Synchronous moulting of krill,<Emphasis Type="Italic"> Euphausia superba</Emphasis>, in the Bransfield Strait (Antarctica)

A large mass of cast exoskeletons of the Antarctic krill Euphausia superba was fished in February 2001 at one station in the Bransfield Strait between 411 and 153 m. We assume that the mass of cast exoskeletons originated from a synchronous moult of thousands of individuals. Depending on the size of the krill moulted, the amount of exoskeletons corresponded to a krill abundance of 1,480–48,000 individuals per 1,000 m³.     

Frugivore assemblage of <Emphasis Type="Italic">Ficus superba</Emphasis> in a warm-temperate forest in Yakushima,Japan

Understanding fig consumption patterns is important because figs are regarded as a keystone resource for many frugivorous species in the tropics. While much work on fig consumption has been conducted in tropical regions, temperate forests are particularly interesting for study owing to pronounced seasonal variations in temperature and community-level fruiting phenology. We studied frugivore consumption of Ficus superba (Miq.) Miq. var. japonica Miq syconia in a warm-temperate forest in Yakushima, southern Japan. We conducted 141 4-h focal observations of fruiting F. superba trees over 12 months. We aimed to assess the relative quantitative contribution of each species of frugivore to F. superba consumption over a year as well as factors affecting seasonal variation in consumption. Japanese macaques were by far the most important F. superba syconia consumer (87.6 %), followed by brown-eared bulbuls (5.0 %), and varied tits (4.2 %). Japanese macaques increased their F. superba consumption when the temperature was high and fruit availability (F. superba and other species) was low. Macaques seemed to avoid searching for rare F. superba trees during winter and used F. superba syconia as a fallback food during fruit scarcity. Birds showed the opposite pattern: they increased F. superba syconia consumption when the temperature was low and fruit availability was high. This was probably because birds eat insects as their main food in the summer and switch to fruit as autumn turns to winter.     

The biology of the spiny icefish <Emphasis Type="Italic">Chaenodraco wilsoni</Emphasis> Regan, 1914

The most abundant ice fish species observed in catches off the northern tip of the Antarctic Peninsula in the last 25–30 years has been the spiny ice fish Chaenodraco wilsoni Regan 1914. C. wilsoni has been exploited on a commercial scale from the late 1970s to the end of the 1980s off Joinville–D’Urville Islands (CCAMLR Statistical Subarea 48.1) and in the Cosmonauts and Cooperation Seas and Prydz Bay in the Indian Ocean sector (CCAMLR Statistical Division 58.4.2). This paper presents new information on biological features and life history characteristics of C. wilsoni, based on research survey collections along the northern Antarctic Peninsula in 2006 and 2007 and samples taken in the commercial fishery in 1987. Length frequency compositions from the research surveys demonstrated that fish 21–34 cm long predominated in the catches. Sexual maturity is attained at 24–25 cm. Absolute fecundity and relative fecundity is low (1,000–2,500 eggs; 6–12 eggs). Oocyte diameter varied from 4.0 to 4.9 mm very close to spawning. Spawning at the tip of the Antarctic Peninsula is likely to occur in October–November. Remotely operated vehicle deployments in the northern Weddell Sea demonstrated that C. wilsoni exhibit parental nest guarding where males protect the eggs. The incubation period is likely to be 8 months long. Fish feed primarily on Antarctic krill (Euphausia superba) in the Antarctic Peninsula region and in the Cosmonauts and Cooperation Seas while fish take ice krill (Euphausia crystallorophias), Pleuragramma antarcticum and myctophids to some extent in other areas. Age determination still awaits validation. Preliminary ageing attempts suggested a maximum age of about 8–10 years.     

Structural changes in the digestive glands of larval Antarctic krill (<Emphasis Type="Italic">Euphausia superba</Emphasis>) during starvation

The effects of starvation on ultrastructure of digestive gland cells were studied in furcilia larvae of Antarctic krill (Euphausia superba: hereafter krill). Under laboratory conditions, larvae were starved for 0, 5, 10, 15, 20 and 25 days, and their R-cells were investigated by transmission electron microscope. R-cells are thought to play a role in the storage and absorption of nutrients. In fed larvae, numerous mitochondria scattered homogenously, and densely packed microvilli were observed on the apical surface of R-cells. After 5 days of starvation, mitochondria were swollen and were found concentrated in the apical region in R-cells. A decrease in cell volume and an increase in thickness of the basal lamina with many irregular infoldings were observed after 10–15 days of starvation. Lipid droplets were rarely found in the R-cells regardless of whether larvae had been fed or starved suggesting an inability to store lipid. Without the ability to store energy in the form of lipid, survival would be dependant on sourcing continuous food until maturation.     

Assessing population-level variation in the mitochondrial genome of <Emphasis Type="Italic">Euphausia superba</Emphasis> using 454 next-generation sequencing

The Antarctic krill (Euphausia superba Dana 1852) is widely distributed throughout the Southern Ocean, where it provides a key link between primary producers and upper trophic levels and supports a major commercial fishery. Despite its ecological and commercial importance, genetic population structure of the Antarctic krill remains poorly described. In an attempt to illuminate genetic markers for future population and phylogenetic analysis, five E. superba mitogenomes, from samples collected west of the Antarctic Peninsula, were sequenced using new 454 next-generation sequencing techniques. The sequences, of lengths between 13,310 and 13,326 base pairs, were then analyzed in the context of two previously-published near-complete sequences. Sequences revealed relatively well-conserved partial mitochondrial genomes which included complete sequences for 11 of 13 protein-coding genes, 16 of 23 tRNAs, and the large ribosomal subunit. Partial sequences were also recovered for cox1 and the small ribosomal subunit. Sequence analysis suggested that the cox2, nad5, and nad6 genes would be the best candidates for future population genetics analyses, due to their high number of variable sites. Future work to reveal the noncoding control region remains.     

The fungicidal activity of an extracellular glycolipid from <Emphasis Type="Italic">Sympodiomycopsis paphiopedili</Emphasis> sugiyama <Emphasis Type="Italic">et al.</Emphasis>

The yeast Sympodiomycopsis paphiopedili (Ustilaginomycetes) produces an extracellular glycolipid, which possesses the maximum antifungal activity at a pH of the medium equal to 4.0–4.5. Among the approximately 300 tested species of yeastlike and mycelial fungi, more than 80% (including species pathogenic for plants, animals, and humans) were found to be sensitive to this glycolipid.Translated from Mikrobiologiya, Vol. 73, No. 6, 2004, pp. 841–845.Original Russian Text Copyright © 2004 by W. Golubev, T. Kulakovskaya, E. Kulakovskaya, N. Golubev.     

<Emphasis Type="Italic">Wolbachia</Emphasis> Infections of the Whitefly <Emphasis Type="Italic">Bemisia tabaci</Emphasis>

We report the first systematic survey for the presence of Wolbachia endosymbionts in aphids and whiteflies, particularly different populations and biotypes of Bemisia tabaci. Additional agriculturally important species included were predator species, leafhoppers, and lepidopterans. We used a polymerase chain reaction (PCR)-based detection assay with ribosomal 16S rDNA and Wolbachia cell surface protein (wsp) gene primers. Wolbachia were detected in a number of whitefly populations and species, whitefly predators, and one leafhopper species; however, none of the aphid species tested were found infected. Single, double, and triple infections were detected in some of the B. tabaci populations. PCR and phylogenetic analysis of wsp gene sequences indicated that all Wolbachia strains found belong to group B. Topologies of the optimal tree derived by maximum likelihood (ML) and a ML tree in which Wolbachia sequences from B. tabaci are constrained to be monophyletic are significantly different. Our results indicate that there have been at least four independent Wolbachia infection events in B. tabaci. The importance of the presence of Wolbachia infections in B. tabaci is discussed. RID= ID= <E5>Correspondence to: </E5>K. Bourtzis; <E5>email:</E5> kbourtz&commat;cc.uoi.gr Received: 9 September 2002 / Accepted: 25 September 2002     

The developmental rate ofEuphausia crystallorophias larvae in Ellis Fjord,Vestfold Hills,Antarctica

 Euphausia crystallorophias is the dominant zooplankton species in the neritic seas of Antarctica, where it occurs in similar abundances to those of Euphausia superba in more offshore areas. Despite its great abundance and probable ecological significance, few details are known of this species’ development, life history and ecology. This study found that E. crystallorophias spawned in Ellis Fjord from late November to early December and completed its larval development under the sea ice during the Antarctic winter. The mean time for E. crystallorophias eggs to develop to furcilia stage VI was 235.5 days, which is virtually identical to the developmental time already reported in the laboratory, but almost twice that of E. superba. This slow development rate is likely to be due either to the low water temperatures (<0^°C) in which E. crystallorophias lives, or to low levels of food being available over winter. Received: 30 August 1995/Accepted: 11 December 1995     

Studying allozyme variation in sexual and apomictic <Emphasis Type="Italic">Taraxacum</Emphasis> and <Emphasis Type="Italic">Pilosella</Emphasis> (Asteraceae) populations

Allozyme spectra of peroxidase, esterase, superoxid dismutase, tyrosinase, alcohol dehydrogenase, lactate dehydrogenase, and acid phosphatase were examined in populations of sexual (Taraxacum serotinum and Pilosella echioides) and apomictic (T. officinale and P. officinarum) plant species. The heterozygosity in these populations (0.455–0.620) proved to be considerably higher than the average level characteristic of plant populations (0.058–0.185). The populations examined did not differ in the mean phenotype number , i.e., they exhibited the same diversity (3.188–3.380). The proportion of rare phenotypes h also did not differ between the sexual and apomictic species of the same genus, whereas this parameter in the Pilosella populations (0.150–0.174) was significantly higher than in the Taraxacum ones (0.093–0.114). The populations were characterized by numerous isozyme spectra (more than 11 per populations) and displayed multiple allelism (the mean allele frequency was 3.63–4.38 per locus). They exhibited a high percentage of rare (occurring at a frequency lower than 5%) spectra (35–80%). This indicates that agamic complexes, to which these populations belong, may have a more complicated genetic structure of both apomictic and sexual populations than the species that do not belong to agamic complexes.Translated from Genetika, Vol. 41, No. 2, 2005, pp. 203–215.Original Russian Text Copyright © 2005 by Kashin, Anfalov, Demochko.     

Molecular detection of <Emphasis Type="Italic">Rickettsia</Emphasis>, <Emphasis Type="Italic">Coxiella</Emphasis> and <Emphasis Type="Italic">Rickettsiella</Emphasis> DNA in three native Australian tick species

Three Australian native animal species yielded 60 samples composed of three indigenous ticks. Hosts included twelve koalas, two echidnas and one wombat from Victoria, and ticks were of the species Ixodes tasmani (n = 42), Bothriocroton concolor (n = 8) and B. auruginans (n = 10), respectively. PCR screening and sequencing detected a species of Coxiella, sharing closest sequence identity to C. burnetii (>98%), in all B. auruginans, as well as a species of Rickettsia, matching closest to R. massiliae, in 70% of the same samples. A genotype sharing closest similarity to Rickettsia bellii (>99%) was identified in three female B. concolor collected from one of the echidnas. Three samples of I. tasmani, taken from three koalas, yielded different genotypes of Rickettsiella. These results represent the first detection of the three genera in each tick species and identify a high level of previously undetected bacterial diversity in Australian ticks.     

Physiological responses to water stress in<Emphasis Type="Italic"> Eucalyptus cloeziana</Emphasis> and<Emphasis Type="Italic"> E. argophloia</Emphasis> seedlings

Effects of water stress duration and intensity on gas exchange and leaf water potential were investigated in 7-month-old seedlings of a humid coastal provenance (Gympie) and a dry inland (Hungry Hills) provenance of E. cloeziana F. Muell. and in a dry inland (Chinchilla) provenance of E. argophloia Blakely supplied with 100% (T₁₀₀), 70% (T₇₀), 50% (T₅₀) of their water requirements, or were watered only after they were wilted at dawn (T₀). Seedlings of E. argophloia had the highest midday net photosynthetic rate (A), stomatal conductance (g _s), stomatal density and predawn leaf water potential (_pd) in all treatments. The E. cloeziana provenances did not differ in these attributes. The T₇₀ and T₅₀ treatments caused reductions in A of 30% in E. argophloia, and 55% in the E. cloeziana provenances. Under the T₀ treatment, E. argophloia maintained higher rates of gas exchange at all levels of water stress than E. cloeziana provenances. The estimates of _pd and midday water potential (_md) at which plants remained wilted overnight were respectively: –2.7 and –4.1 MPa for E. cloeziana (humid), –2.8 and –4.0 MPa for E. cloeziana (dry) and, –3.7 and –4.9 MPa for E. argophloia. Following stress relief, both A and g _s recovered more quickly in E. argophloia and in the dry provenance of E. cloeziana than in the humid provenance. We conclude that E. argophloia is more drought tolerant and has a potential for cultivation in the humid and semi humid climates, whilst E. cloeziana has greater potential in the humid subtropical climates.     

Prevalence,intensity and associated factor analysis of <Emphasis Type="Italic">Tropilaelaps</Emphasis><Emphasis Type="Italic">mercedesae</Emphasis> infesting <Emphasis Type="Italic">Apis</Emphasis><Emphasis Type="Italic">mellifera</Emphasis> in China

Tropilaelaps mercedesae is a serious ectoparasite of Apis mellifera in China. The aim of this study was to investigate the infestation rates and intensity of T. mercedesae in A. mellifera in China, and to explore the relative importance of climate, district, management practices and beekeeper characteristics that are assumed to be associated with the intensity of T. mercedesae. Of the 410 participating apiaries, 379 apiaries were included in analyses of seasonal infestation rates and 352 apiaries were included in multivariable regression analysis. The highest infestation rate (86.3%) of T. mercedesae was encountered in autumn, followed by summer (66.5%), spring (17.2%) and winter (14.8%). In autumn, 28.9% (93) of the infested apiaries were in the north (including the northeast and northwest of China), 71.1% (229) were in the central and south (including east, southeast and southwest China), and 306 apiaries (82.9%) were co-infested by both T. mercedesae and Varroa. Multivariable regression analysis showed that geographical location, season, royal jelly collection and Varroa infestation were the factors that influence the intensity of T. mercedesae. The influence of beekeeper’s education, time of beekeeping, operation size, and hive migration on the intensity of T. mercedesa was not statistically significant. This study provided information about the establishment of the linkage of the environment and the parasite and could lead to better timing and methods of control.     

Dynamics of Microbial Populations and Strong Selection for <Emphasis Type="Italic">Cycloclasticus pugetii</Emphasis> following the <Emphasis Type="Italic">Nakhodka</Emphasis> Oil Spill

Microbial population changes were monitored immediately after the Nakhodka oil spill accident in January 1997 at the heavily oil-contaminated Mikuni coast along the Sea of Japan. The total cell number was almost stable for one year at 2–5 × 10⁵ cells mL^–1, while the relative occurrence of culturable heterotrophs and degraders of oil components such as C-heavy oil, kerosene, and n-tetradecane varied, showing a maximum (>50% of the total) immediately following the accident. Gene amplification and phylogenetic analysis of a dilution culture using C-heavy oil as the sole carbon and energy source revealed that one of the predominant oil degraders at the oil-contaminated coast in 2 weeks after the accident closely resembled the aromatic hydrocarbon decomposer Cycloclasticus pugetii. Microbial community composition in oil-contaminated seawater was estimated at the molecular level using newly developed oligonucleotide probes, probe wash-off curve estimation, and quantitative fluorescence dot-blot hybridization techniques. At two different oil-polluted sites, harbor and intertidal regions, the C. pugetii group was estimated to make up 23–25% of the total Bacteria population, followed by the aliphatic hydrocarbon decomposer Alcanivorax borkumensis, which formed 4–7% of the Bacteria. In incubation experiments using floated oil slick and indigenous microbes collected at the harbor, oil degradation activities were enhanced by the addition of both organic and inorganic nutrients. Significant decreases were found in aromatic and aliphatic hydrocarbon fractions: 54–60% and 22–24% in 2 weeks to 68–77% and 23–32% in 2 months, respectively.     

Regeneration from leaf-base explants of <Emphasis Type="Italic">Lolium perenne</Emphasis> L. and <Emphasis Type="Italic">Lolium multiflorum</Emphasis> L.

The regenerability of Lolium perenne and Lolium multiflorum was investigated using leaf-base sections excised from plantlets grown in vitro. Young leaf bases were cut into three sections each 2 mm in length, the lowest 0–2 mm section adjacent to, but not including, the apical meristem. Callus development followed by embryogenesis occurred only in the lowest 2 mm leaf-base sections of L. perenne cv. Limes, whereas L. multiflorum leaf bases showed an embryogenic response along the entire 6 mm section. Rooted, green plantlets were obtained from 100% of the 0–2 mm sections of L. perenne cv. Limes and from 91%, 65% and 26% of leaf-base sections at 0–2, 2–4 and 4–6 mm respectively from L. multiflorum. Microprojectile bombardment of leaf-base explants resulted in transient expression of the -glucuronidase gene.     

Induction of streptomycin-resistant plantlets in <Emphasis Type="Italic">Solanum surattense</Emphasis> through <Emphasis Type="Italic">in vitro</Emphasis> mutagenesis

The species Solanum surattense Burm.f. has importance in ayurvedic medicine and also as vegetable. Streptomycin-resistant plantlets were induced showing chloroplast encoded mutants in S. surattense from mutagenised (ethyl methane sulphonate and gamma-rays) cotyledon explants. Chloroplast encoded – streptomycin resistant – shoots were developed from green (unbleached) sectors of the cotyledons. The streptomycin-resistant plants were similar to parental plants in morphology and ploidy level (2n=2x=24). Reciprocal crosses between streptomycin-resistant and the original streptomycin sensitive plants have shown the non-Mendelian transmission under the control of chloroplast – DNA. These antibiotic resistant plants are useful in designing biochemical selection schemes aimed at somatic hybrid/cybrid recovery in S. surattense.     

Temperature- and Light-Dependent Performance of the Cyanobacterium <Emphasis Type="Italic">Leptolyngbya Foveolarum</Emphasis> and the Diatom <Emphasis Type="Italic">Nitzschia Perminuta</Emphasis> in Mixed Biofilms

This paper investigates the role of species interactions as a mechanism determining the changing seasonal abundance of microphytobenthic species. Different kinds of interactions can occur between microphytobenthic species, e.g., interference competition (a species directly hindering the growth of another) or resource competition. If such interactions are strong, the capacity of species to exploit parts of the seasonal spectrum of temperature and light conditions could be greatly affected. A model system of two freshwater benthic phototrophs, the cyanobacterium Leptolyngbya foveolarum (Rabenhorst ex Gomont) Anagnostidis et Komárek and the diatom Nitzschia perminuta (Grunow) M. Pergallo, was used to study the capacity of each species to grow in ranges of temperature (7, 15 and 25 °C) and light (5, 40 and 200 μmol m⁻² s⁻¹) conditions in single-species and two-species cultures. Growth was followed for 14–17 days by measuring chlorophyll a and maximum photosynthetic capacity using spectrophotometry and pulse amplitude modulated (PAM) fluorimetry. A PHYTO-PAM fluorimeter facilitated simultaneous observations in mixed cultures on the two species. In mixed cultures, the diatom appeared to be a ‘cool season species’ (low temperature and low light intensity) and the cyanobacterium a ‘summer or autumn species’ (higher temperature and light intensities). This is different than predicted by monoculture experiments, where a wide range of optimal growth conditions was found. Two-species biofilm tests indicated inhibitory effects of the cyanobacterium on the diatom species, especially under conditions favorable to the cyanobacterium. High or low light intensities, increase of local pH caused by depletion of inorganic carbon, and limitation of other inorganic nutrients (resource competition) were examined as factors contributing to diatom inhibition, but none provided an acceptable explanation for observed growth patterns. Our results pointed towards interference competition.     

Prevalence of <Emphasis Type="Italic">Edwardsiella tarda</Emphasis> in Antarctic wildlife

For many years, the Antarctic region has been isolated from human activity. However, there is little data available regarding endemic and exotic diseases. The purpose of this work was to determine the prevalence of Edwardsiella tarda in Antarctic wildlife, including birds, mammals and fish. During the summer of 2000 and 2002 in the Potter Peninsula, and during the summer of 2001 and 2003 in Hope Bay, a total of 1,805 faecal samples from Antarctic animals and 50 infertile eggs of Adelie penguins (Pygoscelis adeliae) were collected in order to isolate E. tarda. The classic Edwardsiella tarda was isolated from 281 (15.1%) of the 1,855 Antarctic wildlife samples. This is the first report of E. tarda isolation from southern giant petrels (Macronectes giganteus), brown skuas (Stercorarius lonnbergi), south polar skuas (Stercorarius maccormicki), kelp gulls (Larus dominicanus), greater sheathbills (Chionis albus), chinstrap penguins (Pygoscelis antarctica), eggs of Adelie penguins and Weddell seals (Leptonychotes weddelli). None of the evaluated animals showed clinical signs of disease. Our results suggest that E. tarda is a common bacterium amongst Antarctic birds and mammals.     

Spatio-temporal variation of colony structure and eusociality level of the Japanese sweat bee<Emphasis Type="Italic"> Lasioglossum</Emphasis> (<Emphasis Type="Italic">Evylaeus</Emphasis>)<Emphasis Type="Italic"> duplex</Emphasis> (Hymenoptera: Halictidae)

Colony structure and eusociality level of the sweat bee Lasioglossum (Evylaeus) duplex were studied in 2001 in Sapporo and Assabu, Hokkaido, northern Japan. Sakagami and his colleagues had also studied this species in Sapporo in 1957–1968. Brood size, sex ratio and queen–worker size dimorphism were geographically and temporally variable, indicating spatio-temporal variation at the eusociality level. Inseminated workers constituted only 7.9% of the populations in 1957–1968 Sapporo but about 60% in 2001 in Sapporo and Assabu. A few of the inseminated workers were believed to leave natal nests for independent colony founding. Thus, partial bivoltinism is likely in this sweat bee species. The presence of workers with developed ovaries and/or corpora lutea suggests the occurrence of worker oviposition.     

Specificity of <Emphasis Type="Italic">Anagyrus</Emphasis> sp. nov. nr. <Emphasis Type="Italic">sinope</Emphasis> and <Emphasis Type="Italic">Leptomastix dactylopii</Emphasis> for six mealybug species

In order to understand better non-target effect and potential uses, the host specificity of two parasitoid species (Anagyrus sp. nov. nr. sinope Noyes & Menezes and Leptomastix dactylopii Howard) (both Hymenoptera: Encyrtidae) for six mealybug species [Ferrisia virgata (Cockerell), Phenacoccus madeirensis Green, Phenacoccus solani Ferris, Planococcus citri (Risso),Pseudococcus longispinus (Targioni-Tozzetti) and Pseudococcus viburni (Signoret)] (all Hemiptera: Pseudococcidae) was studied through behavioral observations and laboratory rearing. The selected mealybug species represent major subfamilies and tribes of Pseudococcidae. Except for F. virgata, all mealybug species induced examinations by Anagyrus sp. nov. nr. sinope and L. dactylopii. Anagyrus sp. nov. nr. sinope was specific to P. madeirensis, which was the only mealybug species selected for oviposition and suitable for complete development of the parasitoid. No encapsulation of Anagyrus sp. nov. nr. sinope in P. madeirensis was observed. Leptomastix dactylopii accepted multiple species for oviposition, with the ranking of species preference as P. citri > P. viburni > P. longispinus > P. solani > P. madeirensis. Only P. citri, P. longispinus and P. viburni supported the development of L. dactylopii. Parasitoids developing in P. longispinus and P. viburni suffered from high encapsulation rates, while no encapsulation was observed when developing in P. citri. The results of this study suggest that Anagyrus sp. nov. nr. sinope is highly host specific. Leptomastix dactylopii, on the other hand, has a wider host range. The use of Anagyrus sp. nov. nr. sinope in a mealybug biological control program is limited to P. madeirensis and L. dactylopii to P. citri. The results presented in this study also lead us to question the accuracy of the reported host range of L. dactylopii, which include all six mealybug species tested.