Earthworm Aporrectodea Caliginosa Research Articles

Stress biomarker response in Aporrectodea caliginosa earthworms exposed to single and combined pesticide treatments (Prosaro and Decis).

This study aims to assess the impact of two pesticides commonly used in Algeria (Prosaro XRT and Decis 25 EC), as well as their combinations at recommended doses, on a non-target species bioindicator of soil pollution, the earthworm Aporrectodea caliginosa, using physiological (mortality and growth) and biochemical parameters (proteins, glutathione, catalase activity and glutathione S-transferase, acetylcholine esterase, lipoxygenase). The recommended dose and its double were tested individually and in combination for this. It should be noted that the protocol used and the initial concentrations selected are the same as those used in the field. After 7 and 14 days (7D/14D) of exposure, all dosages were administered. Our findings show that the pesticides tested had no effect on earthworm survival. However, a significant decrease in their growth rates depending on the different concentrations was observed for the different treatments over the entire exposure period of 7 or 14 D. The greatest reductions (31.62%, 35.04%) are reported after 14D for the high concentrations of Decis alone (D2) as well as for the combined treatment Prosaro/Decis (P2/D2). At the same time, an increase in total protein contents (more than 50% after 14D) as well as a decrease in acetylcholine esterase activity were reported for all treatments. We were also able to identify the induction of oxidative stress after xenobiotic exposure, which is more pronounced at the end of the treatment (14D), resulting in the stimulation of the antioxidant system (gluthione, glutathione S-transférase, catalase) as well as the induction of lipoxygenase, which is responsible for the oxidation of polyunsaturated fatty acids as well as the generation of reactive oxygen species (ROS) involved in the inflammatory phenomenon. Finally, it turns out that the species Aporrectodea caliginosa is sensitive to the different concentrations applied, even those used in the open field, and that Decis (deltamethrin) seems to be more toxic than Prosaro and that the combinaison P2/D2 is as toxic as Decis alone (D2).

Assessment of heavy metals in soil, leaf litter, and their bioaccumulation in terrestrial macroinvertebrates in Sohag Governorate, Egypt.

The presence of elevated levels of heavy metals in soil poses a significant environmental concern with implications for human health and other organisms. The main objective of our study was to reduce the gap information of seasonal abundance, distribution of heavy metals in soil, leaf litter, and some macroinvertebrates in a citrus orchard (Citrus sinensis) in Sohag Governorate, Egypt. The heavy metals copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd) were determined by atomic absorption spectrometry. Degree of contamination (DC) was determined for both soil and leaf litter contamination. However, the bioaccumulation factor (BAF) was estimated to determine metal accumulation in the macroinvertebrates including earwigs Anisolabis maritima, chilopoda Scolopendra moristans, spider Dysdera crocata, and earthworm Aporrectodea caliginosa. The study area had clay-loam with varying organic matter, salinity, and pH levels. The degree of contamination varied among seasons, with the highest levels typically observed in autumn in both soil and leaf litter. The soil ranged from low contamination (1.82) to high contamination levels (4.4), while the leaf litter showed extremely high (30.03) to ultra-high (85.92) contamination levels. The mean ecological risk index results indicated that the sampling area had moderate ecological risk levels for Cd (44.3), Zn (42.17), and Pb (80.05), and extremely high levels for Cu (342.5). Heavy metal concentrations in the selected fauna were the highest in autumn, and the bioaccumulation factor varied among species and seasons with some species classified as e-concentrators, micro-concentrators, and macro-concentrators of certain heavy metals. Scolopendra moristans exhibited the highest mean metal concentrations (Cd, Pb, and Zn), while Aporrectodea caliginosa had the lowest. Thus, the differences in heavy metal concentrations found in different soil taxa highlight the significance of taxing a holistic understanding of feeding mechanisms into account when evaluating the potential risk for animals that consume invertebrates.

Potential ecotoxicological effects of silver nanoparticles and silver sulphide on the endogeic earthworm Aporrectodea caliginosa (Savigny 1826)

Silver nanoparticles (AgNPs) are increasingly used in consumer products and subsequently arrive in wastewater systems, accumulating as silver sulphide (Ag2S) in the resulting biosolids, which are commonly spread onto agricultural fields as a fertiliser. Experiments were performed to investigate the effect of AgNPs, using the endogeic earthworm Aporrectodea caliginosa as a test organism. In an acute toxicity experiment, A. caliginosa were exposed to soil containing different concentrations of AgNPs (0, 1, 5, 10, 50, 100, 250, 500, 750, and 1000 mg kg−1 dry soil) and Ag2S (0, 10, 50, 100, 500, and 1000 mg kg−1 dry soil). Earthworm biomass and mortality were monitored. Earthworms exposed to 500, 750 and 1000 mg kg−1 fresh AgNPs had mortality rates of 20%, 60% and 70%, respectively. Changes in biomass were directly related to AgNP concentration. Exposure to Ag2S did not affect biomass or mortality. Further experiments used 0, 10, 50, 100 and 250 mg kg−1 AgNPs and 0, 50, 100, 500, and 1000 mg kg−1 Ag2S to evaluate sublethal effects on A. caliginosa. Avoidance behaviour in a linear gradient was evaluated after 14 days. Earthworms significantly preferred soil that was free of either AgNPs or Ag2S. The same concentrations were used to assess effects on cocoon production of A. caliginosa exposed to AgNPs and Ag2S. In the first 3 months of AgNP exposure, higher concentrations had a negative effect on cocoon production, but this effect diminished thereafter. Ag2S had no discernible effect on reproduction. Overall, introduction of AgNPs into the soil through the application of biosolids appears to be of low concern to the tested endogeic earthworm.

Ecotoxicity of single and mixture of perfluoroalkyl substances (PFOS and PFOA) in soils to the earthworm Aporrectodea caliginosa

Per and polyfluoroalkyl substances (PFAS) are persistent compounds that are massively used in industry, consumer goods and fire-fighting foams. Soil contamination by PFAS is a major environmental concern, and there is a lack of knowledge on both their ecotoxicological mechanisms and the concentrations that induce adverse effects especially to non-target organisms, particularly in the case of PFAS mixtures. This study contributes to filling these gaps by assessing and modelling the effects of PFAS (in single and in mixtures for PFOS and PFOA at different environmental doses) on juvenile endogeic earthworms of a common species in European soils (Aporrectodea caliginosa) at different levels of biological organization (sub-individual and individual). The results showed for the first time combined strong ecotoxicological effects of PFAS on earthworm survival, integumental integrity, growth, sexual maturity and on genomic stability notably with the induction of DNA breaks associated with no abnormal oxidative DNA-lesion levels. Our results demonstrated significant effects at 0.3 mg kg−1 and additive effects in case of mixtures.

Endogeic Earthworms Avoid Soil Mimicking Metal Pollution Levels in Urban Parks

In response to long-lasting high levels of metallic trace elements (MTEs) in urban soils, we expect soil invertebrates inhabiting urban environments to have evolved detection and avoidance and/or tolerance mechanisms to MTE pollution. In this study, I used artificial soils with concentrations of lead, zinc, copper, chromium and nickel that reflect pollution levels in the soils of Parisian parks. Using choice experiments, I compared habitat preference (i.e., the occurrence of individuals in the polluted vs. unpolluted soil) and health status (i.e., body mass maintenance, mobility, mortality) between three species of endogeic earthworms—Aporrectodea caliginosa, Aporrectodea icterica and Allolobophora chlorotica—originating either from urban or rural grasslands. This study highlights a clear avoidance of MTE-polluted soils in all three species, as well as MTE-induced health impairments, especially in A. chlorotica. Interestingly, earthworm response to MTE exposure only slightly differed between earthworms of urban and rural origin, suggesting the absence of widespread acclimatization or adaptation mechanisms to MTE pollution in cities. As a consequence, MTE pollution is expected to significantly shape earthworm spatial distribution in both urban and rural environments and, as a consequence, affect ecosystem functioning.

Effects of Zinc Accumulation on Earthworm Aporrectodea caliginosa (Haplotaxida: Lumbricidae)

Earthworms are key to the earth's ecosystem, which helps the soil increase its fertility and repair its existing elements, as well as remove contaminants. This study investigated the accumulation of Zn in the earthworm Aporrectodea caliginosa after 15 days of exposure. The worms were grown in media with different concentrations of Zn between 750 and 1500 ppm. Each treatment consisted of three replicates, containing 30 worms. A control group without Zn was also used. Data were analyzed by using Duncan Multi–Range. The results revealed that A. caliginosa had a strong ability to accumulate Zn in its tissue compared to the control group. It was noticed that the increase of the heavy metal in the worm´s tissue is associated with the elevation of the metal in its media. The results show a significant loss of weight in the worm´s body and loss in the growth rate; they also shown a decrease in specific growth rate. Moreover, there was a significant decrease in the worm length, showing a high effect, especially after 15 days of breeding with all concentrations used in this study. The researchers recommend using earthworms to purify the soil from contaminants because earthworm has a great ability to get rid of all pollutants, whether metals or pesticides or parasites, especially in industrialized countries and agricultural lands.

Genetic variability of earthworm populations in soils with different perturbation levels

Density and genetic variability of both soil macro- and meso-fauna are disturbed by productive practices. This study aimed to analyze the genetic diversity and genetic structure of populations of the earthworm Aporrectodea caliginosa caliginosa (Briones, 1996) in two sites of the Argentine Pampa under different levels of disturbance: i) grassland, ii) livestock-raising plot, iii) agricultural-livestock raising plots and iv) agricultural plot (the most disturbed). The genetic diversity of the earthworm population was determined based on the allele number, polymorphism percentage and Similarity Index. Allele number and polymorphism percentage were lower in populations from one of the soils under agricultural-livestock practices, but differed significantly only from the values of the other agricultural-livestock raising plot and the livestock-raising plot. Population structure was low although significant. This study shows that allele number and polymorphism are very useful metrics to provide historical and functional information of soils. However, the genetic differences here recorded probably depend on multiple historical and recent causes. The stability of environmental conditions along with the degree of disturbance must be considered to understand their impact on population genetic structure.

Composition, Structure and Diversity of Soil Bacterial Communities before, during and after Transit through the Gut of the Earthworm Aporrectodea caliginosa.

Earthworms heavily modify the soil microbiome as it passes throughout their guts. However, there are no detailed studies describing changes in the composition, structure and diversity of soil microbiomes during gut transit and once they are released back to the soil as casts. To address this knowledge gap, we used 16S rRNA next-generation sequencing to characterize the microbiomes of soil, gut and casts from the earthworm Aporrectodea caliginosa. We also studied whether these three microbiomes are clearly distinct in composition or can be merged into metacommunities. A large proportion of bacteria was unique to each microbiome—soil (82%), gut (89%) and casts (75%), which indicates that the soil microbiome is greatly modified during gut transit. The three microbiomes also differed in alpha diversity, which peaked during gut transit and decreased in casts. Furthermore, gut transit also modified the structure of the soil microbiome, which clustered away from those of the earthworm gut and cast samples. However, this clustering pattern was not supported by metacommunity analysis, which indicated that soil and gut samples make up one metacommunity and cast samples another. These results have important implications for understanding the dynamics of soil microbial communities and nutrient cycles.

RETRACTED ARTICLE: The assessment of the protective impact of spidroin extract against UV-A radiation damage by using earthworms (Aporrectodea caliginosa) as a robust human skin model via macroscopic and histological observations

Numerous studies have confirmed the damage caused by excessive exposure to ultraviolet-A rays. Malignant melanoma and skin cancer are two of the most serious health consequences. Thus, the UV-A protectant is intended to protect the skin, especially the two primary layers of skin (epidermis that represents the interface between the body and its surroundings and dermis). Spider silk is the most powerful natural fibre due to its regeneration, biocompatibility, antimicrobial, wound healing, antiseptic, and blood clotting properties. This work targeted to determine the protective effect of spidroin extract against UV-A radiation damage. Earthworms Aporrectodea caliginosa were collected from Assiut University’s farm. Each set of ten earthworms was separated into six groups and placed in a plastic container. Webs of spiders collected from trees and old houses. Spidroin was extracted and utilised in this work to determine the potential effects of topical application on UV-A protection. The experiment is divided into two sections: (1) UV-A exposure and (2) the use of spidroin extract to protect the earthworms from ultraviolet radiation. Two control groups (1،2) of worms were not received UV-A exposure, and four groups (3,4,5,6) were exposed to UVR-A. In contrast, groups (5,6) were received spidroin extract before exposure to UV-A. Each group from the groups (3,4,5,6) was exposed for three consecutive days (¼ hour/day, ½ hour/day, and 1 h/day), using a UV-Lamp with a wavelength of 366 nm. The histopathological changes revealed that after 1⁄4 h of UV exposure, the cuticle was swollen with a slightly detached epithelium. The cuticle was down after 1⁄2 h of exposure, and the epidermis was totally damaged and necrosed. After 1 h, the exposure showed destruction of the epidermis in the circular muscle with a loss of muscle filament integrity, varying size, and altered nucleus form, along with mild disintegration of longitudinal muscle. Spidroin extract is critical for earthworm protection against UV-A radiation damage and able to regeneration. For the first time, morphological and histological analysis was established to detect the Spidroin extract evaluated for topical application on earthworms. Earthworms can be considered as a robust human skin model prior to UV-A exposure. It induces a complete protective effect against UV-A radiation damage in earthworms.Graphical abstract

Application of Aporrectodea caliginosa to Mitigate the Waste and the Effects of Vermicompost on the Exomorphological Features of Phaseolus vulgaris

Vermin biotechnology is an eco-friendly technique and economically beneficent process to mitigate organic waste. India’s agro-industrial sector contributes colossal wealth of plant materials in the form of compost. The present study aims to publicize soil healthiness and its plant growth supplying possessions further corroborating the use of organic amendments instead of fertilizers. Plastic replicates investigation is an exercise in eighteen replicates in which fifteen were soil amendment treatments: one triplicate-control, 0% vermicompost, 50%, 25%, 12.5%, 6.25%, and 3.125% vermicompost of soil. Containers contained 2 kg soil each, in which seeds are sown, and the measurement of studied traits (length of shoot, length of internodes, flowers, leaves number and number of branches, and rate of germination) was noticed. The earthworms (Eudrilus eugeniae and Aporrectodea caliginosa) feed on waste like broiler droppings, the dung of sheep and cow, leaves, and decomposed wood and convert it into vermicompost, which required 72 days to extenuate the waste. Each setup was conducted on plastic containers, and there would be control and the test at respective experiments. Vermicompost was prepared; obviously, it contains better farming nutrients analyzed by different scientific methods and is very efficient for plant growth and other features. The main objective of the study was the effect of quality vermicompost produced by A. caliginosa on the exomorphology and rate of germination of Phaseolus vulgaris. Different ratios of vermicompost in respective replicates affect plant growth and external morphology, which is directly linked with nutrients present in treated and untreated soil. The outcomes suggested that vermicompost can be overworked as an efficacious biofertilizer.

Crop residues used as food drive enzyme activation and enzymatic stoichiometry in casts of the earthworm Aporrectodea caliginosa (Savigny, 1826)

Earthworms are drivers of important soil processes such as the nutrient cycle. Earthworms provide soil microbiota with mucus, temperature, and organic resources in their guts, enhancing organic matter decomposition. However, very little is known about the effect of different crop rotations on soil microbiota activation mediated by earthworm activity. We aimed to evaluate the effect of different crop rotations on enzymatic activity in A. caliginosa casts and on enzymatic stoichiometry patterns related to C, N, and P acquisition activities. We conducted a microcosm study using different crop residues as food supply: soybean (S), soybean plus maize (SM), vetch, maize, and soybean (VMS), and with no residue addition (NR). We measured α-glucosidase (AGLU), β-glucosidase (BGLU), cellobiohydrolase (CEL), acetylesterase (ACE), N-acetyl-glucosaminidase (NAG), and phosmonoesterase (PME) activities in A. caliginosa casts, immediately before starting the experiment for evaluating the initial condition (IC) and after the experiment in each residue treatment. SM and VMS residues enhanced BGLU, CEL, and NAG activity regarding S, NR, and IC treatments. S had similar or lower activity than NR and IC for all the analyzed enzymes. There was a positive, strong, and significant relationship among C, N, and P acquiring enzymes regardless of the treatment. We found lower ratios for C and N acquisition related to P acquisition than for C: N acquisition activity ratios. This result suggests P as the limiting nutrient for earthworm microbiomes. Our results indicate that soybean residue is unsuitable for A. caliginosa food requirements and that diversifying crop residues and the inclusion of maize as food enhance enzymatic activity mediated by earthworms and thus organic matter decomposition. We suggest differential activation and likely changes in microbiota composition as mechanisms responsible for higher enzymatic activation when earthworms are fed with different combination of crop residues.

Occurrence of the Aporrectodea caliginosa caliginosa (Savigny, 1826) (Annelida: Clitellata: Haplotaxida) from Kashmir Valley, Jammu & Kashmir, India

The paper describes the earthworm Aporrectodea caliginosa caliginosa (Savigny, 1826) of class Clitellata, order Opisthopora and family Lumbricidae, from Kashmir Valley, Jammu & Kashmir, India. Previously the species was recorded from Himachal Pradesh, and in the present study the species is reported from Gulmarg forest within the geographical coordinates of (34.0500N & 74.3880E). During the study the seasonal variation of A.c. caliginosa in terms of density and biomass along with the soil physiochemical characteristics were reported. A.c. caliginosa showed significant variation in density (t=3.34, p<0.044) and biomass (t=3.40, p<0.042) among different seasons, with maximum density (129.6/m2) and biomass (26.90g/m2) during spring, and minimal values of 34.33/m2 and 6.94g/m2 during winter respectively. Soil physiochemical characteristics also varied significantly among seasons.

Genetic analysis in earthworm population from area contaminated with radionuclides and heavy metals

This study assessed the effects of environmental contamination by naturally occurring radionuclides and heavy metals on the genetic structure of a population of the earthworm Aporrectodea caliginosa. A. caliginosa were collected from four sites and characterized by amplified fragment length polymorphism (AFLP) analyses. No differences in genetic structure and diversity were found between sites that differed greatly in soil contamination levels of radionuclides and metals. However, when the genetic structure of the A. caliginosa population was analyzed without considering information about the sampling site, a complex intraspecific genetic structure was identified. At least three highly divergent lineages were found, in unequal proportions, of each genetically isolated group from each study site. No associations were found between the distribution of the detected genetic clusters and the geographical origin of the samples. Thus, no noticeable adaptive changes or signs of directional selection were detected, despite the long history of genotoxic waste disposal at the sampling site. These results suggest a combined effect of three factors on the genetic structure and diversity of A. caliginosa in soils: the complexity of the contaminant composition, the heterogeneous spatial distribution of the pollutants, and the complexity of the intraspecific genetic structures of A. caliginosa.

Towards a better understanding of the life cycle of the earthworm Aporrectodea caliginosa: New data and energy-based modelling

Earthworms have a major role in soils and are used as biological indicators for ecological risk assessment. Aporrectodea caliginosa s.s. is one of the dominant earthworm species in agroecosystems and a good candidate for ecotoxicological testing. In order to improve knowledge on its life cycle, we performed growth and reproduction experiments. These data were used to calibrate an energy-based model that displayed good descriptions of A. caliginosa life cycle parameters under different feeding conditions (ad libitum, food limitations, or absence of food). Here we showed that the maintenance costs were negligible, resulting in a linear growth in length when food was provided ad libitum (i.e., without any restriction). We also found that the switch from the juvenile to adult stage depended on the individual weight, and that the threshold weight was not influenced by the amount of provided food (horse dung). Moreover, we provided evidence that once adults, if they were not isolated from other individuals, the energy was entirely allocated to cocoon production, which only depended on the available food amount, without any effect of the earthworm density. Finally, we discussed the usefulness of our energy-based model to support the set up and analyses of ecotoxicological tests and experiments.

Genetic, epigenetic and microbiome characterisation of an earthworm species (Octolasion lacteum) along a radiation exposure gradient at Chernobyl

The effects of exposure to different levels of ionising radiation were assessed on the genetic, epigenetic and microbiome characteristics of the “hologenome” of earthworms collected at sites within the Chernobyl exclusion zone (CEZ). The earthworms Aporrectodea caliginosa (Savigny, 1826) and Octolasion lacteum (Örley, 1881) were the two species that were most frequently found at visited sites, however, only O. lacteum was present at sufficient number across different exposure levels to enable comparative hologenome analysis. The identification of morphotype O. lacteum as a probable single clade was established using a combination of mitochondrial (cytochrome oxidase I) and nuclear genome (Amplified Fragment Length Polymorphism (AFLP) using MspI loci). No clear site associated differences in population genetic structure was found between populations using the AFLP marker loci. Further, no relationship between ionising radiation exposure levels and the percentage of methylated loci or pattern of distribution of DNA methylation marks was found. Microbiome structure was clearly site dependent, with gut microbiome community structure and diversity being systematically associated with calculated site-specific earthworm dose rates. There was, however, also co-correlation between earthworm dose rates and other soil properties, notably soil pH; a property known to affect soil bacterial community structure. Such co-correlation means that it is not possible to attribute microbiome changes unequivocally to radionuclide exposure. A better understanding of the relationship between radionuclide exposure soil properties and their interactions on bacterial microbiome community response is, therefore, needed to establish whether these the observed microbiome changes are attributed directly to radiation exposure, other soil properties or to an interaction between multiple variables at sites within the CEZ.

Earthworms Mitigate Pesticide Effects on Soil Microbial Activities.

Earthworms act synergistically with microorganisms in soils. They are ecosystem engineers involved in soil organic matter degradation and nutrient cycling, leading to the modulation of resource availability for all soil organisms. Using a soil microcosm approach, we aimed to assess the influence of the earthworm Aporrectodea caliginosa on the response of soil microbial activities against two fungicides, i.e., Cuprafor Micro® (copper oxychloride, a metal) and Swing® Gold (epoxiconazole and dimoxystrobin, synthetic organic compounds). The potential nitrification activity (PNA) and soil enzyme activities (glucosidase, phosphatase, arylamidase, and urease) involved in biogeochemical cycling were measured at the end of the incubation period, together with earthworm biomass. Two common indices of the soil biochemistry were used to aggregate the response of the soil microbial functioning: the geometric mean (Gmean) and the Soil Quality Index (SQI). At the end of the experiment, the earthworm biomass was not impacted by the fungicide treatments. Overall, in the earthworm-free soil microcosms, the two fungicides significantly increased several soil enzyme and nitrification activities, leading to a higher GMean index as compared to the non-treated control soils. The microbial activity responses depended on the type of activity (nitrification was the most sensitive one), on the fungicide (Swing® Gold or Cuprafor Micro®), and on the doses. The SQI indices revealed higher effects of both fungicides on the soil microbial activity in the absence of earthworms. The presence of earthworms enhanced all soil microbial activities in both the control and fungicide-contaminated soils. Moreover, the magnitude of the fungicide impact, integrated through the SQI index, was mitigated by the presence of earthworms, conferring a higher stability of microbial functional diversity. Our results highlight the importance of biotic interactions in the response of indicators of soil functioning (i.e., microbial activity) to pesticides.

Microbiome dynamics during cast ageing in the earthworm Aporrectodea caliginosa

Earthworm casts are hotspots of microbial activity playing an important role in the nutrient cycling of soil ecosystems. Cast ageing can be considered an ecological succession, where copiotrophic bacteria are replaced by oligotrophic bacteria as the ratio labile/recalcitrant substrates decreases. Here we use next-generation sequencing to describe the bacterial communities (microbiome) of fresh casts (day 0) from the earthworm Aporrectodea caliginosa and how they change over time (7, 15, 30 and 60 days) under natural conditions. We also look for the main, transitional and day-specific core microbiomes of A. caliginosa casts and assessed whether bacterial communities in each ageing stage are clearly distinct in their composition or can be merged into metacommunities. Fresh cast microbiomes were mainly comprised of Bacteroidetes and Proteobacteria (62% of the total sequences) and, in a lesser extent, of Acidobacteria, Actinobacteria Chloroflexi, Planctomycetes and Verrucomicrobia (36% of the total sequences). These fresh casts were richer in amplicon sequence variants (ASVs) than soil microbiomes, which also had lower abundances of Bacteroidetes but higher abundances of other bacterial phyla. As expected, copiotrophic bacteria (Alphaproteobacteria but not Bacteroidetes) significantly (P < 0.0001) decreased in abundance with cast ageing, while oligotrophic bacteria (Actinobacteria, Acidobacteria and Deltaproteobacteria) increased (P < 0.03) their proportion. This also resulted in a significant (P < 0.05) decrease in alpha-diversity over the first 15 days and larger differences in beta-diversity among bacterial communities of ageing casts. Despite differences in beta-diversity, microbiomes of ageing casts were grouped into two metacommunities, one comprised of younger samples collected at days 0 and 7, and another comprised of older samples collected at days 15, 30 and 60. These two metacommunities corresponded to decreased patterns in labile C and N pools in cast ageing. We found a main core microbiome comprised of eight bacterial taxa (~5% of the total sequences). Additionally, we also found transitional and day-specific core microbiomes that were richer and compositionally different from the main core microbiome. This suggests different levels of redundancy in the cast microbiomes to buffer responses to external perturbations (e.g., weather oscillations).

Improving Complementarity Effect of Legume Intercrop by Earthworm Facilitation for Wheat Performance

Intercrops and crop mixtures are considered to be a way to increase nitrogen use efficiency by promoting niche complementarity and facilitation, reducing the input of fertilizers and herbicides, which are important factors when considering the effects of climate change. However, interactions between crop communities and soil functional diversity also have major effects on crop cover function. Our study aimed to investigate the simultaneous effects of plant composition and presence of earthworms on the growth (roots and shoots) of wheat (Triticum aestivum L.). Mesocosms filled with soil were sown with either 6 wheat plants of the same cultivar, or 6 plants of 3 different wheat cultivars, or 3 wheat plants of 3 different cultivars with 3 clover plants (Trifolium hybridum L.). A part of the mesocosms was inoculated with either endogeic earthworms (Aporrectodea caliginosa S.) or a mixture of endogeic and anecic earthworms (Lumbricus terrestris S.). A relative interaction index was calculated to highlight competition strength between plants with or without earthworms. The presence of different cultivars had no influence on wheat performance, but with clover, plant competition decreased to the benefit of wheat biomass and N accumulation. Earthworms also reduced the competitive strength between wheat plants in mixed-cultivar mesocosms and in intercropping. In intercrops with clover, wheat performance was improved as a result of niche complementarity and earthworm facilitation for N resource. Our results suggest that the plant functional group, such as legumes, and earthworm communities work synergistically to improve wheat yields.

Nerve conduction velocity as a non-destructive biomarker in the earthworm Aporrectodea caliginosa exposed to insecticides.

Earthworms are important and useful soil organisms, but in agricultural soils, they are potentially exposed to a wide variety of pesticides. Insecticides represent the highest threat to earthworms and many are neurotoxic. There is a need for a reliable, relevant, simple biomarker to assess the sub-lethal effects of neurotoxic insecticides on earthworms under laboratory or field conditions. The Aporrectodea caliginosa earthworms were exposed to 0 (control), 0.5×, 1× (normal field application rate), and 5× concentrations of a carbamate (Pirimor®) and an organophosphate (Lorsban®) insecticides. The nerve conduction velocity (NCV) of the medial giant fibers of A. caliginosa earthworm was recorded on days 0, 1, 2, 3, 4, and 7 to quantify sub-lethal neurotoxic effects. Acetylcholinesterase (AChE) enzyme activity of A. caliginosa homogenates was measured at the conclusion of the experiment. Pirimor® but not Lorsban® induced a significant decrease in NCV on days 3, 4, and 7 at 1× and 5× doses. A significant dose-dependent decrease was observed on AChE activity to Pirimor® at the doses used but not Lorsban®. A clear relationship is observed between AChE activity and NCV in the case of Pirimor®. This study showed that NCV is a sensitive biomarker that correlates well with classical biomarker measurements such as AChE enzyme activity. This technique could be used to study the impact of insecticides on earthworms and also their recovery.

Impact of tropho-metabolic activity of earthworms (Lumbricidae) on distribution of soil algae within Acer platanoides L. plantation in recultivated territories of Western Donbass (Ukraine)

Rational use of natural resources in conditions of modern environmental management is an ongoing challenge to maintain sufficient level of wellbeing – natural resources and healthy environment in the contest of biodiversity preservation, formation of soil fertility, esthetic properties of landscapes and other ecologically important services. One way to optimize technogenic landscapes is forest recultivation – creation of stable forest ecosystems on disturbed territories, which can be powerful environmentcreation tool. The pertinent activity of animals – ecological engineers has great importance for improvement of ecological state of forest ecosystems on the recultivated territories. Soil engineers, such as earthworms, are the key organisms in functioning of soil – most important component of terrestrial ecosystem. They participate in various ecological processes and play key role in numerous ecosystem services: biogeochemical cycles support, forming of sustainable hydrological regime of territory and soil productivity, protection from the erosion. Additional natural soil biotic factor, multiplying these effects – algae, which reflect biogenic grade of soil and their naturalization in conditions of forest recultivation. Although, soil algae and earthworms are important components, supporting soil fertility, biogenic relationship of these groups of organisms, especially in the conditions of forest recultivation, remains largely unstudied The aim of the research is to evaluate the impact of pedotrubation and tropho-metabolic activity of earthworms ( Oligochaeta : Lumbricidae ) on resettlement of soil algaflora representatives within maple ( Acer platanoides L.) plantation on the soil recultivation plot in Western Donbass in the Steppe zone of Ukraine. In fresh coprolites of earthworms Aporrectodea caliginosa on the studied plot, five species of soil algae ( Chlorella vulgaris Beijerinck , Botrydiopsis eriensis Snow, Phormidium retzii (Agardn) Gomont, Bracteococcus sp ., Chlorococcum pulchrum Archibald et Bold) were found. They belong to divisions Chlorophyta , C уа nophyta , Xantophyta and represented by Ch - and P -living forms, which can dwell in artificial forest ecosystem with severehydrothermal conditions. Such representatives as Phormidium retzii , Chlorococcum pulchrum , Botrydiopsis eriensis were present only in soil and coprolites on the soil surface. This indicates their rise to the soil surface in result of tropho-metabolic and pedotrubation activity of worms. This allows considering that, earthworms in the studied plot of soil recultivation contribute to redistributions and resettlement of soil algae, their exploration to new territories, and ultimately – naturalization of artificial edaphotopes of forest plantations in recultivated lands.