Small-scale spatial resource partitioning in a hyperparasitoid community

Plant-herbivore-natural enemy associations underpin ecological communities, and such interactions may go up to four (or even more) trophic levels. Here, over the course of a growing season, we compared the diversity of secondary hyperparasitoids associated with a common host, Cotesia glomerata, a specialized larval endoparasitoid of cabbage butterfly caterpillars that in turn feed on brassicaceous plants. Cocoon clusters of C. glomerata were pinned to ~30 Brassica nigra plants by pinning them either to branches in the canopy (~1.5 m high) or to the base of the stem near the ground. The cocoons were collected a week later and reared to determine which hyperparasitoid species emerged from them. This was done in four consecutive months (June–September). Cocoons placed in the canopy were primarily attacked by specialized winged hyperparasitoids (Lysibia nana, Acrolyta nens), whereas cocoons on the ground were attacked by both winged and generalist wingless hyperparasitoids (Gelis acarorum, G. agilis), although this changed with season. There was much more temporal variation in the diversity and number of species attacking cocoons in the canopy than on the ground; the abundance of L. nana and A. nens varied from month to month, whereas P. semotus was only prevalent in August. By contrast, G. acarorum was abundant in all of the samples placed near the ground. Our results show that hyperparasitoids partition host resources at remarkably small vertical spatial scales. We argue that spatial differences in the distribution of natural enemies can contribute to the diversity patterns observed in the field.     

Reproduction of Lumbricillus rivalis (Levinsen) in laboratory cultures and in decaying seaweed

The cocoon production of 144 Lumbricillus rivalis cultured in pairs at 10 ± 1 °C was high over the first 2 weeks of breeding activity and then declined, chiefly because of high mortality. Cocoon deposition lasted for between 1 and 16 weeks, eight pairs of worms producing cocoons for 9 weeks and one pair for 16 weeks. During the total period of cocoon deposition over 9000 eggs (mean 17·4 per cocoon) were deposited. Two decaying wrack bed populations of L. rivalis showed a low level of cocoon and egg production in autumn, rising to an annual maximum in late winter/early spring. In these populations the mean egg content varied seasonally from 17·1 to 47·8 eggs per cocoon. When cocoons in the laboratory were transferred from the site of deposition to incubation dishes 31% hatched, but those left in the substrate showed a 92% hatch. In the naturally occurring populations 19% of the cocoons detached from seaweed fronds hatched, but 62% of those left in situ. Eggs and worm embryos developed to relatively late stages in most cocoons, whatever the rate of hatching; development often continued for up to 2 months after deposition without hatching. Over 50% of the fertile eggs in cocoons from decaying wrack hatched and developed to 5 mm worms.     

The lipopolysaccharides (O-antigens) of Rhodopseudomonas viridis

The present paper deals with the isolation, and chemical and serological characterization of the O-antigens (lipopolysaccharides, LPS) of the photosynthetic gram-negative bacterium Rhodopseudomonas viridis. The LPS are extractable with hot phenol/water, but unlike the phenol-soluble LPS of the closely related species Rhodopseudomonas palustris, the R. viridis O-antigens are preferentially extracted into the water phase. A mixture of phenol/chloroform/petroleum ether (PCP-method) does not extract the R. viridis LPS. All R. viridis LPS investigated belong to the same chemotype, the polysaccharide moiety of these O-antigens being composed of 3-O-methyl-l-xylose, 3-O-methyl-d-mannose, d-mannose, d-galactose, d-glucose, in addition to 2-keto-3-deoxyoctonate (KDO), glucosamine, 6-deoxyglucosamine (quinovosamine) and galactosamine uronic acid. The R. viridis O-antigens are clearly distinguishable from the l-glycero-d-mannoheptose containing O-antigens of R. palustris by the lack of this sugar (and of any other heptose) in the R. viridis LPS. The lipid moiety (lipid A) of the R. viridis O-antigen can be split off from the LPS by mild acid hydrolysis. Like lipid A from R. palustris, it differs remarkably from the well known lipid A of Enterobacteriaceae, in that d-glucosamine is replaced by a recently identified 2.3-diamino-2.3-dideoxyhexose in the R. viridis and R. palustris lipid A. Unlike enteric lipid A the R. viridis lipid A is phosphate-free and includes as the only fatty acid β-C₁₄OH which is exclusively amide-linked. All R. viridis strains belong to the same serotype so far as investigated, as shown by passive hemagglutination with the isolated O-antigens and rabbit antisera against heat-killed cells.     

A micro-culture technique for the mitogen stimulation of lymphocytes fromMacaca mulatta (rhesus) andMacaca fascicularis (cynomolgus)

A micro-culture technique was developed to determine the optimum culture conditions for the mitogen stimulation of lymphocytes fromMacaca mulatta (rhesus) andMacaca fascicularis (cynomolgus). The optimum concentrations of PHA and Con A ranged from 10–50 µg/culture, those of lymphocytes from 1?2×10⁵ cells/culture, and those of serum from 10–20%. Tritiated thymidine was used at a concentration of .04µCi/culture.     

Efficient plant regeneration from shoot apex explants of maize (Zea mays) and analysis of genetic fidelity of regenerated plants by ISSR markers

An efficacious regeneration system was developed from shoot apex explants of Zea mays using a two-step culture procedure. Seventeen Indian genotypes were assessed for their regeneration potential. The maximum response of shoot induction was obtained from explants cultured on Murashige and Skoog medium supplemented with 4.5 µM thidiazuron and 26.7 µM glycine. Maximum mean number of shoots (17.2) was observed in genotype COH (m)-5 while NPK was the least responsive (6.7). Shoot clumps transferred from shoot induction medium to multiplication (second) medium amended with 1.1 µM thidiazuron and 0.88 µM N ₆ -benzylaminopurine showed increased number of shoots in COH (m)-5 (36.1 shoots); NPK was the least responsive with an average of 9.5 shoots. The best response in root induction, with a larger number of roots (10.5) and longer roots (6.6 cm), was observed in Murashige and Skoog medium supplemented with 7.3 µM indole-3-butyric acid and 7.9 µM phloroglucinol. Analysis of variance indicated that plant regeneration response varied greatly among the genotypes. In vitro raised plants were successfully transferred to the field after hardening, with a 99 % survival rate. Inter simple sequence repeats analysis revealed that the similarity matrix pair-wise value was 1, the Mantel test value was p 1.0; Analysis of molecular variance genetic variances were 93 % within the population and 7 % between populations; Principal component jolliffe cut off was 0.15, Principal component and Principle coordinate analysis % variance was 13.19. These values were congruent for both the mother and the in vitro-raised plants, confirming genetic integrity.     

Myriophyllum quitense (Haloragaceae) in the United States

A systematic study of more than 15,000Myriophyllum specimens from 189 North American herbaria yielded 63M. quitense specimens. Late 19th century collections were made from Henry's Fork of the Snake River in Jefferson County, Idaho, in 1872, from Santa Cruz Creek, Tucson, Pima County, Arizona, in 1881, from Yellowstone Lake in 1885, and from Crook County, Oregon, in 1894. Twentieth century collections have been made from Yellowstone National Park, at several sites along the Snake River in Idaho, in Summit County, Utah, in Lassen and Shasta counties of northern California, at numerous sites along the Deschutes River, and in Benton County, Oregon, and at three sites in Washington. We contend that the species was introduced into North America by migratory waterfowl more than 100 years ago. Only in the Yellowstone Lake and numerous Deschutes River habitats in which populations now exist are environmental conditions conducive to full morphological development of the species in North America.     

Seasonal dynamics and emergence pattern of a tropical earthworm,Drawida calebi (Oligochaeta)

Cocoon morphology (shape, size, colour and ornamentation), hatching, and seasonal dynamics of cocoon and juveniles of D. calebi have been studied in an Indian pasture site. The average live weight of cocoon is 15.17 mg, length/diameter 0.94, and moisture content 72.5 g%. Just-hatched juveniles weigh on an average 10.4 mg, and are 10.5–17.5 mm in length. The incubation period lasts 56.33 ± 2 days during November—December in laboratory cultures (25°C, and moisture 15 g%). A maximum of 64.0 live cocoons/m² with a live weight of 0.971 g/m² were deposited during October—November 1977, but very few during summer months. A surface-living species, D. calebi shows single peak emergence pattern in December—January. It is estimated that 78 cocoons (live and dead)/m² (780,000/hectare), were produced in the field by D. calebi population in a year (1976–77). Thus the total cocoon production is 11.83 kg/hectare/year. It is estimated that 3 cocoons/individual/year are produced by D. calebi in field conditions.     

Analysis of amino acids by HPLC/electrospray negative ion tandem mass spectrometry using 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl) derivatization

A new method for the determination of amino acids is presented. It combines established methods for the derivatization of primary and secondary amino groups with 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl) with the subsequent amino acid specific detection of the derivatives by LC–ESI–MS/MS using multiple reaction monitoring (MRM). The derivatization proceeds within 5 min, and the resulting amino acid derivatives can be rapidly purified from matrix by solid-phase extraction (SPE) on HR-X resin and separated by reversed-phase HPLC. The Fmoc derivatives yield several amino acid specific fragment ions which opened the possibility to select amino acid specific MRM transitions. The method was applied to all 20 proteinogenic amino acids, and the quantification was performed using l-norvaline as standard. A limit of detection as low as 1 fmol/µl with a linear range of up to 125 pmol/µl could be obtained. Intraday and interday precisions were lower than 10 % relative standard deviations for most of the amino acids. Quantification using l-norvaline as internal standard gave very similar results compared to the quantification using deuterated amino acid as internal standards. Using this protocol, it was possible to record the amino acid profiles of only a single root from Arabidopsis thaliana seedlings and to compare it with the amino acid profiles of 20 dissected root meristems (200 μm).     

Parasitism byPerilitus coccinellae [Hym.: Braconidae] of indigenous coccinellid hosts and the introducedCoccinella septempunctata [Col.: Coccinellidae], with notes on winter mortality

Parasitism ofCoccinella septempunctata L. byPerilitus coccinellae (Schrank) varies seasonally with an 11% overall rate among beetles overwintering in the Hackensack Meadowlands, which is less than that reported in Europe.P. coccinellae may parasitizeC. 7-punctata twice yearly. FemaleC. 7-punctata were parasitized more heavily than males. Although parasitism byP. coccinellae varied significantly among host species, it was not significantly different among 3 habitats. High host density favored greater parasitism in 3 coccinellid species. Rearing for parasite cocoons, consistently showed lower parasitism rates than did dissection for parasitized larvae. Overwintering survival of cagedC. 7-punctata near Stillwater, OK, varied between years averaging 53,5%. Infection of overwinteringC. 7-punctata byBeauveria bassiana (Balsamo) was 1,6% in 1978–1979.     

Glycosylation and subsequent malonylation of isoflavonoids in E. coli: strain development,production and insights into future metabolic perspectives

Genistin and daidzein exhibit a protective effect on DNA damage and inhibit cell proliferation. Glycosylation and malonylation of the compounds increase water solubility and stability. Constructed pET15b-GmIF7GT and pET28a-GmIF7MAT were used for the transformation of Escherichia coli and bioconversion of genistein and daidzein. To increase the availability of malonyl-CoA, a critical precursor of GmIF7MAT, genes for the acyl-CoA carboxylase α and β subunits (nfa9890 and nfa9940), biotin ligase (nfa9950), and acetyl-CoA synthetase (nfa3550) from Nocardia farcinia were also introduced. Thus, the isoflavonoids were glycosylated at position 7 by 7-O-glycosyltranferase and were further malonylated at position 6^″ of glucose by malonyl-CoA: isoflavone 7-O-glucoside-6^″-O-malonyltransferase both from Glycine max. Engineered E. coli produced 175.7 µM (75.90 mg/L) of genistin and 14.2 µM (7.37 mg/L) genistin 6″-O-malonate. Similar conditions produced 162.2 µM (67.65 mg/L) daidzin and 12.4 µM (6.23 mg/L) daidzin 6″-O-malonate when 200 µM of each substrate was supplemented in the culture. Based on our findings, we speculate that isoflavonoids and their glycosides may prove useful as anticancer drugs with added advantage of increased solubility, stability and bioavailability.     

Biosystematics of Aletris lutea Small,Aletris obovata Nash,and natural hybrids (Liliaceae)

Hybrids ofAletris lutea XA. obovata were found to occur extensively throughout the area of overlapping distribution of the two species in Florida and in southern Georgia. Hybrids were found only in disturbed habitats near the parental species. Colonization and dispersal of species and of hybrids were probably implemented by roadside maintenance operations. Fertility was high despite the high incidence of quadrivalent formation in parent and hybrid plants. Since all quadrivalents observed were aligned adjacently and since fertility is relatively high, it is suggested that duplicated chromosomes were present. It is further suggested thatAletris represents a tetraploid with a base number ofx = 6 or 7 that either lost or gained one pair of chromosomes to result inn = 13. Introgression in disturbed habitats is favored by zonation of plants in hybrid swarms, phenology of parents and hybrids, and pollinator behavior.     

Egg diapause and demographic strategy in Lepidocyrtus lignorum Fabricius (Collembola; Entomobryidae)

In this study we found that the surface-dwelling Collembolan Lepidocyrtus lignorum reproduces mainly in autumn. Eggs have a diapause terminated by cold. Hatching occurs synchronously in spring, producing a distinct cohort I. The species overwinters in different stages of postembryonic development, primarily as adults. Some of the overwintering animals lay non-diapause eggs in late spring and summer. This reproduction results in a second, less synchronized cohort II. The egg diapause cannot be explained as an adaptation for winter survival, but it ensures that hatching will occur at an optimal time for low juvenile mortality. Cohort I differs phenologically from all other surface-dwelling Collembola in the area, and we suggest that the timing effect of the diapause reduces interspecific interactions. Cohort II, hatching together with other surface-dwelling species, showed higher mortality than cohort I. The differential mortality of the two cohorts, however, is influenced by environmental conditions. After part of the study area had been clear cut, cohort II gradually increased in dominance. This effect of environmental changes may explain the dimorphic reproductive strategy of L. lignorum.     

Effect of habitat characteristics on the distribution and abundance of damselfish within a Red Sea reef

For coral reef fish with an obligate relationship to their habitat, like Pomacentrid damselfish, choosing a suitable home amongst the reef structure is key to survival. A surprisingly small number of studies have examined patterns in adult damselfish distributions compared to other ontogenetic phases. The aim of this study was to determine which reef and coral colony characteristics explained adult damselfish distribution patterns in a Red Sea reef. The characteristics investigated were reef type (continuous or patchy), coral species (seven species of Acropora), and coral morphology (coral size and branching density). The focal damselfish species were Dascyllus aruanus, D. marginatus, Chromis viridis, and C. flavaxilla. Occupancy (presence or absence of resident damselfish), group size and fish species richness were not significantly different between the seven Acropora species. However, within each coral species, damselfish were more likely to occupy larger coral colonies than smaller coral colonies. Occupancy rates were also higher in patchy reef habitats than in continuous sections of the reef, probably because average coral colony size was greater in patchy reef type. Fish group size increased significantly with coral colony volume and with larger branch spacing. Multi-species groups of fish commonly occurred and were increasingly likely with reduced branching density and increased coral size.     

Differences in surface-dwelling beetles of grasslands invaded and non-invaded by goldenrods (Solidago canadensis,S. gigantea) with special reference to Carabidae

We evaluated surface-dwelling Coleoptera with special reference to ground beetles (Coleoptera: Carabidae) using pitfall traps across fourteen stands of grasslands invaded and non-invaded by invasive goldenrods (Solidago canadensis L. and S. gigantea Ait.) over a 3 year period. We analysed differences in assemblages of invaded and non-invaded grasslands and tested responses of surface-dwelling beetles and carabids to invasion of goldenrods. We identified 29 Coleoptera families and 91 Carabidae species. Solidago invaded grasslands showed significantly higher activity-abundance of rove and carrion beetles and supported greater diversity and significantly higher evenness of surface-dwelling Coleoptera and the number of sampled families and individuals was higher too. We found lower taxonomic richness and significantly lower activity-abundance of carabids across goldenrods stands. Several less common Carabidae species and significantly higher representation of stenotopic brachypterous habitat specialists were also observed within invaded stands. We confirmed that differences in plant cover connected with invasion of goldenrods, soil moisture and abandonment of invaded habitats are the driving mechanisms of changes in surface-dwelling Coleoptera and ground beetles assemblages composition across Solidago invaded grasslands. Overall, changes of grassland biotopes connected with invasion of goldenrods significantly alter Coleoptera families and Carabidae assemblages, but not necessarily reduce diversity.     

<Emphasis Type="Italic">Neoascarophis sinensis</Emphasis> n. sp. (Nematoda: Cystidicolidae), a parasite of <Emphasis Type="Italic">Conger myriaster</Emphasis> (Brevoort) (Anguilliformes: Congridae) in Chinese waters

Neoascarophis sinensis n. sp. collected from the whitespotted conger Conger myriaster (Brevoort) (Anguilliformes: Congridae) in the Yellow and East China Seas, is described using both light and scanning electron microscopy. The new species is characterised mainly by the body size (8.5–10.5 mm in the males, 9.5–14.0 mm in the females), the location of the vulva (near equatorial region of the body), the non-bifurcate deirids, the lengths of the vestibule (40–50 µm in the males, 30–60 µm in the females) and glandular oesophagus (2.5–3.1 mm in the males, 3.1–3.5 mm in the females) and the morphology and length of the spicules (left spicule 400–410 µm, right spicule 130–150 µm). Neoascarophis sinensis n. sp. is the first species of Neoascarophis Machida, 1976 reported from the anguilliform fish and is also the only species of this genus found in the Chinese waters.     

Detection and characterization of phosphatidylcholine in various strains of the genus Chlamydomonas (Volvocales,Chlorophyceae)

The laboratory strains of Chlamydomonas reinhardtii have been reported to contain no phosphatidylcholine (PC), which is considered to be replaced by another zwitterionic lipid, diacylglyceryl-N,N,N-trimethylhomoserine (DGTS). According to the recently published classification, the strains belonged to the subgroup Reinhardtinia. Screening for PC in 13 selected strains of Chlamydomonas in the NIES Algal Collection, which are different in habitats and belong to different phylogenetic subgroups in the genus, revealed the presence of PC in four strains: a strain in the subgroup Polytominia, and three strains in Reinhardtinia. PC was not detected in three other strains of Reinhardtinia analyzed. The presence/absence of PC was not related to the phylogenetic relationship based on 18S rRNA. DGTS was detected in all the strains analyzed. The rare isomer of linolenic acid, 18:3(5,9,12), which has been found in the DGTS of C. reinhardtii, was found in the PC of the two strains and in the DGTS of the five strains. The occurrence of this fatty acid seems limited to a branch of Reinhardtinia. Acquisition and loss of PC in various strains of Chlamydomonas are discussed from the viewpoint of evolution of PC biosynthetic pathway.     

Distribution and evolution of C4 syndrome inRhynchospora (Rhynchosporeae-Cyperaceae)

In order to elucidate the evolution of C₄ syndrome, the taxonomic relationships, leaf anatomy, and ecological and global distribution of C₃ and C₄ species in the genusRhynchospora were investigated. The anatomical observation for 181 species revealed that 26 C₄ species occurred within theCapitatae group of the subgenusHaplostyleae, a natural group showing highly advanced morphological characteristics, together with several C₃ species. In spite of there being rather few C₄ species, they possessed two kinds of Kranz anatomical structure differing from each other in the location of Kranz cells. Some C₃ species ofCapitatae showed radial arrangement in mesophyll cells surrounding vascular bundles, which is distinguished from typical non-Kranz anatomy. The C₄ species extended their ecological ranges from wet habitats to dry savanna grasslands, while the C₃ species showed the best development in wet habitats. The C₃ species were widespread from tropical to temperate regions with partial range extension into subarctic regions of both hemispheres, showing conspicuously high concentration of species in the New World, but being absent from arid climatic regions. The C₄ species were distributed mostly in tropics and subtropics, showing two separate distributional centers in South and Central America and in Tropical Asia and Australia. The range of C₄ species was nearly completely included in the C₃ range. In conclusion, it seems that inRhynchospora the C₄ syndrome evolved relatively recently, and arose in at least two separate phylogenetic trends in the tropics and the subtropics, more probably in the Neotropics.     

Probiotic Supplementation Influences the Diversity of the Intestinal Microbiota During Early Stages of Farmed Senegalese Sole (Solea senegalensis,Kaup 1858)

Ingestion of bacteria at early stages results in establishment of a primary intestinal microbiota which likely undergoes several stages along fish life. The role of this intestinal microbiota regulating body functions is crucial for larval development. Probiotics have been proved to modulate this microbiota and exert antagonistic effects against fish pathogens. In the present study, we aimed to determine bacterial diversity along different developmental stages of farmed Senegalese sole (Solea senegalensis) after feeding probiotic (Shewanella putrefaciens Pdp11) supplemented diet for a short period (10–30 days after hatching, DAH). Intestinal lumen contents of sole larvae fed control and probiotic diets were collected at 23, 56, 87, and 119 DAH and DNA was amplified using 16S rDNA bacterial domain-specific primers. Amplicons obtained were separated by denaturing gradient gel electrophoresis (DGGE), cloned, and resulting sequences compared to sequences in GenBank. Results suggest that Shewanella putrefaciens Pdp11 induces a modulation of the dominant bacterial taxa of the intestinal microbiota from 23 DAH. DGGE patterns of larvae fed the probiotic diet showed a core of bands related to Lactobacillus helveticus, Pseudomonas acephalitica, Vibrio parahaemolyticus, and Shewanella genus, together with increased Vibrio genus presence. In addition, decreased number of clones related to Photobacterium damselae subsp piscicida at 23 and 56 DAH was observed in probiotic-fed larvae. A band corresponding to Shewanella putrefaciens Pdp11 was sequenced as predominant from 23 to 119 DAH samples, confirming the colonization by the probiotics. Microbiota modulation obtained via probiotics addition emerges as an effective tool to improve Solea senegalensis larviculture.     

Accumulation of polychlorinated biphenyls in turbot(Scophthalmus maximus) from seawater sediments and food

Juvenile turbot,Scophthalmus maximus (L.), were exposed to 0.58 μg 1⁻¹ Aroclor 1254 in seawater, to sediments containing 100, 60 and 1 ppm or fed with cockle containing 20 ppm PCB (polychlorinated biphenyls). Concentration factors for liver and muscle were 10⁴ and 10³, respectively, for uptake of PCB from seawater. Contamination of muscle was similar to that of sediments containing 1 and 60 ppm PCB to which turbot were exposed, but less than the 20 ppm in their experimental diet. Contamination of flatfish in the North Sea area is compared with the levels of PCB in the flounder,Platichthys flesus (L.), in the River Thames and predictable values for uptake of PCB from different pathways discussed.