Collembolan Folsomia Candida Research Articles

Presence of microplastics enhanced the toxicity of silver nanoparticles on the collembolan Folsomia candida

There is growing interest in interactions of microplastics (MPs) with other pollutants. However, there is limited understanding of the combined effects of MPs and silver nanoparticles (AgNPs) on nontarget soil organisms. This work aimed to examine the effects of exposure to various AgNPs' concentrations alone (0, 0.1, 1, 10, 100, 1000 mg·kg-1, 50 nm) and in combination with polyvinyl chloride microplastics (PVC MPs, 80-250 μm) at 0.1% concentration for 28 days on reproduction, Ag accumulation, C/N ratio, and isotopic fractionation of the standard soil fauna collembolan Folsomia candida. Results showed that compared to the AgNPs exposure alone, the presence of MPs significantly reduced reproduction by 51.4% and markedly increased Ag content in collembolans by 87.7% at 1000 mg·kg-1 AgNPs, which evidenced a synergistic effect. Co-exposure to MPs and AgNPs resulted in a noticeable reduction in the C/N ratio in F. candida body tissues by 9.90% and 5.27% at 1 and 10 mg·kg-1 AgNPs, respectively, showing additive and synergistic effects. Additionally, this co-exposure altered stable isotope fractionation, with the highest increments of δ15N by 32.3% and inhibition of δ13C by 2.62%, demonstrating the turnover of nutrients shift in the collembolan tissues. Collectively, this study demonstrates that con-current exposure to environmentally relevant concentration of MPs and relatively high doses of AgNPs synergistically induces toxic effects on F. candida, leading to Ag accumulation and reproduction decline. These findings imply that MPs could alter collembolans' responses to AgNPs exposure, potentially enhancing the metal ions' bioavailability in soil environments and posing ecotoxicological threats to soil-dwelling organisms.

Prevention values for copper (low tier approach) in subtropical acidic soils.

Copper is a trace element in plants and animals whose importance can be understood due to its role in different essential metabolic processes. Anthropogenic activities such as agriculture and mining are potential sources of pollution due to the emission of copper into the environment. Brazilian legislation ties soil quality to guideline values, among which the Prevention Value indicates the critical environmental limit for trace elements. The aim of this study was to obtain PVs for copper for two subtropical soils (Cambisol and Nitisol), given that the pedological richness was not considered when deriving the PVs contained in the federal normative. Reproduction assays followed ISO guidelines with the earthworm species Eisenia andrei and Perionyx excavatus, the enchytraeids Enchytraeus crypticus and Enchytraeus bigeminusand the springtails Folsomia candida and Proisotoma minuta. Results showed that the sensitivity of the organisms was greater in Cambisol. The most sensitive species were the earthworms, especially Perionyx excavatus (EC50 = 67.83 in Cambisol; EC50 = 264.96 in Nitisol). The springtails, on the other hand, were the least sensitive to contamination. These findings reinforce the need to include organisms from different ecological groups in ecotoxicological assessments. It was also observed that the PV adopted in federal legislation (= 60mgkg-1) is in fact protective for the species and soils we evaluated, since the PVs we obtained based on the EC50 were 346.74mgkg-1 in Nitisol and 134.05mgkg-1 in Cambisol. It is important to note that our results do not exclude the need for evaluations with other subtropical soils, given the influence of their properties on the toxicity and bioavailability of copper to soil organisms.

Ecotoxicity of alkaline residue from the pulp and paper industry to soil faunal organisms

The increased production and expanding demand for cellulosic products have required companies to provide solutions for the proper disposal of generated residues without compromising soil quality. In this context, the current research aimed at evaluating the ecotoxicological impacts of dregs application in subtropical soils. The experiments were carried out with the earthworm Eisenia andrei, the springtail Folsomia candida, and the potworm Enchytraeus crypticus in two subtropical soils (Neosol and Cambisol) collected in the southern region of Brazil. The considerable differences in texture and organic matter content motivated the choosing of these soils. The reproductive rate of all organisms was influenced, with varying EC50 values depending on the soil type. However, more pronounced effects were observed for Neosol. The springtail F. candida proved to be the most sensitive to contamination (EC50 = 5.8 g kg−1 for Neosol and 48.5 g kg−1 for Cambisol), followed by the earthworm E. andrei (EC50 = 62.4 g kg−1 for Neosol and 129.5 g kg−1 for Cambisol) and the potworm E. crypticus (EC50 = 67.2 g kg−1 for Neosol and 230.4 g kg−1 for Cambisol). As a result, while dregs can be used to correct soil acidity, they have been shown to have negative effects on important organisms responsible for functions critical to maintaining ecosystem quality.

A Dirt(y) World in a Changing Climate: Importance of Heat Stress in the Risk Assessment of Pesticides for Soil Arthropods.

The rise in global temperatures and increasing severity of heat waves pose significant threats to soil organisms, disrupting ecological balances in soil communities. Additionally, the implications of environmental pollution are exacerbated in a warmer world, as changes in temperature affect the uptake, transformation and elimination of toxicants, thereby increasing the vulnerability of organisms. Nevertheless, our understanding of such processes remains largely unexplored. The present study examines the impact of high temperatures on the uptake and effects of the fungicide fluazinam on the springtail Folsomia candida (Collembola, Isotomidae). Conducted under non-optimum but realistic high temperatures, the experiments revealed that increased temperature hampered detoxification processes in F. candida, enhancing the toxic effects of fluazinam. High temperatures and the fungicide exerted synergistic interactions, reducing F. candida's reproduction and increasing adult mortality beyond what would be predicted by simple addition of the heat and chemical effects. These findings highlight the need to reevaluate the current ecological risk assessment and the regulatory framework in response to climate changes. This research enhances our understanding of how global warming affects the toxicokinetics and toxicodynamics (TK-TD) of chemicals in terrestrial invertebrates. In conclusion, our results suggest that adjustments to regulatory threshold values are necessary to address the impact of a changing climate.

Derivation of ecological safety thresholds and risk assessment of new SDHI fungicides in farmland system

Succinate dehydrogenase inhibitor (SDHI) fungicides have become some of the top-selling fungicides in recent years. As the utilization of these fungicides intensifies, the corresponding potential risks to the environment proportionately increase. However, there is still limited knowledge about their toxic effects on ecosystems. In this study, acute toxicity data from laboratory assessments of the springtail Folsomia candida, alongside collected data from terrestrial and aquatic non-target species, were utilized to construct a species sensitivity distribution (SSD) model for both terrestrial and aquatic non-target organisms. Subsequently, we derived ecological baseline values for diverse scenarios within ecosystems. The results indicated that benzovindiflupyr exhibited the highest 7-day median lethal concentration (7d-LC50) to Folsomia candida at 2.0 μg cm−2, while the toxicity levels of other SDHI fungicides varied, ranging from 99 to 304 μg cm−2. In agricultural environments, the Hazard Concentration for 5 % of species (HC5) values for fluxapyroxad, boscalid, sedaxane, and isopyrazam were determined to be 8.0, 1240, 12.97, and 25.37 g ha−1, respectively. In aquatic environments, the HC5 values for benzovindiflupyr, fluxapyroxad, boscalid, sedaxane, isopyrazam, and carboxin were 0.0013, 0.022, 1.76, 0.372, 0.013, and 0.161 mg L−1, respectively. In an evaluation of typical agricultural scenarios within China, SDHI fungicides were found to exert substantial ecological risks to terrestrial non-target fauna and aquatic ecosystems around agricultural fields. Specifically, isopyrazam and fluxapyroxad were identified as posing heightened ecological risks to Typhlodromus pyri and Aphidius rhopalosiphi. Moreover, the application of benzovindiflupyr, carboxin, isopyrazam, and fluxapyroxad in paddy field environments is associated with unacceptable risks to groundwater. The findings of this study contribute significantly to the environmental risk evaluation of SDHI fungicides within farmland system, thereby informing the development of policy frameworks for their scientifically grounded application.

Effects of mycotoxin-producing fungi on the fitness and gut bacterial community of the soil springtail Folsomia candida.

Mycotoxin-producing fungi are widespread in nature and raise concerns for human and livestock health. Although they share the same ecosystem, interactions between mycotoxin-producing fungi and soil arthropods are not well understood. In this study, we report an unexpected finding that the soil arthropod Folsomia candida is rather tolerant to these mycotoxin-producing fungi. F. candida can survive solely on mycotoxin-producing fungi as a food source with reduced physiological parameters. Moreover, the gut microbial community is disturbed by mycotoxin-producing fungi, and some of the bacteria isolated from F. candida's gut can inhibit the growth of corresponding fungi. Notably, the altered physiological parameters and gut microbiota are restored when a normal diet is reintroduced, suggesting F. candida's resilience to mycotoxin-producing fungi. These findings clarify the impact of toxin-producing diets on F. candida, shedding light on how organisms can build resilience to environmental stimuli.

Multigenerational toxicity of microplastics derived from two types of agricultural mulching films to Folsomia candida

Degradation and fragmentation of mulching films represents an increasing source of microplastics (MPs, plastic particles 1 μm to 5 mm in size) to agricultural soils. MPs have been shown to affect many soil invertebrates, including springtails. However, these studies typically use test materials representing less environmentally relevant particle types, such as pristine uniform MPs, which do not represent the large range of particle sizes and morphologies found in the field. This study aimed at providing insight into the adverse effects of MPs originating from agricultural mulching films, by using artificially aged MPs derived from both biodegradable (starch-polybutadiene adipate terephthalate (PBAT)) blend, as well as conventional (linear low-density polyethylene (LLDPE)) plastic polymers. The soil dwelling springtail Folsomia candida was exposed to these MPs for five generations in order to elucidate population effects due to possible reproduction toxicity, endocrine disruption, mutagenesis or developmental toxicity. F. candida were exposed to 0, 0.0016, 0.008, 0.04, 0.2, 1, 2, 3, 4 and 5 % (w/w dry soil) MPs in Lufa 2.2 soil, which includes concentrations within the range of environmental relevance. Juveniles produced at each concentration were transferred to the next generation, with the parental, F2 and F4 generations being exposed for four weeks and F1 and F3 generations for five weeks. No concentration-dependent effects on F. candida survival or reproduction were observed in exposures to either of the MPs, in any of the generations. These results suggest that the particular MPs used in this study, derived from mulching films used on agricultural soils, may not be potent toxicants to F. candida, even after long-term exposure and at elevated concentrations.

Using Folsomia candida (Collembola) for the ecological assessment of sediment samples from three rivers from the QwaQwa region, South Africa

AbstractSince the establishment of a free economic zone and a simultaneous increase in the population of the QwaQwa region, aquatic systems of the area were expected to undergo an increase in metal contamination. The aims of this study were to assess the quality of sediments from the Metsi-Matsho, Namahadi and Elands Rivers of the QwaQwa region, and to investigate their impact on the survival and reproduction of the collembolan Folsomia candida. Due to the lack of freshwater sediment quality guidelines in South Africa, metal contents of the sediments were analysed and critically interpreted using the national action list for the screening of dredged sediment proposed for marine disposal, and international sediment quality guidelines (SQGs). In the laboratory, F. candida was exposed to 0, 50, 75 and 100% of the sediment samples for 28 days at 20 °C. Sediments were variably contaminated with Cr, with the Namahadi River middle site having the highest concentration (569 mg.kg−1, dry weight) followed by the lower site on the Elands River (529 mg.kg−1, dry weight), both above the recommended prohibition level of 500 mg Cr.kg−1. According to the consensus-based SQGs, only the concentrations of Cr and Ni (upper reach of Metsi-Matsho River) were higher than probable effect concentration, denoting that harmful effects of those metals are likely to occur. Of the two endpoints assessed, reproduction was the most sensitive with the upper reach of the Metsi-Matsho River (half maximal effective concentration, EC50 = 24% sediment) being the most deleterious site to the reproduction of F. candida. Ecotoxicological bioassays using F. candida could be suitable complements to chemical analysis in the assessment of the ecological risks of freshwater sediments as this collembolan species is sensitive to sediments with variable ranges of metal contamination.

Chronic Effects of an Insect Growth Regulator (teflubenzuron) on the Life Cycle and Population Growth Rate of Folsomia candida.

Current standard toxicity tests on nontarget soil invertebrates mainly focus on the endpoints survival and reproduction. Such results are likely insufficient to predict effects at higher organizational levels, for example, the population level. We assessed the effects of exposure to the pesticide teflubenzuron on the collembolan Folsomia candida, by performing a full life-cycle experiment exposing single individuals via contaminated food (uncontaminated control and 0.2, 0.32, 0.48, 0.72, 1.08, and 1.6 mg/kg dry yeast). Several life-history traits were considered by following the growth and development of newly hatched individuals over a period of 65 days. We assessed survival, body length, time to first oviposition, cumulative egg production, and hatchability of eggs. A two-stage model was applied to calculate the population growth rate (λ) combined with elasticity analysis to reveal the relative sensitivity of λ to the effects of teflubenzuron on each life-history parameter. Body length was the least sensitive life-history parameter (median effective concentration = 1.10 mg teflubenzuron/kg dry yeast) followed by time to first oviposition (0.96 mg/kg), survival (median lethal concentration = 0.87 mg/kg), cumulative egg production (0.32 mg/kg), and egg hatchability (0.27 mg/kg). Population growth decreased with increasing concentrations of teflubenzuron (λ = 1.162/day in control to 1.005/day in 0.72 mg/kg dry yeast, with populations going extinct at 1.08 and 1.6 mg/kg dry yeast). Elasticity analysis showed that changes in juvenile survival had a greater impact on the population growth rate compared with the other life-history traits. Our study provides a comprehensive overview of individual-level effects of long-term exposure to teflubenzuron and integrates these effects to assess the potential risk to collembolan populations. Environ Toxicol Chem 2024;43:1173-1183. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Exploring the Relationship Among Lipid Profile Changes, Growth, and Reproduction in Folsomia candida Exposed to Teflubenzuron Over Time.

The integration of untargeted lipidomics approaches in ecotoxicology has emerged as a strategy to enhance the comprehensiveness of environmental risk assessment. Although current toxicity tests with soil microarthropods focus on species performance, that is, growth, reproduction, and survival, understanding the mechanisms of toxicity across all levels of biological organization, from molecule to community is essential for informed decision-making. Our study focused on the impacts of sublethal concentrations of the insecticide teflubenzuron on the springtail Folsomia candida. Untargeted lipidomics was applied to link changes in growth, reproduction, and the overall stress response with lipid profile changes over various exposure durations. The accumulation of teflubenzuron in organisms exposed to the highest test concentration (0.035 mg a.s. kg-1 soil dry wt) significantly impacted reproductive output without compromising growth. The results suggested a resource allocation shift from reproduction to size maintenance. This hypothesis was supported by lipid shifts on day 7, at which point reductions in triacylglycerol and diacylglycerol content corresponded with decreased offspring production on day 21. The hypermetabolism of fatty acids and N-acylethanolamines on days 2 and 7 of exposure indicated oxidative stress and inflammation in the animals in response to teflubenzuron bioaccumulation, as measured using high-performance liquid chromatography-tandem mass spectrometry. Overall, the changes in lipid profiles in comparison with phenotypic adverse outcomes highlight the potential of lipid analysis as an early-warning tool for reproductive disturbances caused by pesticides in F. candida. Environ Toxicol Chem 2024;43:1149-1160. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Biotic Ligand Modeling for the Effect of Major Cations on the Uptake of Cadmium in Folsomia candida Exposed in a Sand-Solution Medium.

Biotic ligand modeling (BLM) approaches are already applied to predict the bioavailability and possible risk of metals in surface water, but need further development for soils. The present study investigated the effect of major cations (Ca2+, Mg2+, Na+, K+, and H+) on cadmium bioaccumulation in the springtail Folsomia candida. To avoid the complexity of real soils and enable control of elemental speciation in the exposure medium, the animals were exposed to different cadmium concentrations in an inert quartz sand-solution medium. Accumulation of cadmium in the animals was measured after 7 days exposure at different cation concentrations. Among the cations, only Ca2+ significantly affected the uptake of cadmium in the springtails. Mg2+ also had higher effects compared with other selected cations. Using a BLM approach, the uptake of cadmium in the animals predicted by taking into account both Ca2+ and Mg2+ activities correlated well with the measured values (R2 = 0.68). The final estimated conditional binding constants for cadmium (log KCd-BL), Ca (log KCa-BL), and Mg (log KMg-BL) of 1.06, 2.14, and 1.23 L/mol, respectively, were in agreement with previously reported values. The match between predicted and measured uptake data confirms the applicability and usefulness of the BLM for predicting the bioavailability of cadmium to springtails and opens the way for its application in soil. Environ Toxicol Chem 2024;43:1090-1096. © 2024 SETAC.

Ecological functions of fungal sesquiterpenes in the food preference and fitness of soil Collembola.

Volatile organic compounds (VOCs) emitted by fungi play a key role in locating and selecting hosts for fungivorous arthropods. However, the ecological functions of many common VOC classes, such as sesquiterpenes, remain unknown. Mutants of Trichoderma virens, defective in the emission of most sesquiterpenes owing to the deletion of the terpene cyclase vir4, were used to evaluate the role of this compound class in the food preference and fitness of the soil Collembola Folsomia candida. Choice experiments with and without direct contact with fungal mycelium revealed that Collembola were preferentially attracted to Δvir4 mutants impaired in sesquiterpene synthesis compared to wild-type T. virens. Grazing by F. candida on the sesquiterpene deficient T. virens strain had no effect on Collembola survival, reproduction and growth compared to wild-type T. virens. The results suggest that sesquiterpenes play an important role in fungal defence as repellents, but not as deterrents or toxins, against fungivorous Collembola. Our research contributes to the understanding of ecological interactions between fungi and fungivorous arthropods, providing insights into the specific ecological functions of sesquiterpenes. The study has implications for chemical ecology and the dynamics of multitrophic interactions in soil ecosystems.

Low soil Moisture Slows Uptake and Elimination Rates of Phenanthrene in Springtails

This study investigated the influence of soil water status on the toxicokinetics of phenanthrene in the springtail Folsomia candida allowing estimation of uptake and elimination rates at two contrasting soil water potentials. Fitting a three-phase model to the observations showed that uptake rate (ku) was almost two times higher in moist soil (-2 kPa) than in dry soil (-360 kPa). During the first days of the exposure, elimination rate (ke) was not significantly different in moist and dry soil, but after eight days ke had increased significantly more in moist soil than in dry soil. Our results confirm the general notion that the exposure route via soil pore water is important. Understanding the significance of soil moisture in exposure and effects of contaminants on soil invertebrates is crucial for assessing the ecological risks associated with soil pollution in a changing climate.

Evaluation of the ecotoxicological effects of biogenic amines derived from cadaverous putrefaction on springtails Folsomia candida.

Necro-leachate, a liquid released during cadaveric decomposition, is considered the main culprit for impacts on cemetery environments. The biogenic amines cadaverine and putrescine make up part of the composition of necro-leachate and have a certain toxicity to different organisms. Springtails are among the most used bioindicators to assess the impacts of soil contaminants. As there are no data on the acute and chronic toxicity of springtails exposed to cadaverine and putrescine, the objective of this study was to evaluate the toxic potential of both amines, under the behavioral effect of avoidance and reproduction in the species Folsomia candida. Springtails were exposed to soils contaminated with different concentrations of cadaverine and putrescine, and different mixtures of these amines. To evaluate the avoidance and reproduction test, the individuals were exposed for periods of 48h and 28days, respectively. The results obtained in the avoidance test showed that springtails exhibited a preference for the treated soil in both isolated and mixed treatments. The chronic evaluation assays showed that the reproduction was affected, particularly in the treatments with combined amines, resulting in a reduction in the total number of juveniles. From the results, it is possible to infer that the methods applied in this research have provided information that will contribute to a better understanding of the toxicity of putrefactive biogenic amines, since there exist few ecotoxicological studies carried out with these amines, and especially with those from cemetery environments.

Contrasting impacts of non-native isopods and springtails on ecosystem processes under simulated Antarctic climate conditions

Climate change, coupled with the introduction of non-native organisms, represent major threats to the functioning of ecosystems, especially in species-poor communities such as polar terrestrial ecosystems. In this laboratory study, we quantified the impacts of the non-native springtail Folsomia candida and isopod Porcellio scaber on seed germination and growth of the non-native grass Poa pratensis, and ecosystem respiration. The impacts of invertebrate communities of progressively increasing complexity were assessed, starting with the native springtail Cryptopygus antarcticus alone, followed by C. antarcticus in combination with F. candida or P. scaber and, finally, a community including all three species. The impact of these invertebrate communities were studied in a simulation of contemporary Antarctic soil surface conditions (2 °C) and a +5 °C warming scenario over one growing season.Warming resulted in earlier germination (21 d), 10-fold increased plant biomass, N-content (>5-fold), and higher levels (90%) of ecosystem respiration. Warming also resulted in a 350% increase in C. antarcticus abundance.The presence of the woodlouse P. scaber had the strongest impact on the measured soil and plant variables and this impact was largely irrespective of temperature. Impacts included: delay in seedling emergence (4 d), reduced plant emergence (20%), and higher ecosystem respiration (135%). The presence of both C. antarcticus and P. scaber resulted in 30% higher plant leaf N-content and a reduction in C:N ratio from 21 to 17. The experimental communities containing F. candida showed a 37% reduction in plant biomass under warming. The presence of P. scaber reduced C. antarcticus abundance (94%) but F. candida abundance was unaffected.Our data indicate that non-native invertebrates differ in their ecosystem impacts, with potentially significant consequences for ecosystem functioning and community composition of plants and animals in cold biomes.

Soil habitat function after innovative nanoagriproducts application: Effect of ageing on the avoidance behaviour of the soil invertebrates Enchytraeus crypticus and Folsomia candida

Research on nanotechnology with applications in agriculture has been gathering attention because it may achieve a good balance between agricultural production and environmental integrity. Among the vast nanomaterials, layered double hydroxides (LDHs) are a promising solution for supplying crops with macro- and/or micronutrients. Still, little is known about their safety implications for non-target organisms, such as soil invertebrates. The habitat function of soils might be impacted by potential stressors, which can be assessed through avoidance behaviour tests. This study aimed to assess the effect of two innovative agriproducts, Zn-Al-NO3 LDH and Mg-Al-NO3 LDH, on the avoidance behaviour of the enchytraeid Enchytraeus crypticus and the collembolan Folsomia candida, over time. Simultaneously, Zn and Mg potential release from LDHs to soil was evaluated. Overall, the behaviour of soil invertebrates differed between species, with enchytraeids being more sensitive to LDHs-treated soils than collembolans, possibly explained by their different physiological traits. The behaviour of soil organisms also depended on the LDH structural composition and was time-variable. Soil treated with Zn-Al-NO3 LDH was perceived as less favourable compared to Mg-Al-NO3 LDH, which was preferred to clean soil at most tested concentrations. LDHs toxicity was partly, but not exclusively, related to Zn and Mg release. Cations release over time was demonstrated in the chemical assessment. Still, LDHs toxicity to soil invertebrates decreased as increasing AC50 values were derived over time. Slower dissolution over time might explain the decrease in toxicity. Our study demonstrates that both soil invertebrates could sense LDHs in soil and eventually adapt their behaviour by avoiding or preferring, according to the type and level of LDH present.

Effects of litter quality on foraging behaviour and demographic parameters in Folsomia candida (Collembola).

Litter quality has long been associated with demographic parameters of Collembola populations. However, little is known about the capacity of Collembola to perceive and seek better litter quality. To address this gap, three complementary laboratory experiments were carried out with the Collembola Folsomia candida. First, populations were fed on three different types of leaf litters (Quercus pubescens, Acer opalus and Prunus avium) and a control (agar-agar-brewer's yeast mixture) for 6 weeks to assess their impacts on demography (reproduction rate and population size). Second, the body length of individuals differentially fed with the same four types of resources was measured to assess a functional trait that can potentially affect movement parameters such as prospected area or foraging speed. Third, F. candida single individuals were exposed to the same litter quality gradient and placed at an increasing distance from the litter (from 1 to 5 cm). For 10 min, their foraging behaviour was recorded which included prospected area, foraging speed, perception distance and success in reaching the litter (foraging success). As expected, low-quality litter (i.e. Q. pubescens) contributed to low population growth compared to the control treatment and the high-quality litters (P. avium and A. opalus). In the third experiment, the probability of finding the resource was negatively correlated to the distance, but was unrelated to the litter quality and the Collembola body length. When resource was perceived, F. candida was able to switch from non-directional to directional movements, with a large variability in the perception distance from a few millimetres to several centimetres. Taken together, our results indicate that litter quality plays a relevant role in Collembola demographic parameters once the population settles on litter patch, but not on foraging behaviour to select high-quality resources.

Temporal Dynamics of Biomarker Response in Folsomia candida Exposed to Azoxystrobin

Azoxystrobin (AZO) is widely used to prevent and treat fungal diseases in important crops but can also impact non-target organisms, including mammals, amphibians, aquatic, and soil organisms. Collembolans play important roles in ecosystems as decomposers, fungal feeders, and regulators of microbes. This study aimed to investigate the effects of AZO on Collembola Folsomia candida using a reproduction test and assess biomarker responses over different time intervals (3, 5, 7, 14, and 28 days). Results showed AZO negatively affected reproduction at concentrations of 50, 100, and 200 mg./kg, resulting in decreases of 48.3%, 64.5%, and 81.3%, respectively, compared to the control. Adult survival remained unaffected. The estimated EC50 (reproduction) in artificial soil was 61.28 mg kg−1. Biomarker responses varied with concentration and time. Protein and glycogen concentrations increased with exposure time, while lipid content was affected initially but returned to control levels by day 28. Oxidative stress biomarkers (CAT, SOD, GST, TBARS) indicated AZO induced oxidative stress, intensifying over time. After 28 days, MDA concentrations were significantly elevated compared to the control, suggesting the antioxidant system is overwhelmed which caused damage to lipid membranes. This study showed that azoxystrobin caused negative effects at molecular and population level on non-target species of Collembola.

Corridor quality buffers extinction under extreme droughts in experimental metapopulations.

Corridors with good-quality habitats maintain the spatial dynamics of metapopulations by promoting dispersal between habitat patches, potentially buffering populations, and communities against continued global change. However, this function is threatened by habitats becoming increasingly fragmented, and habitat matrices becoming increasingly inhospitable, potentially reducing the resilience and persistence of populations. Yet, we lack a clear understanding of how reduced corridor quality interacts with rates of environmental change to destabilize populations. Using laboratory microcosms containing metapopulations of the Collembola Folsomia candida, we investigate the impact of corridor quality on metapopulation persistence under a range of simulated droughts, a key stressor for this species. We manipulated both drought severity and the number of patches affected by drought across landscapes connected by either good- or poor-quality corridors. We measured the time of metapopulation extinction, the maximum rate of metapopulation decline, and the variability of abundance among patches as criteria to evaluate the persistence ability of metapopulations. We show that while drought severity negatively influenced the time of metapopulation extinction and the increase in drought patches caused metapopulation decline, these results were mitigated by good-quality corridors, which increased metapopulation persistence time and decreased both how fast metapopulations declined and the interpatch variability in abundances. Our results suggest that enhancing corridor quality can increase the persistence of metapopulations, increasing the time available for conservation actions to take effect, and/or for species to adapt or move in the face of continued stress. Given that fragmentation increases the isolation of habitats, improving the quality of habitat corridors may provide a useful strategy to enhance the resistance of spatially structured populations.

The interaction effects of biodegradable microplastics and Cd on Folsomia candida soil collembolan.

In real-field soil conditions, multiple chemicals exposure may be the real scenario for soil biota. The co-occurrence of microplastics (MPs) and cadmium (Cd) is common in soils, which may pose a potential risk to soil ecosystems. Degradable microplastics are producing more MPs, and the potential effects on soil ecosystems are unknown. Therefore, a standard soil animal collembolan Folsomia candida was used to evaluate the single and interaction effects of biodegradable MPs (PLA) and Cd. The results showed that single and co-biodegradable PLA and Cd all had negative influences on the survival, reproduction, and growth of F. candida, and the effects intensified with PLA concentrations. The survival rate, reproduction rate, adult body length, and juvenile body length decreased by 20.0%, 24.2%, 22.9%, and 32.2% at MPs-100 treatment. But combined PLA and Cd alleviated the toxicity of single Cd on F. candida at lower PLA concentrations. The number of juveniles increased by 29.3%, the survival rate increased by 7.52%, the adult body length increased by 11.7%, and the juvenile body length increased by 19.0% at MPs-1 + Cd than single Cd treatment. Biochemical assays on antioxidant enzymes had the same results. Antioxidant enzymes CAT and POD were more sensitive than SOD. CAT and POD activities were induced quickly at shorter exposure periods, and MP treatment thus may be promising biomarkers on soil collembolan for soil MP exposure. PLA is degraded with time in soils; therefore, the long-term effects of co-MPs and Cd in soils are suggested to be further studied.