Antonio Carapelli

With an estimated 50 000–100 000 described species, mites represent the most diverse group of Chelicerata and include lineages adapted to some of the harshest environments on Earth, including those found in Antarctica. Here, we combine mitochondrial genomics, population genetics, and morphological analysis to investigate the Antarctic oribatid mite Maudheimia petronia, a putative Gondwanan relict species endemic to Victoria Land. Phylogenetic analyses based on mitochondrial protein-coding genes place Maudheimia within Brachypylina and support its affinity with Ceratozetoidea. Beyond species-level characterization, we also place our results in a broader phylogenetic context by discussing relationships within Sarcoptiformes and Oribatida to clarify higher-level evolutionary patterns. The mitochondrial genome exhibits a conserved protein-coding gene order but highly derived transfer RNAs, including extensive arm reduction, frequent mismatches, and overlapping genes. Population analysis of three isolated localities revealed geographically structured but conspecific populations, consistent with long-term persistence in Antarctic refugia. Morphological observations obtained through light and scanning electron microscopy confirmed the diagnostic characters of M. petronia and showed substantial morphological stability among populations. These results provide new insights into the evolutionary history, mitochondrial genome evolution, and historical biogeography of Antarctic oribatid mites.

Mitogenomic datasets are central to molecular evolution and phylogenetics, yet preparatory workflows remain labor-intensive and prone to errors introduced during manual data preparation. EZmito2 is a re-implementation of the widely used EZmito pipeline that offers a fully reproducible and user-accessible solution for mitogenomic dataset curation and result visualization. It is accessible via a public web server for rapid analyses and through local installation, enabling reproducible workflows on personal computers or computational clusters. The pipeline consolidates the core modules—EZpipe, EZskew, and EZcodon—and extends functionality through newly developed tools for genome visualization (EZcircular, EZmap), chimeric region detection (EZmix), gene extraction from NCBI-deposited genomes (EZsplit), structural annotation of transmembrane domains in mitochondrial protein-coding genes (EZtrampo), and population genetic studies (EZdist, EZpcoa, EZpopstat). All tools accept standard input formats and generate ready-to-publish outputs. By providing a user-friendly platform for mitogenomic exploration and quality control, EZmito2 facilitates reproducible analyses for evolutionary and molecular research communities.

Among the life forms that have adapted to the harsh Antarctic environment, springtails and mites are the most abundant arthropod groups of the terrestrial ecosystem, both in continental and maritime Antarctica. The study of the systematics of these organisms originates at the beginning of the last century and, in recent years, has received considerable contributions. The taxonomy of springtail species from continental Antarctica has undergone more systematic revisions by way of the integration of modern morphological characters and molecular techniques, the latter of which prompted us to further investigate the morphology of supposed “cryptic species” within the springtail Cryptopygus terranovus from Victoria Land, Antarctica. In this study, a careful morphological analysis was conducted to parse these strongly divergent genetic lineages in order to characterize, from a morphological point of view, these new taxonomic entities. Results from our investigation reveal consistent morphological differences that strongly coincide with geographic and previously reported molecular evidence. With this, we have described two new species, C. fratii sp. nov. and C. dallaii sp. nov., bringing the total number of species of Cryptopygus within continental Antarctica to six.

The massive production of plastics, together with inadequate waste management, has intensified the problem of plastic pollution. Recently, the scientific community has increasingly investigated the interactions between plastic polymers and biological systems, with particular interest in plastivorous insects and their gut-associated microbial communities. The lesser mealworm Alphitobius diaperinus has emerged as a promising model for studying biological interactions associated with polystyrene (PS) modification during gut transit. In this study, two complementary approaches were applied to characterize gut mediated responses to PS. First, chemical analyses were employed to provide evidence of polymer modification following gut transit; micro-FTIR analysis confirmed the presence of PS residues in larval frass and showed detectable structural changes in the recovered material, while GC-MS analysis identified α-methylstyrene and cumyl alcohol as compounds associated with PS chemical modifications and not detected in controls. Second, gut microbiota composition was assessed through metabarcoding analysis using full-length PacBio HiFi sequencing of the 16S rDNA gene. Differences were observed between the microbiota of PS fed larvae and that of the control group under different experimental conditions. Together, these results indicate that PS ingestion leads to measurable chemical modifications of the polymer and shifts in gut microbial composition, providing insight into insect–microbe interactions associated with PS transformation.

The Japanese beetle (Popillia japonica Newman) is a highly invasive, polyphagous scarab causing significant agricultural and ecological damage across invaded regions. While molecular studies are gaining traction, the unavailability of P. japonica cell lines has constrained in vitro investigations. To overcome these limitations and provide a platform for controlled biological investigation, we developed the first cell culture derived from P. japonica larvae. Fat bodies from field-collected third-instar larvae were dissected and cultured. Cells initially formed floating spheroids before transitioning to adherent monolayers. Cultures remained stable over several splits, whereas a marked reduction in cell number was observed at the eighth split due to the onset of contamination. Fluorescence microscopy confirmed nuclear integrity, while transmission electron microscopy at split 5 revealed cytoplasmic features consistent with insect fat body cells, including lipid droplets. The cell culture predominantly contained trophocyte-like cells, consistent with the known cellular composition of insect fat bodies. Transcriptomic analyses comparing fresh fat bodies and cultured cells revealed moderate transcriptional divergence, with limited upregulation of genes associated with iron homeostasis and stress response, consistent with adaptive responses to in vitro conditions. While not immortalized, this cell culture offers a short-term model for studying P. japonica physiology, toxicology, host–pathogen interactions, and potential gene-targeting strategies under controlled conditions. This work represents a first step toward enabling molecular and cellular research in this economically important pest species.

SmithRNAs are a novel class of small noncoding RNAs that are encoded in the mitochondrial genome and regulate the expression of nuclear transcripts. They have been recently described in the Manila clam Ruditapes philippinarum and their biological function has been confirmed in vivo. It is currently unclear whether smithRNAs are a unique feature of this species, possibly related to the peculiar mechanism of sex determination observed in bivalves, or a common feature of Metazoa. Aiming at a broader survey on the presence and biological features of smithRNAs across Metazoa, 14 species were selected to represent major lineages, and for each species small RNAseq data, as well as the transcriptome, mitochondrial and nuclear genomes, were collected from the literature or sequenced/assembled de novo. Data were analyzed using the SmithHunter pipeline, a recently published tool specifically designed to identify smithRNAs and their targets. Candidate smithRNAs were identified in all species studied, supporting the notion that smithRNAs are a common feature across Metazoa. SmithRNAs are generally encoded within other genes, on the same strand, and with a preference for mitochondrial rRNAs and tRNAs. Based on their strandedness and preferential position at the 5′-end of the encompassing gene, a transcription mechanism is proposed where smithRNAs are cleaved off from gene-specific transcripts after the maturation of the two primary mitochondrial transcripts. A substantial variability was identified concerning the possible nuclear targets of smithRNAs, with a preference for regulation/response terms, mitochondrial functions, and sex/germline associated terms.

Springtails (Collembola) constitute one of the most diverse and ecologically important groups of basal hexapods, yet remain significantly underrepresented in genomic databases. In this study, we present the first genome assembly of Orchesella dallaii, an Italian endemic species, representing a crucial advancement in expanding genomic resources for Collembola. Utilizing PacBio HiFi sequencing combined with an ultra-low input library preparation, we generated a highly contiguous genome assembly (223 contigs covering 304 Mb) that ranks among the most complete ones within the group. Genome annotation, supported by short-read RNA-seq data, predicted 31,769 genes with high completeness. The analysis of repeated sequences revealed a comparatively low abundance of annotated transposable elements. Additionally, the entire mitochondrial genome was assembled and annotated, confirming the gene order characteristic of the Entomobryomorpha lineage. This genomic resource provides a valuable reference for an often-overlooked taxonomic group and offers a basis for future research in comparative genomics, species delimitation, and conservation genetics of Mediterranean soil ecosystems.

Background: The Japanese beetle Popillia japonica is an invasive pest that is creating a major concern due to its spread and damaging potential. Native to Japan, it was introduced in the U.S.A. and the Azores during the twentieth century, and in mainland Europe in 2014. P. japonica is able to attack more than 400 plant species, including some of high economic importance, and the possible losses related to uncontrolled expansion in Europe are substantial. Numerous control measures are being developed to control this pest, with a specific focus on Integrated Pest Management and environmentally safe strategies. Aiming for a genetically informed optimization of the design of these control methods, we studied the gene expression response of the pest following exposure to three different treatments: deltamethrin-coated long lasting insecticidal nets, Bacillus thuringiensis and Metarhizium robertsii spores. Results: The treatment with insecticidal nets resulted in the differential expression of genes related to Ca²⁺ transport and CYP-based detoxification. Exposure to B. thuringiensis was associated with enrichment of gene ontology terms related to antimicrobial peptides and immune function, which suggested potential modulation of immune-related processes. Treatment with M. robertsii led to the production of antifungal peptides as well as an up-regulation of the Toll and MAPK pathways. Conclusions: These findings can be variously interpreted as a response of the insect to minimize the effects of the treatment at the molecular level (e.g. Ca²⁺ increase), as a direct attempt of the insect to combat the agent (e.g. antimicrobial peptides), or as part of a more complex interplay between the insect and the biological control agent (e.g. modulation of the immune system). In general terms, the response to the insecticidal nets and, partly, to B. thuringiensis, appears to arise from a direct interaction of the insecticide molecule, or toxin, with their targets at the molecular level. On the other hand, multiple gene pathways are modulated in the response to M. robertsii, suggesting a more diversified mode of action that impacts a broader spectrum of biological mechanisms, in line with the notion that the fungus actually grows and reproduces inside the insect host.

Invasive species are an increasing global threat given their ability to rapidly spread and adapt to novel environments. The adverse ecological and economic impacts of invasive species highlight the critical need to understand the mechanisms that underpin invasion processes and success. The Japanese beetle, Popillia japonica, is an invasive pest of remarkable interest, as it feeds on hundreds of economically valuable plant species. It has been expanding outside of its native range in Japan since the first decades of the 20th century, colonising large areas of North America and, more recently, Europe. Here, we compared whole‐genome resequencing data from individuals encompassing the entire species distribution to study the geographic differentiation of P. japonica populations and reconstruct expansion routes from Japan to the USA and Europe. We found six genomically distinguishable clusters, corresponding to the approximate colonisation areas at a continental scale. Our analysis supported an ancestral divergence between South and North/Central Japan, with the latter being the source of the initial invasion to the USA. Coalescent simulations supported independent bridgehead events from the USA to the Azores and Italy. We also investigated possible signals of selection to better understand the adaptive mechanisms that underlie the invasion success of P. japonica. However, the absence of strong selection signatures suggested that the beetle's adaptive ability might be embedded in pre‐existing genomic features. Our comprehensive genome‐wide dataset allowed a detailed inference of the invasion process and may be useful in determining the origin of P. japonica individuals in future invasion events.

Isolation and extreme environmental conditions have significantly impacted terrestrial invertebrate biodiversity in Antarctica, with glacial cycles further limiting animal diversity to a small number of species. Among these, springtails are relatively abundant, though their taxonomic diversity remains low. Antarctic glaciers may serve as major dispersal barriers, leading to high levels of genetic divergence among isolated populations. In Victoria Land (continental Antarctica), the Tucker Glacier has been proposed as an example of such a barrier; however, different species or taxa may respond differently to the same geographical features. In this study, we tested whether geographic distance, major glacier tongues, and seawater channels influence the distribution of Kaylathalia klovstadi (Collembola; Isotomidae) in Northern Victoria Land. We conducted mitochondrial DNA haplotype analysis on fragments of cytochrome c oxidase subunit 1 (cox1) and ATP synthase 6 (atp6) in 62 individuals from six K. klovstadi populations. Our analysis provides new insights into the genetic diversity and distribution patterns of K. klovstadi by incorporating additional sampling sites, specimens, and molecular markers. We challenge previous views regarding the role of the Tucker Glacier as a significant physical barrier to springtail dispersal in Northern Victoria Land. Our findings suggest that the impact of physical barriers on the genetic diversity of Antarctic Collembola, including the species studied here, requires a more careful evaluation.