Dietary effects on growth, reproduction, body composition and stress resistance in the terrestrial isopods Oniscus asellus and Porcellio scaber

The effect of differences in food composition on growth, body composition and cold tolerance of the isopods Porcellio scaber (Latreille) and Oniscus asellus (L.) has been studied. The effect on reproduction of P. scaber was included. Total lipid and protein content remained the same in O. asellus, given food with a nitrogen content of 2.4, 2.5, 2.8 or 3.1% for 8 weeks. Those fed on 3.1% N gained significantly more weight than those fed on 2.4, 2.5 or 2.8% N. Cold tolerance after a period of low temperature acclimation could not be tested, due to high mortality at the subzero treatment. Haemolymph osmolality increased after the winter acclimation for all food treatments. Juvenile P. scaber, given food of 1.8, 2.5 or 3.1% N, showed no difference in growth over 18 weeks, nor in body composition over 14 weeks. Diet did not influence cold tolerance ability and haemolymph osmolality remained the same with changing cold tolerance of the animals. Gravid females of P. scaber were separated to examine the effect of diet on reproduction. Diet did not influence the number of juveniles, nor their weight. In all food treatments, a significant correlation was found between the weight of the female and the number and weight of her offspring.     

Body shape in terrestrial isopods: A morphological mechanism to resist desiccation?

Woodlice are fully terrestrial crustaceans and are known to be sensitive to water loss. Their half‐ellipsoidal shapes represent simple models in which to investigate theoretical assumptions about organism morphology and rates of exchange with the environment. We examine the influence of surface area and mass on the desiccation rates in three eco‐morphologically different species of woodlice: Oniscus asellus, Porcellio scaber, and Armadillidium vulgare. Our analysis indicates that the rate of water loss of an individual depends on both the initial weight and the body surface area. Interspecific and intraspecific analyses show that the mass‐specific water loss rate of a species decreases along with the ratio of surface area to volume. In particular, we show that body shape explains the difference in mass‐specific water loss rates between A. vulgare and P. scaber. This observation also explains several known ecological patterns, for example, the distribution and survivorship of individuals. However, in addition to body size and shape, water loss in terrestrial isopods depends also on the coefficient of permeability (i.e., a measure of water loss rate per surface unit), which is high in O. asellus and lower (and at similar levels) in P. scaber and A. vulgare. We discuss morphological, physiological, and behavioral aspects of water loss avoidance in terrestrial isopods. J. Morphol. 276:1283–1289, 2015. © 2015 Wiley Periodicals, Inc.     

The effect of liming a neutral soil on the cycle of manganese

Summary A manganese-deficient soil was mixed at pH 7 and pH 8, both moist and dry with (a) -MnO₂ and (b) MnSO₄. The amounts of bivalent manganese were determined after incubating for varying times. With the moist soils more bivalent manganese was released at pH 8 than at pH 7. However, after long air-drying much more bivalent manganese was released than from the moist soils and more was released at pH 7 than at pH 8.     

Comparison of physicochemical properties of chitins isolated from an insect (Melolontha melolontha) and a crustacean species (Oniscus asellus)

The chitin structures of two common European species belonging to Insecta (Melolontha melolontha) and Crustacea (Oniscus asellus) were isolated. The same procedure is followed for chitin isolations for both the species. First, HCl was used for removing of minerals in the organisms, and then, the protein structure was removed by using NaOH. Chitins obtained from these two species were characterized physicochemically. Physicochemical properties of chitins isolated from the insect and the crustacean were compared to each other. The chitin content for dry weights of M. melolontha and O. asellus were recorded as 13–14 and 6–7 %, respectively. The results of Fourier transform infrared spectroscopy, thermogravimetric analysis and X-ray diffraction analysis were found to be more or less similar. The surface morphologies of chitins were examined via environmental scanning electron microscopy and nanofibers, and pore structures were observed. While the chitin nanofibers of O. asellus were adherent to each other, nanofibers of M. melolontha were non-adherent. On the other hand, the number of pores was much higher in the chitin from M. melolontha than in the chitin from O. asellus. Looking at the elemental analysis results, the M. melolontha chitin was found to be more pure than the O. asellus chitin. For this reason, M. melolontha has been considered more attractive source for chitin than O. asellus.     

Activities of carboxylating enzymes in the CAM species Opuntia ficus-indica grown under current and elevated CO2 concentrations

Responses of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPCase) to an elevated atmospheric CO₂ concentration were determined along with net CO₂ uptake rates for the Crassulacean acid metabolism species Opuntia ficus-indica growing in open-top chambers. During the spring 13 months after planting, total daily net CO₂ uptake of basal and first-order daughter cladodes was 28% higher at 720 than at 360 l CO₂ l^-1. The enhancement, caused mainly by higher CO₂ assimilation during the early part of the night, was also observed during late summer (5 months after planting) and the following winter. The activities of Rubisco and PEPCase measured in vitro were both lower at the elevated CO₂ concentration, particularly under the more favorable growth conditions in the spring and late summer. Enzyme activity in second-order daughter cladodes increased with cladode age, becoming maximal at 6 to 10 days. The effect ofelevated CO₂ on Rubisco and PEPCase activity declined with decreasing irradiance, especially for Rubisco. Throughout the 13-month observation period, O. ficus-indica thus showed increased CO₂ uptake when the atmospheric CO₂ concentration was doubled despite lower activities of both carboxylating enzymes.     

Hemocyanin in Oniscus asellus (Isopoda)

• 1.1. An immunological crossreactivity, as demonstrated by Western blotting, exists between O. asellus hemocyanin and anti-keyhole limpet (Megathura crenulata) hemocyanin.
• 2.2. Using the anti-keyhole limpet hemocyanin, the presence of hemocyanin was detected in the hepatopancreas.
• 3.3. The amino acid composition of the hemocyanin of O. asellus was found to be similar to that of other isopods.

     

Selection favours low hsp70 levels in chronically metal‐stressed soil arthropods

Thirty‐eight populations of woodlice (Oniscus asellus, Porcellio scaber) and millipedes (Julus scandinavius) from 28 differently metal‐polluted field sites were analysed for their 70‐kDa stress protein (hsp70) level. Although ANOVA revealed significant dependence of the hsp70 level on the concentrations of water‐soluble lead, cadmium and zinc and the soil pH, each of these parameters accounted for at most 18% of the intersite variability of the stress protein level only. A multivariate model based on multiple regression analysis explained more than 96% of hsp70 variance and revealed both the pollution history of a site (strong metal contamination for more than 70 years) and invertebrate species identity to act as the most important parameters. The model accounted for the observation that most of the populations from long‐term polluted sites exhibited comparatively low stress protein levels in response to their own (contaminated) habitats. In contrast, isopods (O. asellus) from a control site were not able to maintain a low hsp70 level when they were exposed to either an artificial metal cocktail or soil taken from one of the contaminated field sites. They did not acclimatize to the exposure conditions within 3 months. We propose that selection of insensitive phenotypes in long‐term polluted soils has taken place so as to minimize the stress protein level which, in turn, is indicative of high intracellular protein integrity. Long‐term selection for a high hsp70 level to compensate for adverse metal impact was not observed, which suggests that such a strategy may trade off against other fitness consequences. In this context, insensitivity to metal stress involved increased selectivity in food choice and reduced variability in stress response. Multiple regression models showed species‐specificity in those abiotic factors which determined (1) high hsp70 levels in sensitive populations as well as (2) low hsp70 levels in insensitive ones. Therefore, abiotic factors can be assigned to act as the main components of selection: lead and cadmium for J. scandinavius and O. asellus, zinc for P. scaber.     

The distribution of zinc,cadmium, lead and copper within the woodlouse Oniscus asellus (Crustacea,Isopoda)

Summary The concentrations of zinc, cadmium, lead and copper have been determined in the hepatopancreas, hindgut and rest of the body tissues of Oniscus asellus collected from eight sites in the U.K. The hepatopancreas is by far the most important storage organ of heavy metals, particularly cadmium, and at each site, contains a mean of at least 89% of the total body load of this element. Specimens of Oniscus asellus from contaminated sites may contain concentrations of zinc, cadmium, lead and copper in the hepatopancreas of about 1%, 0.5%, 2.5% and 3% of the dry weight respectively, which are among the highest so far recorded in the soft tissues of any animal.There is a significant positive correlation between the mean relative dry weight of the hepatopancreas of Oniscus asellus and the concentrations of zinc or cadmium in leaf litter from all eight sites. It is suggested that animals from sites which are contaminated heavily with zinc or cadmium have a large hepatopancreas because this enables them to de-toxify a greater amount of the metal.     

Endogenous ammonia production by Anacystis nidulans R-2 induced by methionine sulfoximine

Anacystis nidulans R-2 produced ammonia from endogenous sources for at least 6 h when illuminated without external nitrogen source but with CO₂ in the presence of 50 M methionine sulfoximine. The onset of ammonia release coinciding with complete inhibition of glutamine synthetase. The total quantity of ammonia which could be released exceeded the nitrogen content of small molecule pools, and suggested protein degradation as the most likely source of the nitrogen. Ammonia release was not accompanied by leakage of carbon compounds from the cells. Methionine sulfoximine-induced ammonia release was energy requiring, and was barely detectable under dark anaerobic conditions, or in the presence of 10 M carbonyl cyanide m-chlorophenylhydrazone in light. Phenyl methyl sulfonylfluoride, an inhibitor of serine proteases, eliminated ammonia release, and the rate of release was reduced to one-third of control values, after a lag, in the presence of 50–75 g/ml chloramphenicol. The rate of NH ₊ ⁴ release was maximal (1.4 nmol·min^-1·mg^-1 protein) if suspensions were bubbled with 100% O₂, but could not be reduced below 0.6 nmol·min^-1·mg^-1 protein in air: CO₂, suggesting that release was at most only partly due to photorespiration.Abbreviations used MSX L-methionine D,L-sulfoximine - PMSF phenylmethylsulfonylfluoride - CAP chloramphenicol - CCCP carbonyl cyanide-m-chlorophenyl hydrazone     

Field Release and Establishment of the Decapitating Fly Pseudacteon curvatus on Red Imported Fire Ants in Florida

Decapitating phorid flies in the genus Pseudacteon are being studied as classical biological control agents of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae). Pseudacteon curvatus Borgmeier (Diptera: Phoridae) is a small decapitating fly that attacks small fire ant workers. We released a biotype of P. curvatus from Formosa, Argentina, at three sites near Gainesville, FL. Field releases were conducted in the spring and summer of 2003 and monitored monthly. Flies were discovered within 5 weeks at the spring site and then monthly thereafter. By late spring 2004, flies released at this site had expanded 1.6 km both north and south and about 0.8 km westward. Initially, we found no flies from the two summer 2003 releases but we were successful at finding them 8 months after release during spring 2004. This paper documents the first successful release(s) of P. curvatus on red imported fire ants in the United States.     

Seasonal changes in the efflux of sugars from parenchyma cells into the apoplast in poplar stems (Populus × canademis “robusta”)

Summary The efflux of sugars from parenchyma cells into the apoplast has been studied in the wood of Populus × canadensis robusta in relation to the sugar level of the tissue and the sugar content of the tracheal sap during all physiological stages of the year. In poplar, the spring maximum in sugar content of the tracheal sap is clearly not the result of continuous exosmosis during winter but is reached within a short period in spring. The seasonal patterns of starch and sugar content of the wood and of the sugar content of the tracheal sap are described. The efflux of sugars from tissue sections changes drastically over the year, i.e., from 0.3 to 8.3 g mg^–1DWT day^–1. In general, it is high in fall and winter, and low during late spring and summer. However, high tissue sugar levels proved not always to be correlated with high efflux rates or with high sugar levels in the tracheal sap, indicating that the intracellular compartmentalization of sugars, their passive and catalysed release into, and their re-uptake from the apoplast are all essentially involved in determining the actual sugar content of the sap. Sucrose, which is the dominant sugar in the tracheal sap during winter (pH 7.0–7.5) and in the efflux experiments at pH 7.5, in contrast to the hexoses which prevail in the spring sap (pH around 5.5) and also in the efflux experiments at pH 5.6, is considered to be preferentially released in poplar and to become extraplasmatically hydrolysed. The reasons for tree-specific differences are discussed.     

Physiological properties of the gut lumen of terrestrial isopods (Isopoda: Oniscidea): adaptive to digesting lignocellulose?

Since any given trait of an organism is considered to represent either an adaptation to the environment or a phylogenetic constraint, most physiological gut characteristics should be adaptive in terms of optimizing digestion and utilization of the respective food source. Among the Crustacea, the taxon Oniscidea (Isopoda) is the only suborder that includes, and essentially consists of, species inhabiting terrestrial environments, feeding on food sources different from those of most other Crustacea (i.e., terrestrial leaf litter). Microelectrodes were used to assay physiological characteristics of the gut lumen from representatives of four families of terrestrial isopods: Trichoniscus pusillus (Trichoniscidae), Oniscus asellus (Oniscidae), Porcellio scaber (Porcellionidae), and Trachelipus rathkii (Trachelipodidae). Microsensor measurements of oxygen pressure (Clark-type oxygen microelectrodes) revealed that O₂-consuming processes inside the gut lumen created steep radial oxygen gradients. Although all guts were oxic in the periphery, the radial center of the posterior hindgut was micro-oxic or even anoxic in the adults of the larger species. The entire gut lumen of all examined species was strongly oxidizing (Pt microelectrodes; apparent redox potential, E_h: +600–700 mV). Such conditions would allow for the coexistence of aerobic and anaerobic microorganisms, with both oxidative and fermentative activities contributing to digestion. Although bacterial O₂ consumption was also observed in the midgut glands (hepatopancreas), they remained entirely oxic, probably owing to their large surface-to-volume ratio and high oxygen fluxes across the hepatopancreatic epithelium into the gland lumen. Measurements with pH microelectrodes (LIX-type) showed a slight pH gradient from acidic conditions in the anterior hindgut to neutral conditions in the posterior hindgut of O. asellus, P. scaber and T. rathkii. By contrast, the pH in the hindgut lumen of T. pusillus was almost constant. We discuss to what extent these physiological characteristics may be adaptive to the digestion of terrestrial food sources that are rich in lignocellulose.     

Biological control of the black vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae) with entomopathogenic nematodes (Nematoda: Rhabditida)

Trials conducted under glasshouse conditions showed that control of Otiorhynchus sulcatus larvae in strawberry plants can be effective using Steinernema carpocapsae and Heterorhabditis megidis, given that temperature and moisture extremes are avoided. In field experiments, the double line T-Tape® drip irrigation system performed better than the single line T-Tape® system, effectively distributing the nematodes along and across strawberry raised beds, and placing them close to the root zone where O. sulcatus larvae feed. As soil temperatures are satisfactory for nematode infectivity from late spring to early autumn, nematode applications were aimed at late instar larvae during spring, and early instar larvae during summer. Late summer field treatment with S. carpocapsae induced 49.5% reduction of the early instar larvae, and field application of the same nematode species in late spring resulted in 65% control of late instar larvae. In the same trial, spring application of H. megidis caused 26% mortality of late instar larvae of O. sulcatus.     

Studies of the protein content of individualPergamasus longicornis (Berlese) (Acari: Mesostigmata: Parasitidae)

The protein content ofPergamasus longicornis (Berlese) individuals is of the order of 45 g bovine serum albumen equivalents and varies depending on gender, time of year and gut colour (postulated nutritive state). Variation between males and females closely matches their size difference. A sinusoidal relationship with a late spring/early summer maximum and a late autumn/early winter minimum is shown for females. Gut colour is a useful predictor in females only. Pregnancy and prey utilisation over the year are suggested as important determinants of protein content and are discussed in detail.     

Spatial and temporal variations in phytoplankton biomass and primary productivity in the Southwest Atlantic and the Scotia Sea

Summary Two cruises of the ARA/Islas Orcadas (late winter/early spring 1978 and late summer/early fall 1979) provided data which show that temporal variability of phytoplankton biomass and productivity in the oceanic wates of the Southwest Atlantic and Scotia Sea is insignificant when compared to the influence of geographical variability. Two bloom stations sampled during the late winter/early spring cruise had chlorophyll a concentrations and productivity values an order of magnitude higher than waters sampled from the same locations the following late summer/early fall. However, a comparison of 10 paired stations from the two cruises indicated no seasonal trend, as measured values of chlorophyll a and productivity from the first cruise were randomly larger or smaller than values measured during the second cruise. Consideration of individual stations from both seasons suggests the need to re-examine widely held notions regarding the effect of the Polar Front Zone and the island-mass effect on phytoplankton abundance and productivity. Higher-than-expected standing stock and productivity values at some open-ocean stations and at some stations within the Polar Front Zone indicate that looking for specific factors which promote localized enhancement or impoverishment of phytoplankton would be more useful than continuing with attempts to generalize Antarctic productivity data into broad seasonal or geographical patterns.In memory of Mary Alice McWhinnie (1922–1980)     

Control efficiency of leaf beetle,Ophraella communa,on the invasive common ragweed,Ambrosia artemisiifolia,at different growing stages

Ophraella communa LeSage (Coleoptera: Chrysomelidae), an effective biological control agent of A. artemisiifolia, was unintentionally introduced into China. To understand the biological control potential of O. communa on A. artemisiifolia, plant height, the number of branches and leaf control index of A. artemisiifolia injured by the beetle were determined. The results showed that plant height and number of branches decreased and leaf control index increased with the increasing initial release density of O. communa adults, when they were released at 90–100-cm plant height stage in 2008 and 60–70-cm stage in 2009. Even when O. communa was released at a low average density of 1.07 adults per plant at early growth stage of A. artemisiifolia in 2009, it could significantly suppress plant height and number of branches and led to a higher leaf control index compared with the herbicide treatment with Roundup. Prior to the fructicative period, the leaf control index of A. artemisiifolia by O. communa was up to 1.0 on the 47th day after the average initial release of 12 beetles per plant in 2008 or on the 85th day after the average release of 1.07 beetles per plant in 2009, which was significantly higher than that in the herbicide treatment. We suggest that the initial release average density of O. communa adults should be ≥1.07 beetles per plant at the early growth stage, or ≥12 beetles per plant at the late growth stage for an effective control of A. artemisiifolia in the field.     

Distribution, mechanisms and evolutionary significance of clonality and polyploidy in weevils

Abstract 1 Genetical mtDNA relationships of 41 taxa of weevils were examined using cladistics. Ingroup taxa belong to Otiorhynchus scaber and O. nodosus and outgroup comparison was made with O. singularis. All three species are minor forest pests. 2 Otiorhynchus scaber specimens are either diploid sexuals or diploid, triploid and tetraploid clones, from two different populations (Slovenia and Austria) that belong to two different evolutionary lineages. Otiorhynchus nodosus specimens are tetraploid clones. Both species show geographical parthenogenesis, as do many other Otiorhynchus species. 3 Mitochondrial data indicate that O. nodosus clones are more closely related to Slovenian sexuals of O. scaber than these are to sexuals from Austria. It also shows that almost all clones of O. scaber collected in one of the two regions where sexuals are found are more closely related to sexuals from the other region. 4 Three different hypotheses that may explain the distribution of O. scaber, mechanisms important for the evolution of the clones and implications of the presence of Wolbachia are discussed. 5 We conclude that parthenogenesis is likely to be linked to hybridization in O. scaber and that hybridization events between ancestors of O. nodosus and O. scaber are the probable cause of the presence of O. nodosus in the ingroup. We also find that polyploid clones are superior colonizers compared to sexuals and diploid clones, in O. scaber. 6 The results suggest that systems where both sexuals and clones exist are more complex than previously suggested. The mapping of genetic variation in clonal complexes and the tracing of clonal origins may be useful in pest management.     

Predation of diaspidid scale insects on kiwifruit vines by European earwigs, <Emphasis Type="Italic">Forficula auricularia</Emphasis>, and steel-blue ladybirds, <Emphasis Type="Italic">Halmus chalybeus</Emphasis>

Significant predation of diaspidid scale insects occurs in unsprayed kiwifruit crops. Two predators, Forficula auricularia L. (Dermaptera: Forficulidae) and Halmus chalybeus (Boisduval) (Coleoptera: Coccinellidae) are likely to be important. Most F. auricularia were found as late instars or adults in the canopy of kiwifruit vines in late spring and early summer. Adults of H. chalybeus were present throughout the year but at lower densities on kiwifruit vines than on other host plants. In the field predation of scale insects occurred mainly at night and preferentially on late-instar scale insects consistent with the feeding behaviour of F. auricularia, not H.chalybeus. The latter mainly fed on early instar insects during the day. Numbers of scale insect crawlers were not correlated with numbers of F. auricularia or of H. chalybeus in kiwifruit vine canopies.     

Heavy metals in the terrestrial isopod Porcellio scaber Latreille. II. Subcellular fractionation of metal-accumulating lysosomes from hepatopancreas

Two populations of metal contaminated Porcellio scaber Latreille were studied: one consisting of animals that had been fed heavy metals in the laboratory for several months, and one from a metal-polluted site in the field (Braubach, FRG). Density gradient centrifugation was performed on hepatopancreas homogenates in order to identify cellular fractions and their association with lead, copper and cadmium. Marker enzymes were used for localisation of cellular fractions in the density gradient. Two lysosomal fractions, called the light and heavy fraction, were separated. They contained mainly lead, but also copper and some cadmium.Abbreviations AP acid phosphatase - ER endoplasmic reticulum - LDH lactic dehydrogenase - MDH malic dehydrogenase - NADH nicotinamide adenine dinucleotide - P. scaber Porcellio scaber     

Life history, aspects of reproductive biology and production of Corophium orientale (Crustacea: Amphipoda) in Monolimni lagoon (Evros Delta, North Aegean Sea)

Monthly samples of Corophium orientale were collected during February 1998–February 1999 in both parts of Monolimni lagoon (0.3 < Sal. < 6 psu, 2 < Temp. < 28.5 °C). Corophium orientaleshowed a semiannual life cycle. In the southern part, breeding occurred from early spring to mid autumn having three peaks, in early spring, early summer and early autumn, and three cohorts were produced, a spring cohort, a summer cohort and an overwintering one. In the shallower innermost northern part of Monolimni lagoon, breeding peaked in mid-spring and, also, in early autumn, and two discrete cohorts, a spring and an overwintering one, were produced. A lack of large individuals, attributed to a temporary size – selective predation by migrating shorebirds, was observed during summer. That lack possibly contributed to the hiatus in reproduction. Photoperiod seemed to be a more important cue than temperature in the initiation of the reproductive cycle, while extremely low salinities (<1 psu) did not deter breeding. Females attained maturity at a smaller size in late spring and, especially, in summer than in early spring at lower temperatures. Brood size was a function of females body size. Females, matured during summer at high temperatures, showed the lowest brood size, body length ratio. Mean brood size was small (12–13 early embryos) and embryo loss during development high (54%), possibly due to a negative effect of low salinities. A 1:1 sex ratio existed in the small body length classes, but females preponderated in the large ones. The spring cohort in the southern part, which developed at moderate temperatures, showed the highest growth rate (40 m day^–1). Secondary production of C. orientalecalculated by Hyness method gave a mean annual density of 4562.5 and 9327.6 ind. m^–2, a mean annual crop (B) of 1.03 and 2.67 g DW m^–2, an annual production (P) of 6.91 and 22.54 g DW m^–2 and a P/B ratio of 6.7 and 8.4 in the northern and southern part of the lagoon, respectively.