Evaluating subchronic toxicity of fluoxastrobin using earthworms (Eisenia fetida)

Butyl benzyl phthalate induces neurotoxicity in Eisenia fetida: Mechanisms revealed by biochemical and metabolomic analyses

Phthalates, particularly butyl benzyl phthalate (BBP), are ubiquitous environmental contaminants with potential neurotoxic effects. However, their impact on soil organisms, especially earthworms (Eisenia fetida), remains poorly understood. The current study investigated the neurotoxic effects of BBP on Eisenia fetida in artificial and red soils using an integrated approach combining biochemical assays, metabolomics, and molecular docking. Earthworms were exposed to 0, 1, and 10 mg kg-1 BBP for 14 and 28 days. Biochemical assays revealed significant increases in oxidative stress markers and disruptions in neurotransmission-related enzyme activities. Metabolomic analysis of the cerebral ganglia identified alterations in energy metabolism, lipid metabolism, and neuroactive ligand-receptor interaction signaling pathways. Molecular docking studies corroborated these findings, showing strong interactions between BBP and essential neuronal proteins, particularly the sodium pump. The integration of these data suggests that BBP-induced neurotoxicity in Eisenia fetida is primarily mediated by calcium signaling pathway dysfunction and calcium homeostasis imbalance. Notably, neurotoxic effects were more pronounced in red soil than in artificial soil, highlighting the importance of considering soil type in ecotoxicological assessments. The current study provides novel insights into the mechanisms of BBP-induced neurotoxicity in soil invertebrates and underscores the potential ecological risks associated with phthalate contamination in agricultural environments.

Fluxapyroxad induced toxicity of earthworms: Insights from multi-level experiments and molecular simulation studies

Fluxapyroxad, an emerging succinate dehydrogenase inhibitor fungicide, is widely used due to its excellent properties. Given its persistence in soil with a 50 % disappearance time of 183-1000 days, it is crucial to evaluate the long-term effects of low-dose fluxapyroxad on non-target soil organisms such as earthworms (Eisenia fetida). The present study investigated the impacts of fluxapyroxad (0.01, 0.1, and 1 mg kg-1) on Eisenia fetida over 56 days, focusing on oxidative stress, digestive and nervous system functions, and histopathological changes. We also explored the mechanisms of fluxapyroxad-enzyme interactions through molecular docking and dynamics simulations. Results demonstrated a significant dose-response relationship in the integrated biomarker response of 12 biochemical indices. Fluxapyroxad altered expression levels of functional genes and induced histopathological damage in earthworm epidermis and intestines. Molecular simulations revealed that fluxapyroxad is directly bound to active sites of critical enzymes, potentially disrupting their structure and function. Even at low doses, long-term fluxapyroxad exposure significantly impacted earthworm physiology, with effects becoming more pronounced over time. Our findings provide crucial insights into the chronic toxicity of fluxapyroxad and emphasize the importance of long-term, low-dose studies in pesticide risk assessment in soil. This research offers valuable guidance for the responsible management and application of fungicides.

Green synthesis and evaluation of dual herb-extracted DHM-AgNPs: Antimicrobial efficacy and low ecotoxicity in agricultural and aquatic systems

Uncontrolled applications of weedicide and fertilizer can harm the soil ecology, and most significantly, earthworms are hazardous soil engineers. Thus, we aimed at the toxicity and histopathological alterations in the earthworm Eudrilus euginae following exposure to glyphosate (weedicide), urea (fertilizer), and environmentally friendly dual herb-mixed silver nanoparticles (DHM-AgNPs). The DHM-AgNPs were synthesized using a blend of Alfinia officinarum and Curcuma longa aqueous leaf extracts with 1 mM silver nitrate. The color change from yellow to brown after an hour of incubation was a significant indicator of successful DHM-AgNP synthesis. Characterization of the DHM-AgNPs using UV-Vis spectra indicated a surface plasmon resonance (SPR) peak at 430 nm. In addition to FT-IR spectroscopy and XRD analysis, SEM, TEM, and SEM investigations were performed to identify the DHM-AgNPs. The XPS analysis revealed the oxidation state and surface chemical composition, and Ag NP's specific surface area and degree of porosity were measured using BET. Furthermore, different concentrations of urea and glyphosate were administered to Artemia nauplii and E. euginae to assess their toxicity. The mortality rate for E. euginae exposed to a higher urea concentration (10 g/kg of soil) was 100%. In contrast, a % mortality rate of 83% was noted at 0.5 g/kg of soil. The maximum mortality (90 ± 0.64%) was observed at a 10 mL/kg/L concentration for glyphosate. In contrast, low mortality was noted in E. euginae and A. nauplii exposed with gradient concentrations of DHM-AgNPs compared to glyphosate and urea. As aquaculture and foodborne diseases are widespread, DHM-AgNPs showed significant anti-Vibrio activity against pathogenic Vibrio-related bacteria, inhibiting 80% at 100,100 μg/L, which is of great concern. This study suggests the potential use of DHM-AgNPs in field aqua and crops culture for eco-friendly pest control and anti-Vibrio activity without causing soil and environmental pollution. Further research is warranted to determine the efficacy, safety, and cost-effectiveness of DHM-AgNPs in aqua and agricultural practices.

Ecological risk assessment of castor oil based waterborne polyurethane: Mechanism of anionic/cationic state selective toxicity to Eisenia fetida

Cationic and anionic castor oil-based waterborne polyurethanes (C-WPU/A and C-WPU/C) have great potential for development in agriculture. However, it is still unclear whether these polyurethanes are harmful or toxic to soil fauna. Based on multilevel toxicity endpoints and transcriptomics, we investigated the effects of C-WPU/A and C-WPU/C on earthworms (Eisenia fetida). The acute toxicity results showed that C-WPU/A was highly toxic to the earthworms, whereas C-WPU/C was nearly nontoxic. C-WPU/A significantly affected the body weight, burrowing ability and cocoon production rate of earthworms compared to C-WPU/C. After exposure to C-WPU/A, the results showed accumulation of reactive oxygen species (ROS), abnormal peroxidase activity, and increased malondialdehyde levels. Additionally, more serious histopathological damage was observed in earthworms, such as epidermal damage, vacuolization, longitudinal muscle disorganization, and shedding of intestinal epidermal cells. At the cellular level, C-WPU/A induced more severe lysosomal damage, DNA damage and apoptosis than C-WPU/A. C-WPU/A made more differentially expressed genes and considerably more enriched pathways at the transcriptional level than C-WPU/C. These pathways are largely involved in cell membrane signaling, detoxification, and apoptosis. These results provide an important reference for elucidating the selective toxicity mechanisms of C-WPU/A and C-WPU/C in earthworms.

Response of earthworm enzyme activity and gut microbial functional diversity to carbendazim in the manured soil

The effect of pesticide pollution on environmental microorganisms in soil has become the focus of widespread concern in society today. The response of earthworm gut and surrounding soil microbial functional diversity and enzyme activity to carbendazim (CBD) was studied in a soil-earthworm ecosystem amended with manure. In the experiment, CBD was added to the manured soil (MS). Meanwhile, the pesticide treatment without manure and the control treatment without pesticides were also set up. The activities of catalase (CAT) and acetylcholinesterase (AChE) were measured to evaluate the toxicity of CBD. The Biolog method was used to assess the functional diversity of the microbial community. In the 2 mg/kg CBD treatment, earthworm AChE activity decreased significantly in the MS after 14 d, which occurred earlier than in the un-manured soil (NS). The changes of earthworm CAT activity in the pesticide treatments showed a trend of initially increasing and then maintaining at a high activity level. However, the CAT activities at 28 d in the manured soils were clearly lower than that at 7 d for both the CBD treatments, while they remained stable in the control treatments. The carbon source utilization, Simpson index, Shannon index, and McIntosh index of soil microorganisms in the MS treatments were significantly higher than those in the NS treatments. The overall activity of earthworm gut microorganisms in the MS treated with 2 mg/kg CBD was higher than that in the control. Also, CBD treatment (2 mg/kg) increased significantly the Simpson index and McIntosh index of earthworm gut microorganisms. The results indicated that the enzyme activities in the manured soils increased before 7 d for the pesticide treatments. Furthermore, exposure to CBD at a high concentration in the MS not only led to the earlier inhibition of earthworm enzyme activity but also significantly improved the overall activity of earthworm gut microorganisms and microbial functional diversity. This study revealed the ecotoxicological effects of earthworms in response to pesticide stress following the use of organic fertilizers under facility environmental conditions, which can provide a theoretical basis for the remediation of pesticide pollution in soil in the future.

Oxidative stress and DNA alteration on the earthworm Eisenia fetida exposed to four commercial pesticides

Modern agriculture is mainly based on the use of pesticides to protect crops but their efficiency is very low, in fact, most of them reach water or soil ecosystems causing pollution and health hazards to non-target organisms. Fungicide triazoles and strobilurins based are the most widely used and require a specific effort to investigate toxicological effects on non-target species. This study evaluates the toxic effects of four commercial fungicides Prosaro® (tebuconazole and prothioconazole), Amistar®Xtra (azoxystrobin and cyproconazole), Mirador® (azoxystrobin) and Icarus® (Tebuconazole) on Eisenia fetida using several biomarkers: lipid peroxidation (LPO), catalase activity (CAT), glutathione S-transferase (GST), total glutathione (GSHt), DNA fragmentation (comet assay) and lysozyme activity tested for the first time in E. fetida. The exposure to Mirador® and AmistarXtra® caused an imbalance of ROS species, leading to the inhibition of the immune system. AmistarXtra® and Prosaro®, composed of two active ingredients, induced significant DNA alteration, indicating genotoxic effects. This study broadened our knowledge of the effects of pesticide product formulations on earthworms and showed the need for improvement in the evaluation of toxicological risk deriving from the changing of physicochemical and toxicological properties that occur when a commercial formulation contains more than one active ingredient and several unknown co-formulants.

Enrichment and distribution of 3,6-dichlorocarbazole in red crucian carp (Carassius auratus) and its hepatotoxicity

Polyhalogenated carbazoles (PHCZs) are a class of organohalogen compounds where the hydrogen atom on the carbazole ring is replaced by a halogen atom. In recent years, PHCZs have drawn increasing concern due to their persistence, dioxin-like toxicity, bioaccumulation, potential ecological hazards and widespread occurrence in the environment. Current research on the enrichment and depuration of PHCZs in biological tissues and organs is insufficient, and the liver toxicity is unclear. Herein, to understand the enrichment and elimination of 3,6-DCCZ in fish tissues and organs as well as the hepatotoxicity, we exposed the red crucian carp to 20 and 100 μg/L of 3,6-DCCZ for 20 days followed by a depuration period of 10 days. The 3,6-DCCZ enrichment in each organ tissue was classified from high to low: brain > liver, intestine, gill > muscle. For depuration, 3,6-DCCZ was quickly excreted in the various organs of the red crucian carp; however, the liver depuration was slow, with the concentration of 3,6-DCCZ was maintained at 0.25-0.35 μg/g. 3,6-DCCZ exposure at both tested concentrations induced oxidative stress in red crucian carp, causing lipid peroxidation and DNA damage, as well as some histopathological changes in the liver, such as cell vacuolization, nucleus pyknosis, nucleus pleomorphism, no nucleus areas. Additionally, the 3,6-DCCZ exposure at higher concentration (100 μg/L) caused more serious damage and abnormal lipid metabolism in the red crucian carp liver.

Co-exposure effects of butyl benzyl phthalate and TiO2 nanomaterials (anatase) on Metaphire guillelmi gut health

Phthalic acid esters (PAEs) and TiO2 nanomaterials (nTiO2) are commonly used as plastic additives, nano-fertilizers or nano-pesticides. Their excessive co-applications led to the co-occurrence, which can induce damage to soil organisms such as Metaphire guillelmi (an earthworm widespread in farmland). However, the co-exposure effects of butyl benzyl phthalate (BBP, a typical PAEs) and nTiO2 on Metaphire guillelmi at environmental-relevant concentrations remain unclear. In this study, 1 mg kg-1 BBP and 1 mg kg-1 nTiO2 (anatase) were added into the soil to assess: (1) their effects on oxidative damage, digestive system, and neurotoxicity in Metaphire guillelmi gut on days 14 and 28; and (2) whether BBP and nTiO2 affected Metaphire guillelmi gut health by disrupting intestinal microorganisms. The results demonstrated that BBP and nTiO2 had the potential to inhibit the activity of superoxide dismutase, cellulase, protease, Na+K+-ATPase, and Ca2+-ATPase, as well as cause oxidative damage by altering intestinal bacteria such as Marmoricola and Microvirga at genus levels after 28 d-exposure. However, the exposure did not cause disorders of the intestinal bacteria. The present study provides more evidence for the sustainable application and scientific management of BBP and nTiO2, thus providing better guidance for PAEs and engineered nanomaterials regulations in agroecosystems.

Randomly-shaped nanoplastics induced stronger biotoxicity targeted to earthworm Eisenia fetida species: Differential effects and the underlying mechanisms of realistic and commercial polystyrene nanoplastics

Nanoplastics (NPs) are widely distributed in various environments, including soil, and have been known to adversely affect soil organisms. Currently, most of the obtained studies were principally focused on the ecological risks of commercial sphere-type microbeads (SNPs), while ignoring that they might be different from randomly-shaped nanoplastics (RNPs) in a real environment. Thus, this study was undertaken to probe the shape-dependent effects of NPs on the earthworm Eisenia fetida and the corresponding poisoning mechanisms, and discriminate the toxicity differences between SNPs and RNPs at the molecule, cell, tissue, and animal levels. The results showed SNPs and RNPs exhibited lethal effects to earthworms with the LC₅₀ determined to be 27.42 g/kg and 21.69 g/kg, respectively after a 28-day exposure. SNPs and RNPs exposure can cause ROS-induced ROS release in worm, inducing oxidative stress through mitochondria-mediated pathway, leading to lipid peroxidation, DNA damage, and histopathological changes, thereby contributing to decreased stress resistance against exogenous stressors. To reduce ROS-mediated oxidative damage, the antioxidant defense system in E. fetida can be activated, which scavenges unwanted ROS. High doses of SNPs and RNPs inhibited the AChE activity in worms, causing excess acetylcholine accumulation in the synaptic space, which finally lead to neurotoxicity. Also, two kinds of NPs can induce the abnormal expression of genes relevant to oxidative stress, reproduction, growth, and tight junction protein in E. fetida, which ultimately contribute to various detrimental effects, tissue damage and dysfunction, reproductive and developmental toxicity. The results obtained from the Integrated Biological Response (IBR) suggested that long-term exposure to high-dose SNPs and RNPs can induce the stronger toxicity effects to E. fetida worms, and RNPs-induced toxicity can be different and stronger than that of SNPs. Our results provide insights for revealing the environmental effects posed by randomly-shaped NPs-contaminated soil, and are of importance for assessing the contribution of NPs with different physical characteristics to soil eco-safety.

Analysis of the toxic mechanisms of fluoxastrobin on the earthworm (Eisenia fetida) using transcriptomics

Fluoxastrobin (FLUO), one of the best-selling strobilurin fungicides, could prevent fungal diseases from oilseed crops, fruits, grains, and vegetables. The widespread use of FLUO leads to the continuous accumulation of FLUO in soil. Our previous studies have demonstrated that FLUO exhibited different toxicity in artificial soil and three natural soils (fluvo-aquic soils, black soils, and red clay). The toxicity of FLUO was greater in natural soil than the artificial soil, specifically, showed the highest toxicity in fluvo-aquic soils. To better investigate the mechanism of FLUO toxicity to earthworms (Eisenia fetida), we selected fluvo-aquic soils as representative soil and used transcriptomics to study the gene expression in earthworms after FLUO exposure. The results demonstrated that the differentially expressed genes in earthworms after FLUO exposure mainly presented in pathways involving protein folding, immunity, signal transduction, and cell growth. It may be the reason why FLUO exposure stressed the earthworms and affected their normal growth activities. The present study fills gaps in the literature regarding the soil bio-toxicity of strobilurin fungicides. It also sounds the alarm for the application of such fungicides even at the low concentration (0.1 mg kg^-1).

Effect of different exposure times and doses of cyantraniliprole on oxidative stress and genotoxicity in earthworms (Eisenia fetida)

Cyantraniliprole, the second generation of diamide insecticides, is widely used to control various pests, which will certainly result in adverse effects on earthworms in soil. In this study, after exposure with six doses of cyantraniliprole (0, 0.5, 1, 2.5, 5, and 10 mg kg^-1) by artificial soil method, six biomarkers, four functional genes, and histopathological changes of Eisenia fetida were measured on the 7th, 14th, 21st, and 28th days. The comprehensive toxicity was assessed by the IBR version 2 (IBRv2) method. The results showed that the reactive oxygen species (ROS) level was induced significantly. The superoxide dismutase (SOD) activity was activated in 7-28 days. The catalase (CAT) and glutathione S-transferases (GST) activities were also activated in the initial 14 days. The 8-hydroxy-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) contents in the high treatment increased until the late stage of exposure. On the 28th day, the metallothionein (MT) and calreticulin (CRT) genes were up-regulated, the transcriptionally controlled tumor protein (TCTP) gene was down-regulated. The SOD gene showed a good correlation with SOD activity. Extensive histopathological damage was found in the endoderm and ectoderm of E. fetida. The 5 and 10 mg kg^-1 treatments showed higher comprehensive toxicity than the 0.5, 1, and 2.5 mg kg^-1 treatments on the 28th day. These results suggest that cyantraniliprole exerted certain subchronic toxic effects of oxidative stress, DNA damage, and histopathological changes to E. fetida, which provided theoretical basis for rational use of cyantraniliprole and evaluation of its safety to soil environment.

NMR-based metabolomics approach to assess the ecotoxicity of prothioconazole on the earthworm (Eisenia fetida) in soil

Prothioconazole (PTC) is a widely used agricultural fungicide. In recent years, studies have confirmed that it exerts adverse effects on various species, including aquatic organisms, mammals, and reptiles. However, the toxicological effects of PTC on soil organisms are poorly understood. Here, we investigated the toxic effects, via oxidative stress and metabolic responses, of PTC on earthworms (Eisenia fetida). PTC exposure can induce significant changes in oxidative stress indicators, including the activities of superoxide dismutase (SOD) and catalase (CAT) and the content of glutathione (GSH), which in turn affect the oxidative defense system of earthworms. In addition, metabolomics revealed that PTC exposure caused significant changes in the metabolic profiles of earthworms. The relative abundances of 16 and 21 metabolites involved in amino acids, intermediates of the tricarboxylic acid (TCA) cycle and energy metabolism were significantly altered after 7 and 14 days of PTC exposure, respectively. Particularly, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that multiple different metabolic pathways could be disturbed after 7 and 14 days of PTC exposure. Importantly, these alterations in oxidative stress and metabolic responses in earthworms reveal that the effects of PTC on earthworms were time dependent, and vary with exposure time. In conclusion, this study highlights that the effects of PTC on soil organisms are of serious concern.

Toxicity comparison of atrazine on Eisenia fetida in artificial soil and three natural soils

Atrazine has been widely used in the world and caused environmental pollution, especially soil pollution. When assessing the toxicity of atrazine in soil, most studies used standardized artificial soils, while few studies focused on the real soil environments. In the present study, three natural soils and artificial soil were selected as test soils to study and compare the toxicities of atrazine to Eisenia fetida. Acute toxicity of atrazine was determined by filter paper and soil tests. In chronic toxicity study, after atrazine exposure, the content of reactive oxygen species in Eisenia fetida significantly increased and showed a dose-response relationship. The activity changes of three antioxidant enzymes and glutathione transferase showed that atrazine had obvious oxidative stress effect on earthworms. The contents of malondialdehyde and 8-hydroxy deoxyguanosine in 0.1 and 1 mg/kg atrazine treatment groups were significantly higher than the control, indicating that medium and high concentrations of atrazine could cause lipid and DNA damage in Eisenia fetida. The acute toxicity results and the integrated biomarker response index for chronic toxicity indicated that the toxicity order of atrazine was: red clay > fluvo-aquic soil > artificial soil > black soil, and that the toxicity of atrazine in artificial soil was not representative of its toxicity in real soil environment. The results of correlation analysis showed that three soil property parameters of organic carbon, organic matter and sand were most related to the toxicity of atrazine.

The overlooked toxicity of environmentally persistent free radicals (EPFRs) induced by anthracene transformation to earthworms (Eisenia fetida)

Environmentally persistent free radicals (EPFRs) as intermediate products exist widely in the PAHs-contaminated soils, but toxicity assessment associated with EPFRs for terrestrial invertebrates remains unclear. Using the model organism Eisenia fetida, we compared the adverse effects among anthracene (ANT), anthraquinone (ANQ), and EPFRs induced by ANT transformation on clay surfaces. Our results showed that EPFRs-exposed earthworms experienced histopathological damage, which was more severe than ANT and ANQ-exposed earthworms. The source of EPFRs damage was associated with the obvious dysbiosis of reactive oxygen species in earthworms. Specifically, EPFRs trigged more severe antioxidant responses and oxidative damages (e.g., membrane lipid and DNA injury) in comparison with ANT and ANQ exposure, as evidenced by the values of integrated biomarker response (IBR) following the order of EPFRs (14.5) > ANT (12.8) > ANQ (10.9). Moreover, high-throughput sequencing found that EPFRs induced dramatic changes in the composition and structure of earthworm gut microbiota, which may involve immune and metabolism dysfunction, in turn aggravated EPFRs toxicity. Overall, the obtained information highlights the more severe injury of EPFRs to terrestrial organisms, deserving more attentions for the assessment of potential risks associated with radical intermediates in PAHs-contaminated soils.

Oxidative stress and detoxification mechanisms of earthworms (Eisenia fetida) after exposure to flupyradifurone in a soil-earthworm system

Flupyradifurone (FLU) has great application potential in agricultural production as a new generation of neonicotinoid insecticide after imidacloprid. Nevertheless, the toxic effects of FLU on non-target soil organisms remain unclear, resulting in considerable environmental risks. We evaluated the acute and subchronic toxicities of FLU to earthworms. The results of acute toxicity show that the median lethal concentration (LC₅₀) values (14 d) of FLU were 186.9773 mg kg^-1 for adult earthworms and 157.6502 mg kg^-1 for juveniles, respectively. The subchronic toxicity of FLU that focused on the activities of antioxidant and detoxication enzymes showed the superoxide dismutase (SOD), catalase (CAT), and glutathione-S transferase (GST) activities in earthworms increased while the peroxidase (POD) and acetylcholinesterase (AChE) activities decreased after exposure to FLU. Oxidative damage analyses revealed that the reactive oxygen species (ROS) level and malonaldehyde (MDA) content in earthworms were increased by FLU, resulting in DNA damage. Transcriptomics and RT-qPCR confirmed that FLU influenced the expression of genes related to antioxidant response and detoxification of earthworms. Ultimately detoxification metabolism, environmental information processing, cell processes, and immune system pathways are significantly enriched to respond jointly to FLU. Our study fills the gaps in the toxicity of FLU to earthworms, providing a basis for its risk assessment of soil ecosystems and non-target biological toxicity.

Toxicity of fungicide azoxystrobin to Enchytraeus albidus: Differences between the active ingredient and formulated product

Due to the often-excessive usage of fungicides, increasing attention is being paid to their impact on soil and non-target organisms. Risk assessments are usually based on the pure active ingredient and not on the formulated products applied in the environment. The aim of this study was therefore to investigate how azoxystrobin, the best-selling strobilurin fungicide, affects non-target soil organisms Enchytraeus albidus. To investigate the effects of the different types of azoxystrobin, E. albidus was exposed to the pure active ingredient, AZO_AI, and the formulated product, AZO_FP. Survival, reproduction, and molecular biomarkers of E. albidus were determined for different exposure durations (seven and 21 days). AZO_FP (LC₅₀ = 15.3 mg_a.i./kg) showed a slightly stronger effect on survival than AZO_AI (LC₅₀ = 16.8 mg_a.i./kg), yet the impact on reproduction was much stronger. Namely, while the tested concentrations of AZO_AI (EC₅₀≥ 8 mg_a.i./kg) had almost no effect on reproduction, AZO_FP (EC₅₀ = 2.9 mg_a.i./kg) significantly inhibited reproduction in a dose-dependent manner. Changes in enzyme activities (superoxide dismutase, catalase, glutathione-s-transferase) and malondialdehyde levels in both treatments indicated oxidative stress. Although AZO_FP had a stronger negative effect, the impact depended on the exposure time and the tested concentration. The higher toxicity of AZO_FP was a consequence of increased bioavailability and activity of the active ingredient due to the presence of adjuvants. Overall stronger adverse effects of AZO_FP suggest that the toxicity of azoxystrobin in the agricultural environment on the enchytraeid population may be underestimated. Furthermore, the results of this study highlighted the importance of comparing the toxicity of the active ingredient and the formulated product.

Toxicity evaluation of chlorpyrifos and its main metabolite 3,5,6-trichloro-2-pyridinol (TCP) to Eisenia fetida in different soils

The present study utilized a biomarker response method to evaluate the effect of 3,5,6-trichloro-2-pyridinol (TCP) in artificial and natural soils on Eisenia fetida after 7, 14, 28, 42 and 56 days exposure. Results indicated that TCP induced excessive reactive oxygen species, caused oxidative stress and DNA damage to Eisenia fetida. Biomarker responses were standardized to calculate the Integrated Biomarker Response (IBR) index. The IBR index of three enzymes (superoxide dismutase, catalase and glutathione S-transferase) activities showed that TCP induced the oxidative stress to E. fetida in red clay was stronger than in the other three soils. Specifically, chlorpyrifos exposure group showed a lower toxicity than TCP exposure group after 28 days exposure but a higher toxicity than TCP exposure group after 56 days exposure. Despite the deficiencies of this study, the above information is of great significance for assessing the risk of chlorpyrifos and its metabolite TCP pollution in soil ecosystems.

Toxicity evaluation of pyraclostrobin exposure in farmland soils and co-exposure with nZnO to Eisenia fetida

Although the toxicity of pyraclostrobin (PYRA) to earthworms in artificial soil is well known, the toxicity of PYRA in farmland soils is yet to be explored in detail. Additionally, with more zinc oxide nanoparticles (nZnO) entering the soil environment, the risk of PYRA co-exposure with nZnO is increasing alarmingly. However, toxicity caused by this co-exposure of PYRA and nZnO is still unknown. Therefore, we assessed the biomarkers responses to reveal the toxicity of PYRA (0.1, 1, 2.5 mg/kg) on earthworms in farmland soils (black soil, fluvo-aquic soil, and red clay) and evaluated the biomarkers responses of Eisenia fetida exposed to PYRA (0.5 mg/kg)/PYRA+nZnO (10 mg/kg). Moreover, transcriptomic analysis was performed on E. fetida exposed to PYRA/PYRA+nZnO for 28 days to reveal the mechanism of genotoxicity. The Integrated Biomarker Responses (IBR) showed PYRA induced more severe oxidative stress and damage to E. fetida in farmland soils than that in artificial soil. The oxidative stress and damage induced by PYRA+nZnO were greater than that induced by PYRA. Transcriptomic analysis showed that PYRA and PYRA+nZnO significantly altered gene expression of both biological processes and molecular functions. These results provided toxicological data for PYRA exposure in three typical farmland soils and co-exposure with nZnO.

Oxidative stress and DNA damage induced by trifloxystrobin on earthworms (Eisenia fetida) in two soils

Trifloxystrobin is a new type of fungicide, which is extensively used due to its excellent antifungal activity. In this study, oxidative stress and DNA damage induced by trifloxystrobin exposure was evaluated using Eisenia fetida at subchronic toxicity concentrations in artificial soil and brown soil (0.1-2.5 mg/kg). Throughout the exposure period (days 7, 28 and 56), six biochemical indicators including reactive oxygen species (ROS), antioxidant enzymes (SOD and CAT), glutathione S-transferase (GST), lipid peroxidation and DNA damage (8-hydroxydeoxyguanosine) were measured. In addition, the integrated biomarker response (IBR) index was calculated to make comparison of toxicological response between artificial and brown soils. Results indicated that trifloxystrobin can induce oxidative stress and DNA damage to earthworms with subchronic toxicity greater in brown soil compared to artificial soil as determined through integrated calculations for six biochemical indicators. Trifloxystrobin toxicological experiments in artificial soil may not accurately evaluate its toxicity in natural soil ecosystems, as the toxicity of trifloxystrobin to Eisenia fetida was underestimated.

Toxic effects of benzovindiflupyr, a new SDHI-type fungicide on earthworms (Eisenia fetida)

Benzovindiflupyr has received increasing attention as a new novel succinate dehydrogenase inhibitor (SDHI)-type fungicide. Nonetheless, its traces remaining in soil potentially trigger an ecotoxicological threat to soil organisms including earthworms. This paper evaluates the eco-toxicity of different benzovindiflupyr doses (0.1, 1, 5, and 10 mg kg-1) on earthworms (Eisenia fetida) after long-term exposure. Consequently, benzovindiflupyr at higher doses significantly inhibited the activities of respiratory chain complex II and succinate dehydrogenase (SDH) in E. fetida. Besides, the reactive oxygen species (ROS) and lipid peroxidation (LPO) were significantly induced in earthworms when treated with this fungicide. After benzovindiflupyr exposure, activities of antioxidant enzymes including catalase, peroxidase, and superoxide dismutase were activated. However, glutathione S-transferase activity in E. fetida was initially induced then inhibited in earthworms after treatment. Furthermore, benzovindiflupyr exposure induced the protein carbonylation (PCO) level in cells indicating oxidative damage to the cellular protein. Due to the destruction of the normal function in the coelomocytes, the phagocytic activity was initially activated, then inhibited when earthworms were treated at 5 and 10 mg kg-1 concentrations. Additionally, DNA damage was induced (larger olive tail moment (OTM) values) with the increase of benzovindiflupyr doses and exposure time. The weight was significantly decreased after benzovindiflupyr exposure on days 21 and 28. Benzovindiflupyr at higher doses significantly decreased the reproduction (number of cocoons and juveniles) of E. fetida. These findings reveal that benzovindiflupyr potentially induces a potential toxicological risk to earthworms when applied in the mentioned above dosages.

Influences and mechanisms of nanoparticles on pentachloronitrobenzene accumulation by earthworms

Pesticides and nanoparticles may coexist in soil; however, influences of nanoparticles on accumulation of pesticides in terrestrial organisms are still unclear. This study aims to investigate the influences and mechanisms of metal oxide nanoparticles (nano ZnO and nano CuO) on accumulation of pentachloronitrobenzene (PCNB) in earthworms and their combined toxicity. The earthworms were cultivated in the soil spiked with nanoparticles (10, 50, 250 mg/kg) and PCNB (100 μg/kg) for 21 days. The concentrations of PCNB in earthworms in binary exposure treatments (PCNB + ZnO and PCNB + CuO) reached 2.47 and 3.13 times of that in individual PCNB exposure treatment, indicating that nanoparticles facilitated the accumulation of PCNB in earthworms. The contents of reactive oxygen species (ROS) in earthworms in treatments PCNB + ZnO 250 and PCNB + CuO 250 reached 379 and 316 fluorescence intensity/mg Protein, respectively, which were significantly higher than that in control group (183 fluorescence intensity/mg protein), indicating that nanoparticles would cause oxidative stress to earthworms. Earthworm coelomocytes were extracted from healthy earthworms and cultivated in culture media in cytotoxicity tests. Changes of intracellular ROS contents and cell viability suggested that PCNB and nanoparticles caused serious oxidative damage to earthworm coelomocytes, thus leading to the damage of cell membrane and cell death. In in vivo tests, changes of biomarkers (ROS and malondialdehyde) demonstrated that these pollutants injured the earthworms. Increased accumulation of PCNB in binary exposure treatments was due to the damage of body cavity caused by nanoparticles. This study provides a novel hypothesis for nanoparticles facilitating organic pollutants entering terrestrial organisms and determines whether nanoparticles would bring about greater environmental risks of other pollutants.

Combined toxic effects of dioxin-like PCB77 with Fe-based nanoparticles in earthworm Eisenia fetida

Iron-based nanomaterials hold promise for in situ remediation of persistent halogenated contaminants such as dioxin-like polychlorinated biphenyls, however, their complex interactions and joint toxicity toward beneficial soil biological functions remain unknown. This study examined the effects of nano-zero valent iron (nZVI) on the physiological and morphological changes, on the bioaccumulation of co-existed dioxin-like 3,3',4,4'-tetrachloro-biphenyls (PCB77), and the joint toxicity of nZVI and PCB77 in earthworms Eisenia fetida. An orthogonally designed experiment was conducted through the exposure of E. fetida to the combined and separate nZVI and PCB77 at various concentrations in soil for 28 days (nZVI at the levels of g-Fe/kg-soil and PCB77 at the levels of mg-PCB/kg-soil). Results indicated that both nZVI and PCB77 inhibited the growth and reproduction of earthworms, and the combined exposure resulted in a synergistic effect. The addition of 10 g/kg nZVI decreased the contents of PCB77 and significantly increased the accumulation of PCB77 to a level ranging 14-97 mg/kg in earthworms in a nZVI dose dependent manner. The observed synergism might relate to the aggravated damage of earthworm epidermis in the presence of nZVI. PCB77 and nZVI at their corresponding high levels (10 mg/kg and 10 g/kg) induced oxidative stress and lipid peroxidation in the earthworms through the increased levels of reactive oxygen species and the subsequent inhibition of antioxidant enzymes including superoxide dismutase and catalase. Further metabolomics analyses revealed that the normal glutamic acid metabolism and tricarboxylic acid cycle were disturbed in earthworms exposed to the combined treatment of 10 mg/kg PCB77 and 10 g/kg nZVI. Our findings suggested that earthworms as a sentinel species could be readily employed in toxicity and tolerance studies to succeed the safe applications of nZVI and interestingly earthworms themselves also hold promise for vermiremediation owing to the high bioaccumulation potential of PCBs from contaminated soils.

Ecotoxicity evaluation of azoxystrobin on Eisenia fetida in different soils

Azoxystrobin, a widely used broad-spectrum strobilurin fungicide, may pose a potential threat in agricultural ecosystems. To assess the ecological risk of azoxystrobin in real soil environments, we performed a study on the toxic effects of azoxystrobin on earthworms (Eisenia fetida) in three different natural soils (fluvo-aquic soil, black soil and red clay soil) and an artificial soil. Acute toxicity of azoxystrobin was determined by filter paper test and soil test. Accordingly, exposure concentrations of chronic toxicity were set at 0, 0.1, 1.0 and 2.5 mg kg^-1. For chronic toxicity test, reactive oxygen species, activity of antioxidant enzymes (superoxide dismutase, catalase and peroxidase), detoxifying enzyme (glutathione transferase), level of lipid peroxidation (malondialdehyde) and level of oxygen damage of DNA (8-hydroxydeoxyguanosine) in earthworms were determined on the 7th, 14th, 21st, 28th, 42nd and 56th days after treatment. Both acute and chronic toxic results showed azoxystrobin exhibit higher toxicity in natural soil than in artificial soil, indicating that traditional artificial soil testing method underestimate ecotoxicity of azoxystrobin in a real agricultural environment on the earthworm population. Combining with the analysis of soil physicochemical properties, the present experiment provided scientific guidance for rational application of azoxystrobin in agricultural production systems.

Oxidative stress and genotoxicity of nitenpyram to earthworms (Eisenia foetida)

In this study, the artificial soil poisoning method was used to explore the antioxidative stress mechanism and gene changes of earthworms (Eisenia foetida) after application of nitenpyram. The toxic effects of nitenpyram on earthworms were combined with the method called the second-generation integrated biomarker response index method (IBRv2) to be comprehensively analyzed by studying the reactive oxygen species (ROS) content, superoxide dismutase (SOD) activity, catalase (CAT) activity, glutathione S-transferase (GST) activity, malondialdehyde (MDA) content and DNA damage degree in earthworms. The results showed that the ROS content in the high-concentration (2.5 mg/kg) nitenpyram treatment group changed significantly. The changes of antioxidant enzymes in earthworms were also obvious. In terms of SOD enzyme activity, under the induction of nitenpyram, SOD activity in the 1 mg/kg and 2.5 mg/kg treatment groups was significantly enhanced. The concentration-treated group could all affect the activity of earthworm detoxifying enzyme GST. Earthworm DNA olive tail in the nitenpyram treatment group with different concentrations was mainly concentrated at low and medium levels at 21d, and the proportion was the largest during the whole exposure period, showing a significant dose-effect relationship. This study confirms that nitenpyram not only has a toxic effect on the physiological and biochemical indicators of earthworms, but also cannot be underestimated on its genetic level.

Transcriptomics and enzymology combined five gene expressions to reveal the responses of earthworms (Eisenia fetida) to the long-term exposure of cyantraniliprole in soil

Cyantraniliprole is a novel diamide insecticide that acts upon the ryanodine receptor (RyR) and has broad application prospects. Accordingly, it is very important to evaluate the toxicity of cyantraniliprole to earthworms (Eisenia fetida) because of their vital role in maintaining a healthy soil ecosystem. In this study, an experiment was set up, using four concentrations (0.1, 1, 5, and 10 mg/kg) and solvent control group (0 mg/kg), to investigate the ecotoxicity of cyantraniliprole to earthworms. Our results showed that, after 28 days of exposure to cyantraniliprole, both cocoon production and the number of juvenile earthworms had decreased significantly at concentrations of either 5 or 10 mg/kg. On day 14, we measured the activities of digestive enzymes and ion pumps in the intestinal tissues of earthworms. These results revealed that cyantraniliprole exposure caused intestinal damage in earthworm, specifically changes to its intestinal enzyme activity and calcium ion content. Cyantraniliprole could lead to proteins' carbonylation under the high-dose treatments (i.e., 5 mg/kg, 10 mg/kg). At the same time, we also found that cyantraniliprole can cause the abnormal expression of key functional genes (including HSP70, CAT, RYR, ANN, and CAM genes). Moreover, the transcriptomics data showed that exposure to cyantraniliprole would affect the synthesis of carbohydrates, proteins and lipids, as well as their absorption and transformation, while cyantraniliprole would also affect signal transduction. In general, high-dose exposure to cyantraniliprole causes reproductive toxicity, genotoxicity, and intestinal damage to earthworms.

In Vitro Interactions of TiO2 Nanoparticles with Earthworm Coelomocytes: Immunotoxicity Assessment

Titanium dioxide nanoparticles (TiO₂ NPs) are manufactured worldwide. Once they arrive in the soil environment, they can endanger living organisms. Hence, monitoring and assessing the effects of these nanoparticles is required. We focus on the Eisenia andrei earthworm immune cells exposed to sublethal concentrations of TiO₂ NPs (1, 10, and 100 µg/mL) for 2, 6, and 24 h. TiO₂ NPs at all concentrations did not affect cell viability. Further, TiO₂ NPs did not cause changes in reactive oxygen species (ROS) production, malondialdehyde (MDA) production, and phagocytic activity. Similarly, they did not elicit DNA damage. Overall, we did not detect any toxic effects of TiO₂ NPs at the cellular level. At the gene expression level, slight changes were detected. Metallothionein, fetidin/lysenin, lumbricin and MEK kinase I were upregulated in coelomocytes after exposure to 10 µg/mL TiO₂ NPs for 6 h. Antioxidant enzyme expression was similar in exposed and control cells. TiO₂ NPs were detected on coelomocyte membranes. However, our results do not show any strong effects of these nanoparticles on coelomocytes at both the cellular and molecular levels.

Biochemical toxicity, lysosomal membrane stability and DNA damage induced by graphene oxide in earthworms

With the growing production and use of carbon nanomaterials (CNMs), the risk of their releases to the environment has drawn much attention. However, their potential effect on soil invertebrates has not yet been systematically assessed. Herein, the toxic effects of graphene oxide (GO) on earthworms (Eisenia fetida) were thoroughly investigated. Exposure to different doses of GO (0, 5, 10, 20, and 30 g kg^-1) was conducted for 7, 14, 21, and 28 days. The results showed that enzymatic activity was stimulated at the early stages of exposure (7 days and 14 days) and inhibited after 14 days for catalase (CAT) and after 21 days for peroxidase (POD) and superoxide dismutase (SOD), especially at high GO doses. The content of MDA showed an increasing trend over the whole exposure period and was significantly elevated by GO from 21 days except at the dose of 5 g kg^-1on day 21. Lysosomal membrane stability and DNA damage presented dose- and time-dependent relationships. Graphene oxide remarkably decreased lysosomal membrane stability except at the dose of 5 g kg^-1 on day 7. The tail DNA%, tail length and olive tail moment increased with increasing GO dose throughout the exposure duration, reaching maximum values at the end of exposure (28 days). These findings suggest that GO induces oxidative stress and genotoxicity in Eisenia fetida, resulting in lipid peroxidation, decreased lysosomal membrane stability and DNA damage. Therefore, attention should be paid to the potential pollution and risk associated with graphene oxide application. The results can provide valuable information for environmental safety assessment of graphene nanomaterials in soil.

Ecotoxicology of strobilurin fungicides

Strobilurin fungicides (SFs), a class of new fungicides, use strobilurin A as a lead compound. However, with excessive production and usage, the SF residues in soil and aquatic ecosystems may lead to environmental pollution. The mechanism of action (MOA) of SFs is respiratory inhibition of fungal mitochondria. Specifically, azoxystrobin (AZO), pyraclostrobin (PYR), trifloxystrobin (TRI), fluoxastrobin (FLUO), picoxystrobin (PICO), and kresoxim-methyl (KRE) are considered the most widely used SFs. The toxicities of those six fungicides in the environment are still unclear. The present review summarized the toxicities of the six SFs to terrestrial and aquatic biota, including mice, amphibians, aquatic organisms (fish, daphnia, algae, etc.), apoidea, soil animals (earthworms and Folsomia fimetaria), and soil microorganisms. We also review the residue, fate, and transportation of SFs. The results indicate that SFs are highly toxic to aquatic and soil organisms and pose potential risks to ecosystems. Current toxicology studies are more focused on acute or chronic toxicity, but the underlying mechanisms are still unclear and require further analysis. In addition, a simple and scientific analysis method is needed to compare the toxicity differences of different SFs to the same test organisms or differences in the same SFs to different test organisms.

Acute toxicity, oxidative stress and DNA damage of chlorpyrifos to earthworms (Eisenia fetida): The difference between artificial and natural soils

Pesticides can damage the soil environment, including damage to sentinel organisms such as earthworms. When assessing the toxicity of pesticides towards earthworms, assays are usually performed using standardized artificial soil, however, soil physicochemical properties may affect pesticide toxicity. In the present study, the toxicity of a commonly used insecticide (chlorpyrifos) to earthworms (Eisenia fetida) was determined in artificial soil and three typical natural soils (fluvo-aquic soil, black soil and red clay) by measuring acute and subchronic toxicity. Soil tests were conducted to measure the acute toxicity of chlorpyrifos to Eisenia fetida quantified by the half lethal concentration (LC₅₀) while subchronic toxicity tests assessed the impact of low dose chlorpyrifos exposure (0.01, 0.1, 1 mg/kg; up to 56 d) on reactive oxygen species content, antioxidant enzymes activities, detoxifying enzyme activity, malondialdehyde content, and 8-hydroxydeoxyguanosine content. Subchronic toxicity was quantified using the integrated biomarker response (IBR) which highlighted that the toxicity of chlorpyrifos in artificial and natural soils was not the same. Outcomes from artificial soil studies may underestimate (fluvo-aquic soil and red clay) or overestimate (black soil) chlorpyrifos effects.

Sub-Lethal Effects of Pesticides on the DNA of Soil Organisms as Early Ecotoxicological Biomarkers

This review describes the researches performed in the last years to assess the impact of pesticide sub-lethal doses on soil microorganisms and non-target organisms in agricultural soil ecosystems. The overview was developed through the careful description and a critical analysis of three methodologies based on culture-independent approaches involving DNA extraction and sequencing (denaturing gradient gel electrophoresis, DGGE; next-generation sequencing, NGS) to characterize the microbial population and DNA damage assessment (comet assay) to determine the effect on soil invertebrates. The examination of the related published articles showed a continuous improvement of the possibility to detect the detrimental effect of the pesticides on soil microorganisms and non-target organisms at sub-lethal doses, i.e., doses which have no lethal effect on the organisms. Considering the overall critical discussion on microbial soil monitoring in the function of pesticide treatments, we can confirm the usefulness of PCR-DGGE as a screening technique to assess the genetic diversity of microbial communities. Nowadays, DGGE remains a preliminary technique to highlight rapidly the main differences in microbial community composition, which is able to give further information if coupled with culture-dependent microbiological approaches, while thorough assessments must be gained by high-throughput techniques such as NGS. The comet assay represents an elective technique for assessing genotoxicity in environmental biomonitoring, being mature after decades of implementation and widely used worldwide for its direct, simple, and affordable implementation. Nonetheless, in order to promote the consistency and reliability of results, regulatory bodies should provide guidelines on the optimal use of this tool, strongly indicating the most reliable indicators of DNA damage. This review may help the European Regulation Authority in deriving new ecotoxicological endpoints to be included in the Registration Procedure of new pesticides.

Acute toxicity, oxidative stress and DNA damage of three task-specific ionic liquids ([C2NH2MIm]BF4, [MOEMIm]BF4, and [HOEMIm]BF4) to zebrafish (Danio rerio)

The addition of different functional groups to ionic liquid anions or cations to synthesize task-specific ionic liquids (TSILs) according to specific needs has become a research hotspot. However, there are few studies on the toxicity of TSILs. We selected zebrafish (Danio rerio) to assess the toxicity of three TSILs 1-aminoethyl-3-methylimidazolium tetrafluoroborate ([C₂NH₂MIm]BF₄), 1-methoxyethyl-3-methylimidazolium tetrafluoroborate ([MOEMIm]BF₄) and 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate ([HOEMIm]BF₄). The 96 h median lethal concentration (96 h LC₅₀) of the three TSILs [C₂NH₂MIm]BF₄, [MOEMIm]BF₄ and [HOEMIm]BF₄ on zebrafish determined by an acute toxicity test were 143.8 mg/L, 2492.5 mg/L and 3086.7 mg/L, respectively. In the oxidative damage and DNA damage research experiments, zebrafish were exposed to [C₂NH₂MIm]BF₄ (0, 5, 10, 20 and 40 mg/L), [MOEMIm]BF₄ and [HOEMIm]BF₄ (0, 1, 10, 50 and 100 mg/L) for 28 days, and levels of reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), malondialdehyde (MDA) and olive tail moment (OTM) in zebrafish liver were tested on days 7, 14, 21 and 28 after the exposure test. During the experiment, increased contents of ROS and MDA were detected; enzymatic activities especially SOD were inhibited; and DNA damage occurred in zebrafish. The toxicity of the three TSILs was compared by the integrated biomarker response (IBR). The toxicity order of three TSILs was: [MOEMIm]BF₄ > [HOEMIm]BF₄ > [C₂NH₂MIm]BF₄. In addition, this study can provide a toxicological basis for application research and the evaluation of functionalized ionic liquids with low toxicity in the future.

Effects of tetracycline on the relationship between the microbial community and oxidative stress in earthworms based on canonical correlation analysis

In this study, Eisenia fetida was taken as the test organism and tetracycline was taken as the stress compound. The artificial soil test was conducted to study the utilization intensity of different carbon sources (the Biolog-microplate supplied) by microorganisms under different stress times and stress concentrations. The changes in the in vivo key enzymes activities of earthworms and oxidative stress indicators, such as malondialdehyde (MDA), were explored. The canonical correlation analysis method was the first used to establish a analysis-model to explore the relationship between the functional diversity of microbial community and the oxidative stress in earthworms in vivo under different stress times and concentrations. Research shows: 1) after tetracycline stress, in the earthworm, the CAT, POD, SOD, GPX were related to the microbes that use carbohydrate carbon sources; the GST and AChE were related to the microbes that use polymer carbon sources; the MDA was related to the microbes that use carbon sources: amino acid, carboxylic acid and phenolic acid. 2) Under low concentrations of tetracycline stress, there was no significant relationship between the functional diversity of the microbial communities and the effects of oxidative stress at this concentration. The high concentration of tetracycline can be utilized to screen probiotics that alleviate the effects of oxidative stress. 3) The utilization of carbon sources by microbial community in the earthworm after stress can be used as biomarker of ecotoxicology. It provides a basic theoretical for adding beneficial carbon sources to combat oxidative damage in vivo.

Fluoxastrobin-induced effects on acute toxicity, development toxicity, oxidative stress, and DNA damage in Danio rerio embryos

Strobilurin fungicides (SFs), the most commonly used fungicides, pose threats for controlling fungal diseases. The fungicides were monitored in aquatic ecosystems and may have negative effects on nontarget organisms. This project was undertaken to monitor the toxic effects of fluoxastrobin (FLUO) on Danio rerio embryos and to evaluate the SF risks in aquatic ecosystems. The 96-hour median lethal concentration (96 h LC₅₀), hatching rates, and morphological abnormalities were used to analyze acute toxicity and teratogenicity of FLUO to Danio rerio embryos at an FLUO dose of 0.549 mg/L (95% confidence limits: 0.423 to 0.698 mg/L); the results showed that FLUO has high toxicity in embryos that is analogous to the toxicity observed in adult Danio rerio. Fluoxastrobin may lead embryos to delayed hatching at concentrations >0.6 mg/L, and it may lead to teratogenicity (i.e., pericardial edema and spinal curvature). Based on the 96 h LC₅₀ results, the following parameters were evaluated in Danio rerio: development-related indicators (body length and heart rates), reactive oxygen species (ROS) levels, lipid peroxidation (LPO) levels, the levels of three antioxidants, 8-hydroxy-2-deoxyguanosine (8-OHdG), and apoptosis. The results elucidated that FLUO inhibition of spinal and heart development may be induced by oxidative stress. In addition, FLUO induced a notable climb in ROS content, LPO, the activated activity of superoxide dismutase (SOD) and catalase (CAT), and it inhibited glutathione peroxidase (GSH-PX) activity. Fluoxastrobin led to DNA damage (i.e., a notable climb of 8-OHdG contents and apoptotic cells). Collectively, FLUO posed threats to Danio rerio embryos at multiple levels, and this investigation could be a reminder for people to be more judicious in SF-use to avoid or relieve SF toxicity to nontarget organisms.

Do combined nanoscale polystyrene and tetracycline impact on the incidence of resistance genes and microbial community disturbance in Enchytraeus crypticus?

It has been proved that nanoplastics can effectively adsorb pollutants and thus influence their behavior and availability. The combined toxic effects of nanoplastic and its adsorbed pollutant on the soil fauna are still not well known. We used high-throughput quantitative PCR to explore the effects of oral nanoscale polystyrene and tetracycline exposure on antibiotic resistance genes in the soil invertebrate Enchytraeus crypticus, and used bacterial 16S rRNA gene amplification sequencing to examine the response of the microbiome of E. crypticus. After 14 days of tetracycline and nanoscale polystyrene exposure, we terminated exposure and monitored the restoration of ARGs and microbiome in the E. crypticus. Results showed that the number of ARGs, especially macrolide-lincosamide-streptogramin B (MLSB), tetracycline ARGs, as well as multidrug ARGs, increased with exposure to nanoscale polystyrene and tetracycline. The abundance of Aminoglycoside and Beta_Lactamase ARGs in E. crypticus also significantly increased. The exposure significantly perturbed the abundance of families Microbacteriaceae, Streptococcaceae, Enterobacteriaceae, Rhodocyclaceae and Sphinomonadaceae. After terminating exposure for 14 days, the diversity and abundance of ARGs were not completely restored, while the microbiome was not permanently changed but reversibly impacted.

Biochemical responses and DNA damage induced by herbicide QYR301 in earthworm (Eisenia fetida)

QYR301, a novel herbicidal inhibitor of 4-hydroxyphenylpyruvate dioxygenase (HPPD), has great potential for resistant weed control in paddy fields, but massive use of pesticides may result in toxicity to soil non-target organisms. Thus, this study was designed to assess subchronic toxicity of different doses of QYR301 in artificial soil (0, 0.1, 1.0, 2.5, and 5.0 mg kg^-1) to earthworms (Eisenia fetida) on days 7, 14, 21, and 28 after exposure, using biomarkers of reactive oxygen species (ROS) and malondialdehyde (MDA) contents, activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and glutathione-S-transferase (GST), and DNA damage. The ROS content significantly increased for all treatments on 7 and 14 days then decreased, and recovered to control level for 0.1 and 1.0 mg kg^-1 treatment on day 28. Concerning enzymes activities, QYR301 increased POD, SOD, and GST activities, but inhibited CAT activity. Except for POD activity, SOD, CAT, and GST activities of 0.1 mg kg^-1 group recovered to control level on day 28. Also, the MDA content of 0.1 mg kg^-1 group reached control level on day 28. However, DNA damage was observed for all treatments throughout the experiment and it increased with increasing doses and time except for 5.0 mg kg^-1 treatment on day 28. These results suggested that QYR301 induced excessive ROS production leading to oxidative stress in earthworms, which caused lipid membrane peroxidation and DNA damage ultimately. The findings could provide a theoretical foundation for assessing ecological damage of QYR301 to soils and a guide for future QYR301 applications.

Applying fungicide on earthworms: Biochemical effects of Eisenia fetida exposed to fluoxastrobin in three natural soils

Fluoxastrobin is one of the most widely used strobilurin fungicides, however, application of the fungicides may result in soil residues leading to environmental damage including oxidative stress and damage to sentinel organisms (i.e. earthworms). While this has been demonstrated in artificial soil, the biochemical response of Eisenia fetida exposed to fluoxastrobin in natural soils is unclear. This study utilized three typical natural soils (fluvo-aquic soils, red clay, and black soils) to evaluate the biochemical response of Eisenia fetida exposed to fluoxastrobin (0.1, 1.0, 2.5 mg/kg) including the production of reactive oxygen species, impact on three enzyme activities, lipid peroxidation, and 8-hydroxydeoxyguanosine after a 4-week exposure. The effects of fluoxastrobin on Eisenia fetida in different soils were assessed using an integrated biomarker response (IBR). The findings may be possible to state that the toxic effects of fluoxastrobin in artificial cannot exactly represent that in natural soils. Specifically, the fluoxastrobin subchronic toxicity was highest in red clay and lowest in black soil among the three natural soils. Furthermore, the 8-OHdG content was more sensitive to fluoxastrobin in all six environmental indicators of the present study.

Response of soil microbes after direct contact with pyraclostrobin in fluvo-aquic soil

Agricultural chemicals affect the daily life of food production. However, the abuse of pesticides led to the damage to the environment. Pyraclostrobin (PYR) is commonly used strobilurin fungicide which inhibits fungal respiration through mitochondrial cytochrome-b and c1 inhibition. There is increasing concerns that PYR may adversely impact the environment. Although impacts on ecological receptors have been detailed, little information is available regarding the toxicological impact of PYR on soil microbial community dynamics and functioning. Understanding the potential impact on soil microbial populations is important. The activity of enzymes (urease, dehydrogenase, and β-glucosidase) and diversity of microbial community structure using high-throughput 16S rRNA sequencing were evaluated at different soil-PYR concentrations (0.1, 1.0, and 2.5 mg/kg) over a 48 day exposure period. Urease activity remained stable in general. Pyraclostrobin inhibited dehydrogenase activity during the exposure period. The β-glucosidase activity was inhibited on day 28 and induced on day 48 at 1.0 and 2.5 mg/kg. The genera Gp6, Exiguobacterium, Gp4, and Gemmatimonas were both the dominant genera and significantly changed genera. Pyraclostrobin had different level of influence on soil microbes containg their enzyme activity and community structure. The purpose of the current study was to examine the impact of PYR addition on soil enzymes as an indicator of soil health and to have complementary data on the impact of microbial populations. Furthermore, the study may also be the guide for further rational pesticide selection.

Evaluation of the toxicity of 1-butyl-3-methyl imidazolium tetrafluoroborate using earthworms (Eisenia fetida) in two soils

Herein, to research the toxic effect of ionic liquids (ILs) on earthworms and compare their different toxicities in different soils, 1-butyl-3-methyl imidazolium tetrafluoroborate ([Bmim]BF₄) was selected as a test substance, Eisenia fetida was selected as the experimental indicator organism, and artificial and fluvo-aquic soils were selected as the media. The acute toxicity, reactive oxygen species (ROS) content, detoxification enzyme (GST) activity, anti-oxidant enzyme activities, lipid peroxidation oxidative and DNA damage in earthworms were all measured to evaluate the toxicity of [Bmim]BF₄. The results showed that either in fluvo-aquic soil or artificial soil, [Bmim]BF₄ can stimulate the accumulation of ROS in earthworms, inducing activities of antioxidant enzymes and detoxification enzymes, inevitably causing lipid peroxidation and DNA damage in earthworms. The integrated biomarker response (IBR) indicated that the toxicity of [Bmim]BF₄ in fluvo-aquic soil was greater than that in artificial soil. This experiment is relevant to the reliability of artificial soil toxicity research, and maybe this paper can provide a more authentic understanding of traditional toxicity experiments.

Using enzyme activities and soil microbial diversity to understand the effects of fluoxastrobin on microorganisms in fluvo-aquic soil

Whether now or in the foreseeable future, agricultural production cannot do without chemical pesticides. Strobilurin fungicides, including mitochondrial inhibitors, can easily enter the soil environment and causing pollution. Fluoxastrobin is one of the top-selling strobilurin fungicides. Limited information can be found in the literature on the environmental toxicity of fluoxastrobin in soil. It is essential to understand the effects of fluoxastrobin on microorganisms in fluvo-aquic soil. The present study used a Biolog-EcoPlate method to analyze the effects of fluoxastrobin on soil microbial diversity in groups exposed to 0.1, 1.0, and 2.5 mg/kg fluoxastrobin and in control groups at exposure and on days 7, 14, 21, 28, and 48. The effects of fluoxastrobin on enzyme activities (β-glucosidase, dehydrogenase, and urease) in the soil were also evaluated. The results indicated that the three tested enzyme activities were lower at each dose to a varying degree than those of the controls. The soil microbial diversity was shown to be affected according to the results of average well color development (AWCD) experiments. The present study aimed to assess environmental risks to terrestrial ecosystems under the stress of pesticide use. These results also enrich the basic data on fungicide toxicity to the soil environment and have a guiding significance for the rational use of pesticides and the sustainable utilization of resources.