Diptera (Insecta) play a significant role in forest ecosystems. With wingless larvae developing in soil and flying imagoes, they represent an important link between belowground detrital and aboveground grazing food webs. Despite this, trophic interactions of soil-dwelling Diptera remain poorly understood. In this study, we used emergence traps to follow seasonal changes in diversity, abundance and biomass of Diptera emerging from the soil in three temperate forest stands near Moscow, Russia and measured carbon and nitrogen stable isotope composition (delta 13C and delta 15N values) of emerging Diptera to assess their trophic positions. A greater taxonomic richness (88 species) was revealed by emergence traps compared to heat extraction of soil samples (41 species), highlighting the efficiency of traps in studying soil-associated Diptera. Stable isotope composition was measured for 65 species of winged flies and revealed a very broad range of delta 15N values of individual samples (from -1.6%o to 17.0%o) reflecting diverse trophic niches of Diptera. Notably, more than a half of the emerging dipteran biomass consisted of families with mean delta 15N values exceeding typical delta 15N values of soil predators (Mesostigmata, Chilopoda, and Araneae). The enrichment in 15N can be attributed either to specific dietary sources such as fungi, carrion, and dung, and to an isotopic shift during metamorphosis. Thus, the upstream flux of emerging Diptera carries a specific isotopic signal, untypical of most soil saprophages and predators. This should be taken into account in the reconstructions of the trophic links between belowground and aboveground food webs.

Urban soil biodiversity sustains critical ecosystem functions such as nutrient cycling and plant growth, while also supporting human health through pathogen suppression, soil remediation, and human immune system training. Yet, the distribution of urban soil biodiversity and its dependence on the influencing city-specific factors, such as economic development (e.g., GDP, Human Development Index), population density, and effects of climate change remain poorly understood. To bridge this research gap, we propose a global initiative applying environmental DNA (eDNA) metabarcoding to classify, map and better understand urban soil biodiversity and uncover its environmental drivers. We introduce a sampling and analysis protocol that facilitates the integration of global urban soil biodiversity data using eDNA analysis (acronym: Global-USB). We aim to build and grow a global network of researchers who contribute and analyze urban soil biodiversity data in a standardized way. This initiative will assess the impacts of urban land use and development on soil biota to gain insights into subsequent feedback effects on ecosystem functions and human well-being. By creating new and integrating established global datasets, this effort aims to generate actionable scientific insights to inform sustainable urban planning and policy, contributing to cities that support both ecological integrity and human well-being.

Soil fauna regulates litter decomposition and soil organic matter transformation, acting as both litter and microbial feeders. Whether these feeding modes shift along environmental gradients remains unclear. We tested if microbivory increases with decreasing litter quality and in colder climates, both factors limiting detritus digestion by fauna. Using stable isotope composition (δ13C, δ15N) of 7408 soil invertebrate samples from 228 forest sites across temperate to tropical biomes, we determined δ15N values are positively associated with litter C:N ratio and mean annual temperature, indicating a shift from detritivory toward microbivory under low litter quality with additional modulation by climate. In contrast, δ13C values showed no consistent association with litter C:N ratio or climate, reflecting context dependent microbial carbon routing. Our findings highlight litter quality as the primary driver of the detritivory-to-microbivory shift in soil fauna, with implications for predicting changes in climate and plant communities on carbon cycling in terrestrial ecosystems.

Soil fauna contributes to a wide range of ecosystem functions via their trophic activities. Here we investigate how trophic diversity of soil animals varies across functional groups and major biomes. We use stable isotope analysis (13C/12C and 15N/14N ratios) of 17,306 samples of 28 high-rank taxa from 456 sites across 19 countries to inspect the variability in trophic diversity across climate regions and land-use types. Trophic diversity of soil animal communities is higher for microbial feeders than for detritivores and predators, in agricultural ecosystems compared with woodlands (+32%) and in tropical compared with temperate climates (+40%). Higher trophic diversity is related to more diverse basal resources and longer trophic chains, which could reflect greater niche partitioning in resource-limited environments. Our findings suggest that soil animals could broaden their trophic niches under agricultural land use and possibly in response to warming, but whether such foraging flexibility may offset the loss of trophic specialists remains to be investigated.

Soil food webs channel most of the energy in terrestrial ecosystems. Temperate and tropical forests host different soil invertebrate communities, but consequent differences in the structure and functioning of soil food webs between these major biomes remain unknown. Here, we calculate energy fluxes to explore generic patterns in biomass and energy distribution across micro-, meso- and macrofauna in forest ecosystems spanning from southern taiga to tropical rainforests. Tropical soil food webs have either larger (monsoon forest) or smaller (rainforest) animal biomass than temperate ones, but have consistently higher energy flux, higher share of large organisms (macrofauna) in total biomass and distinct energy distribution. Specifically, tropical soil food webs have proportionally higher predation rates than temperate soil food webs and rely more on plant consumption (living roots), but less on bacterial, fungal and litter consumption. Earthworms act as food-web engineers promoting detrital energy pathways (litter, soil and deadwood consumption) in mixed broadleaved forests overriding climate-associated differences among forests. Our study shows a major change in soil food web from “brown” temperate to “green” tropical functional state, explaining functional implications of soil invertebrate community turnover across biomes. The structure and functioning of soil food webs between biomes remains unknown. Here, tropical soil food webs are shown to have higher energy flux, predation and herbivory than temperate soil food webs which are based on litter and microbial biomass.

RATIONALE:Closely related whale species can appear similar yet occupy distinct ecological niches. Sato's beaked whale (Berardius minimus) was only recently recognized as a separate species and was previously grouped with Baird's beaked whale (Berardius bairdii), limiting our understanding of their ecological differences. Clarifying their trophic ecology is essential for accurate species-specific conservation and management. METHODS:Skin biopsy and necropsy samples of B. bairdii and B. minimus were collected in the western North Pacific in 2017-2025. Carbon (δ13C) and nitrogen (δ15N) stable isotope ratios were measured from three separately analyzed epidermal layers of skin samples using isotope ratio mass spectrometry. RESULTS:B. bairdii exhibited significantly higher δ13C values than B. minimus, whereas δ15N values were broadly similar, indicating comparable trophic positions but distinct foraging habitats. Higher δ13C values in B. bairdii suggest greater reliance on benthic or coastal food webs, whereas lower δ13C values in B. minimus reflect stronger associations with offshore ecosystems. Isotopic variation of different epidermal layers revealed temporal dietary shifts within individuals. CONCLUSIONS:These results demonstrate clear ecological differentiation between B. bairdii and the recently described B. minimus. Historical data attributed to B. bairdii should be re-evaluated to ensure accurate species-specific interpretations of diet and habitat use, improving ecological understanding and conservation assessments.

Soils in urban greenspaces often support higher microbial richness but with more homogenous communities than in natural ecosystems. However, it is not known how urbanization impacts the diversity and homogeneity of soil communities in urban greenspaces compared with other highly managed ecosystems such as farmlands. Here we conducted a continental-scale study spanning 13 cities and four land uses (city parks, residential areas, and adjacent forests and farmlands) in China. We found that urban ecosystems consistently support higher local soil bacterial, protist and fungal (but not metazoan) richness than farmlands and forests. This elevated richness was closely related to higher pH in urban ecosystem soils. Urban greenspaces also supported more homogenous soil communities than farmlands. The results indicate that urbanization drives biotic homogenization and increases synchronous responses to environmental stressors in urban greenspaces at a continental scale. Our findings have important implications for managing soil ecosystem resilience and functional diversity in cities of the future.

Soil biogeochemical cycles are regulated by soil food webs. However, variation of soil food web structure and functioning across key environmental gradients remains unknown, hampering generalisations of any suggested links between fauna and biogeochemistry. Here, we used two complementary approaches to quantify soil animal food web variation across forest types, from southern taiga to rainforests. First, we applied the energy flux approach to explore patterns of energy distribution across micro-, meso- and macrofauna. We showed that tropical soil food webs have consistently higher energy flux, proportionally higher predation rates (31 vs 18-27% of the total energy flux) and relied more on the plant energy channel (21 vs 10%), but less on the bacterial (5 vs 9-18%) and litter energy channels (14 vs 18-32%), than temperate soil food webs. Second, we compiled a large database (>8000 records) of stable isotope composition of soil animals to see how detritivory and microbivory in soil animal communities change with environmental temperature and litter quality. Despite little effect of temperature, shift in 15N concentrations suggested that in most cases low litter quality (high %C and low %N) result in a switch from feeding directly on litter to feeding on microorganisms. Thus, soil animals change their functional role from competitors to consumers of microbes. Our studies show how the functioning of soil animal food webs changes across biomes with different climate and litter quality and summarise functional roles animals play in different biomes.

Metabarcoding is a powerful tool widely used to analyze soil communities but methodological difficulties can introduce biases, resulting in inaccurate estimation of species diversity. We evaluated five DNA extraction methods, two PCR programs, and three post-bioinformatic processing techniques (multiple databases, filtering based on the level of similarity and on the number of reads obtained) using a mock community of soil invertebrates containing 24 species, 23 genera, and 15 families of arthropods and annelids. The choice of DNA extraction kit significantly influenced the accuracy of the metabarcoding results. Kits developed for the isolation of DNA from soil and alkaline lysis without purification showed worse results compared to those designed for isolating DNA from tissues. In the best variant of sample processing, metabarcoding yielded correct identification of 67 % species and 94 % families. Post-bioinformatic filtering dramatically increased the proportion of true positives achieving 100 % at the family, over 73 % at the genus, and more than 60 % at the species level. Thus, an acceptable level of accuracy may be achieved in field surveys with relatively little time and effort.

Significant individual variation in the nitrogen and carbon stable isotope composition (δ15N and δ13C values) of white muscle tissues has been found in samples of three cyprinid fish species, Cyprinion macrostomus (periphytonophage), Cyprinion kais (benthophage), and Luciobarbus schejch (omnivore), which were collected from a small tributary of the upper Tigris system (Turkey). In particular, an exceptionally low value (1.7‰) and abnormally wide intraspecific variability (from 1.7 to 15.8‰) of δ15N have been recorded in the tissues of C. macrostomus. Although all samples were collected synchronously and syntopically, the very broad range of δ15N values indicates a possible heterogeneity of the samples and the involvement of different processes in the formation of the isotopic composition of fish tissues. The studied watercourse is in the zone of agriculture with intensive chemicalization and pollution of the river with mobile forms of nitrogen (mostly ammonium), which might cause the reduction in the δ15N value in resident fishes. Fish with high (normal) δ15N values are supposedly recent migrants that came from a large river for joint spawning with resident fish. The pollution of water bodies, as well as the presence of migrations, should be taken into account in studies of the trophic ecology of fishes based on stable isotope analyses.

Land-use changes drive the microbial community and associated soil resistome. Enrichment of risk antibiotic resistance genes (risk ARGs) is related to 4.95 million deaths across the globe each year, rendering them an urgent threat to human health. To provide better understanding of distribution patterns of risk ARGs and their key biotic/abiotic drivers across land-use systems, we used soil eDNA combined with an ARGs annotation pipeline and ARGs risk assessment list to assess ARGs risks in three human-dominated systems (farmlands, parks and residential areas) and natural forests across thirteen cities in China. Compared to forests, farmlands and parks, residential areas contained a markedly higher diversity of risk ARGs and virulence factors. This study indicates human activity intensity primarily enriched risk ARGs by promoting MGEs richness and relative abundance of potential zoonotic pathogens. In addition, the essential drivers affecting risk ARGs differed in a system-specific manner, with pathogens and soil nutrient level being the most important positive drivers of risk ARGs in highly managed urban systems (residential areas). Our research emphasizes practical approaches to mitigate the risk of ARG dissemination by reducing zoonotic pathogens in urban green spaces within highly urbanized areas, for which benefits the implementation of the One Health framework.

The aim of this study was to estimate the effect of relatively large (1–5 mm) fragments of high-density polyethylene films on two widespread earthworm species belonging to different ecological groups—endogeic Aporrectodea caliginosa and epigeic Lumbricus rubellus. In a microcosm experiment lasting 8 weeks, we tested the food dilution hypothesis, which suggests that the adverse effect of microplastic on earthworms is caused by the dilution of food by plastic, which has zero energetic value. Both earthworm species ingested plastic particles, and both species were seemingly limited by the availability of food. In particular, the addition of food substrate (aspen litter) to the soil had a significant positive effect on the weight of A. caliginosa. In contrast to our expectations, microplastic at relatively high concentrations (0.3

Dragonflies are well-known migratory insects, and stable isotopes have been used successfully to study their migrations in America and Asia but less so in Europe. Here we used the isotopic composition of hydrogen (delta 2H value) in metabolically inert wing tissues of the dragonfly Sympetrum fonscolombii (Selys, 1840) to investigate migration patterns and likely origin of immigrants into the European part of Russia. During spring-summer, sexually mature dragonflies arrive to Russia for reproduction and individuals of the summer generation (descendants of immigrants) presumably migrate in the opposite direction in the fall. Analyses included 39 specimens of immigrant S. fonscolombii dragonflies, 11 specimens from 3 species of resident dragonflies (including S. fonscolombii) from the European part of Russia and 16 specimens representing 9 resident dragonfly species from Iran. The average delta 2H values of the wings of immigrant S. fonscolombii (-71.9 +/- 23.4 parts per thousand) were significantly higher than those of resident dragonflies in European Russia (-121.7 +/- 9.5 parts per thousand) and similar to those of resident dragonfly species from Iran (-72.3 +/- 18.4 parts per thousand). Based on a geostatistical model of the global delta 2H values in precipitation, and considering the distribution of S. fonscolombii, the most probable natal area of immigrants arriving in European Russia is located in Southwest Asia. The suggested migration zone covers regions located between approximately 26 degrees-28 degrees N in the south and 56 degrees-58 degrees N in the north, while the migration distance can reach 2000-4000 km. Dragonflies are well-known migratory insects, and stable isotopes have been used successfully to study their migrations in America and Asia but less so in Europe. We used the isotopic composition of hydrogen in wing of the dragonfly red-veined darter to investigate migrations patterns and likely origin of immigrants into the European part of Russia. During spring-summer, sexually mature dragonflies arrive to Russia for reproduction and individuals of the summer generation (descendants of immigrants) presumably migrate in the opposite direction in the fall. image

Aboveground communities may strongly depend on the detrital subsidy, i.e. the release of energy and nutrients from the soil food webs. Earthworms predated by aboveground animals are seemingly among the most important links connecting belowground and aboveground food webs. Here, we conducted an experiment with plasticine models in alpine tundra, temperate, and monsoon tropical forests to estimate predator pressure on surfaced earthworms compared to aboveground prey (caterpillars). Earthworm models on the ground were attacked several times more often than caterpillar models on the plants. The attack rate was highest in the tropical forest; the most common types of attacks on earthworms were arthropod bites in both forests and mammal bites in tundra.

Diet plays a crucial role in caste differentiation and division of labour in ants, but relationships between behavioural specialization and the nutritional status of workers in monomorphic species remain understudied. We used the red wood ant Formica aquilonia, a key species of forest communities in North Eurasia, to examine whether (i) nurses are fatter than foragers; (ii) task groups collected on the nest surface, ground surface and trees have different fat reserves; and (iii) task groups differ in the diet and trophic level. Higher fat content in nurses including sunbathing workers compared to foragers was shown by abdomen: thorax dry mass, C:N ratio and delta 13C values in the abdomen and thorax. Colony fat reserves were minimal in summer and maximum in autumn, especially in nurses. Ground foragers restoring the foraging territory in spring showed signs of starvation according to the thoracic delta 15N values. Nest guards and foragers were similarly lean in summer. Tree foragers collecting honeydew were leaner than ground foragers (hunters) in autumn. Workers were of similar trophic level. Differences in crop content between nurses and foragers were indicated by the delta 15N value in the abdomen. Our study suggests that the seasonal dynamics of energy reserves and nutritional differences between task groups are linked to the annual life cycle of the colony, contributing to its reproductive success.

Viruses of soil-dwelling invertebrates remain poorly studied. Viruses of eusocial insects are of special interest as they can serve as a model for studying the spread of viruses via social interactions. In this review, we aim to compile and actualize the available information on the diversity of viruses associated with soil-dwelling social insects, termites and ants. Both groups are among the most functionally important soil invertebrates and include numerous pests and invasive species. We analyzed 93 articles dedicated to viral findings in these groups. Viruses were found in 54 species of ants and 28 species of termites. In sum, 270 viruses and viral genetic variants from over 16 viral orders were found to date in soil-dwelling social insects. Complete information on viruses detected in termites and ants, including insect species, viral name, species, replication status, and GenBank accession number is provided. For most of the novel viruses, replication in the insect was not yet confirmed. We encourage more studies of the virome of ants and termites, which should pay more attention to viral replication and infection symptoms.

Animal stoichiometry affects fundamental processes ranging from organismal physiology to global element cycles. However, it is unknown whether animal stoichiometry follows predictable scaling relationships with body mass and whether adaptation to life on land or water constrains patterns of elemental allocation. To test both interspecific and intraspecific body-size scaling relationships of the nitrogen (N), phosphorus (P), and N:P content of animals, we used a subset of the StoichLife database encompassing 9,933 individual animals (vertebrates and invertebrates) belonging to 1,543 species spanning 10 orders of magnitude of body size from terrestrial, freshwater, and marine realms. Across species, body mass did not explain much variation in %N and %P composition, although the %P of invertebrates decreased with size. The effects of body size on species elemental content were small in comparison to the effects of taxonomy. Body size was a better predictor of intraspecific than interspecific elemental patterns. Between 42 to 45% in intraspecific stoichiometric variation was explained by body size for 27% of vertebrate species and 35% of invertebrate species. Further, differences between organisms inhabiting aquatic and terrestrial realms were observed only in invertebrate interspecific %N, suggesting that the realm does not play an important role in determining elemental allocation of animals. Based on our analysis of the most comprehensive animal stoichiometry database, we conclude that (i) both body size and realm are relatively weak predictors of animal stoichiometry across taxa, and (ii) body size is a good predictor of intraspecific variation in animal elemental content, which is consistent with tissue-scaling relationships that hold broadly across large groups of animals. This research reveals a lack of general scaling patterns in the elemental content across animals and instead points to a large variation in scaling relationships within and among lineages.### Competing Interest StatementThe authors have declared no competing interest.

Direct trophic links between aboveground and belowground animal communities are rarely considered in food web models. Most invertebrate animals inhabiting aboveground space eventually become prey of soil predators and scavengers forming a gravity-driven spatial subsidy to detrital food webs, but its importance remains unquantified. We used laboratory-grown 15N-labeled Collembola to trace the incorporation of arthropod rain into soil food webs. Live or euthanized Collembola were supplemented once to field mesocosms in the amount equivalent to the mean daily input of the arthropod rain (19 mg d.w. m−2). After the addition of live Collembola, the isotopic label was found most often in predatory Trombidiformes (83