Environmental pollutants, pathogens and immune system in earthworms

Long-term toxic effects of iron-based metal-organic framework nanopesticides on earthworm-soil microorganism interactions in the soil environment

With the widespread use of controlled-release nanopesticides in field conditions, the interactions between these nanopesticides and biological systems are complex and highly uncertain. The toxicity of iron-based metal organic frameworks (CF@MIL-101-SL) loaded with chlorfenapyr (CF) to terrestrial invertebrate earthworms in filter paper and soil environments and the potential mechanisms of interactions in the nanopesticide-earthworm-cornfield soil microorganism system were investigated for the first time. The results showed that CF@MIL-101-SL was more poisonous to earthworms in the contact filter paper test than suspension concentrate of CF (CF-SC), and conversely, CF@MIL-101-SL was less poisonous to earthworms in the soil test. In the soil environment, the CF@MIL-101-SL treatment reduced oxidative stress and the inhibition of detoxifying enzymes, and reduced tissue and cellular substructural damage in earthworms compared to the CF-SC treatment. Long-term treatment with CF@MIL-101-SL altered the composition and abundance of microbial communities with degradative functions in the earthworm intestine and soil and affected the soil nitrogen cycle by modulating the composition and abundance of nitrifying and denitrifying bacterial communities in the earthworm intestine and soil, confirming that soil microorganisms play an important role in reducing the toxicity of CF@MIL-101-SL to earthworms. In conclusion, this study provides new insights into the ecological risks of nanopesticides to soil organisms.

New insights into vermiremediation of sewage sludge: The effect of earthworms on micropollutants and vice versa

Vermicomposting represents an environmentally friendly method for the treatment of various types of biowastes, including sewage sludge (SS), as documented in numerous studies. However, there are few papers providing insights into the mechanisms and toxicity effects involved in SS vermicomposting to present a comprehensive overview of the process. In this work, the vermiremediation of SS containing various micropollutants, including pharmaceuticals, personal care products, endocrine disruptors, and per/polyfluoroalkyl substances, was studied. Two SSs originating from different wastewater treatment plants (WWTP1 and WWTP2) were mixed with a bulking agent, moistened straw, at ratios of 0, 25, 50, and 75% SS. Eisenia andrei earthworms were introduced into the mixtures, and after six weeks, the resulting materials were subjected to various types of chemical and toxicological analyses, including conventional assays (mortality, weight) as well as tissue- and cell-level assays, such as malondialdehyde production, cytotoxicity tests and gene expression assays. Through the vermiremediation process significant removal of diclofenac (90%), metoprolol (88%), telmisartan (62%), and triclosan (81%) was achieved. Although the concentrations of micropollutants were substantially different in the original SS samples, the micropollutants vermiaccumulated to a similar extent over the incubation period. The earthworms substantially eliminated the present bacterial populations, especially in the 75% SS treatments, in which the average declines were 90 and 79% for WWTP1 and WWTP2, respectively. To the best of our knowledge, this is the first study to investigate the vermiremediation of such a large group of micropollutants in real SS samples and provide a thorough evaluation of the effect of SS on earthworms at tissue and cellular level.

Biomarker response index in earthworms following chronic exposure to leachate from a closed dumpsite: Behavioral, cytotoxicity and antioxidant system alterations

Leachate, an effluent produced during solid waste decomposition, interacts directly with soil, mainly in dumpsite areas. Studies on terrestrial animal exposure to leachate are, however, lacking. Plants are the most frequently studied organisms, while animal studies, especially earthworms, are limited. Nevertheless, ecotoxicological assessments involving earthworms are crucial due to their role in soil health and ecosystem maintenance, which are paramount in understanding potential terrestrial ecosystem leachate effects. In this context, this study aimed to evaluate behavioral effects, sublethal cytotoxicity and antioxidant system alterations in Eisenia andrei earthworms chronically exposed to leachate from a closed dumpsite. Cytotoxicity was determined by coelomocyte density, viability and cell typing, while antioxidant system alterations were assessed through superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), reduced glutathione (GSH) and metallothionein (MT) determinations. Malondialdehyde (MDA) and protein carbonylation (PTC) levels were also determined as oxidative effect markers. Finally, the Biomarker Response Index (BRI) was assessed, aiming to quantitatively integrate the results of the investigated endpoints and establish a biological health state (BHS) for each leachate concentration. Leachate exposure led to leak responses at concentrations of up to 50%, but attraction at higher concentrations. Decreased cell density (28%) was observed after 48 days and reduced viability (50%), after 14 days of leachate exposure. The observed cell typing changes indicate anti-inflammatory immune system effects. Leachate exposure led to several antioxidant system alterations, increasing SOD (2-6 %), CAT (5-35 %) and GST (5-70 %) activities and GSH (7-37%) and MT (3-67%) levels. Earthworm antioxidant defenses were, however, able to prevent lipid peroxidation, which decreased (11-37%) following leachate exposure to concentrations above 12.5%, and PTC, which increased at 42 days (26%) and reduced at 56 days (12 %). This is the first PTC assessment in leachate-exposed earthworms. The increased carbonylation levels observed after 42 days alongside MDA decreases highlight the need for further research employing oxidative effect biomarkers other than MDA. Finally, an integrated approach employing the BRI was carried out, revealing mild initial changes evolving to moderate to major effects at the highest leachate exposure concentration, with an effect attenuation detected at the end of the experiment. In this sense, this study brings forth a significant novelty, employing a biomarker previously not assessed in earthworms, demonstrating an oxidative effect, alongside the use of the BRI as an integrative tool for the endpoints applied in this assessment.

Insight into Bioaccumulation of Decabromodiphenyl Ethane in Eisenia fetida Increased by Microplastics

The rise of electronics inevitably induced the co-pollution of novel brominated flame retardants (NBFRs) and microplastics (MPs). However, studies on how they interact to influence their bioavailability are scarce. Here, we explored the influence mechanism of acrylonitrile butadiene styrene (ABS)-MPs on the bioaccumulation of decabromodiphenyl ethane (DBDPE) in soil-earthworm microcosms. The influence exhibited a temporal pattern characterized by short-term inhibition and long-term promotion. After 28 days of exposure, DBDPE bioaccumulation in a co-exposure (10 mg kg-1 DBDPE accompanied by 1000 mg kg-1 ABS-MPs) was 2.61 times higher than that in a separate exposure. The adsorption process in the soil, intestines, and mucus introduced DBDPE-carried MPs, which had a higher concentration of DBDPE than the surrounding soil and directly affected the bioavailability of DBDPE. MP-pre-exposure (100, 1000, and 10000 mg kg-1) reduced epidermal soundness, mucus secretion, and worm cast production. This eventually promoted the contact between earthworm and soil particles and enhanced the DBDPE of earthworm tissue by 6%-61% in the next DBDPE-postexposure period, confirming that MPs increased DBDPE bioaccumulation indirectly by impairing the earthworm health. This study indicates that MPs promoted DBDPE bioaccumulation via adsorption and self-toxicity, providing new insight into the combined risk of MPs and NBFRs.

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).

Effects of earthworm hydrolysate in production performance, serum biochemical parameters, antioxidant capacity and intestinal function of Muscovy ducks

Earthworm has a variety of molecular biological characteristic, for example, growth promotion, antioxidant, and anti-bacteria. Thus, we decomposed earthworm by earthworm's own protease for preparing of earthworm hydrolysate. Muscovy ducks were fed with basal diet that formulated to contain 1.5% and 2.5% earthworm hydrolysate. Then, we investigated the influences of earthworm hydrolysate on growth performance in Muscovy ducks by performance terminology and measurement for poultry (NY/T 823-2020). The morphology of duodenum and number of intraepithelial lymphocytes were tested by HE staining and immunohistochemical method. Serum biochemical parameters and antioxidant capacity were also determined. High-throughput sequencing technology can sequence 16S rDNA of cecal contents from experimental Muscovy ducks. Results showed that 1.5% earthworm hydrolysate increased ADG (16-70 days old), ALB, HDL-C, T-AOC, CAT, SOD, GSH-PX, villi length, intestine thickness and surface area of villi (P < 0.05 or P < 0.01), and reduced FCR (16-70 days old), UREA, CRE, LDL-C, MDA (P < 0.05 or P < 0.01). Meanwhile, 2.5% improved ADG (16-70 days old), abdominal fat yield, breast muscle yield, heart index, spleen index, ALP, UA, T-AOC, CAT, SOD, GSH-PX, villi length, crypt depth, intestine thickness, surface area of villi, the percentage of intraepithelial lymphocytes (P < 0.05 or P < 0.01), and decreased FCR (42-70 days old and 16-70 days old), UREA, UA, MDA (P < 0.05 or P < 0.01). The sequencing results of gut flora demonstrated that earthworm hydrolysate improved variety of the gut flora in the V4 area of ducks immensely. In a word, our results provide the foundation for preliminary researching the potential principles of earthworm hydrolysate in promoting production performance, adjusting antioxidant function and intestinal functions in the Muscovy duck industry.

Insights into the mechanisms of organic pollutant toxicity to earthworms: Advances and perspectives

Earthworms play positive ecological roles in soil formation, structure, and fertility, environmental protection, and terrestrial food chains. For this review, we searched the Web of Science database for articles published from 2011 to 2021 using the keywords "toxic" and "earthworm" and retrieved 632 publications. From the perspective of bibliometric analysis, we conducted a co-occurrence network analysis using the keywords "toxic" and "earthworm" to identify the most and least reported topics. "Eisenia fetida," "bioaccumulation," "heavy metals," "oxidative stress," and "pesticides" were the most common terms, and "microbial community," "bacteria," "PFOS," "bioaugmentation," "potentially toxic elements," "celomic fluid," "neurotoxicity," "joint toxicity," "apoptosis," and "nanoparticles" were uncommon terms. Additionally, in this review we highlight the main routes of organic pollutant entry into soil, and discuss the adverse effects on the soil ecosystem. We then systematically review the mechanisms underlying organic pollutant toxicity to earthworms, including oxidative stress, energy and lipid metabolism disturbances, neurological toxicity, intestinal inflammation and injury, gut microbiota dysbiosis, and reproductive toxicity. We conclude by discussing future research perspectives, focusing on environmentally relevant concentrations and conditions, novel data processing approaches, technologies, and detoxification and mitigation methods. This review has implications for soil management in the context of environmental pollution.

Vermicompost and Its Derivatives against Phytopathogenic Fungi in the Soil: A Review

Synthetic chemicals, such as fertilizers and pesticides, are abundantly used in agriculture to enhance soil fertility and prevent the occurrence of diseases, respectively. Many studies have reported a negative influence of these chemicals on the soil environment. Natural sources from earthworms and their products, as a result of vermicomposting, may be considered better alternatives. The aim of this review was to reveal the source of antifungal efficiency of vermicompost and its derivatives, such as vermiwash, coelomic fluid, skin secretion of earthworms, and metabolites from decomposer bacteria in vermicompost, in order to highlight their application in agriculture. The synergistic activity of bioactive compounds present in coelomic fluid, mucus, skin secretion, and metabolites from associated bacteria (decomposer) assisted crop plants for effective action against various soil pathogenic fungi, such as Rhizoctoniasolani, Alternaria solani, Aspergillus niger, A.flavus, Fusariumoxysporum, and F. graminearum. Thus, these bioactive metabolites can be recommended to suppress plant fungal diseases. Vermicompost and its derivatives should be considered for use in agricultural fields to control harmful soil fungi and increase crop productivity.

Natural inhibitors from earthworms for the crystallization of calcium oxalate monohydrate

Two proteins are proposed as CaOx nucleation and crystal growth regulators. The site-specific adsorption of inhibitors is confirmed from both macroscopic and microscopic perspectives.

Superoxide-anion triggers impairments of immune efficiency and stress response behaviors of Eisenia fetida earthworms

Superoxide-hydrogen peroxide (S-HP), triggered by Val16Ala-SOD2 human polymorphism, may influence the risk of depression. Therefore, it is plausible that higher basal S-anion levels and chronic inflammatory states associated with the VV-SOD2 genotype can negatively modulate the stress response associated with resilience in various species, from primitive species to humans. To test this hypothesis, Eisenia fetida earthworms were exposed for 24 h to 30 nM rotenone, which causes mitochondrial dysfunction by generating high S-anion levels (known as the "VV-like phenotype"), and 10 μM porphyrin, a SOD2-like compound, which generates elevated HP levels (known as the "AA-like phenotype"). The results suggested that both S-anion and HP acted as signaling molecules, differentially altering the immune function and acute hydric stressful response. Although the AA-like phenotype improved the immune and stress response efficiencies, the VV-like phenotype showed a downregulated expression of the toll-like receptor (EaTLR, JX898685) and antimicrobial peptide (AMP) (AF060552) genes, which triggered the impairment of encapsulation and earthworms extracellular trap (EET) processes used by earthworms to trap and destroy microorganisms. When exposed to adverse environments and dangerous hydric stress, VV-like earthworms exhibited an impulsive behavior and failed to quickly identify and migrate to a protected environment, unlike control earthworms and AA-like earthworms. All results corroborated that the S-anion imbalance could concomitantly induce alterations in immune function and stress behavior related to earthworm survival. From a human perspective, this information may corroborate the potential specific role of superoxide anion in the modulation of the stress response, resilience, and risk of depression.

Vermiwash: An agent of disease and pest control in soil, a review

Vermiwash is a liquid extract produced from vermicompost in a medium where earthworms are richly populated. It comprises a massive decomposer bacteria count, mucus, vitamins, different bioavailable minerals, hormones, enzymes, different antimicrobial peptides, etc. This paper aimed to assess how these natural products in vermiwash suppressed the pathogen and pests. Thus, we have reviewed the importance of vermiwash/vermicompost in disease control, the mechanism of disease suppression, the components of vermiwash applied in disease suppression, and pest control to use the scientific facts in agriculture to enhance the productivity of the crops. The bioactive macromolecules from the skin secretion of earthworm, coelomic fluid, and mucus directly able to defend pathogenic soil microbes against the worm and thereby freed the environment from the disease. Earthworms establish symbiotic relations with microbes, produce an essential product that supports the growth of plants, and suppress plant's root disease. It is recomended that earthworm should be inoculated in an agricultural field, or prepare and apply its vermiwash/vermicompost as a spray or as additive bio-fertilizer in the soil to enhance the productivities of the crops.