Olfactory orientation in some land-isopods (oniscoidea, crustacea)

Isopods absorb water during the day in their humid shelters. They come out at night to evaporate water. This behaviour is part of their osmoregulatory system.When searching for a suitable place to spend the next day they may be guided by different stimuli. Smell might be one of them.This was tested in an olfactometer with slowly flowing air and in an apparatus with stationary air. It appears that each of the three species tested reacts positively to its own specific smell. In some cases also positive reactions to the smell of other species were observed.The reactions are more positive as the desiccation of the animals is more advanced. Furthermore there may be a slightly negative reaction in animals fully saturated with water.This conforms with the fact that they seek shelter, and therefore must react positively to smell after their nightly desiccation excursion, and that they have to leave their shelter when they have accumulated excess of water and must therefore move away from the smell.

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Zummenfassung Isopoden nehmen tagsüber in ihren feuchten Verstecken Wasser auf. Während der Nacht kommen sie heraus und verdunsten dann Wasser. Wenn sie am Ende der Nacht wieder ein Versteck aufsuchen, können sie von verschiedenen Reizen geleitet werden. Auch olfaktorische Reize könnten dabei eine Rolle spielen.Die Reaktion von 3 Isopoden-Arten wurde in einem Olfaktometer in langsam strömender Luft geprüft. Dabei zeigte sich, daß jede Art auf ihren artspezifischen Duft reagiert, zum Teil aber auch auf den anderer Arten. Die Zahl der positiven Reaktionen ist dabei um so größer, je mehr die Tiere ausgetrocknet sind; bei hohem Wassergehalt wurden mehr negative Reaktionen beobachtet.Diese Wahrnehmungen lassen sich gut in unsere Vorstellung über das Verhalten der Tiere einfügen. Nach dem Austrocknen während der Nacht müssen sie zum Aufsuchen ihres Versteckes positiv auf Duftreize reagieren. Sie verlassen ihre Verstecke, wenn sie viel Wasser aufgenommen haben, und brauchen dann nicht positiv, sondern eher negativ auf den Geruchs-gradienten zu reagieren.

     

Experimental studies on homing in the intertidal patellid limpetCellana tramoserica (Sowerby)

Summary A model of two-dimensional random walk was developed to allow statistical tests for the presence of homing behaviour in intertidal populations of the limpetCellana tramoserica. Not all limpets return to a home-site after feeding excursions. Some move around at random. The latter pattern of movement was tested to justify the assumptions of the model. Limpets can stop homing and begin to move at random; moving limpets can become homers. Thus, random movement and consistent homing behaviour are not discrete patterns of behaviour in a population.Controlled field experiments showed that the proportion of animals which home is not affected by the height on the shore, force of wave action, the cover of macroalga, nor the irregularity of the substratum. Small limpets, however, home more than large ones.Close proximity to other homing limpets causes individuals to stop homing and move away. Alterations of density demonstrated thatCellana shows density-dependent dispersal. More limpets emigrate from areas of increased density and more immigrate into areas of decreased density, when compared with control areas. Less animals immigrate into, and remain in, areas from which microalgal food was experimentally removed. More animals emigrate from these areas.These experiments support the hypothesis that homing behaviour is an adaptation which regulates local density and dispersion to maximize utilization of food resources and, thus, to reduce intraspecific competition for food at high densities of limpets.     

Further studies on Mouthpart Receptors in decapoda crustacea

Summary In the lobster Homarus gammarus (L.) (=Homarus vulgaris M. Ed.) three bilateral groups of proprioceptors are arranged around the mouth. These strand receptor organs, termed Mouthpart Receptors (MPRs) 1, 2 and 3, were described previously and their physiological responses, mainly to mandibular movements, were characterised (Laverack and Dando, 1968).The receptor organs are described here for Panulirus argus Latr., Nephrops norvegicus L. and Astacus leptodactylus Esch.. Because of the anatomical differences between the receptors in Panulirus and Homarus the physiological work on Panulirus was designed to characterise the responses of the receptor neurones in some detail. The input from the receptors studied was similar to that of the Homarus receptors. In Nephrops and Astacus where the anatomy is similar to that of Homarus we have demonstrated that these receptors form a non-specialised system which responds to many of the movements associated with the act of ingestion of food.It is suggested that with other work now in progress, particularly on the innervation of the mandible (Wales and Laverack, 1970), a reasonably complete summary of the proprioceptive input associated directly with food ingestion is now possible. The relevance of this work to studies on the stomatogastric ganglia is discussed, and finally an attempt is made to compare the crustacean information with that for several insect species where the anatomy of the receptors in the mouth region is known but physiological experiments are much more difficult.This work was supported partly by the Centre National de la Recherche Scientifique (Equipe de Recherche Associée No. 231).This represents contribution No. 487 from the Bermuda Biological Station. Work carried out in Bermuda was supported by the Science Research Council (B/SR/4866).     

Ecological studies on Chaoborus (Diptera, Chaoboridae) in Lake George, Uganda

(1) Chaoborus anomalus and Chaoborus ceratopogones were found together throughout the year in Lake George, Uganda, the larvae forming 65-85% by number of the macro-benthos of the central lake area. (2) First and second instar larvae were wholly planktonic and third and fourth instar larvae mainly benthic during the day, migrating into the water column at night. A proportion of the third and fourth instar larvae were found in the water column during the day in the centre of the lake where light attenuation was greatest. C. anomalus showed a greater tendency to be benthic than C. ceratopogones. (3) Planktonic larvae were distributed in dense patches thought to be cohorts resulting from oviposition by swarms of adult females. The maximum density of planktonic larvae recorded was 31.7 × 10²/m² column. Third and fourth instar larvae were more evenly distributed in the benthos of the central lake area, the maximum density recorded was 79.9×10²/m². (4) First and second instar larvae occurred mainly in the inshore regions, very few were found in the centre of the lake. Oviposition is likely to take place inshore. The patches of planktonic larvae were not stationary. Dispersal of larvae away from the shore may be active or may result from complex oscillations of the water mass produced by storms. In C. ceratopogones the floating egg batches could he carried away from the north shore by currents produced by inflows and prevailing winds. (5) Adults of C. ceratopogones were more numerous during the rainy seasons than during the dry seasons. A similar, though less marked seasonality was found in the occurrence of C. anomalus adults. The biomass of benthic larvae of C. ceratopo-gones was estimated at 387.0 mg C/m² in the dry season, June 1970, and 130 0 mg C/m² in the rainy season, October 1970. That of C. anomalus was constant at 241.7 and 254.3 mg C/m² in June and October, 1970 respectively. (6) No difference was found in the horizontal distribution of the larvae, or in the size and weight attained by the various stages. (7) Interspecific differences were found in the mean number of eggs per adult female (309, C. anomalus and 224, C. ceratopogones); in the nature ofthe egg batches; n i the morphology of the larval mouthparts and pharyngeal sphincters, as well as i n the vertical distribution of the larvae and seasonal occurrence of the adults. On the basis of these differences the co-existing species are thought not to be competing for the same resources.     

Immunochemical study of oniscoidea hemocyanins (crustacea,terrestrial isopods)

• 1.1. The hemocyanins from six Oniscoidea species are compared by agar immunodiffusion and by quantitative immunoprecipitation.
• 2.2. The hemocyanins of the investigated species give an immunoprecipitation reaction whatever antihemocyanin antiserum was used.
• 3.3. The antigenic structure of the Oniscoidea hemocyanins is based on the presence of five or six antigenic determinants; the number of common determinants between the hemocyanins increases with the systematic proximity of the species.
• 4.4. A model of a phylogenetic species separation is proposed from the antigenic distances between the hemocyanins found by quantitative immunoprecipitation.

     

Spermiogenesis in two species ofNebalia leach (crustacea,malacostraca, phyllocarida)

Summary Spermiogenesis inNebalia pugettensis andN. sp. of the subclass Phyllocarida was investigated by transmission electron microscopy. Spermiogenesis is almost identical in the two species. Early spermatids are found in groups with several nuclei in a common cytoplasm. Specializations of the cell surface appear as small, scattered dense knobs underlying the cell membrane. The spermatids become separated but are kept together by a surrounding vegetative cell, which produces a hyaline secretion. The secretion hardens to a capsule surrounding a number of spermatids. Maturation of the spermatids takes place within the secretion. The cells become dense and compact, the cytoplasm vacuolizes, and the mitochondria show signs of degeneration. The centrioles disappear and the surface of the cell becomes irregular and spiny, as the knobs, present in the early spermatids, develop into small spines. Spermatozoa from a spermatophore are small and compact spiny cells without polarity, with a vacuolized cytoplasm and degenerating mitochondria. Acrosomal structures and axonema or flagellum are absent in all developmental stages of theNebalia sperm.     

Ecological studies on five species of endangered Himalayan poppy, Meconopsis (Papaveraceae)

Ecological studies were carried out on 19 endangered populations of Meconopsis horridula, M. paniculata, M. simplicfolia, M. sinuata and M. villosa from the Sikkim Himalayas. The populations of M. horridula, M. paniculata and M. sinuata inhabit open alpine slopes, those of M. simplicfolia are restricted to alpine meadows, while those of M. villosa are confined to the interiors of temperate forests and along forest fringes. The habitats of these species remain snow-hound from October to February. Analyses suggest that all the species except M. horridula , have a broad area of distribution, but narrow habitats and niches. All five species are confined to moist, clayey to silty soils with acidic pH, high concentrations of organic matter, nitrate, phosphate, potassium and calcium. M. paniculata is a 'generalist', whereas all other species investigated are 'specialists'.     

Global biodiversity and phylogenetic evaluation of remipedia (crustacea)

Remipedia is one of the most recently discovered classes of crustaceans, first described in 1981 from anchialine caves in the Bahamas Archipelago. The class is divided into the order Enantiopoda, represented by two fossil species, and Nectiopoda, which contains all known extant remipedes. Since their discovery, the number of nectiopodan species has increased to 24, half of which were described during the last decade. Nectiopoda exhibit a disjunct global distribution pattern, with the highest abundance and diversity in the Caribbean region, and isolated species in the Canary Islands and in Western Australia. Our review of Remipedia provides an overview of their ecological characteristics, including a detailed list of all anchialine marine caves, from which species have been recorded. We discuss alternative hypotheses of the phylogenetic position of Remipedia within Arthropoda, and present first results of an ongoing molecular-phylogenetic analysis that do not support the monophyly of several nectiopodan taxa. We believe that a taxonomic revision of Remipedia is absolutely essential, and that a comprehensive revision should include a reappraisal of the fossil record.     

Growth and reproduction of eyestalk ablated penaeus canaliculatus (Olivier, 1811) (crustacea:Penaeidae)

The effects of single (unilateral) eyestalk ablation on the growth and reproduction of male and female Penaeus canaliculatus (Olivier) were compared with those of unablated (control) individuals. Prawns ≤ 10 mm in carapace length ablated in the premoult stage suffered high mortality. Prawns recognized as immature when ablated always moulted irrespective of their moulting stage; ovaries in females did not become vitellogenic nor did spermatogenesis occur in males. Mature females ablated in the premoult stage underwent moulting while those in the postmoult stage developed mature ovaries. Mature males in the postmoult or intermoult stages took longer to moult than those that were in the premoult stage when ablated. The Von Bertalannfy equations describing growth in P. canaliculatus were as follows: L_t = 25.6 [1−e^{−0.0756(t−t_o)}]for ablated males; L_t = 25.3 [1−e^{−0.059(t−t_o)}] for unablated males; L_t= 37.2 [1−e^{−0.048(t−t_o)}] forablated females; L_t = 33.4 [1−e^{−0.044(t−t_o)]} for unablated females. Differences in the growth rates were a result of both the moulting frequency and the increment in size at moult. However, the relative contribution of these two factors to growth varied with sex as well as with size. In both sexes, ablated individuals became sexually mature earlier; females spawned earlier. Although moulting frequency and the total number of spawns were greater for ablated females, the mean number of eggs produced (per spawn as well as total) by unablated females was higher and the mean hatching success was better.     

Ecological studies on the parasite complex associated with typhlocybine leafhoppers (Homoptera, Cicadellidae)

Abstract.

• 1 The parasite complex associated with nymphal and adult typhlocybine leafhoppers consists of the following: Dryinidae (Aphelopus species), Pipunculidae (Chalarus species) and Diapriidae (Ismarus dorsiger Curtis), the last being parasitic on species of Aphelopus.
• 2 The life cycles and temporal distribution patterns of twenty-nine species of Typhlocybinae are summarized together with the life cycles of British Aphelopus and Chalarus.
• 3 Closely related primary parasite species differ in their adult emergence times. Species differences in adult emergence times of diapausing Chalarus are correlated with species differences in host relations.
• 4 Each primary parasite genus contains both monophagous and polyphagous species. Each polyphagous species shows a distinct ‘preference’ for a particular range of hosts.
• 5 The parasite complexes of different leafhopper communities are compared, and it is concluded that it is the taxonomic composition of the leafhopper communities which is chiefly responsible for the structure and taxonomic composition of their associated parasite complexes.
• 6 Individual species of both Aphelopus and Chalarus show a degree of sensitivity to the physiology of their hosts, so achieving a high degree of synchrony.

     

The male copulatory system of european pea crabs (crustacea,brachyura, pinnotheridae)

The male copulatory system of the European pinnotherid species Pinnotheres pisum, Pinnotheres pectunculi, and Nepinnotheres pinnotheres was investigated by gross morphology, scanning electron microscopy, histological methods, and confocal laser scanning microscopy. The brachyuran copulatory system is consistently formed by paired penes and two pairs of abdominal appendages, the gonopods, functioning in sperm transfer. In pinnotherids, the long first gonopods transfer the sperm mass into the female ducts. The first gonopod has the ejaculatory canal inside that opens both basally and distally. The second gonopod is solid, short, and conical. During copulation, the penis and the second gonopod are inserted into the basal lumen of the first gonopod. While the penis injects the sperm mass, the second gonopod functions in the transport of spermatozoa inside the ejaculatory canal toward its distal opening. The second gonopod is adapted for the sealing of the tubular system in the first gonopod by its specific shape and the ability to swell. Longitudinal cuticle foldings of the second gonopod hook into structures inside the first gonopod. The second gonopod can interact with the penis during copulation by a flexible flap separating the lumina in which the second gonopod and the penis are inserted. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.     

Studies on a natural population of Cyclestheria hislopi (Baird) (Conchostraca: crustacea)

The present paper adds further notes on the biology of Cyclestheria hislopi (Baird). An attempt has been made to study the variation in the natural population of this species based on its birth-rate. C. hislopi has dist inct preference for the plant Hydrilla verticellata (Royle) on which they remain attached. It is considered completely parthenogenic, having no males. The period from October to January can be considered to be the growth period for this species, after which the population declines. This decline has been found to be due to the low birth-rate exhibited during the subsequent months.     

An intertidal Rhabdopleura (Hemichordata, Pterobranchia) from Fiji

Rhabdopleura has been discovered living in coral rubble on reefs in Fiji. The habitat is unusual, being the underside of coral boulders in the intertidal zone. Some features of the environment and the fauna associated with the Rhabdopleura are briefly described. The Rhabdopleura zooids exhibit other modes of tube building besides the regular cylindrical horizontal and erect tubes. The colony ramifies through interstices in the dead coral and the zooids can line larger cavities within the coral with coenecial tissue. It is probably these cavities, together with the overall porosity of coral, that retain enough water to keep the zooids alive while the intertidal reef flat is exposed to the air. Within the depths of the coral the black stolons are frequently naked. The species is probably R. normani Allman.     

Carbohydrate metabolism during osmoregulation in Chasmagnathus granulata dana, 1851 (crustacea,decapoda)

• 1.1. Since glucose is one of the main energetic substrates for general metabolic processes in crustaceans, analysis of carbohydrate levels can furnish information on the energy metabolism of intact animals during osmoregulation.
• 2.2. Different groups of Chasmagnathus granulata were transferred to different salinities (0 and 40%), and the glucose and glycogen concentrations in blood, gills, muscle and hepatopancreas were determined at the beginning of the experiment and 24, 72, 168 and 360 hr after the salinity changes.
• 3.3. Differences in tissues carbohydrate levels were observed between summer and winter, that reflected differences in reserve mobilization.
• 4.4. In the summer, hypo- and hyperosmotic shocks induced an increase in carbohydrate levels in almost all tissues studied, indicating gluconeogenesis.
• 5.5. In the winter, a carbohydrate mobilization occurred only in the gills and hepatopancreas after both osmotic shocks.
• 6.6. Thus, the substrate reserve used for energy production required for osmoregulation seems to be dependent on the season and tissues.

     

Follicle duct cell ultrastructure and eggshell formation in Triops cancriformis (crustacea,notostraca)

Electron microscopy of the cells of the follicle duct of Triops cancriformis shows that the follicular ducts are lined by a single-layered epithelium which also produces the eggshell material. The cytoplasm is rich in rough endoplasmic reticulum that synthesizes the eggshell material which subsequently aggregates into preformed vacuoles. Newly formed spheres of eggshell material are then excreted into the lumen. At the end of vitellogenesis the oocytes descend toward the longitudinal oviduct and pass through the eggshell material which fills the follicle ducts. The production of the eggshell and its chemical composition in some Phyllopoda are compared. The paper discusses the relationship between the eggshell construction and the reproductive biology of the population.     

Amphipoda (crustacea) from palau, micronesia: families ampeliscidae, ampithoidae, aoridae, colomastigidae and cyproideidae

12 species of amphipod in 5 families, collected from shallow reefs in Palau by S. DeGrave during 2002, are reported here. Of these, five species are new to science and Microdeutopus tridens Schellenberg (1938) is redescribed and transferred to the genus Bemlos Shoemaker (1925). The collection included several additional species in the genera Amphilochus Bate, 1862, Ampithoe Leach (1814), Bemlos, Byblis Boeck (1871), Colomastix Grube (1861) and Notopoma Lowry & Berents (1996), that were either incomplete or juvenile and could therefore not adequately be described. In addition, two new species of Plumithoe Barnard & Karaman (1991) are erected from the literature. Other families collected in Palau will be considered in later contributions.     

Ecological, morphological and molecular studies on Ganaspis individuals (Hymenoptera: Figitidae) attacking Drosophila suzukii (Diptera: Drosophilidae)

Ganaspis individuals parasitizing Drosophila suzukii (Matsumura), a pest of fruit crops, were examined for host use and molecular and morphological differences from those attacking D. lutescens Okada and some other Drosophila species that breed on fermenting fruits. Wild cherry fruits were collected in the suburbs of Tokyo, and drosophilid pupae obtained from these fruits were examined for parasitism. Drosophila suzukii was the only drosophilid species infesting fresh wild cherry fruits, and Ganaspis individuals were the major parasitoids attacking D. suzukii in wild cherry fruits. In parasitism experiments, these Ganaspis individuals parasitized D. suzukii larvae in fresh cherry fruits, but did not parasitize those in Drosophila medium. In addition, they did not parasitize larvae of some other fruit-feeding Drosophila species even when these occurred in fresh cherry fruit. These Ganaspis individuals parasitizing D. suzukii were different from those parasitizing D. lutescens and some other drosophilids in nucleotide sequences of the COI gene, as well as in ITS1 and ITS2. They were also different in forewing and antenna morphology, although they showed some overlap in morphological traits. They are tentatively assigned as the suzukii- and lutescens-associated types of G. xanthopoda Ashmead. In the present field survey, Leptopilina japonica Novkovi? & Kimura and some Asobara species were also observed to attack D. suzukii larvae in wild cherry fruit.