Article

Olfaction in terrestrial isopods (Crustacea: Oniscidea): Responses of Porcellio scaber to the odour of litter

January 1996
European Journal of Soil Biology 32(3):141-147

January 1996
32(3):141-147

Authors:

Leibniz Centre for Tropical Marine Research (ZMT)

In a choice-chamber experiment, we tested the olfactory responses of the common woodlouse, Porcellio scaber (Crustacea: Isopoda), to different food sources. From our results the following conclusions were drawn: . Porcellio scaber is able to perceive food by olfaction. . The specimens do not react to the litter itself, but to the odour of some metabolites of the microorganisms colonizing the leaves. . At least one attractant for the woodlice is one of the by-products of cellulolytical activity. . Olfactory responses to metabolites released by microorganisms serve as a mechanism in habitarfinding behaviour. L'ofaction chez les isopodes terrestres (Crustacea: Oniscidea) : röponses de Porcellio scaber ä I'odeur de la litiäre. Dans un dispositif de choix expdrimental, la r6ponse olfactive du cloporte cofirmun Porcellio scaber (Crustacea: Isopoda) ä diffdrentes sources trophiques a €t6 testde. Les rdsultats ont men€ aux conclusions suivantes : , Porcellio scaber est capable de percevoir la nourriture par olfaction. . Les individus ne r6agissent pas ä la litiöre el1e-m6me, mais ä I'odeur de certains m6tabolites dlabor€s par les microorganismes qui colonisent les feuilles. . Au moins un attracteur pour les cloportes est un sous-produit de I'activit€ ceilulolytique. . Les rdponses olfactives aux m6tabolites 6labor6s par les microorganismes constituent un m6canisme dans le comportement de sdlection d'un habitat. Mots-cl6s : Isopodes terestres, olfaction, litiöre de feuilles, microorganismes, sdlection de I'habitat.

Leaf litter-colonizing microbiota: Supplementary food source or indicator of food quality for Porcellio scaber (Isopoda: Oniscidea)?

Article

Oct 2003
EUR J SOIL BIOL

Different explanations have been proposed for why terrestrial isopods prefer, and gain from, feeding on microbially inoculated food materials. In the present study, no-choice feeding experiments are used to test three contrasting, but not mutually exclusive, hypotheses. (1) The digestion and nutritional utilization of microbial cells enhance the nutritive value of leaf litter; (2) extracellular digestive enzymes of microbial origin promote digestion of leaf litter; (3) leaf litter-colonizing microbiota serve as indicators for easily digestible leaf litter of high nutritive value. Predictions derived from these hypotheses are compared with the results of a study with experimentally manipulated leaf litter, serving as food sources for the common woodlouse Porcellio scaber. Leaf litter-colonizing microbiota increased consumption of leaf litter by isopods and contributed somewhat to biomass gain of isopods, but not to the assimilation of ingested food. Thus, the present results coincide with predictions derived from hypothesis (3) suggesting that leaf litter-colonizing microbiota stimulate consumption by indicating high food quality. Their positive effects on assimilation and growth, however, are context-specific, being stronger in case of high-quality food than in case of low-quality food.

More than one way to smell ashore – Evolution of the olfactory pathway in terrestrial malacostracan crustaceans

Article

Jan 2021
ARTHROPOD STRUCT DEV

Crustaceans provide a fascinating opportunity for studying adaptations to a terrestrial lifestyle because within this group, the conquest of land has occurred at least ten times convergently. The evolutionary transition from water to land demands various morphological and physiological adaptations of tissues and organs including the sensory and nervous system. In this review, we aim to compare the brain architecture between selected terrestrial and closely related marine representatives of the crustacean taxa Amphipoda, Isopoda, Brachyura, and Anomala with an emphasis on the elements of the olfactory pathway including receptor molecules. Our comparison of neuroanatomical structures between terrestrial members and their close aquatic relatives suggests that during the convergent evolution of terrestrial life-styles, the elements of the olfactory pathway were subject to different morphological transformations. In terrestrial anomalans (Coenobitidae), the elements of the primary olfactory pathway (antennules and olfactory lobes) are in general considerably enlarged whereas they are smaller in terrestrial brachyurans compared to their aquatic relatives. Studies on the repertoire of receptor molecules in Coenobitidae do not point to specific terrestrial adaptations but suggest that perireceptor events – processes in the receptor environment before the stimuli bind – may play an important role for aerial olfaction in this group. In terrestrial members of amphipods (Amphipoda: Talitridae) as well as of isopods (Isopoda: Oniscidea), however, the antennules and olfactory sensilla (aesthetascs) are largely reduced and miniaturized. Consequently, their primary olfactory processing centers are suggested to have been lost during the evolution of a life on land. Nevertheless, in terrestrial Peracarida, the (second) antennae as well as their associated tritocerebral processing structures are presumed to compensate for this loss or rather considerable reduction of the (deutocerebral) primary olfactory pathway. We conclude that after the evolutionary transition from water to land, it is not trivial for arthropods to establish aerial olfaction. If we consider insects as an ingroup of Crustacea, then the Coenobitidae and Insecta may be seen as the most successful crustacean representatives in this respect.

The role of animal-microbe interactions in isopod ecology and evolution

Article

Full-text available

Jan 2006

Martin Zimmer

Due to their world-wide distribution in marine and terrestrial (as well as freshwater) habitats, the order Isopoda (Crustacea: Malacostraca: Peracarida) provides an excellent model for the evolutionary ecology of terrestrialization. (1) Terrestrial isopods (Oniscidea) harbor endosymbiotic bacteria in their midgut glands (hepatopancreas) that are lacking in marine isopods of the suborders Valvifera and Sphaeromatidea, considered being (part of) a sister taxon of Oniscidea. Thus, these bacterial endosymbionts seem to be significant in the context of living in terrestrial habitats and may have been important during the course of terrestrialization. In truly terrestrial species (Crinocheta), two different endosymbionts have been characterized that are distantly related to known parasites and pathogens of the orders Rickettsiales and Mycoplasmatales, respectively. Both these endosymbionts form cytoplasmic appendages that are in contact with the host epithelium and may serve in the exchange of nutrients and information and or serve as holdfasts. In non-crinochete terrestrial isopods (Diplocheta, Tylida, Synocheta), hepatopancreatic bacteria belong to the genus Pseudomonas. Both marine and freshwater Asellota also harbor bacteria in their midgut glands. The lack of bacteria in other marine suborders (as studied so far) may be due to antibiotic agents in these isopods. Based on the present findings, I propose a common (marine) ancestor of Asellota and Oniscidea that acquired the ability to harbor bacterial endosymbionts inside the hepatopancreas. While symbiotic relationships remained unspecific in marine Asellota, they developed towards specific primary symbioses with bacteria that aid in digesting cellulosic and phenolic compounds, and thus, facilitate the utilization of terrestrial food sources in semi-terrestrial and terrestrial Oniscidea and in freshwater Asellota. I, further, hypothesize that later during early phylogeny of Crinocheta, primary symbionts have been replaced by secondary endosymbionts that are still characteristic of recent Crinocheta. In contrast to previous studies, suggesting a role of hepatopancreatic bacteria in nutrition, our present knowledge does not provide any evidence for crinochete symbionts to supply any digestive enzymes to their isopod host. However, Pseudomonas spp. are well-known to degrade both cellulosic and phenolic compounds. Thus, I hypothesize that, while primary symbionts of Oniscidea provide cellulases and/or phenol oxidase, a transfer of cellulase and/or phenol oxidase genes from symbiont to host occurred in early Crinocheta, resulting in endogenous cellulase of evolutionarily bacterial origin. Besides (a) providing enzymes for the digestion of leaf litter, further possible contributions of hepatopancreatic endosymbionts to their hosts physiological constitution and fitness include (b) increasing the availability of nitrogen on a nitrogen-poor food source, (c) protecting their host from secondary (pathogenic) infection, (d) protecting their host from predatory attack, or (e) increasing fertility, mating success and fecundity of their host these hypotheses are briefly discussed. (2) Terrestrial isopods interact with leaf litter-colonizing microbiota that they ingest along with their major food source. While, however, it is well-documented that isopods gain from feeding on microbially inoculated leaf litter, reasons for this dependence are not well understood. Possibly, (a) microbiota serve as supplementary high-quality food source and provide essential or otherwise limiting nutrients; (b) microbiota promote digestion of leaf litter itself, either prior to ingestion or during the gut passage; (c) microbiota simply act as indicators of easily digestible food sources of high quality. These explanations are not mutually exclusive, and the prevailing reason for preferentially consuming microbially inoculated leaf litter depends on both the species and developmental stage of the isopod and the nutritional context, i.e. the food source as such; recent results, however, indicate that cellulolytic capabilities of litter-colonizing microbiota [see (b)] may be less significant than previously thought, while a role of litter-colonizing microbiota in indicating high-quality food [see (c)] is supported. The ability to digestively utilize microbial cells as supplementary food [see (a)] depends on cell wall characteristics as indicated by gram-staining of the microbes, gram-positive bacteria being digested more effectively than gram-negative bacteria and fungi, and being preferred as food source. Despite numerous studies, the most recent ones using modern molecular techniques, it is still debated whether or not terrestrial isopods harbor resident gut microbes in their hindgut. Most hindgut bacteria that may be candidates for hindgut residents appear to belong to gram-negative bacterial taxa, and are taxonomically related to anaerobic species. Thus, we have to assume anoxic microhabitats in cuticular wrinkles. Further, the radial center of the hindgut is anoxic, too, allowing for fermentative digestive processes, while the periphery of the hindgut lumen is largely oxic and oxidizing, thus, allowing for aerobic and oxidative digestive processes. These processes are promoted through cell compounds of ingested microbiota resulting in homeostatic maintenance of a slightly acidic pH that is optimal for the activity of involved enzymes. Potentially harmful effects of phenolic food compounds that are likely under such conditions are counteracted through hydrolytic enzymes and surfactants of microbial origin. In conclusion, our up-to-date knowledge as summarized and discussed herein strongly confirms the assumption that (terrestrial) isopods strongly depend on microbial activity and nutrients for their capability of digestively utilizing terrestrial leaf litter; on an evolutionary scale, this dependence may indicate the role that microbiota played during the course of terrestrialization, although this aspect of isopod-microbe interactions is far from being understood.

Does Porcellio scaber (Isopoda: Oniscidea) gain from coprophagy?

Article

Sep 2002
SOIL BIOL BIOCHEM

In feeding experiments, leaf litter of different tree species and isopod feces derived from these leaf litter materials were offered to the common woodlouse, Porcellio scaber. Consumption indices were used to elucidate the nutritional significance of coprophagy. Consumption rates of P. scaber clearly differed between feeding assays with alder (Alnus glutinosa) litter and those with isopod feces derived from alder. Differences between feeding assays depended on microbial activity of the food sources when oak (Quercus robur) litter or isopod feces derived from oak were offered. Further, microbiota increased the digestibility of oak material, but did not change digestibility of alder litter and reduced digestibility of feces derived from alder. Thus, the significance of litter-or feces-colonizing microbiota decreased with increasing nutritive value of the leaf litter. Inoculated feces derived from oak provided better growth than any other oak-derived food. In contrast, isopods grew better on alder litter than on alder-derived feces. In sum, we found little evidence to support the notion that P. scaber gains from coprophagy. We reject the hypothesis that coprophagy meets a need for nutrients that, due to digestive incapabilities, cannot be satisfied by feeding on leaf litter alone. The hypothesis that microbial colonizers render feces attractive as a source of microbial enzymes or nutrients is only partly corroborated. P. scaber gains from coprophagy through microbial activity or biomass only if leaf litter quality is low. q

Food selection as a means of Cu intake reduction in the terrestrial isopod Porcellio scaber (Crustacea, Isopoda)

Article

Mar 2004
APPL SOIL ECOL

The idea that terrestrial isopods regulate copper intake through the state of their copper stores by selection of an optimal copper diet has never been experimentally assessed. We investigated discrimination between untreated and Cu-enriched diets in the isopod Porcellio scaber in relation to their copper stores. Animals were pre-exposed to untreated or Cu-enriched poplar leaves. After 14 and 28 days of pre-exposure, two-way food choice experiments were performed for 14 days. Food consumption rates and the amount of copper accumulated due to the copper content of the food and the duration of pre-exposure were compared. Food selection and rejection as ways by which P. scaber may reduce or avoid the toxic effects of copper were evaluated. P. scaber offered both Cu-enriched food and untreated food preferred the latter, irrespective of the amount of assimilated copper. Copper body burdens increased with copper concentration in the food. In animals offered both Cu-enriched and untreated food, copper body burden also increased, but to a lower extent than in animals fed only a Cu-enriched diet. Therefore, food selection is a way of regulating copper intake, but only to a limited extent. The mortality of experimental animals increased significantly after longer exposure to highly Cu-enriched food. We conclude that in P. scaber, the possibility of selecting food of different copper content may mitigate but cannot prevent the toxic effects of copper in copper-polluted environments.

Colonisation of Beach-Cast Macrophyte Wrack Patches by Talitrid Amphipods: A Primer

Article

Full-text available

Jul 2011
ESTUAR COAST

Sandy beaches are characterised by heterogeneously distributed food sources both in time and space. The major energy supply is derived from marine subsidies in the form of beach-cast macrophyte wrack. Wrack patches are short-lived, and their position on the beaches varies with tidal and seasonal cycles as well as weather conditions. Little is known about how sandy beach inhabitants orient themselves towards, and colonise, wrack patches. In a series of field studies on islands off Vancouver Island (British Columbia, Canada), colonisation patterns of wrack patches by beach fleas and sand hoppers (Amphipoda: Talitridae), the most abundant macrofaunal detritivores, were studied. As indicated by colonisation of experimental patches of wrack and wrack surrogates that were either visible or buried in the sand, beach fleas (Traskorchestia traskiana) rely on olfactory cues for locating freshly deposited wrack patches in their patchy and dynamic habitat. Dense colonisation of freshly deposited algal wrack generally occurred within less than 1 h but depended upon the tidal height of wrack patches. Beach flea density in freshly deposited wrack patches increased with increasing tidal height. By contrast, sand hoppers (Megalorchestia californiana) colonised freshly deposited wrack patches in densities that decreased with tidal height. Discussing these interspecific differences, we provide a primer for future detailed studies on transport of matter along the marine– terrestrial gradient of sand beaches.

Comparative exploratory movements of two terrestrial isopods (suborder: Oniscidea), in response to humidity and availability of food

Article

Apr 2022

Unfavourable conditions within familiar environments may prompt organisms to make forays into other habitats, at least temporarily. This behaviour is in turn linked to key demographic processes such as immigration, emigration, and eventually, metapopulation dynamics. How such movements are triggered by environmental conditions (much less their interaction effects) has rarely been experimentally tested. To address this, we examined how environmental conditions (3 levels of food and 3 levels of humidity) within a microcosm affect the movements of two species of isopods ( Armadillidium vulgare and Porcellio scaber ) out of their familiar habitat. We used web-camera checkpoints to record the movements of individually marked animals as they conducted forays along corridors that lead to new, unused habitats. Thirty-six trials were run in total for each species, with each trial involving 16 animals (8 ♂♂, 8 ♀♀). Relatively unfavourable conditions of low humidity, low food levels, and their interaction prompted changes to all the foray metrics we measured. However, different levels of mobility and tolerance to desiccation between the two species also appeared linked to the degree of responses, e.g., Porcellio demonstrated a greater tendency to depart from familiar habitat under low humidity, possibly due to their superior mobility and greater susceptibility to desiccation. This study improves our understanding of how different environmental conditions act in concert to affect the exploratory movements away from familiar habitat, and how these responses differ even for closely-related species.

Distribution spatio-temporelle des Myriapodes dans un site anthropisé et un site naturel du Nord-Est de l'Algérie

Article

Full-text available

Jan 2012
REV ECOL-TERRE VIE

Les Chilopodes et les Diplopodes présents au niveau de deux sites localisés dans le nord-est de l’Algérie (site anthropisé d’Annaba et site naturel d’El Tarf) ont été étudiés par piégeage durant une année (juin 2006 à mai 2007). Au total 901 Chilopodes et 411 Diplopodes ont été récoltés. Les diversités spatiotemporelles des deux taxons ont été évaluées. Nos résultats suggèrent que les paramètres physico-chimiques édaphiques tels que le taux de limon, le pourcentage de matière organique ou le pH mais aussi les paramètres climatiques tels que le volume de précipitation et le taux d’hygrométrie qui en résulte ont une influence significative sur l’abondance et la répartition spatiale des Chilopodes et des Diplopodes avec une nette différence de comportement entre les deux taxons. L’estimation de l’intensité des perturbations introduites par l’homme influençant la diversité écologique des deux taxons indique que la région d’Annaba, qui est plus anthropisée que celle d’El Tarf, subit une perte en matière de diversité concernant à la fois les Chilopodes et les Diplopodes.

Avoidance behaviour of isopods (Porcellio scaber) exposed to food or soil contaminated with Ag- and CeO2- nanoparticles

Article

Sep 2019
APPL SOIL ECOL

The main goal of the study was to evaluate the avoidance behaviour of isopods (Porcellio scaber) to food or soil contaminated with different nanoparticles (NPs): Ag-NPs, sulfidized Ag-NPs (Ag2S-NPs) or CeO2-NPs. These NPs are characterized by different physiochemical properties, and antimicrobial and toxic potentials. Isopods were exposed in three scenarios: (i) 14 d feeding test where animals were fed solely on contaminated leaves; (ii) 14 d food selection test where leaves spiked with NPs were offered simultaneously with uncontaminated leaves; and (iii) 48 h soil avoidance test where animals could choose between uncontaminated and soil spiked with NPs. The isopods decreased feeding on Ag-NP contaminated food and clearly avoided contact with Ag-NP contaminated soil. Substantial accumulation of Ag in the body of isopods was found both in feeding and food selection test. This means that food selection might mitigate but could not prevent Ag accumulation in woodlice. In contrast, no such behavioural response of isopods was found for CeO2-NP. These data suggest that the presence of metal ions in the case of Ag-NPs may be the main reason for differential behaviour. Interestingly, moderate avoidance behaviour was observed also towards Ag2S-NPs although no Ag⁺ was detected in stock suspensions. This avoidance was not statistically significant and needs to be further explored. Behavioural test with isopods showed again their value in estimation of potential adverse effects of pollutants comparable to collembolans and earthworms.

A crossover design to assess feeding preferences in terrestrial isopods: A case study in a Mediterranean species

Article

Full-text available

Feb 2017

A crossover design was used to study food preferences and capability of nutritional acclimation to different food sources in terrestrial isopods, which live in xeric environments, by using Armadillo officinalis as an experimental model. The foods chosen for this experiment were three fresh foods with different content of water (potato, carrot, lettuce), and a dry food (leaf of plane tree). In order to quantify these preferences, two kinds of data able to provide complementary information were collected: number of droppings produced and food ingested per week. These data were used to fit some mixed effects models, in order to highlight statistically significant differences among the foods provided to the animals at a level of preferences. In addition, the buccal appendages of A. officinalis were observed and drawn in details, to provide further information at this level. Our results showed that A. officinalis seems not to have particular preferences between fresh foods with a moderate quantity of water and dry food, commonly eaten in its natural habitat. In contrast, foods with high quantity of water, like the lettuce, seem not to be instead particularly palatable for its taste, or its nutritional needs. Also, this study seems to have highlighted a better capability of digestion and absorption of the potato tuber compared to the leaf of plane tree for an equal quantity of ingested food. Anyway, this hypothesis needs further insights in order to be able to be verified.

Exposure to heavy metal stress does not increase fluctuating asymmetry in populations of isopod and hardwood trees

Article

May 2017

Occurence of Gregarina typographi (Sporozoa: Gregarinidae) and Metschnikowia cf. typographi (Ascomycota: Metschnikowiacae) in Ips sexdentatus (Coleoptera: Scolytidae) from Austria

Article

Full-text available

Jan 2007

Life: The Excitement of Biology 4(2) Responses of Four Arthropod Prey Species to Mechanosensory, Chemosensory and Visual Cues from an Arachnid Predator: A Comparative Approach 1

Article

Full-text available

Jul 2016

Comparisons of multiple invertebrate prey species to direct predator sensory cues are relatively uncommon. We compared prey responses to arachnid predators (Araneae: Lycosidae) of four species: Blattella germanica (Blattodea: Blattellidae), Acheta domesticus (Orthoptera: Gryllinae), Armadillidium vulgare (Oniscidea: Armadillidae), and Porcellio laevis (Oniscidea: Porcellionidae). Prey experienced combinations of direct mechanosensory, chemosensory or visual cues. All species responded to all cues, but response structure differed among species. Mechanosensory and chemosensory predator cues elicited frequent shifts between behaviors, whereas visual stimuli tended to diminish responses. Mechanosensory stimuli produced the most extreme responses, particularly in crickets and cockroaches, but responses to mechanosensory stimuli diminished when accompanied by visual stimuli. Crickets were particularly sensitive to chemical cues and reduced activity in response to them. Isopods were sensitive to visual stimuli, reducing activity in response. These behavioral similarities and differences provide insight into the sensory ecology of different species of arthropod.

Mate choice is not consistent with short-term effects of intraspecific admixture in woodlice

Article

Apr 2016
BIOL J LINN SOC

Theory posits that individuals should exhibit mate preferences partly based on genetic relatedness such that fitness is maximized. Intraspecific genetic admixture can have different effects depending on the genetic characteristics and evolutionary histories of the individuals and populations involved. We investigated whether female mate choice behaviour in the common rough woodlouse (Porcellio scaber) matched the fitness consequences of genetic admixture. Most females from two populations that were introduced in sequence to one male from each of the populations were found to mate with both males and, furthermore, monandrous females (i.e. females that only mated with one male) predominantly mated with males from their own population. To test for the effects of genetic admixture, females from four populations were divided into two replicate pairs and assigned to mate either with a male from the same population as the female (pure) or with a male from the other population (admixed). The effect of mating treatment on the proportion of females that produced eggs and hatched young, as well as on the number and viability of offspring, depended on female source population. Mating treatment had opposing effects in two of the populations, whereas there were no detectable effects in the other two populations. By contrast to expectations, the mating patterns did not match the observed effects of genetic admixture. We discuss alternative adaptive and non-adaptive explanations for the observed patterns.

Food choice experiments with cadmium nitrate dosed food in terrestrial isopod Oniscus asellus (Crustacea)

Article

Full-text available

May 2002

This paper describes a study of behavioural response in terrestrial isopod Oniscus asellus when offered two food pellets of different quality. One group had a choice of sterilised food and food pellets covered with mould. The other group had a choice of uncontaminated and cadmium-dosed food. During the behavioural test, the animals were monitored by a video camera and each visit to food pellets and time spent around it was counted. The results show that animals spent significantly less time near sterilised and cadmium-dosed food than with uncontaminated or mould-covered food. Discrimination between offered food pellets showed that avoidance behaviour can be used as an indicator of different food quality.

Researches on entomopathogenic bacteria and applications for fly pest control in a Mediterranean region (Sardinia, Italy)

Article

Jan 2007

During the last few years, investigations were carried out in Sardinia (Italy) to isolate naturally-occurring soil bacteria and detect their toxicity against medfly (Ceratitis capitata), olive fruit fly (Bactrocera olea) and housefly (Musca domestica) as well as some of their pupal parasitoids. Strains of Bacillus thuringiensis were isolated and then comparatively studied with strains of other geographic origin. Morphological (presence of parasporal inclusions) and genetic (16S rRNA gene sequence, detection of cry genes) observations and protein profile analysis by SDS-PAGE were used for identification and characterization of the Bacillus thuringiensis isolates. Among about 300 different bacterial isolates, 4 were significantly toxic to housefly adults, 1 to housefly larvae, 11 to adult of olive fruit fly, 20 to olive fruit fly larvae, 4 to adult of medfly, and 22 to medfly larvae. No significant toxicity was detected against the Hymenoptera Opius concolor and Muscidifurax raptor (olive fruit fly and housefly pupal parasidoids, respectively). Experimental treatments in olive crops against olive fruit fly adults and in livestock against both housefly adults and larvae were carried out with formulations of the most toxic bacterial strains, encouraging the introduction of microbiological control in the integrated pest management of these fly species

Reproductive Pattern of the Neotropical Terrestrial Isopod Benthana Cairensis (Isopoda: Philosciidae)

Article

Mar 2013

Population studies on terrestrial isopods, particularly those examining temperate and certain tropical species, are often performed through an investigation of life history traits, such as size at sexual maturity, fecundity and life span. In this study, some of the life history traits of Benthana cairensis Sokolowicz, Araujo, and Boelter, 2008, a neotropical species, were evaluated and tested against the hypothesis that this species has an iteroparous mode of reproduction, with females' reproduction occurring year-round. Samples were collected over an 18-month period from a small area in southern Brazil. Reproduction of B. cairensis peaked in the spring, females' mean fecundity was 10.4 +/- 2.73 eggs (Mean +/- SD) and mean reproductive allocation was 17% +/- 4.08 (Mean +/- SD). Females attain sexual maturity when they are approximately five months old and live over one and a half year. Males grow faster, reach smaller sizes and live approximately 13 months. We determined that a female only reproduces for one season, although it is capable of having more than one brood during this season; this result confirms that B. cairensis exhibits an iteroparous mode of reproduction and that reproduction is concentrated in the warmer months.

Strategies to control woodlice with entomopathogenic nematodes

Conference Paper

Full-text available

Jan 2007

The efficacy of entomopathogenic nematodes in different formulations against woodlice was investigated. Individual Porcellio scaber and Armadillidium spp. woodlice treated with nematodes were more susceptible to Steinernema carpocapsae than to S. feltiae. Experiments with different nematode doses, nematode carriers and bait substances revealed that after 14 days incubation time, 86 to 100% mortality was reached when S. carpocapsae was formulated into quartz sand with compost as bait. Tests with cucumber plants indicated that older plants are protected from woodlice attack by the nematode bait formulation.

Brain anatomy of the marine isopod Saduria entomon Linnaeus, 1758 (Valvifera, Isopoda) with special emphasis on the olfactory pathway

Article

Full-text available

Oct 2013

Representatives of at least six crustacean taxa managed to establish a terrestrial life style during their evolutionary history and the Oniscidea (Isopoda) are currently held as the most successfully terrestrialized malacostracan crustaceans. The brain architecture of terrestrial isopods is fairly well understood and studies on this field suggest that the evolutionary transition from sea to land in isopods coincided with a considerable size reduction and functional loss of their first pair of antennae and associated brain areas. This finding suggests that terrestrial isopods may have no or poor abilities to detect volatile substances but that their chemosensory ecology is most likely restricted to contact chemoreception. In this study, we explored how the brain of a marine isopod and particularly its olfactory system compares to that of terrestrial relatives. Using histochemical and immunohistochemical labeling, brightfield and confocal laser-scan microscopy, we show that in the marine isopod Saduria entomon aesthetascs on the first pair of antennae provide input to a well defined deutocerebrum (DC). The deutocerebral chemosensory lobes (DCL) are divided into spherical neuropil compartments, the olfactory glomeruli (og). Secondary processing areas in the lateral protocerebrum (lPC) are supplied by a thin but distinct projection neuron tract (PNT) with a contralateral connection. Hence, contrary to terrestrial Isopoda, S. entomon has at least the neuronal substrate to perceive and process olfactory stimuli suggesting the originally marine isopod lineage had olfactory abilities comparable to that of other malacostracan crustaceans.

Evolutionary adaptation of oniscidean isopods to terrestrial life: Structure, physiology and behavior

Article

Full-text available

Jun 2011

Hornung Elisabeth

Terrestrial isopods (Oniscidea) are the most successful crustacean colonizers of land habitats. From an evolutionary point of view, they are excellent examples of model organisms that have adaptated to terrestrial life. The aquatic-terrestrial branching of the phylogenetic lines of the Oniscidea occurred in the marine littoral zone. The most oniscid species-rich areas are found in the circum-Mediterranean region. Studies on the morphology, physiology, ecology and biogeography of Oniscidea highlight the diversity of the group. They successfully colonized a wide range of terrestrial habitats by solving such ecological and physiological challenges as reproduction, respiration, excretion and protection against desiccation. During terrestrial adaptation, they evolved diverse morphological, ecological and behavioral traits. This review summarizes our present knowledge of some aspects of the morphology, physiology and behavior as it related to oniscidean adaptation to the terrestrial realm.

Development of secondary sexual characters in juvenile males of Benthana cairensis (Crustacea, Oniscidea, Philosciidae)

Article

Sep 2011

Terrestrial isopods undergo direct development in which the animals molt to juvenile stages after the manca stages in which the sex cannot be recognized. The first three juvenile stages of Benthana cairensis are described with emphasis on the male secondary sexual characters. The ontogeny of the genital papilla, pleopods 1 and 2 and pereiopods were followed. At the Juvenile I stage, males are characterized by a slightly developed papilla, although dimorphism of the pleopod 1 exopod and pereiopods is still not evident at this stage. In Juvenile II individuals, the sub-apical protrusion of the pleopod 1 exopod begins to appear, and it is more evident in Juvenile III. The complete formation of this protrusion is only seen when males reach a cephalothorax width of approximately 1.0 mm; dimorphism of the setation of the four pairs of pereiopods begins later and is evident when males reach approximately 1.04 mm CW.

Feeding preferences of supralittoral isopods and amphipods

Article

Full-text available

Nov 2000

We examined the feeding preferences of 3 supralittoral crustacean species in the Pacific Northwest of North America. The isopod Ligia pallasii (Brandt, 1833), the rocky-shore amphipod Traskorchestia traskiana (Stimpson, 1857), and the sandy-beach amphipod Megalorchestia californiana (Brandt, 1851) had similar feeding preferences, suggesting that feeding preferences were based on general algal traits rather than on adaptations particular to specific herbivores. No single trait clearly distinguished low- and high-preference seaweeds, although pH and phenolic compounds may have been important for two chemically defended seaweeds (Desmarestia sp. and Fucus sp., respectively). Feeding preferences of L. pallasii were affected by dietary history, but effects were minor compared with differences among seaweeds. All 3 consumers tended to prefer wrack (aged, stranded seaweeds) over fresh seaweeds of the same species. Our results suggested that increased organic and mineral contents of wrack were important in mediating these preferences, but that toughness and salt and nitrogen contents were not. Reduced levels of defensive compounds may have made wrack more palatable than fresh seaweeds in the case of the two chemically defended seaweeds.

Distribution pattern of woodlice (Isopoda) and millipedes (Diplopoda) in four primeval forests of the Western Carpathians (Central Slovakia)

Article

Jan 2006
SOIL BIOL BIOCHEM

We collected 1605 isopod individuals (eight species) and 671 diplopod individuals (17 species) in four primeval forests of the Western Carpathians, Central Slovakia, by leaf litter extraction. The forests are of different temperate deciduous forest types varying in tree species, aspect, elevation and soil characteristics. The oak forests, established on southwest oriented slopes at an elevation of 280–600 m, were characterized by Hyloniscus riparius, Porcellium conspersum, Enantiulus nanus and Ophioiulus pilosus. The beech forests, established on northeast oriented slopes at an elevation of 700–1100 m, were characterised by Ligidium hypnorum, Trachysphaera costata and Polyzonium germanicum. A remarkable increase of the total number of species and individuals occurred in both forest types adjacent to coarse woody debris (CWD). Woodlice density close to CWD was between 200 and 630 individuals m−2 (35–130 individuals m−2 distant from CWD); millipede density close to CWD ranged from 60 to 230 individuals m−2 (15–75 individuals m−2 distant from CWD). Species richness of both taxa close to CWD varied from 13 to 16 species m−2 (7–12 species m−2 distant from CWD). Thus, CWD has a significant influence on saprophages. However, structural components such as CWD and the amount of leaf litter did not significantly alter species assemblages. Species at sites distant from CWD were a subset of species at sites close to CWD. According to a canonical correspondence analysis (CCA), ‘forest type’ and ‘elevation within a slope’, as well as chemistry of the upper soil layer, i.e. ‘acidification’ and ‘nutrition’, strongly influenced species assemblages.

Effects of elevated CO2 and O3 on leaf litter phenolics and subsequent performance of litter-feeding soil macrofauna

Article

Mar 2007

Two field-growing silver birch (Betula pendula Roth) clones (clone 4 and 80) were exposed to elevated CO2 and O3 for three growing seasons (1999–2001). The phenolic compounds of naturally abscised leaf litter were analyzed in order to determine the possible CO2- and O3-induced changes in the litter quality. The potential litter-mediated CO2 and O3 effects on litter-feeding soil macrofauna (detritivore) performance were assessed in microcosm experiments, i.e., the relative growth rates (RGR) of Lumbricus terrestris and Porcellio scaber, the relative consumption rates (RCR) of P. scaber, and mortality of the test animals were measured. The leaf litter grown under elevated CO2 had increased concentrations (weight per mass unit) and contents (weight per leaf) of phenolic acids, flavonol glycosides, condensed tannins and total measured phenolics. Elevated O3 increased the concentrations of 3,4’-dihydroxypropiophenone 3-β-d-glucoside (DHPPG) and flavonoid aglycones but only under ambient CO2. However, elevated O3 effects on the content of some low-molecular-weight phenolic (LMWP) compounds (i.e. phenolic acids, DHPPG, flavonoid aglycones) and total LMWP changed over time emphasizing the importance of conducting long-term (>3years) exposure studies. In general, RGR of young L. terrestris was affected by the litter quality changes induced by elevated CO2 and O3, as the animal growth rates were reduced when they were fed with CO2- and O3-exposed leaf litter of clone 80 in Experiment 1. P. scaber RCR or RGR responses to CO2- and O3-induced changes in litter quality were more variable and inconsistent, and neither were there any litter-mediated CO2 and O3 effects on animal mortality in these microcosm experiments. In conclusion, elevated CO2 has the potential to alter silver birch leaf litter quality, but the possible O3 effects on phenolic compounds and litter-mediated CO2 and O3 effects on detritivores are more difficult to validate.

Relationships between woodlice (Isopoda: Oniscidea) and microbial density and activity in the field

Article

Full-text available

Nov 1999

Field studies on microbial populations and their activity in soil and litter layers of different sites revealed statistically significant correlations with climatic factors, soil characteristics and the number of terrestrial isopods (Isopoda: Oniscidea). The number of captured Porcellio scaber was negatively correlated with the density of soil microbiota, but positively correlated with both respiration and cellulolytic activity of litter-colonizing microorganisms. By contrast, the number of Oniscus asellus was positively correlated with soil microbial density and respiration, and cellulolytic and respiratory activity of the litter. These interspecific differences were unexpected between species that frequently occur sympatrically, and, thus, probably have similar ecological requirements. Hence, the results suggested species-specific interactions of these species with soil and litter-colonizing microbiota. However, further field studies are required to prove this.

Homeostatic responses in the gut of Porcellio scaber (Isopoda: Oniscidea) optimize litter degradation

Article

Full-text available

Jan 1997

In order to examine the influence of differences in food conditions on gut characteristics in Porcellio scaber, pH-manipulated and microbially inoculated leaf litter from three different tree species were offered. Microbial activity was clearly influenced by the pH levels of the leaves. Analyses of the pH levels in the gut indicated the ability of P. scaber to buffer the pH value in the intestinal tract to about 5.5–6.0 in the anterior hindgut, and to about 6.0–6.5 in the posterior hindgut. The pH levels of the gut sections remained in this range, within a range of food pH from 4.0 to 7.5, no matter what kind of leaves the animals were fed. Homeostatic responses to changes in food pH guarantee optimized digestion of leaf litter. However, when the pH level of the litter dropped below 3.5, P. scaber was not able to maintain the pH conditions in the gut. Furthermore, microorganisms colonizing the litter biased the pH level in the anterior hindgut where digestive processes mainly take place. These results indicate a decline of litter quality with regard to the nutrition of terrestrial isopods, caused by acidification and consequently reduced microbial activity.

Chemical Communication in Peracarid Crustaceans

Chapter

Full-text available

Jan 2011

Martin Thiel

Chemical communication plays an important role during the life of peracarid crustaceans, where the two main taxa, the amphipods and isopods, have representatives in both aquatic and terrestrial habitats. As in other crustaceans, the antennae bear the most important chemosensory structures, which are used for food-finding, predator detection and intraspecific interactions. The chemical nature of peracarid pheromones is unknown, but numerous experimental studies confirm that chemical signals can be soluble/volatile or contact pheromones. Waterborne chemicals mediate mate finding while contact pheromones are mainly involved in mate assessment. Males of some species appear capable to determine the reproductive status of females (closeness to the reproductive molt), which is possibly mediated by chemical compounds. Contrasting with this fine-tuned chemoreception in male–female interactions are other examples that suggest that reproductive isolation between closely related congeneric species is incomplete. The fact that males form precopulatory associations with heterospecific females indicates that chemicals mediating these interactions are not sufficiently specific to permit species discrimination. Gregarious behavior in many species is also guided by chemical cues that lead to aggregation on shared food sources or in communal shelters. Studies on kin recognition in mother–offspring groups have produced ambiguous results – in some species females appear unable to discriminate between their own and unrelated offspring, while females of other species recognize their own juveniles. The best example for kin recognition comes from desert isopods where family-specific chemical signatures allow parents to recognize their offspring. In summary, there is abundant experimental and observational evidence that numerous intra- and interspecific interactions in peracarids are mediated via chemical stimuli, but knowledge about the chemical structure of these compounds is still very limited. Given that all species have direct development and that many species can be easily cultured in the laboratory, peracarid crustaceans are proposed as ideal model organisms for studies aiming at the identification of the compounds used in chemical communication.

Evolutionary adaptation of oniscidean isopods to terrestrial life: Structural – physiological – behavioural aspects

Article

Full-text available

Jan 2011

Hornung Elisabeth

Terrestrial isopods (Oniscidea) are the most successful crustacean colonizers of land habitats. From an evolutionary point of view, they are excellent examples of model organisms that have adaptated to terres- trial life. h e aquatic-terrestrial branching of the phylogenetic lines of the Oniscidea occurred in the marine littoral zone. h e most oniscid species-rich areas are found in the circum-Mediterranean region. Studies on the morphology, physiology, ecology and biogeography of Oniscidea highlight the diversity of the group. h ey successfully colonized a wide range of terrestrial habitats by solving such ecological and physiological challenges as reproduction, respiration, excretion and protection against desiccation. During terrestrial adaptation, they evolved diverse morphological, ecological and behavioral traits. h is review summarizes our present knowledge of some aspects of the morphology, physiology and behavior as it related to oniscidean adaptation to the terrestrial realm.

Impacts of chitinase-transformed silver birch on leaf decomposition and soil organisms

Article

Jul 2004
EUR J SOIL BIOL

Genetically manipulated silver birch (Betula pendula) leaves were used in microcosms experiments to evaluate their impacts on different groups of decomposing soil fauna. Birches were transformed to produce chitinase IV from sugar beet. We compared decomposition rates of leaves, growth and reproduction of soil fauna deriving nutrition from these leaves. Population numbers of collembolans (Folsomia candida and Lepidocyrtus lignorum) and nematodes were measured and decomposition rates of the birch leaves were recorded. Woodlice (Porcellio scaber) juveniles living in the microcosms were weighed at 2- to 4-week intervals to determine growth rate. This study revealed that birch leaves manipulated to produce chitinase affected negatively to the numbers of nematodes and positively on numbers of collembolans. Total decomposing rate and leaf mass loss per nematode were highest in chitinase leaves. No differences in growth or survival of woodlouse juveniles between transgenic and control birches were detected.

Transition from marine to terrestrial ecologies: Changes in olfactory and tritocerebral neuropils in land-living isopods

Article

May 2011

In addition to the ancestors of insects, representatives of five lineages of crustaceans have colonized land. Whereas insects have evolved sensilla that are specialized to allow the detection of airborne odors and have evolved olfactory sensory neurons that recognize specific airborne ligands, there is so far little evidence for aerial olfaction in terrestrial crustaceans. Here we ask the question whether terrestrial Isopoda have evolved the neuronal substrate for the problem of detecting far-field airborne chemicals. We show that conquest of land of Isopoda has been accompanied by a radical diminution of their first antennae and a concomitant loss of their deutocerebral olfactory lobes and olfactory computational networks. In terrestrial isopods, but not their marine cousins, tritocerebral neuropils serving the second antenna have evolved radical modifications. These include a complete loss of the malacostracan pattern of somatotopic representation, the evolution in some species of amorphous lobes and in others lobes equipped with microglomeruli, and yet in others the evolution of partitioned neuropils that suggest modality-specific segregation of second antenna inputs. Evidence suggests that Isopoda have evolved, and are in the process of evolving, several novel solutions to chemical perception on land and in air.

Individual Preferences and Social Interactions Determine the Aggregation of Woodlice

Article

Full-text available

Feb 2011
PLOS ONE

The aggregation of woodlice in dark and moist places is considered an adaptation to land life and most studies are focused on its functionality or on the behavioural mechanisms related to the individual's response to abiotic factors. Until now, no clear experimental demonstration was available about aggregation resulting from inter-attraction between conspecifics. We present the dynamics of aggregation, not previously described in detail in literature, as being independent of the experimental conditions: homogeneous and heterogeneous environments with identical or different shelters. Indeed whatever these conditions, the aggregation is very quick. In less than 10 minutes more than 50% of woodlice were aggregated in several small groups in the homogeneous environment or under shelters in the heterogeneous environment. After this fast aggregation, woodlice progressively moved into a single aggregate or under one shelter. Here we show for the first time that aggregation in woodlice implies a strong social component and results from a trade-off between individual preferences and inter-attraction between individuals. Moreover, our results reveal that the response to the heterogeneities affects only the location of the aggregates and not the level of aggregation, and demonstrate the strong inter-attraction between conspecifics which can outweigh individual preferences. This inter-attraction can lead to situations that could seem sub-optimal.

Joint effects of three plant protection products to the terrestrial isopod Porcellionides pruinosus and the collembolan Folsomia candida

Article

Aug 2010

The effects of simultaneous application of plant protection products are of concern since the uses of different products pose an additional risk to non-target soil organisms. The effects of binary combinations of dimethoate, glyphosate and spirodiclofen, an insecticide an herbicide and an acaricide, on the avoidance behaviour of the terrestrial isopod Porcellionides pruinosus and the reproductive effort of Folsomia candida were assessed using the two reference models of concentration addition (CA) and independent action (IA). Results of single exposure to the three pesticides indicated a clear dose related avoidance response of the isopods in the highest concentrations tested of the three as well as a strong decrease in collembolan adult survival and concomitant number of juveniles produced. In the combined experiments, antagonism was found in 7 out of the 12 combinations, four combinations followed the reference models, and only in one combination synergism was detected (lower doses of glyphosate and spirodiclofen applied to P. pruinosus). In conclusion, it seems that mixing and applying these products, at the recommended field application rate, does not lead to enhanced toxicity, hence limited risk is associated with the joint application of these pesticides.

Izbjegavanje uzimanja hrane Oniscus assellusa kao pokazatelj kakvoće hrane

Article

Full-text available

Jan 2003

Do Stable Isotopes Reflect the Food Web Development in Regenerating Ecosystems?

Article

Feb 2000

We evaluated the use of delta15N- and delta13C-values to monitor the development of food web complexity and biodiversity in a regenerating ecosystem. Therefore a model food chain was established feeding cultivated woodlice (Porcellio dilatatus) on a cellulolytic fungus (Chaetomium globosum) grown on cellulose paper. Two diets of different quality (C:N ratios of 54 vs. 200) with different delta15N- (1.3% vs. 3.1%) but identical delta13C-values caused low and high dietary stress in animals of treatment A and B, respectively. After an incubation time of 7 weeks amount, elemental and isotopic composition of collected faeces and exuviae as well as woodlice and remaining food were determined. The increase of delta15N-values of woodlice relative to the diet was 5.7% and 2.5% in treatments A and B, respectively, whereas delta13C-shifts were 1.0% and 1.6%, showing a reverse relationship. Modelling of elemental and isotopic mass balances indicated that faeces recycling explains the unexpected high 15N-enrichments. Moreover, 13C-enrichments were positively correlated to the degree of starvation. Considering the effects of starvation and recycling of faeces, stable isotopes represent a useful tool to elucidate trophic interactions in regenerating food webs.

Porcellio scaber Latr. and Lumbricus terrestris L.—PAHs Content and Remediation of Long-Term Aging Soil Contamination with Petroleum Products during a Single- and Two-Species Experiment

Article

Full-text available

Oct 2022

The presence of earthworms in soil contaminated with petroleum products (PPs) increase the rate of decomposition. The use of more than one animal species simultaneously in soil remediation could accelerate the process. However, the effects may be different when long-term aging soil contamination exists during which toxic by-products can be formed. This study evaluated the effect of soil contamination with PPs (petrol, diesel fuel, and used engine oil) carried out 12 and 24 months earlier on the life parameters of Lumbricus terrestris L. during single- and dual-species breeding with Porcellio scaber Latr. The changes in the content of total petroleum hydrocarbons (TPH) in the soil were also measured, as were the levels of polycyclic aromatic hydrocarbon (PAH) accumulation in the bodies of the test animals. Survival of earthworms cultivated separately (single-species experiment) in soil contaminated with diesel fuel 12 months earlier significantly decreased, while body mass gain was not significantly changed under the influence of tested PPs. Breeding of L. terrestris together with P. scaber contributed to significant mortality of earthworms regardless of treatments, while woodlice showed much greater resistance to PPs. Occurrence of both animals in soil contaminated with engine oil 24 months earlier resulted in a significant reduction in TPH after 4 weeks (by 29% compared to the initial soil). The content of PAHs in the tissues of L. terrestris was higher than in P. scaber, and the highest amounts of PAHs were found when earthworms were exposed to engine oil. Use of L. terrestris together with P. scaber can be considered a promising scenario for increasing the effectiveness of remediation of soils contaminated with petroleum products, however, further research is needed to establish conditions preventing excessive mortality of earthworms in such a layout.

Integration of behavioral tests and biochemical biomarkers of terrestrial isopod Porcellio scaber (Isopoda, Crustacea) is a promising methodology for testing environmental safety of chars

Article

Dec 2017

We investigated how different carbonized materials, or chars (olive mill pomace biochar (BC) and urban greens pruning residues hydrochar (HC)) affect an important member of soil fauna, the terrestrial isopod Porcellio scaber. The selection behavior of isopods towards chars after a 48 h exposure was studied in (i) soil-char amended tests with single and multiple choices, and (ii) tests with chars offered as pure material. Finally, we exposed the isopods to char-amended soils for a period of 14 days to follow the effect on food consumption, body mass and activities of enzymes that are commonly altered upon stressor exposure (acetylcholinesterase, AChE, and glutathione S-transferase, GST). We showed that isopods are able to select between char amended and un-amended soil and different forms of char amendments: a clear preference for BC, and avoidance of HC were evidenced. The preferences remained the same when the chars were sterilized leading to the conclusion that initial microorganism composition was not the reason for selection, but selection was governed by other chars' physico-chemical properties. It remains to be elucidated which of these properties were the dominant reason for the selection. We also showed that isopods intentionally use BC as food at a similar rate to alder leaves. Medium-term exposure to HC resulted in adverse effects on isopods because it led to reduced feeding and growth, in addition to increasing GST activity, although no alterations in AChE activity were found. We suggest that behavioral tests with P. scaber could be used as a fast, reliable and economically feasible screening method for determining the safety of chars for the soil environment. Results represent significant contribution in the field of char toxicity testing, highlighting the importance of tests with isopods as important members of soil meso fauna, with the aim of influencing environmental policies and quality standards.

Spatio-temporal distribution of Myriapods in an anthropized site and a natural site in north-eastern Algeria

Article

Mar 2012
REV ECOL-TERRE VIE

Chilopoda and Diplopoda, were studied in two areas located in north-eastern Algeria (anthropized site of Annaba and natural site of El Tarf). Pitfall traps were used to collect individuals during one year (June 2006 to May 2007). In total, 901 Chilopoda and 411 Diplopoda were collected. Spatio- temporal diversities were evaluated for the two taxa. Our results suggest that the soil physico-chemical edaphic parameters such as the quantity of alluvium, the proportion of organic matter or the pH but also climatic parameters such as the amount of precipitation and the relative humidity of air have a significant influence on the abundance and spatial distribution of Chilopoda and Diplopoda with a clear difference of behaviour between the two taxa. The estimation of the intensity of perturbation due to human activities influencing the ecological diversity of the two taxonomic groups studied indicated that Annaba area, which is more anthropized than that of El Tarf, loosed in terms of Chilopoda and Diplopoda diversity.

Fundamentals of Soil Ecology: Second Edition

Article

Jul 2004

This fully revised and expanded edition of Fundamentals of Soil Ecology continues its holistic approach to soil biology and ecosystem function. Students and ecosystem researchers will gain a greater understanding of the central roles that soils play in ecosystem development and function. The authors emphasize the increasing importance of soils as the organizing center for all terrestrial ecosystems and provide an overview of theory and practice of soil ecology, both from an ecosystem and evolutionary biology point of view. This volume contains updated and greatly expanded coverage of all belowground biota (roots, microbes and fauna) and methods to identify and determine its distribution and abundance. New chapters are provided on soil biodiversity and its relationship to ecosystem processes, suggested laboratory and field methods to measure biota and their activities in ecosystems.

Nutritional biology of terrestrial isopods (Isopoda: Oniscidea): Copper revisited

Article

Apr 2013
Isr J Zool

In Porcellio scaber, we detected extensive oxidation of phenolics by copper-containing enzymes in the hindgut. The activity of these phenol oxidases significantly correlated with the number of bacteria in the hepatopancreas. About one quarter of the hepatopancreatic copper was localized in these bacterial cells. We conclude that copper-containing phenol oxidases in the gut of P. scaber originate from the hepatopancreatic bacteria. Furthermore, our data provide evidence that microbial colonization and coprophagy, serving as an “external rumen", may be less important with respect to litter degradation by terrestrial isopods than has been previously assumed.

Interaction between soil fauna and their environment

Chapter

Full-text available

Jan 1999

Jean-François Ponge

Interactions between soil animals and their environment can be described in terms of positive and negative feed-back loops taking place in the build-up and steady-state of soil ecosystems, respectively. The size of animals determines the scale at which they interact with their physical and biotic environment. Nevertheless varying scales at which animals intervene in functional processes is not relevant to any hierarchical position within the ecosystem, due to symmetrical patterns in the relationships between microbes, animals, humus forms and vegetation types. The present knowledge has been reviewed and discussed to the light of an integrated view of the soil ecosystem, with a particular accent put on soil acidity.

An assemblage of terrestrial isopods (Crustacea) in southern Brazil and its contribution to leaf litter processing

Article

Full-text available

Mar 2008
REV BRAS ZOOL

We present an assemblage of terrestrial isopods in Parque Estadual de Itapuã, southern Brazil, and estimate the contribution of two species to the leaf litter processing. After one year of sampling, we obtained 3748 individuals of six species and four eco-morphologic groups (in order of abundance): Balloniscus glaber Araujo & Zardo, 1995, Atlantoscia floridana (van Name, 1940), Pseudodiploexochus tabularis (Giambiagi de Calabrese, 1939), Trichorhina sp., Alboscia itapuensis Araujo & Quadros, 2005 and ovamundoniscus gracilis Lopes & Araujo, 2003. Total monthly density corresponded to 368 individuals per square meter. The species A. itapuensis and N. gracilis represented less than 1% of total individuals. All the others showed aggregated distribution. Atlantoscia floridana and B. glaber had the highest proportion of individuals occurring together (88%) and a significant species association. Their monthly biomass averaged 4.92 kg ha-1 for B. glaber and 0.97 kg ha-1 for A. floridana. Consumption rates, obtained in the lab (in mg mg-1 day-1) were 0.34 ± 0.04 and 0.70 ± 0.18 for B. glaber and A. floridana, respectively and assimilation efficiency was about 30%. We estimated that both species together could process 860 kg leaves ha-1 year-1.

A Bibliography of Terrestrial Isopods (Crustacea: Isopoda: Oniscidea)

Article

Summary A reference list is presented containing most scientific publications on the biology of terre- strial isopods (suborder Oniscidea) published in a European language until the year 2000. Not considered are popular accounts, textbooks, faunal lists and preliminary reports if these are summarised in later publications, and publications before 1850 if they do not contain descrip- tions of new species.

The toxicity of sublethal lead concentrations for the woodlouse, Porcellio laevis (Crustacea, Isopoda)

Article

May 1999

The effects of sublethal concentrations of lead nitrate on the terrestrial isopod Porcellio laevis were studied experimentally under controlled conditions over a period of 8 weeks. Changes in body mass were recorded. Avoidance-behaviour studies were undertaken to determine whether P. laevis can detect and possibly avoid lead in the environment. P. laevis was affected negatively by the presence of lead nitrate and showed a loss in body mass. More than 86% of the total body burden of lead was compartmentalized in the hepatopancreas. The isopods were capable of avoiding leaves contaminated with 200 mg kg–1 lead nitrate in behavioural tests but did not avoid leaves contaminated with a higher concentration.

Locating food in a spatially heterogeneous environment: Implications for fitness of the macrodecomposer Armadillidium vulgare (Isopoda: Oniscidea)

Article

Oct 2005

To assess the fitness consequences of foraging on patchy resources, consumption rates, growth rates and survivorship of Armadillidium vulgare were monitored while feeding in arenas in which the spatial distribution of patches of high quality food (powdered dicotyledonous leaf litter) was varied within a matrix of low quality food (powdered grass leaf litter). Predictions from behavioural experiments that these fitness correlates would be lower when high quality food is more heterogeneously distributed in space were tested but not supported either by laboratory or field experiments. To investigate whether A. vulgare can develop the ability to relocate high quality food patches, changes in foraging behaviour, over a comparable time period to that used in the fitness experiments, were monitored in arenas in which there was a high quality food patch in a low quality matrix. A. vulgare increased its ability to relocate the position of high quality food over time. It reduced time spent in low quality food matrices and increased time spent in high quality food patches with time after the start of the experiment. When the position of a high quality food patch was moved, the time spent in the low quality food matrix increased and less time was spent in high quality food patches, compared to arenas in which the food was not moved. The fitness benefits for saprophages of developing the ability to relocate high quality patches while foraging in spatially heterogeneous environments are discussed.

Intestinal Microbiota of Terrestrial Isopods

Chapter

Jan 2006

Ectomycorrhizal fungi

Technical Report

Full-text available

Sep 1998

Jean-François Ponge

The role of mycorrhizal fungi in the stability of ecosystems is still poorly known and deserves more attention. The present review is focused on ectomycorrhizal fungi and their relationships with processes such as tree growth, litter decomposition and forest dynamics.

Trophic interactions as indicators of ecosystem regeneration in disturbed grasslanda stable isotope approach ;

Article

Jan Rothe

Short-Term Toxicological Effects of Cadmium on the Woodlouse,Porcellio laevis(Crustacea, lsopoda)

Article

Jun 1999

Terrestrial isopods have been used in a number of studies as test organisms concerning the effects of chemicals in a (eco-)toxicological context. They are saprophages, which are in direct contact with polluted plant material. Cadmium is a metal with no known biological function and is toxic to life. There are a variety of anthropogenic sources of cadmium in the environment. The aims of this study were to determine the LC50 for cadmium sulfate for Porcellio laevis and the acute effect of this metal salt on the mass of this species and also to determine if P. laevis could distinguish and avoid cadmium sulfate-contaminated leaves. Acute toxicity tests and behavioral tests were conducted using concentrations ranging from 10,000 to 40,000mg/kg cadmium sulfate. The LC50 obtained of 26,700 mg/kg cadmium sulfate is an indication of P. laevis' tolerance to cadmium contamination. P. laevis also exhibited the ability to distinguish and avoid leaves contaminated with high cadmium sulfate levels.

Nutrition in terrestrial isopods (Isopoda: Oniscidea)

Article

Dec 2002

Martin Zimmer

The nutritional morphology, physiology and ecology of terrestrial isopods (Isopoda: Oniscidea) is significant in two respects. (1) Most oniscid isopods are truly terrestrial in terms of being totally independent of the aquatic environment. Thus, they have evolved adaptations to terrestrial food sources. (2) In many terrestrial ecosystems, isopods play an important role in decomposition processes through mechanical and chemical breakdown of plant litter and by enhancing microbial activity. While the latter aspect of nutrition is discussed only briefly in this review, I focus on the evolutionary ecology of feeding in terrestrial isopods.

Behavioural response in paired food choice experiments with Oniscus asellus (Crustacea, Isopoda) as an indicator of different food quality

Article

Full-text available

Oct 2003
Arch Ind Hyg Toxicol

Pheromones, 97. The Sex Pheromone Complex of the Female Arctiid Moth Thyria jacobaeae (Lepidoptera, Arctiidae)

Article

Full-text available

Jun 2014
Z NATURFORSCH C

By means of gas chromatographic, mass spectrometric methods and combined GC-electroantennogramm techniques as well as activity comparison with pheromones of related species (3Z,6Z)-c/s-9,10-epoxyeicosadiene 1 and (3Z,6Z)-cis-9,10-epoxyheneicosadiene 2 were identified as the biological active components of the sex pheromone complex of the female arctiid moth Thyria jacobaeae

Isopod distribution in a heterogeneous grassland habitat

Article

Full-text available

Jan 1991

Hornung Elisabeth

The function of chemo- and mechanoreceptors in lobster (Homarus americanus) feeding behavior

Article

Full-text available

Jun 1982

The behaviour of lobsters preying on live mussels (Mytilus edulis) was observed before and after chemosensory or chemosensory-mechanosensory deafferentation of different sensory appendages. Deafferentation of the antennules, leg tips, or maxillipeds (but not the carapace or proximal leg segments) interfered with feeding performance by causing an increase in the time necessary to crush a mussel after search initiation. In addition, deaf-ferentation of the leg tips or the maxillipeds caused a decline in number of mussels crushed but for different reasons: leg-treated lobsters walked over the mussels without picking them up, whereas maxilliped-treated lobsters grasped the mussels as usual but either did not crush or did not eat them as readily as did normal lobsters. Deafferentation of leg chemoreceptors resulted in the same behavioural deficiencies as deafferentation of leg chemo-and mechanoreceptors, demonstrating that it is the leg chemoreceptors that are essential in releasing this grasping response. Chemoreceptors on different appendages of lobsters therefore fulfill different functional roles in their feeding behaviour.

Habitat selection in the Carabidae

Article

Jan 1983

W.G. Evans

A factorial analysis of distribution in three species of diplopods

Article

Jan 1957

C.A. Barlow

Die Sinnesorgane der Antennula von Porcellio scaber Latr. (Crustacea, Isopoda)

Article

Jan 1977

H. Risler

Water regulation in terrestrial isopods, with comments on their behavior in a stimulus gradient

Article

Jan 1968

O.V. Lindqvist

Humidity reactions of the young of the terrestrial isopods Porcellio scaber Latr and Tracheoniscus rathkei (Brandt)

Article

O. Lindqvist

Morphological and comparative studies on the second antennae of terrestrial isopods

Article

Jan 1989

B. Hoese

Fungal Odour Discrimination in Two Sympatric Species of Fungivorous Collembolans

Article

Dec 1995

1. Resource partitioning of two sympatric species of collembolans, Orchesella cincta and Tomocerus flavescens, was explored from differences in their food odour perception. 2. Preferences of the collembolans of odours from four fungal species and a green alga were tested in a Y-tube olfactometer. The collembolans were separated by only one difference in odour preference; Cladosporium herbarum was significantly more attractive to O. cincta than the other food sources, whereas T. flavescens was most attracted to Mortierella isabellina. 3. Fungal odours were trapped in an activated carbon filter, extracted with diethylether and subjected to GC-MS analysis. The analysis revealed a number of differences in the odour composition of the two fungal species but the odour of C. herbarum could not be distinguished from that of C. cladosporioides, which was lower ranked by O. cincta. 4. Nine fungal odour compounds were used in an electroantennogram (EAG) assay. There were differences in antennal responses between the collembolan species to 2-methyl-1-propanol, dipentene, 1-octanol and camphor. The identity of the compounds responsible for attracting O. cincta to C. herbarum and T. flavescens to M. isabellina could not be resolved. A cluster analysis of the EAG responses emphasized the physiological origin of the differences in food preferences between the two collembolan species and suggested that P. cincta was more variable in its odour perception than T. flavescens.

Electrophysiological Studies of Arthropod Chemoreception. III. Chemoreceptors of Terrestrial and Fresh-Water Arthropods

Article

Aug 1958

Edward S. Hodgson

1. Electrophysiological tests with externally applied, fluid-filled electrodes were performed upon thirty-seven species representing four classes of arthropods. Afferent chemoreceptor impulses were recorded in animals of five types: a crayfish (Cambarus), a millipede (Pseudopolydesmus), two orthopterans (Ceuthophilus and Hadenoecus), a helomyzid fly (Amoebaleria), and six species of butterflies.2. Receptors sensitive to chemical, tactile, and temperature stimuli within normal physiological ranges are found in certain Lepidoptera (Epargyreus and Limenitis) and Diptera (Amoebaleria). Receptors with a dual sensitivity to at least two of the above types of stimulation are found in Pseudopolydesmus, Ceuthophilus, and Hadenoecus. It is concluded that multiple sensitivities of receptors are not exceptional in arthropods.3. Chemoreceptors sensitive to amino acids, but insensitive to tactile and temperature stimuli, are found on the chelae and protopodites of the first two walking legs of Cambarus bartonii scioten...

Chemically mediated habitat recognition in shore insects (Coleoptera: Carabidae; Hemiptera: Saldidae)

Article

May 1988

W G Evans

Adults of 14 species of Carabidae and mixed nymphs and adults of two species of Saldidae, collected in habitats associated with a saline lakeshore, sedge fen, vernal pond, stream mud flat, salt spring, mud and sand river bank, pebble river bank, and a marine sand beach, aggregated in choice chambers above volatiles (allelochemics) collected from their habitats. In other tests adults of some carabid species responded to volatiles from habitats other than their own, and to arbitrarily selected individual components and mixtures of components of saline lakeshore volatiles. These results suggest that shore insects recognize habitat allelochemics and aggregate in areas where these compounds are emitted by resident microflora. It is proposed that some habitat allelochemics are short-range signals that indicate locations of microhabitats used by shore insects for behaviors such as feeding, mating, and resting; in contrast, long-range allelochemics allow these insects to select their habitats from a distance. This hypothesis provides a mechanism for explaining how different shore habitats are partitioned among different species of shore insects.

Chemosensory induced bradycardia in the kelp crab, Pugettia producta (Randall)

Article

Apr 1979
J EXP MAR BIOL ECOL

Bradycardia was induced in specimens of Pugettia producta (Randall) by chemical stimulation of the branchial chamber with synthetic clam extract. Chemical stimulation of the dactyls, antennules, and mouthparts did not effect cardiac inhibition. Stimulation of the branchial chamber with amino acids and sugars evoked cardiac inhibition that was significantly greater than that induced by sea-water controls. Of the sugars tested, disaccharides were generally found to have a greater capacity to induce bradycardia than monosaccharides. The possibility of a disaccharide or polysaccharide receptor is discussed. Taurine and β-alanine induced bradycardia was significantly greater than that effected by other amino acids. All tested amino acids were, however, at least mildly effective (P < 0.10): thus it appears that several types of amino-acid receptors are likely to exist. Response amplitude, a measure of the relative change in heart rate over the first 15 sec following initial stimulus application, and response duration were found to be positively correlated. In addition, both amplitude and duration were found to depend on the concentration and type of chemical used as stimulus. Stimulation of the branchial chamber with water-soluble petroleum fraction (20–25 ppm) also induced bradycardia. It appears that the mode of action of the water-soluble petroleum fraction mimics that of other tested amino-acid and sugar solutions.From these results and from observations described by other investigators, it is apparent that the branchial chamber is a major chemoreceptive site in decapod crustaceans.

Response characteristics and specificity of chemoreceptors in Hemilepistus reaumuri (Crustacea, Isopoda)

Article

Jun 1983

Giinter Seelinger

1.Chemoreceptor units were investigated electrophysiologically in the apical sensory cone on the antenna of the desert isopod,Hemilepistus reaumuri. Activity of 141 single units was recorded from fibres in the antennal nerve.2.The receptors responded to a variety of chemical substances with excitation up to 300 imp/s or with inhibition. They were classified into distinct physiological response types with non-overlapping response spectra (Table 1).3.Two physiological response types were excited by airborne odour stimuli: (a) butyric acid cells were sensitive to short-chain fatty acids and aldehydes (Table 3); (b) amine cells responded to short-chain mono- and diamines (Table 5).4.Four groups of gustatory cells were found: (c) sugar cells responded to several sugars and a-glucosides (Table 6); (d) calcium cells were excited by CaCl2 which was inhibitory in most other cells; (e) amino acid cells were found in only two cases, responding to 1-asparagine and 1-methionine; (f) 29 cells responded only to an aqueous rinse of desert woodlice, and not to other stimuli tested.5.Olfactory cells responded to n-fatty acids (namines, respectively) with phasic-tonic excitation at low concentrations, but with phasic excitation followed by an off-response at higher concentrations (Figs. 1, 3). Complete inhibition could be caused by applying still higher concentrations of the same substances.6.Transition from phasic-tonic to phasic responses occurred at low initial impulse frequencies with some stimulus substances, but at high initial frequencies with other substances in the same receptor cell (Figs. 1, 3). Chain length of the stimulus molecule influenced phasic-tonic behaviour in a different manner in both olfactory cell groups (Tables 2, 4).7.No influence of stimulus concentration on time course was found in sugar cells (Figs. 4a, b, 5). There were, however, remarkable differences in the poststimulatory frequency decay for different sugars (Fig. 4a, b).

Der Antennenendzapfen der tunesischen W??stenasselHemilepistus reaumuri, ein komplexes Sinnesorgan (Crustacea, Isopoda)

Article

Jan 1977

Gfinter Seelinger

The apical sensory cone on the antenna of a terrestrial isopod,Hemilepistus reaumuri, was investigated by both morphological and electrophysiological methods. It was found to consist of about 50 hair-like units, each containing 3–11 receptor cells which communicate with the environment through an apical porus. Single fiber recordings in the antennal nerve showed activity of receptor cells responding to mechanical, gustatory or olfactory stimuli. Two groups of olfactory and four groups of gustatory receptors were found.

Odor-mediated responses of Bembidion obtusidens (Coleoptera: Carabidae) in a wind tunnel

Article

Dec 1984
CAN ENTOMOL

W. G. Evans

Cyanobacterial mats of Oscillatoria spp., found in the habitat of Bembidion obtusidens, a halophilic carabid beetle, emit metabolites that act as allelochemic attractants to these insects. In a wind tunnel designed for use with small, fast-running carabid beetles, B. obtusidens adults responded to a homogeneously dispersed wind-borne mixture of these allelochemics by walking upwind. These results suggest that wind-borne metabolites of Oscillatoria spp. could act as distant chemical cues that invoke positive, odor-mediated anemotaxis in migrant B. obtusidens, enabling them to locate their habitat.

The Distribution of Length and Components of the Sum of $n$ Random Unit Vectors

Article

Jun 1955
Ann Math Stat

Statistical problems involving angular observations may arise in diverse scientific fields, either from direct measurement of angles--say the direction of winds or of glacial pebbles or of fracture planes--or they may arise from the measurement of times reduced modulo some period and converted into angles--say time of day when train wrecks occur. Specifically, we consider a set of $n$ points $\xi_\nu$ situated on a unit circle and assumed to constitute a sample from a distribution having the p.d.f. $g(\xi)$, where $0 \leqq \xi < 2\pi$. Let the $n$ random unit vectors thus defined have the components $\sin \xi_\nu$ and $\cos \xi_\nu$, and set \begin{equation*}\tag{0.1} V = \sum \cos \xi_\nu,\quad W = \sum \sin \xi_\nu,\quad R = \sqrt{V^2 + W^2}.\end{equation*} Let $P(r, n)$ be the probability that $R \leqq r$, and let $Q = 1 - P(r, n)$. This paper shows how the statistics $V$ and $R$ provide tests for the uniform distribution $g(\xi) = 1/2\pi$. The distribution of $R$ on the hypothesis of uniformity was derived by Kluyver as a solution to Pearson's random walk problem, and is tabulated here for use in significance tests. The distribution of $V$ is derived here, but has not been calculated. To illustrate the type of tests that might employ the statistics $R$ and $V$, consider a carnival wheel--first from the standpoint of the punter who suspects bias, second from the standpoint of the mechanic who has attempted to introduce bias. The punter, by studying the performance of the wheel, might wish to answer two questions: first, does the wheel differ credibly from an unbiased wheel? second, what is the direction and extent of the bias, if any? An answer to the first question is obtainable from the distribution of $R$, and an answer to the second has been provided by Mises. The mechanic, on the other hand--because he knows the direction of the bias, if there is a bias--might better use the statistic $V$ as a test of his success, and he might appropriately modify the Mises approach in estimating the extent of the bias.

The effect of acquired microbial enzymes on assimilation efficiency in the common woodlouse, Tracheoniscus rathkei

Article

Jun 1986

The digestive tract of the common woodlouse, Tracheoniscus rathkei Brandt (Isopoda: Oniscoidea), contains digestive enzymes active against α-1,4-glucans, which are the chief storage polysaccharides of vascular plants, algae, fungi, and animals, and β-1,3-glucans, which are present in algae and fungi. Digestive tract extracts also exhibit significant activity toward xylan and carboxymethyl-cellulose but negligible activity toward microcrystalline cellulose, substrates representative of the major structural polysaccharides of vascular plants. Low activity was detected toward pectin, and no activity was detected toward chitin. Activity toward xylan is due in part to microbial enzymes acquired from the leaf litter which was the isopod's normal food. Although ingested microbial xylanases are stable and active in the gut fluid, they do not make a quantitatively significant contribution to the isopod's ability to assimilate the hemicellulosic component of its diet. However, the assimilation of carbon from labeled plant fiber is enhanced in isopods which have acquired a cellulase by ingestion of leaf litter amended with a commercial preparation of the cellulase complex from the fungus, Penicillium funiculosum . This result demonstrates the potential contribution of acquired enzymes to the digestion of plant fiber in terrestrial detritivores. We urge caution, however, in assigning an important digestive function to ingested enzymes on the basis of evidence that only indicates that such enzymes are present in the gut fluid without additional evidence that their presence results in an enhancement of digestive efficiency. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/47763/1/442_2004_Article_BF00377057.pdf

Wind-orientation in running insects

Article

Feb 1973
Progr Zool

K. Eduard Linsenmair

Habits and social behavior of the desert woodlouse Hemilepistus aphaganicus Borutzky 1958

Article

Oct 1971
Z Tierpsychol

P Schneider

Olfaction in terrestrial isopods (Crustacea: Oniscidea): Responses of Porcellio scaber to the odour of litter

Abstract

No full-text available

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