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Release of marketed individuals increases the risk of genetic disturbance in the pet insect Trypoxylus dichotomus
No full textGenetic disturbance can be caused by the release or escape of individuals with different genetic characteristics into wild habitats, risking impacts on native biodiversity. The risk of genetic disturbance in pet insects due to release and escape is particularly common because a wide variety of affordable pets are available on the market. Trypoxylus dichotomus (Coleoptera, Scarabaeidae), the Japanese rhinoceros beetle, is a renowned pet insect in Japan and thus is a suitable target species for studying genetic disturbances in pet insects. However, the detailed spatial genetic structure and genetic disturbances of this species in Japan remain unclear. Here, we estimated the genetic diversity and spatial genetic structure of wild and marketed individuals using mitochondrial DNA sequences and genome-wide single-nucleotide polymorphisms (SNPs) obtained via MIG-seq. Using MIG-seq, 570 SNPs were obtained, revealing a weak yet significant spatial genetic structure in the Japanese archipelago. Although significant isolation by distance (IBD) was observed in wild individuals, no significant IBD was observed in marketed individuals. Comparisons between wild and marketed individuals revealed clear differences in spatial genetic structure. These findings highlight the risks of releasing marketed individuals into the wild owing to their artificial long-distance migration. Our results provide valuable insights into the genetic disturbance of human-mediated distribution and underscore the need for informed management practices to protect native biodiversity
Estimation of the Size of the Second Generation of Migrants in Russia and the West
No full textThe article addresses the issue of statistical accounting for the population category known as second generation of migrants. Descendants of migrants constitute a significant portion of the population in many countries, often representing a group in a vulnerable socio-economic position. Integrating this category into national statistical systems enables direct estimates of second-generation migrant populations in several countries of the West. The study presents a critical analysis of the Russian demographic data sources, which lack specialized classifications for identifying second-generation migrants, thereby complicating reliable population estimates. As an alternative approach, this work employs cohort-component analysis to model the number of second-generation migrants born in Russia between 2001 and 2020. The model results indicate that this group is over 1 million individuals. The findings underscore the need to improve existing statistical methodologies in Russia. This article is the output of a research project implemented as a part of the Basic Research Program at the National Research University Higher School of Economics (HSE University)
Predatory interactions between two global aquatic invaders beyond their native ranges: An experimental approach
No full textThe widespread distribution of invasive species inevitably leads to the emergence of a new category of biotic relationships: interspecific predatory interactions between invasive species. We assessed the vulnerability of different life stages of the clawed frog, Xenopus laevis (eggs, hatchlings, tadpoles, newly-metamorphosed froglets, and adults), to predation by the Eastern mosquitofish, Gambusia holbrooki, and evaluated whether adult clawed frogs prey upon juvenile and adult mosquitofish. The results confirm differences in the palatability of different ontogenetic stages of the clawed frog by mosquitofish, as well as the low palatability of mosquitofish for adult frogs, with the exception of fish juveniles, which are relatively protected in the light but highly vulnerable under low-light conditions. Therefore, these fish-amphibian interactions are complex and can be defined as unequal bidirectional predation: the mosquitofish readily eliminates its early-stage opponent, but may become prey for its adult individuals. The revealed existence of a vulnerable mosquitofish stage makes it difficult to predict the unconditional suppression of clawed frog populations by this fish species when these two global aquatic invaders become syntopic in new regions. In any case, mosquitofish are likely to dominate in urban water bodies in locations with constant artificial lighting. We emphasise the importance of studying interactions at all ontogenetic stages, as well as taking into account the lifestyle of the organisms studied when analysing the mechanisms of predatory interactions between any pairs of invasive species in new areas of the planet. Graphical abstrac
Mapping the northernmost transnational non-native population of Xenopus laevis using pooled eDNA sampling
No full textEarly-detection-rapid response (EDRR) programs are invaluable for managing incipient invasions, but require monitoring strategies that maximize search coverage and minimize costs. While environmental DNA (eDNA)-based monitoring techniques are now widely used for monitoring aquatic invasions, the large monitoring efforts in EDRR programs demand further improvements in sampling strategies. This need is exemplified by the recently discovered African clawed frog Xenopus laevis (Daudin, 1802) invasion along the French-Belgian border region – its northernmost introduced population – where it was first detected in France in 2018 near the Belgian border. In response to the risk of its permanent establishment and cross-boundary spread, we employed quantitative eDNA barcoding analyses in the context of an EDRR program. We (i) developed and validated a novel cost-efficient sampling strategy that involves pooling water from multiple sites allowing for broader area coverage, (ii) delineated the spatial extent of the invasion, and (iii) assessed whether lotic systems serve as cross-boundary dispersal corridors. In 2020, 2022, and 2023, we determined the presence and eDNA concentrations of X. laevis from a total of 426 sites by pooling water from 366 sites in 83 samples, and sampling 59 additional sites individually. We found that this pooled approach can accurately determine X laevis presence and approximate its average eDNA concentration across pooled sites. We detected X. laevis in 26 samples, revealing an interconnected population spanning an area of 103 km2, contradicting prior assumptions of an early invasion stage. We provide evidence that the river Lys and the Douvebeek facilitate cross-boundary movement. The pooled sampling technique presented here is a cost-effective method for providing timely, actionable data to inform management decisions; however, further validation is needed to confirm its reliability and broader applicability. The X. laevis invasion along the French-Belgian border underscores the complexities of managing biological invasions across national and administrative boundaries, providing valuable insights for other transboundary invasions
Eradication attempt for an early detected invasive crayfish: the case of Pacifastacus leniusculus (Decapoda, Astacidae) in the Clitunno River (central Italy)
No full textThe signal crayfish Pacifastacus leniusculus (Dana, 1852) is one of the most ecologically impactful decapod crustaceans introduced in Europe. As a species of Union concern, early detection and rapid eradication measures are required to prevent its establishment and spread. We aimed to: i) test the effectiveness of an eradication attempt undertaken to counteract the spread and contain the demographic growth of P. leniusculus in the Clitunno River Basin (central Italy), where the species has been detected in 2020; ii) assess distribution, age structure and growth of P. leniusculus in this invaded area. The removal actions were conducted biweekly, from June 2022 to December 2024, using both traps and electrofishing. Biometric parameters were individually recorded, and the demographic features and growth of P. leniusculus population were assessed. In total, 259 removal activities were carried out and a biomass of 39.74 kg was removed. The presence of six cohorts (from 0+ to 5+), including the young-of-the-year (0+), attested to the rapid acclimatisation of P. leniusculus, which gave rise to a self-sustaining population in a short time. The greatest removal efforts have been concentrated on a small tributary, named Fosso Vecchio, where the average values of Catch Per Unit Effort (CPUE) showed a significant decreasing trend over time, suggesting the effectiveness of the removal actions. Our findings provided some evidence that early detection and eradication measures conducted on a small scale, but with high effort, represent effective management tools to limit population abundance and prevent invasive crayfish from spreading further
A global synthesis of naturalised and invasive plants in aquatic habitats
No full textGlobal databases have contributed to our understanding of alien, naturalised and invasive plant species distributions. Still, the role of species invasions in habitats, specifically in aquatic habitats, remains underexplored at the global scale. Accordingly, a comprehensive global synthesis of the status of plant invasions in aquatic habitats has been missing. Here, we focus on macroecological patterns of naturalised non-invasive and invasive plants in aquatic habitats using the recently built SynHab database. Amongst all the plant records compiled in SynHab, 592 are assigned to aquatic habitats, of which 183 are unique plant taxa (further termed ‘species’) belonging to 49 families. Of the total number of records, 462 refer to taxa with naturalised non-invasive occurrences and 130 to invasive occurrences. The species pool analysed here refers to 78 regions distributed across all botanical continents as defined by the World Geographical Scheme for Recording Plant Distributions. The number of naturalised non-invasive aquatic species is similar across different continents and biomes, but Tropical Asia had more and the Mediterranean zonobiome had fewer invasive species than expected. Tropical Asia, Temperate Asia and Africa have the highest proportions of naturalised species that have become invasive, while across continents, invasive proportions were highest for tropical and subtropical zonobiomes. New Zealand, Italy and California contained disproportionately more naturalised species than expected, given the area covered by aquatic habitat in those regions, whereas South Sudan, Papua New Guinea and Kyrgyzstan had disproportionately fewer species. In pairwise dissimilarity comparisons, all continents had distinct species compositions (from 0.73 to 0.92 of the Jaccard dissimilarity index) and so did zonobiomes (0.69 to 1.00). The high proportion of invasive species in Tropical Asia in comparison with terrestrial invasions in this region, indicates a greater susceptibility of warmer regions to aquatic plant invasions. This may be exacerbated by further naturalisations in the future, as data from temperate regions suggest a larger pool of available species
Exploring the drivers and effects of biodiversity change in the coast of Cantabria and Santander Bay (Southern Gulf of Biscay)
No full textThis preprint has been retracted, due to duplication. Please refer to: https://doi.org/10.3897/arphapreprints.e175173 for its content
Aextoxicola pilolcurensis, a new genus and species of false skin beetles (Coleoptera, Biphyllidae) from the Chilean Valdivian rainforest
No full textAextoxicola Tello & Tello-Arriagada, gen. nov., with its type species Aextoxicola pilolcurensis Tello & Tello-Arriagada, sp. nov., a new South American genus and species of the family Biphyllidae, are described from the Valdivian rainforest in Chile. The morphological characters are illustrated and compared with morphologically similar extant and extinct genera. Finally, a key for genera of Biphyllidae recorded in Chile is provided
First record of the subfamily Geracinae Brindle, 1971 and genus Pseudovostox Borelli, 1926 (Dermaptera, Spongiphoridae) in China, with a description of a new species
No full textThe subfamily Geracinae Brindle, 1971, and the genus Pseudovostox Borelli, 1926, are recorded for the first time from China. These new records were confirmed by collections from Guiyang City in Guizhou Province, located in southwestern China. Pseudovostox guizhouensis sp. nov. is described and illustrated based on specimens from this region. Although the new species closely resembles the Oriental species Pseudovostox fasciatus (de Bormans, 1894), it can be distinguished by a combination of unique morphological characters. An updated key and distribution map for Pseudovostox species are provided to aid future research and species identification
Nitrogen under cladding of fuel pins with mixed uranium-plutonium nitride
No full textIn gas-bonded fuel pins the interior space is filled with helium in order to provide heat removal from the fuel. Under irradiation, as a result of gaseous fission products release, the initial gas composition under the fuel pin cladding changes, which leads to a change in its thermophysical characteristics. Post-irradiation examinations have shown that the partial pressure of nitrogen under the fuel pin cladding increases with fuel burn-up increase, since nitrogen atoms also release from uranium-plutonium nitride fuel under the cladding, in addition to the krypton, xenon and helium inert gases. The mechanisms of release of inert gases and nitrogen from nitride are different: the diffusion mechanism for inert gases and the knocking out of fission fragments for nitrogen. The difference in the gas release mechanisms leads to a significant quantitative difference in the gases release under the cladding. The specific nitrogen yield under the fuel pin cladding is significantly lower than the specific yield of other gases, but its presence is an important factor, since the dissociation temperature of the mixed nitride, as well as the nitriding of the inner surface of the cladding, depends on the nitrogen pressure under the fuel pin cladding. A generalization and analysis of the results of post-irradiation examinations of the nitrogen content in the gas mixture under the claddings of 87 investigated fuel pins after irradiation in the BN-600 reactor as part of 17 experimental fuel assemblies with mixed uranium-plutonium nitride fuel, irradiated to maximum fuel burn-up from 3 at. % to 9 at. % is carried out in the paper