Armadillidium Nasatum Research Articles

Dual roles of terrestrial isopods in seed predation and seed dispersal in Phacellanthus tubiflorus (Orobancheaceae)

AbstractTerrestrial isopods are known to play significant roles in litter decomposition and seed predation. The present study examines the function of terrestrial isopods, particularly Armadillidium vulgare and Armadillidium nasatum, in the seed dispersal of a nonphotosynthetic plant, Phacellanthus tubiflorus. These isopods were observed ingesting seeds in the natural habitat of P. tubiflorus in Hyogo Prefecture, Japan. Contrary to the prevailing belief that invertebrates do not serve as effective internal seed dispersers, our analysis demonstrated that some seeds ingested by A. vulgare and A. nasatum were excreted whole, with viability rates comparable to those of seeds directly sourced from fruits. This indicates that these isopods could act not only as seed predators but also as seed dispersers. The research highlights the importance of further exploration into the ecological contributions of isopods and other invertebrates as seed dispersers.

Fungal Diversity Associated with Armadillidium Isopods: A Case Study in Central Park of Gwacheon, South Korea

The symbiotic relationship between macroorganisms, such as plants and animals, and the microorganisms in their environment plays a crucial role in shaping their physiology and ecology. Thus, many studies have examined microbial symbiosis in relation to plants, humans, and insects. However, little is known about the microbial diversity associated with isopods. Hence, in this study, we investigated the fungal diversity associated with two species of terrestrial isopods, Armadillidium nasatum and A. vulgare. In this study, we used a metabarcoding approach to compare fungal diversity between the two species for the first time. Our results indicated that A. nasatum had significantly greater mycobiome alpha diversity than A. vulgare. In contrast, fungal communities (beta diversity) did not differ significantly between hosts, except in beta dispersion of relative abundance. The majority of fungi identified belonged to Ascomycota and Basidiomycota, phyla that are dominated by saprotrophs. In conclusion, our findings shed light on the fungal communities associated with Armadillidium species, providing valuable insight into the biology of terrestrial isopods.

Aggregation and sheltering behavior of Armadillidium vulgare and Armadillidium nasatum (Isopoda: Armadillidiidae) exposed to fluorescent and ultraviolet light

Terrestrial isopods are gregarious invertebrates, aggregating in colonies. Aggregation reduces risk of predation and desiccation. Isopod aggregation and sheltering behavior have been observed under fluorescent and color-filtered light, but not under ultraviolet (UV) light. With UV levels on the rise, it is important to understand how soil ecosystems might be impacted by human-induced ozone depletion. We examined aggregation and sheltering behaviors of the terrestrial isopods Armadillidium vulgare and Armadillidium nasatum under fluorescent light and under fluorescent light with added UV light. Upon testing, each species was randomly assigned into groups of 10 individuals. Each group was released into a circular arena with a black disk in the middle of the lid which functioned to block light and served as a shelter. Sheltering and aggregation behaviors were recorded every 15 minutes for 45 minutes under the presence versus absence of increased UV light. There was no significant difference in the total number of sheltering events, but positive thigmotaxis (movement toward or away from a physical stimulus) may have influenced sheltering. However, there was a significant increase in the average number of aggregated individuals and the total number of aggregates in groups exposed to increased UV conditions, perhaps reflective of their desiccation avoidance behavior and negative phototaxis. Additionally, A. nasatum individuals were significantly more likely to form aggregates than A. vulgare when exposed to increased UV light conditions, perhaps because A. nasatum is less desiccation-resistant than A. vulgare.

Citizen science data opens multiple avenues for iridovirus research and prompts first detection of Invertebrate iridescent virus 31 in Australia

From citizen science data we report the first records of blue to violet-colored oniscideans (Oniscidea: Isopoda), indicating potential invertebrate iridescent virus (IIV; Betairidovirinae: Iridoviridae) infection: in Africa, South America, and Oceania; and of the new hosts Armadillidium nasatum and Balloniscus sellowii. DNA sequencing of indigo Porcellio scaber confirms the presence of Invertebrate iridescent virus 31 in Australia. Beyond the Oniscidea, new, putative IIV hosts are identified: hoverfly pupae (Eristalinae), a tortrix moth larva (Phaecasiophora niveiguttana), and a millipede (Harpaphe haydeniana). In addition, the purported positive correlation between virion diameter and wavelength of iridescence is analyzed qualitatively for the first time.

Impact of transposable elements on genome size variation between two closely related crustacean species

Identifying and quantifying genome size variation among species and understanding the underlying causes is a long-standing objective in evolutionary biology. Here, we investigated the basis of genome size variation between two closely related species of terrestrial isopods: Armadillidium vulgare and Armadillidium nasatum. The two species diverged 25 million years ago and the A. vulgare genome is ~500 megabases larger than the A. nasatum genome (1.7 vs. 1.2 gigabases, respectively). Our analyses indicated that genome size difference is essentially attributed to transposable elements (TEs). We found that the deletion rate may be slightly higher in A. nasatum than in A. vulgare, but it is unlikely to explain the observed genome size difference. As the two genomes largely share the same TE families, differential transpositional activity also contributes to the observed variation. Analyses of TE expression suggested that the cumulative expression level of all expressed TEs was higher in A. nasatum than in A. vulgare. Assuming TE expression level is a good proxy for TE transpositional activity, our results suggest that the two species may have recently been experiencing different TE transposition dynamics. Overall, our results illustrate the important impact TEs can have on genome structure and evolution between closely related species.

Sex chromosomes control vertical transmission of feminizing Wolbachiasymbionts in an isopod.

Microbial endosymbiosis is widespread in animals, with major ecological and evolutionary implications. Successful symbiosis relies on efficient vertical transmission through host generations. However, when symbionts negatively affect host fitness, hosts are expected to evolve suppression of symbiont effects or transmission. Here, we show that sex chromosomes control vertical transmission of feminizing Wolbachia endosymbionts in the isopod Armadillidium nasatum. Theory predicts that the invasion of an XY/XX species by cytoplasmic sex ratio distorters is unlikely because it leads to fixation of the unusual (and often lethal or infertile) YY genotype. We demonstrate that A. nasatum X and Y sex chromosomes are genetically highly similar and that YY individuals are viable and fertile, thereby enabling Wolbachia spread in this XY-XX species. Nevertheless, we show that Wolbachia cannot drive fixation of YY individuals, because infected YY females do not transmit Wolbachia to their offspring, unlike XX and XY females. The genetic basis fits the model of a Y-linked recessive allele (associated with an X-linked dominant allele), in which the homozygous state suppresses Wolbachia transmission. Moreover, production of all-male progenies by infected YY females restores a balanced sex ratio at the host population level. This suggests that blocking of Wolbachia transmission by YY females may have evolved to suppress feminization, thereby offering a whole new perspective on the evolutionary interplay between microbial symbionts and host sex chromosomes.

Reproductive Patterns of Terrestrial Isopods (Crustacea, Isopoda, Oniscidea) from Uruguay

<em>Armadillidium vulgare</em> (Latreille, 1884) and <em>Armadillidium nasatum </em>(Schultz, 1961) are among the most common species of terrestrial isopods in Uruguay. The reproductive pattern of these species was studied, for first time, on a natural population at Department of San Jose (Uruguay) from June 2010 to July 2011. A total of 9136 individuals were sampled, of these 7010 were <em>A. </em><em>vulgare</em> and 2126 were <em>A.nasatum.</em> Adults of <em>A. vulgare</em> were present throughout the year and juveniles appeared from February to November. Juveniles and adults of <em>A. nasatum</em>appeared from January to October, and practically disappeared from November to December. For both species ovigerous females were collected from spring to summer (October to March), this would indicate a seasonal reproduction followed by a sexual rest. In <em>A. vulgare</em> reproductive females cephalothorax width that varied between 1.7 to 3 mm, average fecundity was equal to 39 ± 5 eggs and average fertility was equal to 27 ± 4. In <em>A. nasatum</em> cephalothorax width of reproductive females oscillated between 1.5 to 2.9 mm and the average fecundity was 44 ± 5 eggs. For both species, fecundity and fertility were positively correlated with the size of the females. The incubation period ( = 13 days) and the mancas born ( = 21) were similar for both species.

Comparative paleovirological analysis of crustaceans identifies multiple widespread viral groups.

BackgroundThe discovery of many fragments of viral genomes integrated in the genome of their eukaryotic host (endogenous viral elements; EVEs) has recently opened new avenues to further our understanding of viral evolution and of host-virus interactions. Here, we report the results of a comprehensive screen for EVEs in crustaceans. Following up on the recent discovery of EVEs in the terrestrial isopod, Armadillidium vulgare, we scanned the genomes of six crustacean species: a terrestrial isopod (Armadillidium nasatum), two water fleas (Daphnia pulex and D. pulicaria), two copepods (the salmon louse, Lepeophtheirus salmonis and Eurytemora affinis), and a freshwater amphipod (Hyalella azteca).ResultsIn total, we found 210 EVEs representing 14 different lineages belonging to five different viral groups that are present in two to five species: Bunyaviridae (−ssRNA), Circoviridae (ssDNA), Mononegavirales (−ssRNA), Parvoviridae (ssDNA) and Totiviridae (dsRNA). The identification of shared orthologous insertions between A. nasatum and A. vulgare indicates that EVEs have been maintained over several millions of years, although we did not find any evidence supporting exaptation. Overall, the different degrees of EVE degradation (from none to >10 nonsense mutations) suggest that endogenization has been recurrent during the evolution of the various crustacean taxa. Our study is the first to report EVEs in D. pulicaria, E. affinis and H. azteca, many of which are likely to result from recent endogenization of currently circulating viruses.ConclusionsIn conclusion, we have unearthed a large diversity of EVEs from crustacean genomes, and shown that four of the five viral groups we uncovered (Bunyaviridae, Circoviridae, Mononegavirales, Parvoviridae) were and may still be present in three to four highly divergent crustacean taxa. In addition, the discovery of recent EVEs offers an interesting opportunity to characterize new exogenous viruses currently circulating in economically or ecologically important copepod species.Electronic supplementary materialThe online version of this article (doi:10.1186/s13100-015-0047-3) contains supplementary material, which is available to authorized users.

Caracterización de isopodos terrestres (Crustacea: Isopoda) y su impacto en cultivos hortícolas de Boyacá

Las “cochinillas de humedad” (Crustacea: isopoda), han ido surgiendo como organismos plaga de importancia en agricultura, en países como Brasil y Argentina, en donde causan daños en soya, girasol y pastos. Recientemente se han detectado en Boyacá, afectando cebolla de bulbo, frijol y frutales. Por lo anterior, fué necesario iniciar la caracterización de las especies presentes y la determinación de su impacto en la producción hortícola en algunos municipios de esta región. Se realizó muestreos en Paipa, Tibasosa, Nobsa y Santa Rosa de Viterbo, para determinar la presencia y diversidad de especies de “cochinilla de humedad”; así como, una encuesta para establecer la percepción que tenían los agricultores del daño de estos crustáceos y las estrategias de manejo empleadas. Se evaluaron 8 veredas en Paipa, 7 en Nobsa, 3 en Tibasosa y 1 en Santa Rosa de Viterbo. Se comprobó la presencia de “cochinillas de humedad” en cultivos de frutales, hortalizas y otros, en los municipios muestreados. Se identificaron las especies: Porcellios caber, Porcellio dilatatus, Porcellio pruinosus, Armadillidium vulgare y Armadillidium nasatum. El daño por estos organismos se evidenció en lechuga, brócoli, repollo, remolacha, espinaca, cebolla, cilantro, durazno, frijol, fresa, maíz y papa, especialmente en semillero. El daño observado fué mordedura en hojas (50%), raíz (32,35%), tallo (20,85%) y ramas (2,94%). Se percibió falta de conocimiento de los agricultores en el manejo de las “cochinillas de humedad”, utilizándose insecticidas en un 79,41% de los casos, un manejo orgánico en 2,99% y ningún manejo en el 5,88%.

Isolation and Characterization of Microsatellite Loci for the Isopod Crustacean Armadillidium vulgare and Transferability in Terrestrial Isopods

Armadillidium vulgare is a terrestrial isopod (Crustacea, Oniscidea) which harbors Wolbachia bacterial endosymbionts. A. vulgare is the major model for the study of Wolbachia-mediated feminization of genetic males in crustaceans. As a consequence of their impact on host sex determination mechanisms, Wolbachia endosymbionts are thought to significantly influence A. vulgare evolution on various grounds, including population genetic structure, diversity and reproduction strategies. To provide molecular tools for examining these questions, we isolated microsatellite loci through 454 pyrosequencing of a repeat-enriched A. vulgare genomic library. We selected 14 markers and developed three polymorphic microsatellite multiplex kits. We tested the kits on two A. vulgare natural populations and found high genetic variation, thereby making it possible to investigate the impact of Wolbachia endosymbionts on A. vulgare nuclear variation at unprecedented resolution. In addition, we tested the transferability of these kits by cross-species amplification in five other terrestrial isopod species harboring Wolbachia endosymbionts. The microsatellite loci showed good transferability in particular in Armadillidium nasatum and Chaetophiloscia elongata, for which these markers represent promising tools for future genetic studies.

Eco-morphological studies on pleopodal lungs and cuticle in Armadillidium species (Crustacea, Isopoda, Oniscidea)

Terrestrial isopods (Crustacea, Isopoda, Oniscidea) have adapted to land life by diverse morphological, physiological and behavioral changes. Woodlice species exhibit a large variety in this respect, their preferences ranging from moist to dry habitats. These moisture preference values are related to various morphological adaptations, rendering terrestrial isopods amenable to studying morphological adaptations to terrestrial life. We performed a comparison of four Armadillidium species (Armadillidium zenckeri, Armadillidium nasatum, Armadillidium versicolor, Armadillidium vulgare), by quantifying two morphological traits: the extent of the interfacial endothelium between the respiratory space and the hemolymph within pleopodal lungs and the thickness of tergite cuticle, which are ‘key factors’ in determining protection from desiccation. These values were measured from light micrographs of cross-sectioned lungs. The cosmopolitan A. vulgare, as a habitat generalist, seems to be the most resistant against desiccation and other environmental conditions, while A. zenckeri is the most sensitive one. Light microscopic studies revealed that the four species can be ordered similarly, if we compare them by the extension of the endothelial interface and cuticle thickness, suggesting that these morphological traits are important determinants of their distribution on habitat, microhabitat scales and through the existence of suitable habitats – together with many other factors – the geographical pattern of species occurence.

Characterizing prevalence and ecological impact of non-native terrestrial isopods (Isopoda, Oniscidea) in tallgrass prairie

Isopods are terrestrial crustaceans whose role and impact in the tallgrass prairie ecosystem remains little explored despite being rather prevalent non-native inhabitants. To better understand this role, we conducted two related studies. The first was a rapid survey of isopods in experimental treatments at Konza Prairie LTER site to investigate the diversity and relative abundance of isopod species present. Of the four species known in Kansas thus far, all non-native, Armadillidium vulgare (Latreille, 1804) was the most abundantly found, accounting for 93% of individuals found. Armadillidium nasatum Budde-Lund, 1885, Cylisticus convexus (De Geer, 1778) and Porcellionides pruinosus (Brandt, 1833) were also found and we report the first record of Porcellio laevis Latreille, 1804 in the State of Kansas. Survey results showed no evidence for a relationship between isopod abundance and fire frequency or grazing treatment. The second experiment was a food preference study to explore granivory in non-native isopods and characterize their seed predator behavior on native plants. Individual isopods were placed in Petri dishes with food options including leaf litter and seeds from one of 15 species; dishes were then incubated for 6-12 days and preference was assessed based on pre- and post-trial weights of the feed and individual isopod. Isopods showed a significant preference for leaves compared to seeds in nine of the 15 seed species evaluated; no evidence for leaf-vs.-seed preference was apparent in the remaining six seed species. However, in all cases, isopods did consume some amount of seeds even when leaf litter was present. Taken together, the relatively low abundance of non-native terrestrial isopods and their lack of apparent preference for native plant seeds suggest that isopods are unlikely to pose considerable threat to tallgrass prairie ecosystems. More extensive research, including a preference study with greater representation of seed species and a quantitative survey throughout the year, would be needed to further characterize the ecological role of isopods in the tallgrass prairie.

Marsupial extension in terrestrial isopods (Crustacea, Isopoda, Oniscidea)

In Oniscidea, the marsupium is a ventral pouch where the offspring develop independently of an external water source. The marsupium is formed by five pairs of overlapping oostegites that develop in the females during their reproductive period. In this study, ovigerous females of 35 species were dissected, their oostegites were extracted, and the intra-marsupial offspring were counted. Two marsupium forms were recognized: distended, in which the oostegites protrude distally in relation to the sternites; and non-distended, in which the oostegites are parallel to the sixth and seventh sternites. Armadillidium nasatum, A. vulgare, Pudeoniscus birabeni, Circoniscus gaigei and Cubaris murina, conglobating species with a non-distended marsupium, and Neotroponiscus daguerri and N. carolii, non-conglobating species with a distended marsupium, have a concavity on the ventral floor of the 6th and 7th pereionites, here called the marsupial extension. This is the first record of a marsupial extension which extends beyond the area formed by the oostegites in Oniscidea.

Subacute effects of transgenic Cry1AbBacillus thuringiensiscorn litter on the isopodsTrachelipus rathkiiandArmadillidium nasatum

Laboratory studies were conducted to investigate the subacute effects of transgenic Cry1Ab corn leaf material containing Bacillus thuringiensis (Bt) protein on the terrestrial isopods Trachelipus rathkii and Armadillidium nasatum. Survival and growth were measured for eight weeks in isopods fed leaf material of two Bt11 corn varieties, two Monsanto 810 (Mon810) corn varieties, and the isolines of each. Total lipid and protein content of the organisms was measured to examine effects on energetic reserves. Armadillidium nasatum individuals in all treatments responded similarly. For T. rathkii, no statistically significant effect of Bt was observed, but statistical differences were observed in growth between hybrids. Protein and sugar content of the food were found to be correlated with the differences in growth for T. rathkii. Total protein content was higher in T. rathkii and A. nasatum fed material with higher protein and sugar content. A trend toward less growth in T. rathkii on Bt corn varieties versus their isolines triggered a concentration-response assay with purified Cry1Ab protein. No adverse effects of purified Bt protein were observed. These results indicate that little hazard to T. rathkii and A. nasatum from Bt corn leaf material from these hybrids exists. However, nutritional differences in corn hybrids contributed to differences in isopod growth.

Investigations on the potential of woodlice as bioindicators of grassland habitat quality

As intensive land-use practices may reduce available leaf litter, woodlice—important decomposers of leaf litter—may show a loss of biomass and a decrease in number of species. Their diversity as grassland detritivores could thus be a potential guide to ecosystem activity in natural and cultivated grasslands. Woodlice diversity was studied in different grassland types at three sites in Western France: Avon, with semi-natural grasslands; Fors, with mixed farming; Lusignan, with intensive farming. Woodlice were collected by hand in plot centres, borders and field boundaries. Isopod numbers were higher at Fors than at Lusignan; species assemblages were dominated by Philoscia muscorum at Lusignan whereas this species is less numerous at Fors than Armadillidium vulgare and Armadillidium nasatum. These results also differ with grassland type, with higher species diversity or number of individuals in temporary and permanent grasslands at Fors. Hedges were important in increasing isopod diversity within plots. Assemblages reflect grassland quality with high densities and diversity of woodlice in the permanent grasslands at Avon.

EM Study of Isopod Hemocytes

Crustacean hemocytes have been characterized on the basis of cell size and nature of cytoplasmic granules. Based on light microscopic morphological analysis and cytochemistry, investigators variously named the hemocyte types (agranular, small-granule, large granule, undifferentiated, hyaline cells, non-explosive, explosive granulocytes, etc.). In his study of the isopod Armadillidium vulgare Faso adopted the terminology of Benjamin and James and referred to the hemocytes as hyaline cells, semi-granulocytes and granulocytes.In the present investigation we have studied the hemocytes of two isopods, Oniscus asellus and Armadillidium nasatum, using transmission electron microscopy. Hemolymph was collected by penetrating the posterior dorsal exoskeleton of 20 animals of each genus with a microcapillary pipette and drawing 3-5μL per isopod. The samples were processed following a standard technique. Thin sections were collected on 300 mesh copper grids, counterstained with 2% aqueous uranyl acetate and lead citrate, and viewed with a JEOL 1010 electron microscope.

Caenorhabditis Vulgaris Sp.N. (Nematoda: Rhabditidae): a Necromenic Associate of Pill Bugs and Snails

Caenorhabditis vulgaris sp.n. (Nematoda: Rhabditidae), a necromenic associate of pill bugs (Armadillidium vulgare and Armadillidium nasatum) and snails (Oxychilus sp.), is described. C. vulgaris is known from two locations, both in the northeastern United States. It is gonochoristic, with males & females equally abundant. Its associations with pill bugs and snails are as dauer juveniles and appear not to be deleterious to the host animal. These associations are not a requisite part of the C. vulgaris life-cycle; cultures of C. vulgaris can be maintained indefinitely if grown on a bacterial lawn. C. vulgaris can be distinguished from other species of Caenorhabditis based on reproductive, molecular and morphological criteria.

Dispersal of Cellular Slime Molds by Two Soil Invertebrates

Earthworms and pillbugs are known to feed upon substrates likely to be inhabited by cellular slime molds. Gut contents of earthworms (Aporrectodea calignosa and Octolasion tyrtaeum) and pillbugs (Armadillidium nasatum and A. vulgare) collected from northeastern Kansas were found to contain living cellular slime molds. Eleven species of dictyostelid cellular slime molds were isolated from soil samples and gut contents of soil macrofauna. Lumbricus terrestris specimens were force-fed separate spore and myxamoeba suspensions of Dictyostelium mucoroides, and the results suggest that spores can survive passage through the gut better than myxamoebae. Pillbugs were fed spores of D. purpureum and Polysphondylium violaceum, and these dictyostelids were isolated from fecal pellets. Potential benefits of short range dispersal of slime mold propagules by invertebrates are discussed.

The Effects of Crowding on Terrestrial Isopods

Caged populations of two species of oniscoid isopod, Armadillidium nasatum and A. vulgare, were maintained at varying levels of density, food availability, species composition, and population size structure. Growth rate, of mortality, and the size at first reproduction of the young animals were measured in each cage. Increased density reduced the growth rate, survivorship, and the size at first reproduction of both species. Limited food reduced the growth and mortality rates of A. nasatum and the growth rate of A. vulgare. Including both species in the cage increased the growth rate, survivorship, and size at first reproduction of A. nasatum and increased the growth rate of A. vulgare. The presence of large animals increased the growth rate of A. nasatum and reduced it for A. vulgare. These results demonstrate that the density and species composition affect growth, survivorship, and reproduction when food is in excess, probably by interference competition between conspecifics.

Color-morph genetics in the terrestrial isopods Armadillidium nasatum and Porcellionides virgatus

This paper reports the inheritance of color morphs in two terrestrial isopods, Armadillidium nasatum and Porcellionides virgatus. Six and three pure breeding color morphs have been developed in the isopods, A. nasatum and P. virgatus, respectively. In the former species, pigmented morphs involve body and eye colors and the albino morph lacks body pigments but possesses normal eyes. The morphs have been explained by way of three loci each with two alleles. The latter species exists in two body pigment morphs and an albino form essentially lacking all pigments. Two loci are involved. The homologous nature of gene loci in terrestrial isopods is reviewed and areas of evolutionary genetics are identified where these markers may be employed.Key words: isopod color morphs, homologous loci.