Collembolan Reproduction Research Articles

Assessment of the reproduction of six collembolan species in tropical soils naturally rich in potentially toxic elements.

Laboratory ecotoxicological tests are important tools for the management of environmental changes derived from anthropogenic activities. Folsomia candida is usually the model species used in some procedures. However, this species may not be sufficiently representative of the sensitivity of the other collembolan species. This study aimed to evaluate (i) the effects of soils naturally rich in potentially toxic elements (PTE) and soil characteristics on the reproduction and survival of different collembolan species, (ii) whether the habitat function of these soils is compromised, and (iii) to what extent F. candida is representative of the other collembolan species. For this, reproduction tests with six collembolan species were conducted in 14 different samples of soils. In general, collembolan reproduction was not completely inhibited in none of the natural tested soils. Even soils with high pollution load index values did not negatively affect collembolan reproduction for most of the species. In contrast, the lowest collembolan reproduction rates were found in a visually dense soil (lowest volume/weight ratio), highlighting that soil attributes other than total PTE concentration also interfere in the reproduction of collembolans. Our results support the idea that the F. candida species might not be representative of other collembolan species and that laboratory tests to assess soil contaminations should be conducted using diverse collembolan species.

Arthropods and ultraviolet radiation: Survival, growth and development

Abstract Ultraviolet radiation (UVR) has positive and negative impacts on organisms and affects entire ecosystems. It is currently receiving attention because of the interactions of UVR with changes in climate that are likely to affect agriculture and food security. A review is provided on the effects of different types of UVR on the survival, development and reproduction of insects, collembolans and mites. The foci are on how UVR is used in pest control and how it affects arthropod coloration and distribution. Direct exposure to UV‐A, UV‐B and UV‐C delays development and reduces survival and host‐seeking ability of arthropods; immature stages are more sensitive than the adults. Increased exposure of crops to UVR has indirect effects on herbivory, and regions with high UVR levels may permit crop production in the absence of certain pest insect species. The Bunsen‐Roscoe law of reciprocity was upheld for Diaphorina citri and Tetranychus urticae under the range of irradiances and durations of exposure used in two studies, which showed that, for a constant dose, the effects of low irradiances of long durations were equivalent to those of higher irradiances of shorter durations. DNA damage caused by UV‐C and UV‐B can be repaired by photoreactivation; both white light and UV‐A are effective.

Exploring ecological effects of arsenic and cadmium combined exposure on cropland soil: from multilevel organisms to soil functioning by multi-omics coupled with high-throughput quantitative PCR

Arsenic (As) and cadmium (Cd) pose potential ecological threats to cropland soils; however, few studies have investigated their combined effects on multilevel organisms and soil functioning. Here, we used collembolans and soil microbiota as test organisms to examine their responses to soil As and Cd co-contamination at the gene, individual, and community levels, respectively, and further uncovered ecological relationships between pollutants, multilevel organisms, and soil functioning. At the gene level, collembolan transcriptome revealed that elevated As concentrations stimulated As-detoxifying genes AS3MT and GST, whereas the concurrent Cd restrained GST gene expression. At the individual level, collembolan reproduction was sensitive to pollutants while collembolan survival wasn’t. At the community level, significant but inconsistent correlations were observed between the biodiversity of different soil keystone microbial clusters and soil As levels. Moreover, soil functioning related to nutrient (e.g., carbon, nitrogen, phosphorus, and sulfur) cycles was inhibited under As and Cd co-exposure only through the mediation of plant pathogens. Overall, these findings suggested multilevel bioindicators (i.e., AS3MT gene expression in collembolans, collembolan reproduction, and biodiversity of soil keystone microbial clusters) in cropland soils co-contaminated with As and Cd, thus improving the understanding of the ecotoxicological impact of heavy metal co-contamination on soil ecosystems.

Ecotoxicological relevance of glyphosate and flazasulfuron to soil habitat and retention functions - Single vs combined exposures.

Glyphosate (GLY) and flazasulfuron (FLA) are two non-selective herbicides commonly applied together. However, research focused on their single and combined ecotoxicological impacts towards non-target organisms is still inconclusive. Therefore, this study aimed to test their single effects on soil's habitat and retention functions, and to unravel their combined impacts to earthworms and terrestrial plants. For this, ecotoxicological assays were performed with plants (Medicago sativa), oligochaetes (Eisenia fetida) and collembola (Folsomia candida). Soil elutriates were also prepared and tested in macrophytes (Lemna minor) and microalgae (Raphidocelis subcapitata). FLA (82-413µgkg-1) reduced earthworms' and collembola's reproduction and severely impaired M. sativa growth, being much more toxic than GLY (up to 30mgkg-1). In fact, the latter only affected plant growth (≥ 9mgkg-1) and earthworms (≥ 13mgkg-1), especially at high concentrations, with no effects on collembola. Moreover, only elutriates from FLA-contaminated soils significantly impacted L. minor and R. sucapitata. The experiments revealed that the co-exposure to GLY and FLA enhanced the toxic effects of contaminated soils not only on plants but also on earthworms'. However, such increase in toxicity was dependent on GLY residual concentrations in soils. Overall, this work underpins that herbicides risk assessment should consider herbicides co-exposures, since the evaluation of single exposures is not representative of current phytosanitary practices and of the potential effects under field conditions, where residues of different compounds may persist in soils.

The use of sewage sludge as remediation for imidacloprid toxicity in soils.

This study investigated the influence of the sewage sludge (SS) soil amendment on the chronic toxicity of imidacloprid (through the seed dressing formulation MUCH 600 FS®-600g active ingredient L-1) to collembolans Folsomia candida. Individuals 10-12days old were exposed to two contrasting tropical soils (Oxisol and Entisol) amended with SS doses (0, 20, 40, 80, 160, and 320g SS kg-1 soil; the SS doses have low intrinsic toxicity, which was checked before its application) in a full factorial combination with five imidacloprid concentrations (varying from 0.25 to 4mgkg-1 in Oxisol and 0.03-0.5mgkg-1 in Entisol) plus a control. None of the SS doses (without imidacloprid) in both soils reduced the number of generated juvenile collembolans. The imidacloprid concentrations reducing the collembolan reproduction in 50% (EC50) in Oxisol and Entisol without SS were 0.49 and 0.08mgkg-1, respectively. However, the EC50 values generally increased with increasing SS doses in soils, varying from 1.03 to 1.41 in Oxisol and 0.07 to 0.21 in Entisol. The SS-amended soils showed 2.1- to 2.9-fold lower imidacloprid toxicity (EC50-based) in Oxisol and 1.8- to 2.7-fold lower toxicity in Entisol. Our results suggest the most effective SS doses alleviating the imidacloprid toxicity (EC50-based) to collembolans are 20gkg-1 in Oxisol and 80gkg-1 in Entisol. These results indicate that the tested SS has the potential to be employed as a soil amendment agent by reducing the toxicity of imidacloprid to the reproduction of F. candida.

QSAR models for soil ecotoxicity: Development and validation of models to predict reproductive toxicity of organic chemicals in the collembola Folsomia candida

Soil pollution is a critical environmental challenge: the substances released in the soil can adversely affect humans and the ecosystem. Several bioassays were developed to investigate the soil ecotoxicity of chemicals with soil microbes, plants, invertebrates and vertebrates. The 28-day collembolan reproduction test with the springtail Folsomia candida is a recently introduced bioassay described by OECD guideline 232. Although the importance of springtails for maintaining soil quality, toxicity data for Collembola are still limited. We have developed two QSAR models for the prediction of reproductive toxicity induced by organic compounds in Folsomia candida using 28 days NOEC data. We assembled a dataset with the highest number of compounds available so far: 54 compounds were collected from publicly available sources, including plant protection products, reactive intermediates and industrial chemicals, household and cosmetic ingredients, drugs, environmental transformation products and polycyclic aromatic hydrocarbons. The models were developed using partial least squares regression (PLS) and the Monte Carlo technique with respectively the open source tools Small Dataset Modeler and CORAL software. Both QSAR models gave good predictive performance even though based on a small dataset, so they could serve for the ecological risk assessment of chemicals for terrestrial organisms.

Susceptibility of Folsomia candida to Agrochemicals after Multigenerational Exposure to Human Pharmaceuticals.

In realistic environmental scenarios, soil organisms can be exposed to a combination of pharmaceuticals and agriproducts or within different time frames. Therefore, it is necessary to increase knowledge on soil organism susceptibility under a complex mixture exposure scenario. The present study aimed to assess the susceptibility of the collembolan Folsomia candida to copper and dimethoate on a pre-exposure for 3 generations to human pharmaceuticals (fluoxetine and carbamazepine). Carryover effects on reproductive output and survival were observed after a multigenerational pre-exposure to carbamazepine or fluoxetine, considerably increasing the sensitivity of collembolans to both copper and dimethoate. This was more evident for collembolans pre-exposed to the highest concentrations of both pharmaceuticals (40 mg/kg soil), as demonstrated by a significant reduction in the number of juveniles and increased mortality. In addition, pre-exposure to carbamazepine and fluoxetine induced varying effects on subsequent exposure to the same chemical. Although pre-exposure to carbamazepine led to a decrease in collembolan reproduction, even when transferred to a clean medium, fluoxetine induced severe effects but only when collembolans were exposed to other contaminants (i.e., not when transferred to clean soil). The present study highlighted the need to consider carryover effects and possible interactions between pharmaceuticals and other contaminants under simultaneous exposure. Environ Toxicol Chem 2022;41:592-600. © 2021 SETAC.

Ecotoxicity of imidacloprid to soil invertebrates in two tropical soils with contrasting texture.

Imidacloprid is one of the most commercialized insecticides in agriculture in the world, with a broad spectrum of action. However, little is known about the effects of commercial formulations containing this active ingredient (a.i.) on non-target organisms in tropical soils. Our objective was to assess the toxicity based on the predicted environmental concentration (PEC) of imidacloprid, in the avoidance behaviour of earthworms and collembolans as well as in the reproduction of collembolans, in two representative soils of the Brazilian Cerrado with contrasting texture (clayey Oxisol and sandy Entisol). Ecotoxicity tests were carried out according to ISO protocols to assess the avoidance behaviour of earthworms (Eisenia andrei) and avoidance and reproduction of collembolans (Folsomia candida). In the earthworm's avoidance test, more than 80% of the individuals were found in the control, in all tested concentrations, indicating a possible habitat function loss in both soils. The avoidance behaviour of collembolans was observed in both soils, being more expressive (up to 75% of escape) in Oxisol. In Entisol, only the two highest concentrations were avoided (up to 63%). There was a negative effect on the reproduction of collembolans in both soils, with a higher EC50 value (0.255 mg kg-1) in Oxisol than in Entisol (0.177 mg kg-1), demonstrating higher toxicity in the sandy soil. These differences were attributed to the contrasting texture of the studied soils, probably due to lower retention of the a.i. in the sandy soil, causing an increased bioavailability. This study demonstrated that imidacloprid can be highly toxic to soil invertebrates, even in soil concentrations lower than those expected from recommended dose, causing an impact on the edaphic organisms and, consequently, compromising its functions in the soil ecosystem.

Low concentration effects and different outcome in repeated reproduction tests with silver nanoparticles, silver nitrate and Folsomia candida (Collembola)

BackgroundToxicity of silver nanoparticles (AgNP) has been studied frequently due to a rise in application in various products. Various studies on AgNP toxicity with terrestrial and aquatic organisms confirmed their negative effects. In our previous experiments, strong variability was observed in the reproduction of Collembola (Folsomia candida) in different repeats. To investigate the effects of silver on the reproduction of Folsomia candida, they were exposed in laboratory-controlled conditions to AgNP and silver nitrate (AgNO3) at a concentration of 30 mg/kg dry soil for 28 days and compared to controlled individuals not exposed to silver. We repeated reproduction tests on the toxicity of silver to Folsomia candida four times throughout one year (April, July, October and January) in order to explore the temporal variability of their outcome.ResultsWhile adult survival was similar in all treatments and seasons, reproduction in the control increased from April to October. Significantly lower reproduction was found in January with only 385–424 juveniles per vessel, compared to 504–633 individuals in other months. Strong toxic effects of both silver treatments were observed in July, April and October. However, AgNP showed no toxic effects on the reproduction of F. candida in January. The relative toxicity of both substances varied between single experiments: AgNP were more toxic than AgNO3 in April and July, and less toxic in October and January.ConclusionThese findings indicate that the reproduction of F. candida in the control had a significant effect on the results of the toxicology experiments. Moreover, we demonstrated the reproductive toxicity of AgNP in soil at a much lower concentration than reported thus far. Therefore, to guarantee reliability and reproducibility, we recommend to disregard any test results where the reproduction rate of F. candida in the control is significantly different from the average in the respective laboratory, even if the validity criteria of the test are met.

Litter leachates have stronger impact than leaf litter on Folsomia candida fitness

It is well known that soil physico-chemical conditions and the nature of organic matter have important effects on soil micro-arthropod communities, including collembolans. However, mechanisms by which the physical or chemical quality of litter influence collembolan communities remain unclear. Plant secondary metabolites are partially released in soils through leaf and litter leaching and decomposition, and can have a strong influence on soil communities and their activity. In order to disentangle effects of the water-soluble compounds contained in the litter versus its physical effect, a microcosm experiment was set up exposing the collembola species Folsomia candida to either litter or litter leachates mixed to the substratum. Litter from three species with different chemical properties and one mixture (hybrid poplar, white spruce, grass and a mixture of poplar – spruce litter) and two concentrations of litter leachates (at 5% and 10% concentration) were used in microcosm experiments. After 30 days of incubation, reproduction and mortality rates of F. candida were assessed. Results showed that the tree litter leachates had a stronger impact on collembolan fitness compared to the litter itself, with a net reduction of survival and reproduction rates. Between 78 and 100% of mortality was observed in microcosms that received tree leachates, indicating a strong influence of the soluble compounds contained in tree leaves on collembolan. In contrast, collembolan reproduction was positively affected by the grass litter or 10% grass litter leachates compared to control (water). Our findings help to understand how chemical properties and leaf leaching may have important impacts on micro-arthropods communities and litter decomposition processes.

Studying the toxicity of SLEnS-LAS micelles to collembolans and plants: Influence of ethylene oxide units in the head groups

Mixed micelles of linear alkylbenzene sulfonic acid (LAS) and ether sulfate-based surfactants (SLEnS) can be added in household products and cleaning agents. SLEnS with higher ethylene oxide (EO) units in the head groups have economic and environmental advantages. This work aims to assess the influence of the number of EO units in the ecotoxicity of seven variants of SLEnS-LAS micelles (0–50 EO units) in soils. Ecotoxicological tests were carried out to assess emergence and growth of four plants species and reproduction of collembolans. Most of the variants inhibited plants growth at the highest concentrations (1237.5 μg SLEnS kg−1 of soildw). For reproduction, lower number of EO units resulted in EC50 from 924.2 (95 % CL: 760.7–1063.4) to 963.2 (95 % CL: 676.9–1249.6) μg SLEnS kg−1 of soildw, whereas for higher number of EO units (50 and 30) no inhibition was reported. Based on these results, we suggest that a higher number of EO units contribute to less hazardous formulations, confirming that different designs of surfactants may contribute to changes in the responses of terrestrial organisms. Therefore, we demonstrate that standardized ecotoxicological assays may contribute to more sustainable and effective formulations, when used upstream, prior to manufacture and marketing.

Impact of temperature on the toxicity of Kraft 36 EC® (a.s. abamectin) and Score 250 EC® (a.s. difenoconazole) to soil organisms under realistic environmental exposure scenarios

Pesticides can affect all receiving compartments, especially soils, and their fate and effects may be enhanced by temperature, increasing their risk to ecological functions of soils. In Brazil, the most widely used pesticides are the insecticide Kraft 36EC® (a.s. abamectin) and the fungicide Score 250EC® (a.s. difenoconazole), which are commonly used in strawberry, often simultaneously as a mixture. The aim of this study was to evaluate the toxicity of realistic environmental applications, single and in mixtures, for both pesticides to the springtail Folsomia candida and the plant species Allium cepa (onion) and Lycopersicum esculentum (tomato). Mesocosms filled with Brazilian natural soil (lattosolo) were dosed with water (control), Kraft (10.8g a.s/ha), Score (20g.a.s/ha) and Kraft+Score (10.8+20g a.s./ha). The applications were repeated every 7 days, during 18 days of experiment, and simulating rainfall twice a week. Collembola reproduction tests were conducted with soils from the first (day 1) and last day (day 18) of experiment for each treatment. Plant toxicity tests were carried out in the experimental units. The experiments were run at 23°C and 33°C. Kraft, alone and in the binary mixture, showed high toxicity to the springtails in soils from both days 1 and 18, especially at 23°C where it caused 100% mortality. Score however, was not toxic to the springtails. Plant growth was reduced by Score, but responses varied depending on temperature. This study indicates a high environmental risk of the insecticide Kraft, particularly at lower temperatures (23°C), and an influence of temperature on pesticide fate and effects.

Synthesis and Characterization of Zero-Valent Iron Nanoparticles, and the Study of Their Effect against the Degradation of DDT in Soil and Assessment of Their Toxicity against Collembola and Ostracods.

Of late, novel magnetic nanomaterials have drawn worldwide attention because of the uniqueness in their properties and uses. In our studies, we have prepared nearly monodisperse zero-valent iron nanoparticles (nZVIs) of diameter of less than 60 nm in aqueous medium by a reductive precipitation process and pectin as stabilizing agent. The characterization of these nanoparticles was done by dynamic light scattering and transmission electron microscopy (TEM) techniques. The TEM images confirmed that the average size of the nZVIs was about 25 nm. The resultant nZVIs were then employed to degrade DDT (dichlorodiphenyltrichloroethane) in spiked soil, and their toxicity toward Collembola (Folsomia candida) and Ostracods (Heterocypris incongruens) was measured. The fabricated nZVIs degraded DDT in soil quite effectively. Further, the effects of nZVIs on Collembola and Ostracods were found to be negative. This was due to the oxidation of nZVIs and creation of anoxic conditions thereupon, and the generation of excess Fe(II) in soil. In addition, the negative effects of DDT on ostracod development and Collembola reproduction were found to be quite weak.

The fungicide mancozeb affects soil invertebrates in two subtropical Brazilian soils

Mancozeb is a dithiocarbamate non-systemic fungicide widely used to control fungal diseases of plants, commonly applied in apple orchards in Brazil. Instead of its common use, there are no reports about the risk to non-target organisms in Brazilian soils. We studied the risk of Mancozeb (in the commercial formulation Dithane® NT) for standard invertebrate species (Folsomia candida, Eisenia andrei and Enchytraeus crypticus) in two subtropical Brazilian soils, Oxisol and Ultisol, which are representative of apple production areas in Brazil. Reproduction and survival tests were carried out following ISO guidelines. Results showed that Mancozeb in Oxisol reduced the survival and reproduction of collembolans (LC50 54.43 and EC50 2.72 mg a.i. kg-1) and enchytraeids (LC50 6.97 and EC50 3.56 mg a.i. kg-1), in lowest values than those observed in Ultisol (F. candida LC50 > 1000 and EC50 > 100 mg a.i. kg-1; E. crypticus LC50 280.21 and EC50 29.67). Effects to E. andrei were similar in both soils and indicated a lower sensitivity of this species to Mancozeb. The species F. candida and E. crypticus were more sensitive than E. andrei. These results reinforce the need to include other soil organisms besides earthworms, using chronical endpoints and considering different types of soils, to better predict the risk of pesticides for subtropical soils.

The Effect of Biochar Mixed with Compost on Heavy Metal Concentrations in a Greenhouse Experiment and on Folsomia Candida and Eisenia Andrei in Laboratory Conditions

Organic wastes treated, used on agricultural land, can replace inorganic fertilizers, due to physical and chemical properties that improve soil and crop quality on long-term. In this study, was used biochar produced from sewage sludge, compost obtained from cattle manure, and mixtures made from biochar-compost in different concentration, at 5 t/ha and 30 t/ha, application rates. The aim of the study is to determine the influence of this organic wastes on the heavy metals bioavailability in greenhouse conditions and on Folsomia candida and Eisenia Andrei, used as test organisms under laboratory conditions. Compared to control variants, the use of biochar mixed with compost in different concentration at 5 t/ha and 30 t/ha, application rates, in a greenhouse experiment did not significantly affect the concentrations of heavy metals (Cu, Cd, Zn and Pb). Reproduction of collembolans has not been influenced by increasing application rate of the mixtures, and by concentrations of biochar or compost. The earthworms recorded weight losses, only in the experimental treatments with sewage sludge biochar used in different concentrations, at both application rates.

Ecotoxicological evaluation of dredged sediments from Rodrigo de Freitas Lagoon (Rio de Janeiro State, Brazil) using bioassays with earthworms and collembolans

The toxicity and metal bioavailability were studied in dredged sediments from Rodrigo de Freitas Lagoon (Rio de Janeiro, RJ, Brazil) using acute and avoidance tests with Eisenia andrei, and reproduction tests with Folsomia candida. The sediment was mixed with an artificial soil, and two natural soils (ferralsol and chernosol—representative Brazilian tropical soils) to obtain the following doses: 1, 3, 6, 12, 18, 24 and 30%. Total metal concentrations were determined in the sediment to support the interpretation of ecotoxicological data. Metal concentrations in the mixtures were in agreement with the threshold limits established by Brazilian law. However, significant avoidance responses were found on doses ≥ 3% and were the most sensitive endpoint. Earthworm mortality found in artificial soil mixtures (LC50 = 3.9) suggests higher toxicity levels than those obtained in ferralsol (LC50 = 7.6%) and chernosol (11.0%) treatments. Earthworm mortality, avoidance responses and collembolan reproduction levels found in ferralsol mixtures (LC50 = 9.2; avoidance EC50 = 2.3%; reproduction EC50 = 2.8%) were higher compared to chernosol treatments (LC50 = 11.0%; avoidance EC50 = 4.3%; reproduction EC50 = 4.9%). The reduction of toxicity levels in chernosol mixtures is probably due to the abundance of expansive clay minerals in chernosols with capacity of adsorbing metals and other xenobiotic substances from soil pore water, decreasing metal bioavailability. Finally, threshold limits defined by Brazilian legislation for soil quality and land disposal of dredged sediments are not sufficient to prevent noxious effects on soil fauna and should be complemented with a preliminary ecotoxicological evaluation.

Do recommended doses of glyphosate-based herbicides affect soil invertebrates? Field and laboratory screening tests to risk assessment

Despite glyphosate-based herbicides are widely used in agriculture, forestry and gardens, little is known about its effects on non-target organisms. The present work evaluated the ecotoxicity of four formulated products (Roundup® Original, Trop®, Zapp® Qi 620 and Crucial®) on soil invertebrates. Screening ecotoxicity tests were carried out with soil and oat straw collected in a field experiment, besides laboratory-spiked soils. Screening tests included avoidance behaviour of earthworms (Eisenia andrei), collembolans (Folsomia candida) and isopods (Porcellio dilatatus) in single and multispecies tests; reproduction of collembolans (F. candida), and bait lamina in field. Non-avoidance behaviour was observed in standard tests (earthworms) in soil, neither in multispecies tests (earthworm + isopods) using oat straw, while for collembolans it occurred for the product Zapp® Qi 620 even at the recommended dose. Reproduction of F. candida was not impaired even at high doses in laboratory-spiked soils. Feeding activity on bait lamina test was impaired in treatment corresponding to the red label product, Crucial®. Results showed the relevance of bait lamina test on screening the impact of herbicides in the field. The findings highlight the importance of considering different formulations for the same active ingredient in risk assessment of pesticides.

Selenium toxicity to survival and reproduction of Collembola and Enchytraeids in a sandy loam soil

We investigated the toxicity of selenium (Se) to the soil invertebrates Folsomia candida (Collembola) and Enchytraeus crypticus (potworm). Studies were designed to generate ecotoxicological benchmarks for developing ecological soil screening levels (Eco-SSLs) for risk assessments of contaminated soils. For the present studies, we selected Sassafras sandy loam, an aerobic upland soil with soil characteristics (low levels of clay and organic matter, soil pH adjusted from 5.2 to 7.1) that support high relative bioavailability of the anionic Se species that is typically found in aerobic soil. The Se was amended into soil as sodium selenate, subjected to weathering and aging using 21 d of alternating cycles of air-drying/rehydration to 60% of the water-holding capacity of the Sassafras sandy loam soil, under ambient greenhouse conditions. Effective concentrations at 20 and 50% (EC20 and EC50) levels for production of juveniles (reproduction) were 4.7 and 10.9 mg of Se/kg of soil (dry mass basis), respectively, for Collembola, and 4.4 and 6.2 mg/kg, respectively, for the potworms. The data enabled the derivation of toxicity benchmarks, contributing to the development of a soil invertebrate-based Eco-SSL of 4.1 mg/kg for Se. Environ Toxicol Chem 2018;37:846-853. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Exposure of soil collembolans to microplastics perturbs their gut microbiota and alters their isotopic composition

Effects of microplastics on aquatic organisms have been widely studied in recent years but effects on soil biota, and especially on the gut microbiota of soil animals, remain poorly understood. An experiment was therefore conducted using the common soil collembolan Folsomia candida exposed to microplastics for 56 days to investigate the effects of plastics on gut microbiota, growth, reproduction and isotopic turnover of collembolans in the soil ecosystem. A diverse microbial community was observed in the collembolan gut, consisting of (at phylum level) Actinobacteria (∼44%), Bacteroidetes (∼30%), Proteobacteria (∼12%) and Firmicutes (∼11%). Distinctly different bacterial communities and lower microbial diversity were found in the collembolan gut compared with the surrounding soil. We also found that exposure to microplastics significantly enhanced bacterial diversity and altered the microbiota in the collembolan gut. Moreover, collembolan growth and reproduction were significantly inhibited (by 16.8 and 28.8%, respectively) and higher δ15N and δ13C values were observed in the tissues after exposure to microplastics. These results indicate that exposure to microplastics may impact non-target species via changes in their microbiota leading to alteration of isotopic and elemental incorporation, growth and reproduction. The collembolan gut microbial data acquired fill a gap in our knowledge of the ecotoxicity of microplastics.

Digestate and Fugate - Fertilizers with Ecotoxicological Risks

Increasing number of decentralised biogas plants increases not only the amount of biogas produced, but also the production of digestate. Digestate and fugate are believed to be good fertilizers. However, there is often a tradeoff between other environmental impacts linked to agricultural production like eutrophication or ecotoxicity. Only limited ecotoxicological information is known about the effects of digestate or fugate on terrestrial fauna and flora. This is the first study comparing the survival and reproduction of collembolans as the representative soil fauna and the root growth and photosynthetic activity of Sinapis alba and Panicum miliaceum plants when exposed to digestate and fugate. Comparison of ecotoxicological results with chemical analysis of both digestate and fugate has led to the conclusions that application of digestate and fugate was beneficial neither for tested plants, nor for zooedaphon. Under practically used dosing both digestate and fugate can represent potential ecotoxicological problems, which can affect zooedaphon diversity and reproduction resulting in degradation of soil structure, reduction of microbial activity or water retention capacity of treated soils. That is why we do recommend at least simplified ecotoxicological testing of digestate as presented in this study. Ecotoxicity testing can support decision of direct application on soil, or mixing the digestate with other materials (like compost, manure, pond sediments, or biochar), what will help to utilize nutrients and consequently can prevent degradation of soil fertility.