Cylisticus Convexus Research Articles

Distribution and Demographics of the Tropical Soil Pill Bug, Cylisticus convexus

Distribution and Demographics of the Tropical Soil Pill Bug, Cylisticus convexus

A first record of seven species of terrestrial isopoda-crustacea in central Iraq

This study is the first kind of it in Iraq. The samples were collected from April to Junuary 2018, we recorded seven species for the first time in Iraq (Procellio laevis, P. cingendus, Lacasius pallidus, Armadillidium album, A. assimile, Orthodillo chiltoni, Cylisticus convexus). These species belong to four famillies (Procellionidae, Armadillidae, Armadillidae, Cylistieidaeà). The samples were saved in the natural histroy museum in Baghdad-Iraq.

Tamarisk Alters Arthropod Composition, but has Little Negative Effect on Richness and Abundance in Southwestern Colorado

Riparian corridors are vulnerable to invasion by non-native plant species that can alter arthropod communities and ecological functions. Tamarisk (Tamarix4 spp. L.) replaced native riparian vegetation on 1.6 million acres in the southwestern United States. Our study investigated arthropod communities in three riparian habitats, two dominated by native vegetation (willow (Salix exigua5 Nutt.) in lower floodplain and mixed-native xeroriparian shrubs in upper floodplain) and one invaded by non-native tamarisk in lower floodplain. Tamarisk was predicted to lessen arthropod abundance and richness, change composition, and associate with nonnative arthropods. We sampled 41,124 arthropods identified to 258 taxa and seven functional groups during 2 years along the Dolores River in Colorado. Richness and abundance were not less in tamarisk, but composition differed among the three habitats. Trends varied across taxonomic and functional groups. Lower floodplain habitats, tamarisk and willow, were relatively similar in composition, with large numbers of beetles, hemipterans, detritivores, and herbivores. More ants, pollinators, and greater diversity were in upper floodplain shrub habitat. Tamarisk hosted several non-native arthropods: Armadillidium vulgare (Latreille)6, Cylisticus convexus (De Geer)7, Diorhabda carinulata (Desbrochers)8, and Coniatus splendidulus (Fabricius)9, while willow housed non-native weevils (Otiorhynchus spp. Germar)9. Tamarisk was favored by some non-native arthropods and altered community composition but did not lessen abundance or richness of functional or taxonomic groups. The results highlighted effects of non-native plants on arthropod communities and have implications for conservation of insectivorous riparian wildlife.

Histological studies on the marsupium of two terrestrial isopods (Crustacea, Isopoda, Oniscidea).

The marsupium, a brood pouch in peracarid crustaceans (Crustacea, Malacostraca) has evolved in terrestrial environment for providing nutrition and optimal conditions for embryogenesis. In the present study we give details on the histology and ultrastructure of its constituting elements such as oostegites and cotyledons. Marsupia of two different eco-morphological types of woodlice, namely the non-conglobating species Trachelipus rathkii Brandt, 1833 and the conglobating species Cylisticus convexus De Geer, 1778 were investigated. Light microscopic (LM) studies showed some differences in the main structure of the two species’ brood pouch: in Trachelipus rathkii, a ‘clinger’ type woodlice, the oostegites bend outwards during brood incubation as growing offspring require more space, while in Cylisticus convexus, a ‘roller’ type isopod, the sternites arch into the body cavity to ensure space for developing offspring and still allowing conglobation of the gravid females. The quantitative analysis of the oostegites’ cuticle proved that the outer part is about 2.5 - 3 times thicker compared to the inner part in both species. Electron microscopic (TEM) examinations show only small histological differences in the oostegites and cotyledon structure of the two species. Cellular elements and moderately electron dense fleecy precipitate are found in the hemolymph space between the two cuticles of oostegites. The cells contain PAS positive polysaccharide areas. TEM studies revealed some differences in the cotyledon ultrastructure of the two species. Cotyledons of Trachelipus rathkii consist of cells with cristate mitochondria and granular endoplasmic reticulum with cisterns. Cotyledons of Cylisticus convexus consist of cells with densely cristate mitochondria and ribosomes attached to vesicular membrane structures. In both species cells with electron dense bodies were observed. We conclude that - besides the differences in marsupial shapes - the fine structure of the oostegites and cotyledons is hardly affected by the eco-morphological type, specifically the conglobating or non-conglobating character of the studied species.

Demography of some non-native isopods (Crustacea, Isopoda, Oniscidea) in a Mid-Atlantic forest, USA.

Introduced species dominate the terrestrial isopod fauna in most inland habitats of North America, including urban landscapes. These non-native species are often very abundant and thus potentially play a significant role in detritus processing. We monitored isopod assemblages in an urban forest for a year to examine the relationship between surface activity and abiotic environmental factors, and to analyze reproductive characteristics that might contribute to their successful establishment. Using pitfall trap samples we recorded five species, two of which, Trachelipus rathkii and Cylisticus convexus, were highly abundant. We determined size, sex and reproductive state of each individual. Surface activity of both species reflected variability in abiotic stress factors for isopods, such as soil moisture and soil temperature. Early spring the main trigger was soil temperature while later in the season increasing temperature and decreasing soil moisture jointly affected population dynamics. Activity significantly correlated with soil moisture. The temporal pattern of sex ratios supported the secondary sex ratio hypothesis. Males dominated the samples on the onset of the mating season in search of females. The pattern was reversed as females searched for suitable microsites for their offspring. Size independent fecundity decreased as conditions became more stressful late in the season.

Multiple Conserved Heteroplasmic Sites in tRNA Genes in the Mitochondrial Genomes of Terrestrial Isopods (Oniscidea)

Mitochondrial genome structure and organization are relatively conserved among metazoans. However, in many isopods, especially the terrestrial isopods (Oniscidea), the mitochondrial genome consists of both ∼14-kb linear monomers and ∼28-kb circular dimers. This unusual organization is associated with an ancient and conserved constitutive heteroplasmic site. This heteroplasmy affects the anticodon of a tRNA gene, allowing this single locus to function as a “dual” tRNA gene for two different amino acids. Here, we further explore the evolution of these unusual mitochondrial genomes by assembling complete mitochondrial sequences for two additional Oniscidean species, Trachelipus rathkei and Cylisticus convexus. Strikingly, we find evidence of two additional heteroplasmic sites that also alter tRNA anticodons, creating additional dual tRNA genes, and that are conserved across both species. These results suggest that the unique linear/circular organization of isopods’ mitochondrial genomes may facilitate the evolution of stable mitochondrial heteroplasmies, and, conversely, once such heteroplasmies have evolved, they constrain the multimeric structure of the mitochondrial genome in these species. Finally, we outline some possible future research directions to identify the factors influencing mitochondrial genome evolution in this group.

Feminization of the Isopod Cylisticus convexus after Transinfection of the wVulC Wolbachia Strain of Armadillidium vulgare.

Reproductive parasites such as Wolbachia are able to manipulate the reproduction of their hosts by inducing parthenogenesis, male-killing, cytoplasmic incompatibility or feminization of genetic males. Despite extensive studies, no underlying molecular mechanism has been described to date. The goal of this study was to establish a system with a single Wolbachia strain that feminizes two different isopod species to enable comparative analyses aimed at elucidating the genetic basis of feminization. It was previously suggested that Wolbachia wVulC, which naturally induces feminization in Armadillidium vulgare, induces the development of female secondary sexual characters in transinfected Cylisticus convexus adult males. However, this does not demonstrate that wVulC induces feminization in C. convexus since feminization is the conversion of genetic males into functional females that occurs during development. Nevertheless, it suggests that C. convexus may represent a feminization model suitable for further development. Knowledge about C. convexus sexual differentiation is also essential for comparative analyses, as feminization is thought to take place just before or during sexual differentiation. Consequently, we first described gonad morphological differentiation of C. convexus and compared it with that of A. vulgare. Then, wVulC was injected into male and female C. convexus adult individuals. The feminizing effect was demonstrated by the combined appearance of female secondary sexual characters in transinfected adult males, as well as the presence of intersexes and female biases in progenies in which wVulC was vertically transmitted from transinfected mothers. The establishment of a new model of feminization of a Wolbachia strain in a heterologous host constitutes a useful tool towards the understanding of the molecular mechanism of feminization.

Winter activity of terrestrial isopods from thermal habitats in western Romania

Terrestrial isopods from warm shores neighboring the thermal waters from western Romania remain active in the winter. This phenomenon is registered in 35 habitats, affecting 12 species (Hyloniscus transsilvanicus, H. riparius, Hap- lophthalmus danicus, Trichoniscus sp., Androniscus roseus, Cylisticus convexus, Protracheoniscus politus, Trachelipus nodulo- sus, T. rathkii, Porcellio dilatatus, Armadillidium vulgare, A. versicolor), the most common being T. nodulosus. Females with a marsupium were observed in the cold season in the case of some small-sized species that are present in the immediate vicinity of the shores of thermal waters (A. roseus, H. riparius and H. transsilvanicus). The high temperatures of the thermal waters warm the surrounding terrestrial environment, affecting the life cycle of the terrestrial isopods.

Terrestrial isopods (Crustacea, Oniscidea) at the Baltic Sea coast in Lithuania

A survey between 2004 and 2010 yielded 2434 individuals of seven terrestrial isopod species – Cylisticus convexus, Oniscus asellus, Trachelipus rathkii, Porcellio scaber, Porcellio spinicornis, Porcellium conspersum, along Ligidium hypnorum – along the Curonian Spit and in various woodlands in Lithuania. The data on the Lithuanian fauna of all terrestrial isopods are presented for the first time. Isopod richness was the highest in woody habitats (dune pine forests and old mixed forests) where common European and Holarctic species (O. asellus, P. scaber, and T. rathkii) formed the majority of isopod assemblages. Additionally, more specialized isopods (L. hypnorum, P. conspersum) were also found in mixed and deciduous forests. Porcellio scaber and T. rathkii, the species tolerating human and natural disturbances, were the only isopods found in sand dunes at the coast. The article includes a detailed list of Isopoda occurrences and the numbers of individuals captured. 2004–2010 metais Kursių nerijoje ir įvai...

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.

A new species and new records of terrestrial isopods from Sicily (Isopoda: Oniscidea)

In this paper three species of terrestrial isopods from Sicily are discussed. Spelaeoniscus coiffaiti and Cylisticus convexus are new to the Sicilian fauna. Sicilian specimens of Spelaeoniscus coiffaiti are examined and illustrated, and the biogeographical significance of this species in Sicily is discussed. Trichoniscus panormidensis is described as a new species, and the affinities are treated.

Changes of isopod assemblages along an urban–suburban–rural gradient in Hungary

Responses of isopod assemblages to urbanisation were studied along an urban–suburban–rural gradient representing a decrease in the intensity of human disturbance. Pitfall trapping collected six species ( Armadillidium vulgare, Porcellio scaber, Porcellium collicola, Trachelipus ratzeburgii, Cylisticus convexus, and Trachelipus rathkii). A. vulgare occurred abundantly in all sites reflecting the broad tolerance and invasive nature of this species. Indicator species analysis demonstrated that P. scaber and T. rathkii were significant quantitative character species for the urban site, while T. ratzeburgii was characteristic for the natural habitats (suburban and rural sites). CANOCO revealed that ground and air temperature show positive correlation with the distribution of P. scaber and T. rathkii, and negative correlation with T. ratzeburgii. Nested ANOVA on trap level showed that there were no significant differences between the number of isopod species and individuals, and the diversity of isopod assemblages in the three studied areas. Significant differences were observed at site level. The results did not support the hypothesis that diversity should decrease in response to habitat disturbance. They also contradicted the intermediate disturbance hypothesis; species richness was not the highest in the moderately disturbed suburban area. Multivariate methods detected that the isopod assemblages of the rural and suburban areas were relatively similar, while that of the urban area was relatively separated.

Wolbachia endosymbiont responsible for cytoplasmic incompatibility in a terrestrial crustacean: effects in natural and foreign hosts

Wolbachia bacteria are vertically transmitted endosymbionts that disturb the reproduction of many arthropods thereby enhancing their spread in host populations. Wolbachia are often responsible for changes of sex ratios in terrestrial isopods, a result of the feminization of genotypic males. Here we found that the Wolbachia hosted by Cylisticus convexus (wCc) caused unidirectional cytoplasmic incompatibility (CI), an effect commonly found in insects. To understand the diversity of Wolbachia-induced effects in isopods, wCc were experimentally transferred in a novel isopod host, Armadillidium vulgare. wCc conserved the ability to induce CI. However, Wolbachia were not transmitted to the eggs, so the capacity to restore the compatibility in crosses involving two transinfected individuals was lost. The feminizing Wolbachia hosted by A. vulgare was unable to rescue CI induced by wCc. These results showed that Wolbachia in isopods did not evolved broadly to induce feminization, and that CI and the feminizing effect are probably due to different mechanisms. In addition, wCc reduces the mating capacity of infected C. convexus males, suggesting that the bacteria might alter reproductive behaviour. The maintenance of wCc in host populations is discussed.

Brackenridgia sphinxensis N. Sp. from a Cave with Notes on Other Species from Arizona and California (Isopoda, Oniscoidea)

A new species of oniscoid from Sphinx Cave, Cochise County, and eight other species of oniscoids are recorded from Arizona. Other species are recorded from California. The cave species is in the genus Brackenridgia Ulrich and the validity of that generic name is discussed. The new species is blind, pigmentless and a true troglobitic oniscoid. Venezillo arizonicus (Mulaik and Mulaik) is redescribed and reillustrated. The other species recorded are Haplophthalmus danicus Budde-Lund, Agabiformius lentus (Budde-Lund), Porcellionides pruinosus (Brandt), Porcellio laevis Latreille, Porcellio dilatatus Brandt and Ratzeburg, Cylisticus convexus (DeGeer) and Armadillidium vulgare (Latreille). Three of the species, H. danicus, P. laevis and P. dilatatus are also recorded from California, the first two being recorded from there for the first time. The nine species from Arizona included all oniscoids recorded from the state and a key and diagnostic characters are presented to identify them. One new cave inhabiting (troglobitic) and eight normal terrestrial isopods or oniscoids are described from Arizona. The nine species represent all of the oniscoids from Arizona (Table 1). Three of the species are also recorded from California, two for the first time from that state. The new species is from Sphinx Cave, Cochise County, and the eight others are from one to several locations throughout the state. The eight are, except for Venezillo arizonicus, common expansive species and are present in suitable habitats in much of temperate North America. Some of the species, especially Agabiformius lentus, have been collected in subtropical locations as well. Venezillo arizonicus is endemic to the southwestern part of the United States and northern Mexico. The records of Haplophthalmus danicus and Agabiformius lentus are the first from Arizona and H. danicus also is recorded from California for the

Protein and cation content of the hemolymph of some oniscoidea

1. 1. Analysis were carried out to determine Ca, Mg, K, Na and protein content, as well as pH, of the hemolymph of three species of Oniscoidea ( Oniscus asellus, Porcellio scaber and Cylisticus convexus). 2. 2. Statistically significant differences were found, concerning the protein and cation concentrations, among the species studied. 3. 3. There is a correlation between Ca 2+ and Mg 2+ level in the hemolymph examined.

Water Content and Water Activity in the Cuticle of Terrestrial Isopods

ABSTRACT The water content of the cuticle of both desiccated and non-desiccated terrestrial isopods Porcellio scaber and Armadillidium vulgare was measured. The animals were desiccated for various times (up to 3 h) over silica gel and the mean water content of the cuticle was 54·0 ± 0·78% for P. scaber and 52·7 ± 1·11% for A. vulgare. There was no trend as regards the desiccation time, nor did the body weight affect the water content. The water content of the cuticle remained virtually unchanged as long as the animal was alive in the desiccator. It dropped significantly after the animal had died after having lost some 30 % of its body weight. The cuticular water content of non-desiccated P. scaber tended to be slightly higher than that of desiccated ones. In A. vulgare no significant difference was observed between non-desiccated and desiccated specimens. The water activity of the excised cuticle of the above two species and of Oniscus asellus and Cylisticus convexus was above that of the haemolymph and therefore not in osmotic equilibrium with it. The osmotic equilibrium points were below the osmotic pressures of the blood; the difference amounted from 1·5 to 2·8 atm. in different species. The difference in water activity between blood and cuticle, the maintenance of water content with desiccation, and the drop in water level at death, all indicate the presence of an active mechanism regulating the cuticular water in terrestrial isopods.

Effect of Temperature and Radiation Stresses on the Survivorship of Isopods: Armadillidium vulgare and Cylisticus convexus

Gamma radiation affects many metabolic processes whose rates are temperature-dependent in poikilothermic organisms. Laboratory experiments were designed to test the effects of temperature,60 Co radiation, and their interactions on the survivorship of isopods-Armadillidium vulgare and Cylisticus convexus. A central composite rotatable design with dose and temperature as independent variables was used to construct three-dimensional response surfaces described by quadratic polynomial equations. Temperature treatments ranged between 12.9 and 27.1°C; radiation doses were between 8.3 and 19.7 kilorads. The response surfaces (survivorship) varied through time (from 0 to 60 days) both within and between species. Both temperature and dose became significant (P ${\rm LD}_{50\text{-}30}\text{'}{\rm s}$</tex-m...

Radioisotope Turnover and Energy Flow in Terrestial Isopod Populations

Radiocesium turnover rates in terrestrial isopod populations were used to measure food consumption and metabolism under natural and laboratory—simulated field conditions. Four old—field and forest species were studied: Armadillidium vulgare (Latreille), Armadillidium nasatum Budde—Lund, Cylisticus convexus (DeGeer), and Metoponorthus pruinosus (Brandt). Uptake, body burden equilibria, and elimination rates for 134Cs were related to environmental temperatures (Q10°2). dietary supplements of stable Na, K, and Cs salts produced no effect upon 134Cs elimination rates. Assimilation fractions from food were 60 to 64% for digestible dry matter, 70 to 73% for caloric intake, and 70 to 87% for radiocesium. Body equilibrium concentrations and biological half—lives of radiocesium in each species permitted estimates of food consumption comparable to gravimetric determinations. Food intake varied between different species and ranged from 1.5 to 3.5% of dry body weight per day. Bomb calorimetry and respirometry measurements were used to partition the total energy budgets, caloric inputs required for maintenance, production, and growth were determined. Radiocesium elimination rates were correlated with the metabolic rates of individual species, and radionuclide turnover rates in tagged individuals were demonstrated to be a practicable means of determining the activity and metabolism of species in the natural habitats.

ON THE MECHANISM OF TONIC IMMOBILITY IN VERTEBRATES

1. The durations of successive periods of induced tonic immobility in the lizard Anolis carolinensis was examined as a function of temperature. An automatic recording method was employed and observations were made of 12,000 to 15,000 immobilizations with six animals over a temperature range of 5 degrees to 35 degrees C. during 5 months. 2. The durations of the immobile periods were found to vary rhythmically in most cases. The reciprocal of the duration of the rhythm, i.e., the rate of change of the process underlying the rhythms, when plotted as a function of temperature according to the Arrhenius equation show distributions of points in two straight line groups. One of these groups or bands of points extends throughout the entire temperature range with a temperature characteristic of approximately micro = 31,000 calories, and the other covers the range of 20 degrees to 35 degrees C. with micro equal to approximately 9,000 calories. 3. The initial stimulus in a series of inductions of immobility appears to set off a mechanism which determines the duration of the state of quiescence. Succeeding forced recoveries seem to have no effect on the normal duration of the rhythm. 4. These results are interpreted by assuming the release, through reflex stimulation, of hormonal substances, one effective between 5 degrees and 35 degrees C. and the other effective between 20 degrees and 35 degrees C. These substances are assumed to act as selective inhibitors of impulses from so called "higher centers," allowing impulses from tonic centers to pass to the muscles. 5. In some experiments a progressive lengthening in successively induced periods of immobility was observed. The logarithm of the frequency of recovery when plotted against time in most of these cases (i.e., except for a few in which irregularities occurred) gave a linear function of negative slope which was substantially unaffected by temperature. In these cases it is assumed that a diffusion process is controlling the amount of available A substance. 6. The results are similar to those obtained by Crozier with Cylisticus convexus. The duration of tonic immobility seems to be maintained in both arthropod and vertebrate by the chemical activity of "hormonal" selective inhibitors. The details of the mechanisms differ, but there is basic similarity. 7. Injections of small amounts of adrenalin above a threshold value are found to prolong the durations of tonic immobility of Anolis, by an amount which is a logarithmic function of the "dose." It is possible that internally secreted adrenalin, above a threshold amount, may be involved in the maintenance of tonic immobility. 8. The production of tonic immobility reflexly is a problem distinct from that of the duration of immobility. It is suggested that the onset may be induced by "shock" to the centers of reflex tonus causing promiscuous discharge of these centers with accompanying inhibition of the higher centers. Such a condition may result when an animal is suddenly lifted from the substratum and overturned, or when, as in the case of Anolis, it struggles with dorsum down. This reaction of the "tonic centers" may at the same time lead to discharge of the adrenal glands by way of their spinal connections thus prolonging the state.

A NOTE ON THE RELATIVE PHOTOSENSORY EFFECT OF POLARIZED LIGHT

Experiments were made to compare the stimulating effectiveness of vertically and horizontally polarized lights and non-polarized lights of equal intensity upon phototropic movements of the beetle Tetraopes tetraopthalmus; and to compare the effectiveness of two light beams polarized at right angles to one another upon phototropic orientation of the land isopod Cylisticus convexus. Tetraopes is positively, and Cylisticus, negatively phototropic. Tests were also made of the intensities of horizontally and of vertically polarized light required to inhibit stereotropism in larvae of Tenebrio. Under the conditions of the tests, no certain qualitative effect connected with polarization could be detected.