Collembolan Species Research Articles

The Thermal Tolerance of Springtails in a Tropical Cave, with the Description of a New Coecobrya Species (Collembola: Entomobryidae) from Thailand

A new species of Collembola in the genus Coecobrya, C. microphthalma sp. nov., is described from a cave environment in Saraburi province, central Thailand. The new species is the second described species of the boneti-group found in the country. It is most similar to C. chompon Nilsai, Lima & Jantarit, 2022, which is also described from a Thai cave. However, the new species is morphologically different from C. chompon in having orange dot pigmentation on its body and a combination of other morphological characteristics such as the number of sublobal hairs on the maxillary outer lobe and the number of medio-sublateral mac on Th. II, Abd. I, Abd. III and Abd. IV and the anterior face of the ventral tube. The morphological comparison of all known boneti species and a key to the world species of Coecobrya of the boneti-group are given. Coecobrya microphthalma sp. nov. was successfully cultured in the laboratory. The thermal tolerance of the new species was studied and tested with seven different temperature experiments (27 °C as a control, 30, 32, 33, 34, 35 and 36 °C). The results showed that C. microphthalma sp. nov. cannot survive at a temperature higher than 32 °C after exposure to the experimental heat for 7 and 14 consecutive days. At 27, 30 and 32 °C, C. microphthalma sp. nov. remained alive and produced eggs, but the duration of egg production and number of egg-laying days significantly declined when the temperature increased (p < 0.001). An interesting aspect of their reproduction concerns temperature. At 32 °C (5 °C above the control temperature), the F1 generation survived, was active and was able to molt to the adult stage. However, specimens were unable to produce the next generation of offspring. For postembryonic development, C. microphthalma sp. nov. required six molts to reach the adult stage. The development rate (from egg to adult) varied and differed significantly between the tested temperatures (p < 0.001). An increase in temperature from the control temperature significantly accelerated the developmental rate from egg to juvenile instars to adult with a statistical significance (p < 0.01). This study is the first attempt that provide information on the impact of increasing temperature on the population dynamics, reproductive capacity and life history of a subterranean tropical Collembola.

Survival and reproduction effects of microplastics from three agricultural mulching films on Folsomia candida, Sinella curviseta, Heteromurus nitidus and Ceratophysella denticulata (Collembola).

An estimated 467 kt of plastic used in agriculture annually end up in European soils, potentially breaking down into secondary microplastics (MPs). Not much is known about the possible effects of these MPs on organisms residing in the soil. To properly assess their environmental risk, experimental data is needed on the toxicity of MPs to the survival and reproduction of model organisms. This study aimed at assessing the toxicity of three MP types derived from commonly used agricultural plastics to different Collembola species, representing an important and highly diverse class of soil arthropods. Starch- polybutadiene adipate terephthalate blend (starch-PBAT blend) MPs were produced from mulching films that were artificially aged by mechanical recycling. MPs were also made from virgin low density polyethylene (LDPE) mulching films and from linear low density polyethylene (LLDPE) films that underwent the same mechanical recycling process as the starch-PBAT blend films. Four Collembola species were tested: Folsomia candida, Sinella curviseta, Heteromurus nitidus and Ceratophysella denticulata, representing epedaphic, hemiedaphic and euedaphic, as well as sexually reproducing and parthenogenetic species. Each species was exposed in Lufa 2.2 soil spiked with nine MP concentrations: 0.0016, 0.008, 0.04, 0.2, 1, 2, 3, 4 and 5% (w/w dry soil) and a control without additional MPs added to the soil. No dose-dependent effects were found for any of the exposed organisms, to any of the MPs tested. The results of this study suggest that the MPs used in this study, derived from commonly applied agricultural plastics, do not pose an immediate hazard to Collembola.

Ecological and faunistic characteristics of taxoсenes of Collembola in the agrocenoses of Zhovkivsky (Lviv District

As a result of the conducted research, a total of 43 species of collembola were found, which belong to 29 genera and 10 families. In the course of longer and larger-scale research in agrocenoses, it is possible to detect significantly more species (according to literature data, no less than 70). The studied coenotic fauna (αb-diversity) includes from 5 to 21 species of collembola (on average 13.9). One soil sample (αa-diversity) contains from 1 to 8 species of Collembola (on average 2.1). The highest capacity of the medium for collembola at the level of αa-diversity is characteristic of wheat agrocenosis, and the smallest – of potato. The βa-diversity index of collembola (differentiating diversity) of the studied agrocenoses is 3.5 times higher than in natural biotopes of the broad-leaved forest zone, which is associated with a greater contrast of edaphic conditions of the arable environment. The noted high values of the βa-diversity index in agrocenoses are associated with relatively small values of the so-called point αa-diversity. A noticeable decrease in the ecological capacity of the environment for collembola at the level of αa-diversity in the studied agrocenoses is due to the contrast of physical and chemical conditions in specific edaphotopes, the weak edifying effect of the cultivated crop, as well as the implementation of agrotechnical measures. The analysis of the βα-diversity index shows that the greatest unevenness of intracenotic conditions for collembola was found in agrocenoses of wheat (βα-diversity = 5.9), the average in potatoes (5.3), and the smallest in rapeseed (4.7, respectively). The indicator of the average population of collembola in the studied types of agrocenoses varies in a 30-fold interval of values. It has the highest average value in wheat agrocenosis and the lowest value in potato. However, in comparison with natural forest and meadow coenoses, the maximum indicator of the number of pintails in the studied agrocenoses is about an order of magnitude lower. The obtained data on the share of families in the studied coenotic fauna generally agree with the literature data that are known for the natural coenoses of western Ukraine.

Seasonal changes in the structure of the bog taxocene of Collembola of the «Zalizna voda» forest park (Lviv)

An analysis of the taxonomic and ecological structure of the bog taxocene of collembola of the «Zalizna voda» forest park in the city of Lviv in different seasons of the year was carried out. 36 species of collembola belonging to 24 genera and 12 families were found in the investigated urboecosystem. It has been established that a characteristic feature of the studied bog collembolan taxocene is its great species diversity, super-specialization and super-dominance, which are preserved in different seasons of the year. It was found that the point alpha-diversity in different seasons of the year varies from 6 to 16 species, and the coenotic alpha-diversity - 23-27 species, which indicates a large capacity of the soil environment for collembola in this bog urboecosystem, compared to the natural bog ecosystems of Roztochchia region. The investigated taxocene of collembola are also characterized by high population density in different seasons of the year, from 11.34 to 15.48 thousand inhabitants/m2. In certain seasons of the year, from 3 to 5 mass (dominant) species were established, which account for 66.4-83.6% of the collembolan population. Over the entire period of research, the invasive species D. trispinata was superdominant, the share of which in certain seasons of the year was 57.4-68.6% of the population. The analysis of the ecological structure showed that in terms of species richness and abundance, it is dominated by complexes of hygro-mesophilic (11 species, 76.8% of the total abundance), hygrophilic (9, 11.3%) and mesophilic (9, 7.7%) springtails. The studied taxocene includes seven biotope groups of species. Among them, representatives from the group of meadow-bog (65.4% of the population), erytopic (10%), forest and forest-meadow (18% in total) species of Collembola predominate in terms of relative abundance. It has been established that a super-specialized bog taxocene of Collembola is formed in the studied ecosystem, where the share of specialized species to this bog edaphotope (meadow-bog, bog and arroundwater) is more than 70% of the total abundance.

Expanding Soil Invertebrate Knowledge in Panama: The Genus Lepidocyrtus (Collembola, Entomobryidae) in the Parque Natural Metropolitano as a Study Case.

Panama, located in the heart of the Mesoamerican hotspot, harbors an extraordinary species diversity across the Tree of Life. The Collembola species of the genus Lepidocyrtus play an important role in soil biological processes such as decomposition, being used to monitor soil health and functional parameters. However, the limitation of morphological characters and molecular resources hampers the evaluation of local soil diversity. Here, using 30 Lepidocyrtus specimens collected in the Parque Natural Metropolitano (PNM), we unravel the diversity of this Panamanian protected area through molecular tools and new taxonomic traits. Our phylogenies, in combination with species delimitation analyses, indicate that the PNM harbors an extremely rich community of Lepidocyrtus species, two of them cited in Panama for the first time, and three of them potentially new to science. We highlight that the presence of the dental tubercle and pseudopores on the BP4 region are not monophyletic and, therefore, can be used as supplementary characters to morphologically resolve species complexes. Overall, this study sheds light on the Lepidocyrtus richness of the PNM, which acts as a shelter for Panamanian and the Mesoamerican hotspot species.

Resilience of Collembola communities to extreme drought is moderated by land use at a regional scale

In a world undergoing climate and usage change, soil biodiversity, which accounts to 25 % of the terrestrial biodiversity, is under severe threats. However, scenarios of climate change are based on known sensitivity of aboveground communities while there are differences on the responses to these changes with soil biodiversity. Here, we investigate the effects of an extreme climatic – due to an exceptionally drought year in 2011 - in various land use types (grassland, arable land, forest) through a study conducted at a regional scale (146 sites in Meuse, France) during 5 years. We characterized the responses of Collembola communities to climate change using (i) taxonomic indices and species dynamics, and (ii) species' functional traits and trait-based indices to reveal community assembly mechanisms. Our results demonstrated a total of 98 Collembola species collected during the five year project over the three land uses. Density and species richness were modulated by year, by land use and by their interaction. Three different distribution patterns in response to extreme drought events were demonstrated according to land use. Our findings thus reveal various effects according to land use, with a fast recovery of communities in arable lands, a long term effect for grasslands, and almost no effects observed in forests. These results show that the diversity of Collembola communities may be used as indicators of the resilience of ecosystems facing extreme climatic events.

Transcriptome Responses of the Soil-Dwelling Collembolan (Entomobrya proxima Folsom) to Fertilizer Type and Concentration.

Soil collembolans have been regarded as the effective bioindicator of environmental changes. However, the physiological mechanisms through which collembolans respond to agricultural activities are largely unknown. Given the plasticity and sensitivity to environmental changes, even subtle responses can be quantified via transcriptomics. Therefore, the relevant in situ soil ecosystem and numerically dominant collembolan species Entomobrya proxima Folsom was selected to explore the dynamic responses to fertilizer type and concentration using transcriptome sequencing over three periods (6 h, 24 h and 10 d). The results showed that exposure duration caused significant alterations in gene expression profiles. At day 10 after exposure, gene expression patterns differed remarkably between the two fertilizer types and the control. Relative to organic fertilizer, the number of DEGs was increased by 114.31% under inorganic fertilizer, which declined with increasing inorganic fertilizer concentrations. Functional enrichment analysis was indicative of enhanced fatty acid and carbohydrate metabolism and reduced disease occurrence by organic fertilizer; however, an inhibited lipid synthesis process promoted susceptibility to infection, triggered oxidative stress, etc. by inorganic fertilizer. Overall, fertilizer addition changed the transcriptional pattern of the collembolan, potentially causing shifts in pathways related to metabolism, immunity, etc. In comparison to inorganic fertilizer, organic fertilizer impacted less on the gene expression patterns, implying that organic fertilizer application may be more beneficial to soil animal health.

Collembola growth in heavy metal-contaminated soils

Collembola play a key role in soil ecosystems by decomposing organic matter. Most of them inhabit the upper layers of the soil and are susceptible to contamination present in the pore water. These arthropods serve as model organisms in ecotoxicology for short and long-term exposure. This study aimed to assess the toxicity of three heavy metals (lead [Pb], cadmium [Cd], and copper [Cu]) using the springtail species Folsomia candida as the test organism, with mortality and growth inhibition as the measure of toxicity. We hypothesised that increasing metal concentrations in the soil would correspond to a growth reduction of Collembola. Each heavy metal was tested at a minimum of eight increasing concentrations in six replications. Twenty 10-12-day-old individuals were introduced into each test container filled with contaminated or control soil and incubated for 14 days. The test endpoints included growth inhibition determined by comparing F. candida growth rates in contaminated soil with those in control soil, as well as mortality rates. The EC50 values (mg/kg) for heavy metals were as follows: Cd = 66.89, Cu = 791.01, Pb = 10075.48. Our findings suggest that growth inhibition is a reliable indicator of Collembola toxicity to heavy metals.

Two new species of Collembola (Arthropoda, Hexapoda) from Cova Urbana, a cave under a city

The Collembola fauna of the Cova Urbana located under the city of Tarragona (Spain) is studied, and the climatic characteristics of the cave, its partial geomorphology and its planimetry are presented. For the first time in this cave, some specimens of Collembola have been captured and studied, and two new species for science belonging to the genera Coecobrya and Pygmarrhopalites are described and illustrated. In addition, a specimen of the genus Arrhopalites probably belonging to another new species has been studied, but it could not be described because only one specimen was available. The presence of so few specimens and only four species is attributed to the absence of organic matter from percolation and detritus (oligotrophic cave).

Survival and reproduction tests using springtails reveal weathered petroleum hydrocarbon soil toxicity in boreal ecozone.

Survival and reproduction tests were conducted using two native springtail (subclass: Collembola) species to determine the toxicity of a fine-grained (< 0.005 - 0.425 mm) soil from an industrial site located in the Canadian boreal ecozone. Accidental petroleum hydrocarbon (PHC) release continuously occurred at this site until 1998, resulting in a total hydrocarbon concentration of 12,800mg/kg (soil dry weight). Subfractions of the PHC-contaminated soil were characterized using Canadian Council of Ministers of the Environment Fractions, which are based on effective carbon numbers (nC). Fraction 2 (> nC10 to nC16) was measured at 8400mg/kg and Fraction 3 (> nC16 to nC34) at 4250mg/kg in the contaminated soil. Age-synchronized colonies of Folsomia candida and Proisotoma minuta were subject to 0%, 25%, 50%, 75%, and 100% relative contamination mixtures of the PHC-contaminated and background site soil (< 100mg/kg total PHCs) for 28 and 21days, respectively. Survival and reproduction decreased significantly (Kruskal-Wallis Tests: p < 0.05, df = 4.0) in treatments of the contaminated site soil compared to the background soil. In both species, the most significant decline in survival and reproduction occurred between the 0% and 25% contaminated soil. Toxicity responses in the two springtails were ascribed to the standardized test design, short lifespans, and high fecundity in both species. This study showed that 25 + years of soil weathering has not eliminated the toxicity of fine-grained PHC-contaminated soil on two native terrestrial springtail species. Adverse effects to springtail health were attributed to exposure to soils dominated by genotoxic PHC Fraction 2 compounds and slow weathering processes due to the cold climate at the site.

Different mulch films, consistent results: soil fauna responses to microplastic

Agricultural activities contribute to plastic pollution, with unintentional introduction and intentional use of plastic mulch films leading to the accumulation of microplastic particles in soils. The lack of removal techniques and scarce information on the effects on soil organisms, especially for biodegradable mulch films, necessitate an assessment of potential effects. This study aimed to elucidate the effects of mulch film microplastic on soil fauna by investigating reproduction output and subcellular responses before and after recovery from exposure. Two common soil organisms, Folsomia candida and Eisenia fetida, were exposed to petroleum-based polyethylene (PE) and biodegradable polylactic acid/polybutylene adipate terephthalate (PLA/PBAT) microplastic for 28 days, according to OECD guidelines 232 and 222, respectively. Juvenile numbers revealed no polymer- or concentration-dependent effects on E. fetida and F. candida reproduction after exposure to up to 5 and 10 g/kgdw soil, respectively. To provide a more sensitive and early indication of sublethal effects, subcellular responses in E. fetida were analyzed. Glutathione S-transferase (GST) activity increased with rising microplastic concentration; however, catalase (CAT), acetylcholine esterase (AChE) activity, and reactive oxygen species (ROS) did not differ from control levels. Further, the more environmentally relevant PE polymer was chosen for in-depth assessment of subcellular response after 28-day microplastic exposure and subsequent 28 days in uncontaminated soil with E. fetida. No significant differences in biomarker activity and stress levels were observed. We conclude that mulch film–derived microplastic did not adversely affect earthworm and collembolan species in this scenario, except for a slight induction in the detoxification enzyme glutathione S-transferase.

Diversity and distribution of springtails (Collembola) from Jharkhand, India

This paper included the diversity and distribution of collembolan fauna in Jharkhand. A checklist of collembolan fauna from Jharkhand has been formulated. Endemic species from Jharkhand have also been reported. Affinities between species and habitat as well as another species of Collembola is basic character for diversity as well as distribution. Different types of methodologies have been deployed for collection from distinctive habitats. Climatic conditions are the limiting factor for species distribution and endemism. Lepidocyrtus is the most diverse and distributed genus. Isotomurus is the highest endemic genus. Some collembolan fauna from Jharkhand are prevailing only in this state while some are distributed in different biogeographic zone in world.

Seasonal dynamics of microbiota in winter-adapted Collembola: Insights into symbiotic relationships and adaptation to low temperatures

Soil-dwelling invertebrates, found worldwide, are essential for decomposition of plant litter and other soil processes, requiring adaptations to changes in the climate. The microbiota associated with these animals profoundly impacts their health and fitness. While seasonal changes have been shown to shape vertebrate microbiota, the microbiota of arthropods adapted to winter remains unknown. In this study, we investigated microbiota of two Collembola species with different overwintering strategies, Tomocerus cf. jilinensis and Tomocerus nigrus, in summer and three different periods in winter (early, mid, and late winter) using 16S rRNA gene amplicon sequencing. The results reveal pronounced alterations in microbial diversity and composition of the Collembola driven by seasonal variations and temperatures. Collembola associated microbiota exhibited higher Shannon diversity during mid and late winter. Furthermore, early, mid, and late winter periods were characterized by an enrichment of representatives from Hungateiclostridiaceae, Pseudomonas, and Pedobacter, respectively. Distinct seasonal patterns in microbiota were observed across different Collembola species. Bacterial community networks in winter Collembola were predominatly marked by positive interactions. Ground temperature exhibited a negative correlation with the Shannon index of Collembola-associated bacteria and the relative abundance of Comamonadaceae, Renibacterium, Mycobacterium, Sphingomonas, and Aeromicrobium. Our study indicates that season alters Collembola associated microbiota and these microbial changes could facilitate Collembola activity in low temperatures. Overall, our study extends our knowledge of symbiotic relationships between winter-adapted animals and their microbiota.

Collembola and ants: Influence of trails of red wood ants (Formica lugubris) on the community of soil springtails

Red wood ants are keystone species in forest ecosystems. Because ants are active polyphagous predators, they control the abundance of other arthropods. In addition to direct effects on other species, there are a number of indirect effects caused by ants. In our study, we investigated the influence of ants on springtails, which they rarely come into contact with. Springtails have been set as a model group to assess the state of soil animals, since they are one of the most numerous and widespread groups of soil microarthropods. They are characterized by high sensitivity to environmental changes. The basic characteristics (abundance, species richness, and species diversity) of the springtail community and the response of certain species to the presence of ant trails have been studied. The total abundance and species richness of springtails decreased along ant trails. Among occurred species Parisotoma ParIsotoma notabilis, Lepidacyrtus lignorum, Isotomiella minor, Desoria tigrina, and Pseudasinella alba are the most numerous species both along ant trails and in control samples. There are no significant changes in species diversity (assessed by the Shannon-Weaver index). Species structure of springtail communities along ant trails and in control is different. Two groups of common Collembola species are identified: (1) increasing their numbers in the presence of ants, (2) on the contrary, decreasing. The presence of ants in a forest ecosystem influences the soil springtail community, although ant-Collembola interactions are indirect.

Life history strategies of two springtails species (Hexapoda: Collembola) from saline soils

Springtails are a very common, widely spread component of soil fauna that play a significant role in numerous physical, chemical, and biological processes in the soil. Therefore, it is important to understand how their evolution and demographic parameters have changed throughout time. Since salinity is a relevant condition in the soils around the World and particularly in Mexico, the major goal of the current research is to understand the life cycle strategies of two springtail species from saline soils in Mexico. The studied species are Clavisotoma filifera and Brachystomella gabrielae, both widely distributed in Mexico, but their development or life history strategies are unknown. We found from laboratory cultures that C. filifera had a shorter life cycle and a faster reproduction rate than B. gabrielae. Nevertheless, both species show the same number of developmental stages, but there are interspecific differences in their duration. Although both species continuously reproduce throughout the year, the reproductive rate is lower in the months that are associated with the dry season at the source site. Additionally, we discovered variations in both the size and number of eggs in each species. It was found that the species under study had various life strategies for growth in the same environment. Clavisotoma filifera shows a more r-focused strategy (high fecundity, numerous offspring, shorter gestation and faster maturity), B. gabrielae shows an opposite strategy, closer to q strategy, with a lower fecundity, larger eggs, fewer reproductive events and slower maturity.

Dissection of the synthesis of polyunsaturated fatty acids in nematodes and Collembola of the soil fauna

It is becoming increasingly clear that not only unicellular, photoautotrophic eukaryotes, plants, and fungi, but also invertebrates are capable of synthesizing ω3 long-chain polyunsaturated fatty acids (LC-PUFA) de novo. However, the distribution of this anabolic capacity among different invertebrate groups and its implementation at the gene and protein level are often still unknown. This study investigated the PUFA pathways in common soil fauna, i.e. two nematode and two Collembola species. Of these, one species each (Panagrellus redivivus, Folsomia candida) was assumed to produce ω3 LC-PUFA de novo, while the others (Acrobeloides bodenheimeri, Isotoma caerulea) were supposed to be unable to do so. A highly labeled oleic acid (99 % 13C) was supplemented and the isotopic signal was used to trace its metabolic path. All species followed the main pathway of lipid biosynthesis. However, in A. bodenheimeri this terminated at arachidonic acid (ω6 PUFA), whereas the other three species continued the pathway to eicosapentaenoic acid (ω3 PUFA), including I. caerulea. For the nematode P. redivivus the identification and functional characterization of four new fatty acid desaturase (FAD) genes was performed. These genes encode the FAD activities Δ9, Δ6, and Δ5, respectively. Additionally, the Δ12 desaturase was analyzed, yet the observed activity of an ω3 FAD could not be attributed to a coding gene. In the Collembola F. candida, 11 potential first desaturases (Δ9) and 13 front-end desaturases (Δ6 or Δ5 FADs) have been found. Further sequence analysis indicates the presence of omega FADs, specifically Δ12, which are likely derived from Δ9 FADs.

New cave species of Cyphoderus Nicolet and Pararrhopalites Bonet & Tellez (Hexapoda, Collembola) from Caatinga biome, Brazil.

In recent years, surveys have revealed a high diversity of troglophilic and troglobitic species of Brazilian Collembola, mainly represented by the Entomobryidae and Sminthuridae, which hold some representative genera in Brazilian caves such as Cyphoderus Nicolet and Pararrhopalites Bonet & Tellez. Here we describe in detail two new species of these genera sampled from caves of the semiarid region of Rio Grande do Norte state, Brazil. Cyphoderus caatinguensis sp. nov. is similar to other Neotropical species of the tridenticulati group, but it is unique by the combination of labial chaetotaxy, ungues with a filamentous apical tooth and number of feathered chaetae on the dorsal face of the dens. Pararrhopalites iataganii sp. nov. differs from other Neotropical species of the genus especially by the number of subsegments of the fourth antennomere, number of cephalic spines, manubrium chaetotaxy and ventral dens formula. Recognition of these species enhances our understanding of the subterranean fauna in the Neotropics, and their identification may support future conservation policies for caves of the Rio Grande do Norte state, Brazil.

Assessing the multi-dimensional impact of lead-induced toxicity on collembola found in maize fields: From oxidative stress to genetic disruptions

The prolonged exposure of agricultural soils to heavy metals from wastewater, particularly in areas near industrial facilities, poses a significant threat to the well-being of living organisms. The World Health Organization (WHO) has established standard permissible limits for heavy metals in agricultural soils to mitigate potential health hazards. Nevertheless, some agricultural fields continue to be irrigated with wastewater containing industrial effluents. This study aimed to assess the concentration of lead in soil samples collected from agricultural fields near industrial areas. Subsequently, we determined the lethal concentration (LC50) of lead (Pb) and other heavy metals for two Collembola species, namely Folsomia candida, a standard organism for soil ecotoxicity tests, and comparing it with Proisotoma minuta. The research further examined the toxic effects of lead exposure on these two species, revealing depletion in the energy reservoirs and alterations in the tissue histology of both organisms. The study revealed that lead can induce genotoxic damage as it evidently has moderate binding affinity with the ct-DNA and hence can cause DNA fragmentation and the formation of micronuclei. Elevated lipid peroxidation (LPO) levels and protein carbonylation levels were observed, alongside a reduction in antioxidant enzymes (CAT, SOD & GPx). These findings suggest that lead disrupts the balance between oxidants and the antioxidant enzyme system, impairing defense mechanisms and consequential derogatory damage within microarthropods. The investigation elucidates a complex network of various signaling pathways compromised as a result of lead toxicity. Hence, it presents a novel perspective that underscores the pressing necessity for implementing an integrated risk assessment framework at the investigated site.

Characterization of Springtail (Arrhopalites caecus) for Use in Soil Ecotoxicity Testing.

Springtails (subclass: Collembola) represent one of the most extensively studied invertebrate groups in soil ecotoxicology. This is because of their ease of laboratory culture, significant ecological role, and sensitivity to environmental contaminants. Folsomia candida (family: Isotomidae) is a globally widespread parthenogenetic species that is prevalent in laboratory toxicity testing with springtails. Conversely, Arrhopalites caecus (family: Arrhopalitidae), a parthenogenic globular springtail species, remains untested in soil ecotoxicology. This species is found in diverse habitats, including cave systems and forest leaf litter, and has a global distribution. The sensitivity of A. caecus to environmental contaminants, such as neonicotinoid insecticides, as well as its life history and optimal culturing conditions, are largely unknown. The present study describes the establishment of a pure A. caecus laboratory culture and characterization of its life cycle and culturing conditions. We assessed the sensitivity of A. caecus to various insecticides, including exposures to the neonicotinoid thiamethoxam in soil and through a novel feeding assay as well as to clothianidin and cyantraniliprole in spiked soil exposures. In 7- and 14-day exposures to thiamethoxam in agricultural soil, the 50% lethal concentration (LC50) values were determined to be 0.129 mg/kg dry weight and 0.010 mg/kg dry weight, respectively. The 14-day LC50 for exposure to thiamethoxam via spiked food was determined to be 0.307 mg/kg dry weight. In addition, the 28-day 50% effect concentration for inhibition of juvenile production from cyantraniliprole exposure in the same soil type was 0.055 mg/kg dry weight. Challenges encountered in using this species included susceptibility to mite infestation and low adult survival rates in the 28-day cyantraniliprole test. Environ Toxicol Chem 2024;43:1820-1835. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

The effect of terrain on the fine-scale genetic diversity of sub-Antarctic Collembola: A landscape genetics approach.

Biodiversity patterns are shaped by the interplay between geodiversity and organismal characteristics. Superimposing genetic structure onto landscape heterogeneity (i.e., landscape genetics) can help to disentangle their interactions and better understand population dynamics. Previous studies on the sub-Antarctic Prince Edward Islands (located midway between Antarctica and Africa) have highlighted the importance of landscape and climatic barriers in shaping spatial genetic patterns and have drawn attention to the value of these islands as natural laboratories for studying fundamental concepts in biology. Here, we assessed the fine-scale spatial genetic structure of the springtail, Cryptopygus antarcticus travei, which is endemic to Marion Island, in tandem with high-resolution geological data. Using a species-specific suite of microsatellite markers, a fine-scale sampling design incorporating landscape complexity and generalised linear models (GLMs), we examined genetic patterns overlaid onto high-resolution digital surface models and surface geology data across two 1-km sampling transects. The GLMs revealed that genetic patterns across the landscape closely track landscape resistance data in concert with landscape discontinuities and barriers to gene flow identified at a scale of a few metres. These results show that the island's geodiversity plays an important role in shaping biodiversity patterns and intraspecific genetic diversity. This study illustrates that fine-scale genetic patterns in soil arthropods are markedly more structured than anticipated, given that previous studies have reported high levels of genetic diversity and evidence of genetic structing linked to landscape changes for springtail species and considering the homogeneity of the vegetation complexes characteristic of the island at the scale of tens to hundreds of metres. By incorporating fine-scale and high-resolution landscape features into our study, we were able to explain much of the observed spatial genetic patterns. Our study highlights geodiversity as a driver of spatial complexity. More widely, it holds important implications for the conservation and management of the sub-Antarctic islands.