enzymes and non-enzymatic antioxidants was affected by BTR in earthworms. Moreover, the analyses of lysosomal neutral red retention time and total antioxidant capacity indicated a detoxification effect of BTR on Cu-induced impairments of the antioxidant defense capacity in earthworms. The apoptotic rate of coelomocytes in earthworms of the co-exposure treatment was lower than that in earthworms treated with Cu only, indicating that BTR alleviates Cu mediated lysosomal membrane damage and antioxidant defense system responses in earthworms.

Insight into the mechanisms of plant growth promoting strain SNB6 on enhancing the phytoextraction in cadmium contaminated soil

Plant growth-promoting rhizobacteria (PGPR) assisted accumulator has been proposed as a phytoextraction method to clean cadmium (Cd) in contaminated soil, while the mechanisms were few studied regrading PGPR-soil-accumulator as an assemble. In this study, we revealed the possible mechanisms of the plant growth-promotion strain SNB6 on enhancing the Cd phytoextration of vetiver grass by the analysis of the whole genome of SNB6, soil biochemical properties and plant growth response. Results showed that SNB6 encoded numerous genes needed for Cd tolerance, Cd mobilization and plant growth promotion. SNB6 increased HOAc-extractable Cd that showed a positive correlation with Cd uptake in accumulator. In addition, SNB6 improved the biochemical activities (bioavailability of nutritional substances, bacterial count, soil respiration and enzyme activity) in rhizosphere soil. Moreover, the antioxidative enzymes activities of accumulator were significantly enhanced by SNB6. Consequently, SNB6 promoted Cd uptake and biomass of accumulator, thus enhancing the Cd phytoextraction. The maximum Cd extractions in root, stem and leaf reached to 289.47 mg/kg, 88.33 mg/kg and 59.38 mg/kg, respectively. Meanwhile, the total biomass of accumulator was increased by 9.68-45.99% in SNB6 treatment. These findings could be conducive to the understanding the mechanisms of PGPR on enhancing the Cd phytoextraction of accumulator.

Impacts of four ionic liquids exposure on a marine diatom Phaeodactylum tricornutum at physiological and biochemical levels

With the increasing applications in various industrial areas, toxicity of ionic liquids (ILs) has gained much attention in recent years. In this work, 1-octyl-3-methylimidazolium nitrate ([C₈mim]NO₃), 1-octyl-3-methylimidazolium chloride ([C₈mim]Cl), N-octyl-3-metylpyridinium chloride ([C₈mpy]Cl) and N-octyl-3-metylpyridinium bromide ([C₈mpy]Br) were used to investigate the impacts of different types of cations and anions on their toxicity to a marine diatom Phaeodactylum tricornutum. Results showed that the four ILs had poor degradability under the culture conditions used in this study, and significantly inhibited the growth of this diatom with 96-h EC₅₀ values of 24.0, 33.6, 16.1 and 14.4mgL^-1 for [C₈mim]NO₃, [C₈mim]Cl, [C₈mpy]Cl and [C₈mpy]Br, respectively. The data indicated that types of cations and anions would affect the toxicity of ILs to this diatom. Additionally, photosynthesis of this diatom was inhibited because significant decrease of chlorophyll a content and damage of PSII reaction centers were observed when it was exposed to the four ILs. Remarkable physiological and biochemical responses occurred in the cells of this diatom to alleviate the damaging effects of the four ILs. For example, content of soluble protein and activities of superoxide dismutase (SOD) and catalase (CAT) in the cells of this diatom increased significantly to form a protective mechanism against the toxicity of ILs, although they decreased in the cultures with high concentrations of ILs (≥20mgL^-1). Thus, these results would not only provide strong evidences for evaluating the ecological risks and toxicity of ILs to marine ecosystem, but also help for understanding their toxic mechanisms to marine diatoms.

Acute toxicities and effects on multixenobiotic resistance activity of eight pesticides to the earthworm Eisenia andrei

Investigations of deleterious effects on non-target species, including earthworms, have been conducted for a number of pesticides, but there is a need for additional assessments of potential adverse effects. In the present study, the acute toxicity of eight pesticides to the earthworm Eisenia andrei was assessed and compared. The exposures were conducted using the filter paper contact toxicity method. Based on the 48-h LC₅₀ values, one pesticide was classified as supertoxic (combined fungicide containing difenoconazole and fludioxonil), four as extremely toxic (combined herbicide containing pethoxamide and terbuthylazine, combined fungicide containing fluopyram and tebuconazole, fungicide containing pyrimethanil, and combined fungicide containing thiram and carboxin), two as very toxic (combined fungicide containing flutriafol and thiabendazole, and herbicide containing fluroxypyr-meptyl), and one as moderately toxic (insecticide containing thiamethoxam). Additionally, effects of pesticides on the multixenobiotic resistance (MXR) activity were measured. Results showed that four pesticides caused significant effects with a recorded inhibition of the activity, which can consequently lead to a higher toxicity due to longer retention of the pesticides in the cells. Finally, for three chosen pesticides, gene expression of cat, sod, and gst was measured, and significant changes were observed. The obtained results show that earthworms could be significantly affected by pesticides commonly used in agriculture.

Biochemical and transcriptomic response of earthworms Eisenia andrei exposed to soils irrigated with treated wastewater

In order to ensure better use of treated wastewater (TWW), we investigated the effect of three increasing doses of TWW, 10%, 50%, and 100%, on biochemical and transcriptomic statuses of earthworms Eisenia andrei exposed during 7 and 14 days. The effect of TWW on the oxidative status of E. andrei was observed, but this effect was widely dependent on the dilution degree of TWW. Results showed a significant decrease in the catalase (CAT) activity and an increase in the glutathione-S-transferase (GST) activity, and considerable acetylcholinesterase (AChE) inhibition was recorded after 14 days of exposure. Moreover, malondialdehyde (MDA) accumulation was found to be higher in exposed animals compared to control worms. The gene expression level revealed a significant upregulation of target genes (CAT and GST) during experimentation. These data provided new information about the reuse of TWW and its potential toxicity on soil organisms.

Toxicity of 1-alkyl-3-methyl imidazolium nitrate ionic liquids to earthworms: The effects of carbon chains of different lengths

Ionic liquids (ILs), which are alternatives to traditional organic solvents, have the potential to enter soil and cause negative effects on the soil micro-environment, especially soil organisms. The objective of this study was to determine the "alkyl chain effect" and "cut-off effect" mechanisms underlying the toxicity of ILs. The assessment for subchronic toxicity toward earthworms (Eisenia fetida) by five common imidazole nitrate ILs ([C_nmim]NO₃ (n = 4, 6, 8, 10, and 12)) was conducted on day 28 after exposure to five concentrations (0, 5, 10, 20, and 40 mg kg^-1) of ILs. Earthworms showed oxidative stress and oxidative damage, and both "alkyl chain effect" and "cut-off effect" (occurred in C₁₀) were observed. In addition, the toxicity of ILs increased with the increase in concentration. Analysis of imidazolium ILs in artificial soil at the end of the experiment indicated that these selected ILs remained relatively stable, with a rate of change of less than 7.39%. The present study provides theoretical support for decisions regarding IL use and helps to establish a friendly IL structure database.

Comparative toxicity and bioaccumulation of two dinotefuran metabolites, UF and DN, in earthworms (Eisenia fetida)

Dinotefuran, as the latest generation of neonicotinoid insecticide, has broad application prospects around the world. However, dinotefuran is easily metabolized and the two main metabolites are 1-methyl-3-(tetrahydro-3-furylmethyl) urea (UF) and 1-methyl-3-(tetrahydro-3-furylmethyl) guanidium dihydrogen (DN). In the present study, the risks of UF and DN in soil on typical non-target species earthworm were investigated. In the same time, the degradation in soil and accumulation in earthworms of UF and DN were monitored. The present results showed that the toxicities of UF and DN were similar in their effect on earthworms and they were supertoxic pollutants to earthworms. The degradation trend in soil and accumulation trend in earthworms of UF and DN were consistent throughout the whole exposure period. At 1.0 mg/kg and 2.0 mg/kg, UF and DN could induce the excess production of ROS, resulting in oxidative stress effects in earthworm cells. The excess ROS induce changes in antioxidant enzyme activities, damage in biomacromolecules, and abnormal expression of function genes. The present results showed that UF and DN may have high risks for earthworms.

Biomarker responses of earthworms (Eisenia fetida) to soils contaminated with perfluorooctanoic acid

Perfluorooctanoic acid (PFOA) is considered a persistent environmental pollutant. The aim of this study was to assess the potential toxicity of PFOA to earthworms (Eisenia fetida) in artificial soil. The activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and glutathione S-transferase (GST) as well as the contents of malondialdehyde (MDA) were measured after exposure to 0, 5, 10, 20, and 40 mg kg^-1 PFOA in soils for 7, 14, 21, and 28 days. The results showed that SOD activity increased at 14 days and decreased from 21 to 28 days; MDA levels were highest in the treatment with 40 mg kg^-1 PFOA after 28 days of exposure. In contrast, CAT and POD activities increased after 14-21 days of exposure and significantly decreased with long-term exposure (28 days). GST activity increased significantly from 14 to 28 days. Our results indicate that PFOA has biochemical effects on E. fetida, thereby contributing to our understanding of the ecological toxicity of PFOA on soil invertebrates.