bluuebunny/crossref_metadata_2025 huggingface dataset:
Signification adaptative des différents types de développements postembryonnaires chez les Gamasides (Acariens: Anactinotriches)
Authors: Athias-Binche Françoise
Published: March 2009

This review of the adaptive significance of various patterns of postembryonic development in the gamasid mites is restricted to the phenotypic and adaptive aspects of the different developmental patterns. Postembryonic development is redefined as beginning with achievement of embryonic ectoderm differentiation into a sclerified recognizable integument. The various kinds of postembryonic development depend on the ecology of the species and their adaptative strategies, ranging from generalized edaphic forms to more specialized species, either colonizing unpredictable habitats or being parasitic. In relation to progressive specialization, the relative duration of development tends to decrease from four active instars to three or two instars, or even to an abbreviated adult–adult cycle in endoparasitic species. One can distinguish the following main features: full development with four active instars, full development but comprising one or several phoretic instars; abbreviated development, with regressed apomorphic larva, with ovolarviparity, with regressed protonymph or with both regressed protonymph and deutonymph associated with ovolarviparity, and occasionally with phoresy. Phenotypic plasticity may occur and can be marked by facultative, behavioural, or polymorphic phoresy, facultative ovolarviparity, occasional arrhenotoky, or appearance of dormancy. The adaptive fitness of these different characters is discussed in terms of r–K selection strategies, colonizing dynamics, and specialized microhabitats. The concepts of adaptative and evolutive processes are briefly discussed, including Grandjean's theory of "l'évolution selon l'âge."
Laccornellus (Coleoptera: Dytiscidae), a new hydroporine genus from austral South America
Authors: Roughley R. E. , Wolfe G. William
Published: March 2009

Laccornellus, new genus, is proposed for two austral South American species previously assigned to Laccornis Gozis (L. lugubris (Aube, 1838), the type species, known from Argentina and Uruguay, and L. copelatoides (Sharp, 1882), known from Chile). The valvifer is absent in the adult stage of females of these species and the males have a greatly enlarged internal sac on the aedeagus; these characters exclude them from Laccornis. The most similar and possibly most closely related genus to Laccornellus is the African genus Canthyporus Zimmermann, although no conclusive synapotypy was found. Relationships of extant, plesiotypic hydroporines remain problematic; however, divergence of Laccornellus and Canthyporus probably began about 120 million years ago when Africa and South America separated. The vicariant event preceding divergence of L. copelatoides and L. lugubris probably was the uplift of the Andes Mountains which began in the late Oligocene – early Miocene.
Fine structure of the compound eye of the black fly Simulium vittatum (Diptera: Simuliidae)
Authors: O'Grady Gail E. , McIver Susan B.
Published: March 2009

The fine structure of the ommatidia in light- and dark-adapted eyes of male and female Simulium vittatum Zetterstedt was investigated using scanning and transmission electron microscopy. The male eye is divided into distinct dorsal and ventral regions. The facets in the dorsal region are approximately two times larger than those in the ventral one, which are similar in size to the ones in the female eye. All ommatidia of S. vittatum examined consist of two general regions: a distal dioptric apparatus with bordering primary and accessory pigment and Semper cells, and a sensory receptor layer. Each ommatidium in the female eye and ventral eye of the male has eight retinular cells (R cells): six peripheral (R1–6) and two central (R7, R8). R7 occurs distally and R8 basally. Strikingly, the ommatidia in the dorsal eye of the male lack the R7 cell. In all ommatidia, rhabdomeres on the inner surface of the peripheral R cells are separate throughout their length, creating an open rhabdom. A greater diameter of corneal facets, elongated peripheral R cells, and perhaps the lack of the R7 cell are specializations of the dorsal region of the eye that help the male to detect small, rapidly moving females against the skylight as they fly above the swarm of males. Differences observed between light- and dark-adapted eyes of male and female S. vittatum were the same and were associated with the internal components of the peripheral R cells.
Common Murre (Uria aalge) attendance patterns at Cape St. Mary's, Newfoundland
Authors: Piatt John F. , McLagan Ruth L.
Published: March 2009

Attendance patterns of common murres (Uria aalge) at Cape St. Mary's, Newfoundland, were observed during hatching to post-fledging periods of 1980 to 1984. Six study plots on breeding ledges (ca. 450 birds total) and a "club" on the water were monitored for seasonal fluctuations in numbers attending. Attendance on ledges was similar between years, being relatively stable from hatching through to median fledging, and declining steadily thereafter. Attendance at the club usually peaked between median hatching and fledging, then declined rapidly during the fledging period. Numbers of murres attending neighboring study plots were often significantly correlated, but correlations were much weaker between distant plots. There were few significant correlations between attendance and wind speed or tidal oscillations in any year of study. Numbers of murres attending individual study plots varied significantly between years; four declined, one increased, and one showed no significant change. Overall, there was a small decline in total numbers of murres attending all study plots between 1980 and 1984.
Respiratory gas concentrations and temperatures within nest cavities of the northern flicker (Colaptes auratus)
Authors: Howe Stephen , Kilgore Jr. Delbert L. , Colby Conrad
Published: March 2009

We measured respiratory gas concentrations and air temperatures within nest cavities occupied by the northern flicker. (Colaptes auratus). The means of all measurements of carbon dioxide and oxygen concentrations were 0.37 and 20.42%, respectively. The maximal carbon dioxide level recorded was 2.56%, while the minimal oxygen level was 18.04%. There was a diel cycle in the levels of respiratory gases in nest cavities, with peak carbon dioxide and minimal oxygen levels occurring between 22:00 and 24:00. However, the gaseous conditions within nest cavities remained essentially unchanged throughout the nestling period. Cavity air temperature averaged 21.2 °C, ranging from 10.2 to 33.8 °C, and nearly always exceeded the outside air temperature. The mean difference between inside and outside air temperatures was 7.1 °C and is comparable with those reported in other studies of cavity microenvironments. The elevated cavity temperatures may reduce energy requirements of developing young and also may induce a convective transfer of air between the cavity and free atmosphere that would moderate gaseous conditions within the cavity.
Causes and functions of brood amalgamation in Barrow's Goldeneye and Bufflehead
Authors: Savard Jean-Pierre L.
Published: March 2009

I recorded 42 cases of brood amalgamation in Barrow's Goldeneye (Bucephala islandica) and 31 cases in Bufflehead (B. albeola). In four witnessed brood encounters, there was no evidence of behaviour facilitating brood amalgamation in either the young or the female. Females did not attempt to steal other females' young but rather tried to chase them away or even kill them. Females abandoned their young only after violent fights and often made several attempts to regain them. Brood encounters had various outcomes: (i) establishment of territorial boundaries, (ii) expulsion from lake, (iii) death of young, (iv) complete or partial brood amalgamation. In 3 years of observations there was no significant relationship between brood size and duckling survival. I contend that brood amalgamation in Barrow's Goldeneye and in Bufflehead has not evolved as an adaptation to increase young and (or) female survival but that it is simply an accidental outcome of territorial aggressiveness.
Just how unstable are agroecosystems?
Authors: Woolhouse M. E. J. , Harmsen R.
Published: March 2009

Although it is widely believed that agroecosystems are less "stable" than natural ecosystems, the idea is only loosely based on empirical evidence. We compare the annual variability in population abundance for published data on temperate terrestrial arthropod communities from both natural and agricultural sites. Annual variability values are, as expected, significantly higher for agricultural communities. We briefly review proposed mechanisms for such an effect but conclude that none is sufficiently well tested to form the basis for any general ecological rule.
Displacement and dispersion of parturient caribou at calving as antipredator tactics
Authors: Bergerud A. T. , Page R. E.
Published: March 2009

Survival of caribou (Rangifer tarandus) calves until 4 months of age was monitored for 8 years in four herds in northern British Columbia, Canada. The chief cause of mortality was predation by wolves (Canis lupus) and grizzly bears (Ursus arctos) and this mortality was correlated within years between all herds. More calves died in years with late springs when extensive snow patches remained during calving in June than in early springs when larger snow-free areas existed. Before calving and after birth, caribou cows sought to space themselves out on snow-free areas in small aggregations at high elevations above treeline. By placing themselves at high elevations, the females increased the distance between themselves and wolves and bears travelling in the valley bottoms, as well as the main alternate prey, moose (Alces alces), which calved only in forest cover at lower elevations. In addition, the reduced snow in early springs meant that there was more space for dispersion. The variation in calf survival for three herds was negatively correlated with the heterogeneity of the calving area. Snow cover disappeared in smaller patches in more rugged mountains regardless of spring phenology, thereby providing a more constant search area for predators from year to year. More uniform mountains had either extensive areas of snow cover (late years) or brown substrates (early years), thus greatly varying the space that predators had to search between years. As stochastic variation in snow cover at calving time alters the searching ability of predators, the aggregation responses of prey, and the spatial overlap between predators and prey, it promotes short-term stability of the prey and lessens the probability of extinction.
Ecological relationships between Common Murres, Uria aalge, and Thick-billed Murres, Uria lomvia, at the Gannet Islands, Labrador. III. Feeding ecology of the young
Authors: Birkhead T. R. , Nettleship D. N.
Published: March 2009

A simultaneous comparison of the foods of Common Murre, Uria aalge, and Thick-billed Murre, Uria lomvia, chicks at the same location showed that the species composition of fish fed to chicks of the two murre species differed significantly. In both years of the study, Common Murre chicks were fed predominantly capelin, Mallotus villosus (78–80% by weight), whereas Thick-billed Murre chicks were fed mainly daubed shanny, Lumpenus maculatus (61–70% by weight). Thick-billed Murres tended to feed their chicks more frequently than Common Murres, probably because in both years the mean caloric value of their prey was lower than that of the Common Murre's. No other statistically significant interspecific differences were consistent between years. Prey lengths and weights overlapped considerably between the murre species, and the caloric intake of chicks showed no consistent interspecific difference. Marked interyear differences in feeding rate, prey size, and caloric intake occurred in both species. In 1982 ice breakup was late, and the murres' breeding seasons were delayed; this appeared to result in poor synchronization between the temporal pattern of food availability and the timing of each species' chick-rearing period, and the caloric intakes of chicks of both species were lower in that year than in 1983.
Preliminary observations on seasonal changes in prevalence and intensity of Cosmocercoides variabilis (Nematoda: Cosmocercoidea) in Bufo americanus (Amphibia)
Authors: Vanderburgh Daryl J. , Anderson R. C.
Published: March 2009

Individuals of Bufo americanus were examined from April to October for the presence of Cosmocercoides variabilis (Harwood, 1930) Travassos, 1931. Fourth-stage larvae were present in lungs in late April to early May. Larvae found in lungs in spring migrated to the rectum and matured by the end of May. Transmission of C. variabilis probably occurs throughout the season. Larval and adult worms encountered in toads in early spring were probably acquired the previous year.
Effects of low pH and nickel on growth and survival of the shredding caddisfly Clistoronia magnifica (Limnephilidae)
Authors: Frankenhuyzen Kees van , Geen Glen H.
Published: March 2009

In laboratory experiments with larvae of the shredding caddisfly Clistoronia magnifica, toxicity of nickel chloride hexahydrate was highly pH dependent. Larvae were exposed from first instar until pupation to three nickel concentrations (55, 215, 700 μg Ni2+/L) in soft water adjusted to pH 4.1, 5.5, and 6.2. Nickel reduced the survival of larvae and pupae at all pH levels but toxicity decreased with increasing H+ concentration. In addition, Ni at 215 μg/L temporarily ameliorated H+ toxicity to early instar larvae at pH 4.1. Reduced toxicity with decreasing pH fits the hypothesis that free metal ions compete with H+ for the same binding–uptake sites. Available data suggest that this phenomenon is not restricted to a particular metal or organism but that it applies to pH–metal interactions in general.
Distribution of ferric iron in juveniles of the lamprey Petromyzon marinus L.
Authors: Youson J. H. , Cheung R.
Published: March 2009

Sites of iron deposition in tissues and organs of juvenile lampreys (Petromyzon marinus L.) were compared in animals feeding on Salmo gairdneri and nonfeeding individuals using light microscopy and the Prussian blue stain. The liver and adipose tissue are the primary sites of iron storage in all animals and they contain slightly higher concentrations of iron in nonfeeding individuals. Substantial amounts of iron are present in several regions of fibrous connective tissue, in cartilage, and in the meninges. The presence of iron-positive granules and globules in both the mucous cells of the epithelium and the lumen of the posterior intestine suggests that this region of the intestine is a site where excess iron is eliminated. Mucous cells of the dorsal epidermis and the gills probably also release excess iron during mucous secretion. Heavy deposits of iron in subepithelial macrophages and light iron staining of the epithelium of the anterior intestine during times of active feeding imply that the epithelium of this part of the intestine is involved in absorption and that macrophages concentrate the iron. The extensive distribution and heavy concentration of iron in this obligate sanguivore may necessitate the existence of an efficient mechanism for controlling iron intake during feeding.
A new name for the Atlantic whitefish: Coregonus huntsmani to replace Coregonus canadensis
Authors: Scott W. B.
Published: March 2009

The Atlantic whitefish, indigenous to Nova Scotia, was originally described as Conegonus canadensis. The name canadensis is shown to be unavailable and a new name, Coregonus huntsmani, is proposed. The holotype is a mature male from Tusket River, Nova Scotia (Royal Ontario Museum no. 16674). Counts and measurements of the holotype are given.
Effects of a cestode (Schistocephalus sp.) on the response of ninespine sticklebacks (Pungitius pungitius) to aquatic hypoxia
Authors: Smith Roger S. , Kramer Donald L.
Published: March 2009

Sticklebacks (Pisces, Gasterosteidae) serve as one of the intermediate hosts for cestodes of the genus Schistocephalus. Previous authors have suggested that, by increasing oxygen demand, these parasites induce sticklebacks to swim nearer the surface, where the fish are more vulnerable to piscivorous birds, which are the definitive hosts. We compared surface use and survival of parasitized and nonparasitized ninespine sticklebacks (Pungitius pungitius) at different levels of dissolved oxygen. Parasitized Pungitius spent more time in contact with the surface performing aquatic surface respiration under hypoxic conditions (0.75–2.0 mg O2∙L−1) than nonparasitized individuals did. When frightened by a model simulating an aerial predator, parasitized sticklebacks left the surface for a shorter time than nonparasitized fish. Parasitized sticklebacks also had a higher lethal oxygen level than nonparasitized sticklebacks, suggesting that the differences in surface use are due, at least in part, to differences in oxygen demand.
A new genus and species of Rhagidiidae (Acari: Prostigmata) from Chihuahuan Desert litter in New Mexico
Authors: Lindquist Evert E. , Zacharda Miloslav
Published: March 2009

A new genus and species of rhagidiid mite, Arhagidia monothrix, is described and illustrated from specimens collected from the Jornada ecological research site of the Chihuahuan Desert in southern New Mexico. Uniquely derived morphological characteristics of this taxon include a reduced palpal chaetotaxy, an unpaired seta inserted on the naso, enlarged and nearly contiguous coxisternal plates I, absence of rhagidial depressions where solenidia are inserted on tarsi I and II, two pairs of setiferous tubercles dorsodistally on tarsus I, and an elongated body with short appendages. Some of these reflect adaptations to living in the soil. Eupathidial setae are distinguished and denoted from setiform setae on the femoral, genual, fibial, and tarsal segments of the legs of a rhagidiid mite for the first time.
Diversity, density, efficiency, and effectiveness of pollinators of cicer milkvetch, Astragalus cicer L.
Authors: Richards K. W.
Published: March 2009

Diversity, density, efficiency, and effectiveness of pollinators of cicer milkvetch, Astragalus cicer L., grown at two locations in southern Alberta were studied from 1978 to 1983. Twenty-seven species of bees were identified as pollinators. At Lethbridge, honey bees (Apis mellifera) comprised 74% of the observations, bumble bees 16%, and leafcutter bees 10%, while at Spring Coulee, the proportions were honey bees 14%, bumble bees 69%, and leafcutter bees 17%. The rate of foraging by pollinator species from flower to flower varied; bumble bee species, especially Bombus nevadensis Cress., foraged consistently more efficiently than honey bees or alfalfa leafcutter bees, Megachile rotundata (F.). A theoretical approach used to predict the bee populations required to pollinate varying flower densities shows that the population of B. nevadensis required is about half those of Bombus huntii Greene and M. rotundata and less than one-quarter that of the honey bee. Pollination by B. nevadensis consistently resulted in more seeds per pod than with any other bumble bee species, the honey bee, or M. rotundata. Of the nine species of bumble bee that established colonies in artificial domiciles near the field, B. nevadensis established the most colonies each year. The number of workers and sexuals produced per colony varied considerably among bumble bee species with only 55% of the colony establishments producing workers and 31% producing sexuals. The propagation rate and quality of alfalfa leafcutter bees produced on cicer milkvetch was excellent.
Genome constitution and reproductive biology of hybrid salamanders, genus Ambystoma, on Kelleys Island in Lake Erie
Authors: Bogart James P. , Lowcock Leslie A. , Zeyl Clifford W. , Mable Barbara K.
Published: March 2009

On Kelleys Island, Ohio, in Lake Erie, are found bisexual Ambystoma tigrinum and Ambystoma texanum as well as five different combinations of diploid and polyploid hybrid female salamanders. Genome composition and ploidy of salamanders from five breeding sites on the island were examined using starch gel electrophoresis, erythrocyte area measurements, and chromosome counts. All of the hybrids contained at least one Ambystoma laterale genome, yet pure individuals of this species were not encountered. Embryonic mortality was severe among eggs deposited by 42 hybrid females. The few resulting offspring, when compared electrophoretically with their mothers, showed no evidence of being the product of parthenogenesis. Recently described Ambystoma nothagenes Kraus is not a valid species as this trihybrid is demonstrated to be genetically heterogeneous and independently derived from diploid A. laterale × texanum hybrids.
A review of freshwater species of Diphyllobothrium with redescriptions and the distribution of D. dendriticum (Nitzsch, 1824) and D. ditremum (Creplin, 1825) from North America
Authors: Andersen Karin , Ching Hilda Lei , Vik Rolf
Published: March 2009

Plerocercoids of Diphyllobothrium were studied from fish samples representing eight species of salmonids from British Columbia, Wyoming, Quebec, and Maine. Adults were studied mainly from experimental infections of golden hamsters, Mesocricetus auratus (Waterhouse). Using scanning electron microscopy and histological techniques, the plerocercoids and adults were identified as Diphyllobothrium dendriticum or Diphyllobothrium ditremum. Morphological comparisons were made with European specimens of these two species and those of Diphyllobothrium latum (Linnaeus, 1758). Among the nine freshwater species reviewed, Diphyllobothrium cordiceps (Leidy, 1872), Diphyllobothrium sebago (Ward, 1910), and Diphyllobothrium ursi Rausch, 1954, are considered synonyms of Diphyllobothrium dendriticum.
The prebasic moult and basic plumage of female mallards (Anas platyrhynchos)
Authors: Heitmeyer Mickey E.
Published: March 2009

The prebasic moult and subsequent basic II plumage of immatures and the definitive basic plumage of adult female mallards (Anas platyrhynchos) in late winter were examined from collected birds of known pair status. Female mallards moult into these basic plumages from November to March but an individual completes the prebasic moult in 6–7 weeks; variation among individuals is related to age, pair status, and habitat and weather conditions. The prebasic moult is a complete body moult. Feathers of the crown, facial, neck, upper back, scapular, and flank areas are replaced earlier than feathers in other areas of the body. The basic II and definitive basic plumages are characteristically darker and more sepia than the alternate I and definitive alternate plumages, respectively. The light bands on dorsal feathers are more V-shaped in basic feathers and more sigmoid-shaped in alternate feathers. Colours of the bill and tarsus change to resemble male colouration of these parts during the middle to late portions of the moult. The timing, sequence of feather replacement, and change in plumage aspect of the prebasic moult may reflect adaptations to pressures selecting for reduction of overlapping nutrient requirements of annual cycle events, camouflage, and signaling of pairing status.
Colonization of wood substrates by the aquatic xylophage Xylotopus par (Diptera: Chironomidae) and a description of its life history
Authors: Kaufman Michael G. , King Robert H.
Published: March 2009

Xylotopus par populations were monitored in a central Michigan stream during the summer growth period by sampling two types of indigenous logs and four types of introduced wood block "baits." Populations of larvae in the two indigenous logs were very similar over the course of the study with regard to number of individuals, biomass accumulation, developmental rate, and spatial distribution within colonized areas. Populations of larvae in the wood baits followed trends in density and biomass accumulation that differed between wood types. A positive relationship of the parameters with substrate softness was observed. Populations of larvae in the introduced wood baits developed faster than those in indigenous logs, with portions of the bait-inhabiting populations apparently able to complete development during the summer. Populations in indigenous logs normally require a full year for development and the accelerated growth in the "fresh," introduced substrates indicates a plastic phenology that allows X. par to exploit wood of variable quality. A prerequisite for terrestrial decay in determining wood suitability for X. par is also discussed.
Food habits of prairie mink during the waterfowl breeding season
Authors: Arnold Todd W. , Fritzell Erik K.
Published: March 2009

We studied the food habits of radio-marked male mink (Mustela vison) in southwestern Manitoba from April through July of 1984 and 1985. Mammals were the major prey during April (99% of diet) and, to a lesser extent, May through July (44–21%). Muskrats, ground squirrels, and voles were the most important mammalian prey. Avian prey comprised from 55 to 75% of the diet during May, June, and July. Waterfowl (adults, ducklings, and eggs) accounted for 23% of the total diet. Other important avian prey included coots, grebes, and marsh-nesting blackbirds. We estimated total prey requirements for our radio-marked male mink and concluded that their predation had little impact on populations of prairie waterfowl during this study.
The effects of Plagiorchis noblei (Trematoda: Plagiorchiidae) matacercariae on the susceptibility of Aedes aegypti larvae to predation by guppies (Poecilia reticulata) and meadow voles (Microtus pennsylvanicus)
Authors: Webber R. A. , Rau M. E. , Lewis D. J.
Published: March 2009

Infection with the metacercariae of the digenean Plagiorchis noblei had no effect on the susceptibility of Aedes aegypti larvae to predation by guppies (Poecilia reticulata). In contrast, infected larvae were rendered more susceptible to being taken by meadow voles (Microtus pennsylvanicus) than were uninfected controls. Since voles, which will feed at the edge of water, are capable of supporting the adult fluke, transmission of the parasite to the definitive host may be facilitated.
The influence of water velocity on particle capture by the labral fans of larvae of Simulium bivittatum Malloch (Diptera: Simuliidae)
Authors: Braimah Stephen A.
Published: March 2009

Larvae of Simulium bivittatum Malloch exposed to water velocities of 3.2–47.0 cm/s consumed a maximum of particles at velocities of 10.0–25.0 cm/s. Larvae consumed significantly fewer particles at velocities below and above the suitable (10.0–25.0 cm/s) range. The inability of larvae to capture particles efficiently at low velocities (3.2–4.5 cm/s) is attributed to the formation of thick boundary layers around filtering structures (labral fans). Steep velocity gradients in the boundary layer around fans and probably high drag forces on fans contribute to the low retention efficiency at high velocities (35.0–47.0 cm/s). The drag forces and the torque on particles at the water–fan interface enhance the adhesion of small (0.5–5.7 μm) particles, which form the bulk of food particles in the guts of larvae. The relevance of this study to the control of larvae of pest species of black flies is discussed.
High-affinity Cortisol receptor activity in the liver of the brook trout, Salvelinus fontinalis (Mitchill)
Authors: Chakraborti P. K. , Weisbart M.
Published: March 2009

In vitro binding of [3H]cortisol to brook trout liver cytosol and salt-soluble nuclear extracts demonstrated a high affinity (cytosol association constant, Ka = (0.18 ± 0.03) × 109M−1, n = 4; nuclear extract association constant, Ka = (0.033 ± 0.01) × 109M−1, n = 4) and low maximum binding capacity (cytosol, Nmax = 167 ± 18 fmol∙mg−1 protein, n = 4; nuclear extract, Nmax = 858 ± 81 fmol∙mg−1 protein, n = 4). Kinetics of binding of [3H]cortisol to cytosol at 2 °C revealed association and dissociation rate constants of 6.95 × 104∙M−1∙s−1 and 2.38 × 10−4 s−1, respectively. Gel filtration chromatography using Sephacryl S-300 as the matrix showed a molecular mass for the cytosol binding activity of 319 000 ± 4486 Da and Stokes' radius of 6.23 ± 0.03 nm (n = 3). Competition studies with different steroids indicated considerable specificity for the cytosol binding. The competitive hierarchy was as follows: dexamethasone > triamcinolone acetonide > Cortisol > corticosterone > cortisone > testosterone > estrone > 17β-estradiol > 11-deoxycortisol > progesterone > 11β, 17α, 21-trihydroxy-4-pregnen-3,20-dione-21-phosphate > 17α,20β-dihydroxy-4-pregnen-3-one > pregnenolone. These results support the concept of cytosolic and nuclear forms of glucocorticoid receptors in the liver of brook trout.
Revised classification of the genus Euplokamis Chun, 1880 (Ctenophora: Cydippida: Euplokamidae n. fam.) with a description of the new species Euplokamis dunlapae
Authors: Mills Claudia E.
Published: March 2009

The cydippid ctenophore Euplokamis dunlapae n.sp. from fjords and inlets in British Columbia and Washington State is described and illustrated. The monotypic new family Euplokamidae has been erected to accommodate this genus, which is characterized by tentacle side branches containing striated muscle, unique in the phylum Ctenophora. These side branches are tightly coiled when at rest, but extend very rapidly during prey capture. Feeding and swimming behavior and larval morphology are discussed. A review of the literature has led to a reassessment of the affinities of several cydippid ctenophores and a dichotomous key is included for the identification of six species of the genus Euplokamis.
Costs of transport for the scyphomedusa Stomolophus meleagris L. Agassiz
Authors: Larson R. J.
Published: March 2009

The rhizostome scyphomedusa Stomolophus meleagris swims continuously at speeds up to 15 cm∙s−1. Mean velocities increased as a power function of wet weight up to 70 g but were mostly constant thereafter. Bell pulsations ranged from 1.7 to 3.6 Hz. Reynolds numbers equalled 900 – 13 000. During activity, medusae consumed 0.05 mL O2∙h−1∙g WW−1 (1.2 mL O2∙h−1∙g DW−1), at 30 °C. Rates for inactive medusae were 50% less. The estimated cost of transport ranged from 2 J∙kg−1∙m−1 at 5 g to 1 J∙kg−1∙m−1 at 1 kg. These rates are comparable to those of fishes and about 1/50th that of planktonic crustaceans. These results were unexpected in light of the typical inefficiency (power output/power input) of jet swimming. However, S. meleagris has a very low respiration rate relative to crustaceans and fish, which probably compensated for low swimming efficiency.
The Simuliidae (Diptera) of Sri Lanka. Descriptions of three new species of Simulium (Simulium)
Authors: Davies D. M. , Györkös H.
Published: March 2009

This is the second paper in a series treating the Simuliidae of Sri Lanka. In it are described three new species of Simulium Latreille belonging to the subgenus Simulium s.str., Simulium (Simulium) cremnosi, Simulium (Simulium) bulla, and Simulium (Simulium) nubis. Taxonomic comparisons are made with related Oriental species and biological notes are given, including records of biting on men.
Pelecitus fulicaeatrae (Nematoda: Filarioidea) of coots (Gruiformes) and grebes (Podicipediformes): skin-inhabiting microfilariae and development in Mallophaga
Authors: Bartlett Cheryl M. , Anderson R. C.
Published: March 2009

Pelecitus fulicaeatrae (Diesing, 1861) was found among tendons near the ankle (tibiotarso-tarsometatarsalis articulation) in 11 of 15 adult coots (Fulica americana) from Brooks, Alberta, Canada, in 6 of 9 adult coots from Delta, Manitoba, Canada, and in 2 of 4 adult red-necked grebes (Podiceps grisegena) from Brooks. Microfilariae of P. fulicaeatrae were found in skin of the feathered portions of the legs of infected birds, generally in the dermis around feather follicles; this is the first report of skin-inhabiting microfilariae among avian filarioids. Development of P. fulicaeatrae to the third stage in the chewing louse Pseudomenopon pilosum (Scopoli) (Mallophaga: Amblycera) is described. Microfilariae and developing first-stage larvae were found in nymphal and adult lice but third-stage larvae were found only in adults; prevalence of third-stage larvae was significantly higher in females than in males. Adult P. fulicaeatrae were recovered from an experimentally inoculated, laboratory-reared coot and from laboratory-reared coots that had been housed with infected and infested wild-caught coots. Pelecitus fulicaeatrae is the first filarioid in the Dirofilariinae known to be transmitted by lice and the third found in birds. Pseudomenopon pilosum was found on 40 (85%) of 47 coots of undetermined ages from Alberta and Pseudomenopon dolium (Rudow) was found on all of 5 juvenile red-necked grebes also from Alberta. Possibly, P. pilosum occasionally transfers to grebes and (or) P. dolium also transmits P. fulicaeatrae.
Dehydration of seabird prey during transport to the colony: effects on wet weight energy densities
Authors: Montevecchi W. A. , Piatt J. F.
Published: March 2009

We present evidence to indicate that dehydration of prey transported by seabirds from capture sites at sea to chicks at colonies inflates estimates of wet weight energy densities. These findings and a comparison of wet and dry weight energy densities reported in the literature emphasize the importance of (i) accurate measurement of the fresh weight and water content of prey, (ii) use of dry weight energy densities in comparisons among species, seasons, and regions, and (iii) cautious interpretation and extrapolation of existing data sets.
The measurement of exposed host volume by the parasitoid wasp Trichogramma minutum and the effects of wasp size
Authors: Schmidt J. M. , Smith J. J. B.
Published: March 2009

The parasitoid wasp Trichogramma minutum Riley (Hymenoptera: Chalcidoidea: Trichogrammatidae) adjusts its progeny allocation to the exposed volume of its insect egg host. This paper deals with the mechanism for this size discrimination, which is not dependent upon chemical or visual cues or repeated parasitism. The wasps are also able to discriminate between hosts of the same diameter that differ in exposed surface area, and do not use curvature to determine progeny allocation under these conditions. A computer-based event recorder was used to collect information about the host-examining behaviour of the wasp. Of the examining-path parameters that change with surface area, only the duration of the wasp's initial transit across the exposed surface of the host correlated significantly with the number of eggs subsequently laid by the wasp. Artificially reducing the initial transit of the wasp by obstructing its path resulted in significantly fewer eggs per host. Both large and small wasps allocate the same number of progeny to hosts of the same exposed volume, and take the same time to complete their initial transits. We propose that Trichogramma use the absolute length of their initial transit, measured as the transit's duration, to set clutch size to absolute exposed host volume. This behaviour allows Trichogramma to lay the number of eggs into each host that ensures maximum reproductive success, regardless of the wasp's own dimensions.
Hatching asynchrony and food allocation within broods of Pied-billed Grebes, Podilymbus podiceps
Authors: Forbes Mark R. L. , Ankney C. Davison
Published: March 2009

Broods of Pied-billed Grebes, Podilymbus podiceps, breeding near Minnedosa, Manitoba (55°16′ N, 99°50′ W), in the summer of 1984, hatched from five to eight eggs over 3–7 days. We found a negative correlation (partial r = −0.56, df = 11, p < 0.05) between the length of the hatching interval and the number of chicks surviving to 35 days of age, after controlling for clutch size. The mean number of sibling aggressions ([Formula: see text], n = 20, 2 SE = 0.4) was higher during foraging bouts with below-average rates of food delivery by parents, as opposed to bouts ([Formula: see text] aggressions, n = 18, 2 SE = 0.2) with above-average rates. Also, larger chicks initiated and won more disputes over positions near adults (Fisher's exact test, p < 0.05, n = 40) than did their smaller sibs. Thus, size hierarchies among siblings influenced food allocation within Pied-billed Grebe broods. Food distribution, however, was nonrandom for 12 of 18 foraging bouts in which there were no apparent size differences between attendant chicks. Signals of hunger status from begging chicks, and parental regulation of which chicks maintained positions near them, also affected food allocation among siblings. Finally, handling times of prey, captured by adults and fed to chicks, depended on brood age (partial r = −0.21, df = 183, p < 0.05) after controlling for prey size. For Pied-billed Grebes, noticeable size hierarchies among chicks remained throughout most of brood development and may have been advantageous during times of low food availability, or may have enabled parents to forage more effectively on a wide range of prey types and sizes.
Individual variability in reproductive success of Triaenophorus crassus Forel (Cestoda: Pseudophyllidea), with comments on use of the Lorenz curve and Gini coefficient
Authors: Shostak Allen W. , Dick Terry A.
Published: March 2009

Maturity, mass, and lifetime fecundity were detemined in individual Triaenophorus crassus from spawning pike (Esox lucius) from Falcon Lake, Manitoba. Only 33% of worms contained eggs, and only 73% of these could release their eggs (up to 4 400 000 per worm). Inequalities in mass and fecundity were quantified using Lorenz curves and Gini coefficients calculated for worms pooled across hosts, and separately for worms in each host. Inequalities in mass were correlated with, but always lower than, corresponding inequalities in fecundity, although inequalities in fecundity and mass were more similar at high infection intensities. Consequently, inequalities in worm mass did not provide an accurate estimate of inequalities in reproductive success but could be used as an indirect index for comparative purposes. These inequalities can potentially modify parasite transmission. Ten percent of worms accounted for 85% of all parasite fecundity and, as a result of a contagious distribution of worms among pike and a lack of detectable intensity-dependent effects on parasite fecundity, 55% of worm eggs came from 10% of spawning pike. Worm numbers and distribution among hosts, maturity, and inequalities in mass and fecundity were consistent over 3–4 consecutive years, indicating that these inequalities are a normal component of the life cycle. The concentration of parasite fecundity in relatively few worms or hosts suggests that the population dynamics of T. crassus may be affected by short-term changes in parasite genotype, host activity patterns, or mortality of the few heavily infected hosts.
Fish community structure in relation to acidity in three Nova Scotia rivers
Authors: Lacroix Gilles L.
Published: March 2009

The occurrence, density, and age-class structure of endemic fish species were compared over a period of 24 months in three Nova Scotia streams of differing pH. The absence of acid-sensitive species and very low densities of fish characterized the stream with a pH range of 4.5–5.0. Fish densities were lower in the stream with a pH range of 4.7–5.4 than in the stream with a pH range of 5.6–6.3. Juvenile salmon and cyprinids were the most abundant species in the least acidic stream. Their densities were considerably lower in the stream with pH levels of 4.7–5.4, and the young age-classes of the cyprinid species were rare or absent. Both salmon and cyprinids were absent in the most acidic stream. In contrast, American eels were most abundant in the two streams with pH levels less than 5.5, and they accounted for an increasingly large proportion of the fish biomass at the lowest pH levels. White sucker was the most abundant species at the lowest pH levels, but its contribution to biomass was unimportant because of the absence of most age-classes older than 0+. Several other species found in the most acidic stream were not very abundant, and old age-classes were usually absent for most of these. The observed distributional patterns were considered to be mostly pH related.
Community structure of arthropod ectoparasites on Alaskan seabirds
Authors: Choe Jae C. , Kim Ke Chung
Published: March 2009

A total of 28 species of arthropods was recovered from 29 common murres (Uria aalge), 8 thick-billed murres (Uria lomvia), 22 black-legged kittiwakes (Rissa tridactyla), and 10 red-legged kittiwakes (Rissa brevirostris) collected from the Pribilof Islands, Alaska, U.S.A. The ectoparasite community on each bird species almost invariably consisted of three species of chewing lice, two species of ticks, and five to nine species of mites. Astigmatid feather mites (Alloptes spp., Laronyssus martini (Trouessart)) were the most numerous group of ectoparasites except on black-legged kittiwakes on which Ixodes ticks were the most abundant. The second most abundant taxa were ticks on common murres and thick-billed murres, and quill mites (Syringophilidae) on red-legged kittiwakes. Kittiwakes usually supported more diverse communities of ectoparasites than did murres, probably because of differences in nesting and foraging behavior. Ectoparasite communities between the congeneric species of birds were particularly similar in terms of species composition and general structure, and supported our hypothesis that phylogenetic relatedness of hosts is reflected in similarity of their ectoparasite communities. Community structure of ectoparasites was much more similar between the two murre species than between the two kittiwake species, probably because of gregarious flocking and mixed-species nesting of murres.
Description of male and redescription of female Phlyctainophora squali Mudry and Dailey, 1969 (Nematoda; Dracunculoidea) from elasmobranchs
Authors: Adamson M. L. , Deets G. B. , Benz G. W.
Published: March 2009

Coiled globose nematodes identified as Phlyctainophora squali Mudry and Dailey, 1969 (Nematoda; Dracunculoidea) were found associated with ulcer-like and cyst-like lesions on the external surface and in the buccal cavity of 19 of 63 Squalus acanthias, 1 of 21 Heterodontus francisci, 1 of 117 Rhinobatus productus, and 7 of 16 Prionace glauca from the California Bight (northeast Pacific). A single male worm was recovered from one of the cysts in S. acanthias and the present redescription of the species includes the first description of a male Phlyctainophora. Certain characters of the male (i.e., form of cephalic extremity, reduced caudal alae, reduced number of caudal papillae) agree with those of members of the Philometridae; other characters of the male (form of the oesophagus) and female (monodelphy) agree with those of the Guyanemidae. Phlyctainophora is treated as a Dracunculoidea incertae sedis.
A review of the Neuroptera of the Galápagos Islands with a new record for Sympherobius barberi (Banks) (Hemerobiidae)
Authors: Klimaszewski Jan , Kevan D. K. McE. , Peck Stewart B.
Published: March 2009

A checklist of species of Neuroptera described and (or) recorded from the Galápagos Islands, Ecuador, is presented together with a review of existing records. Sympherobius barberi (Banks) is recorded from the Galápagos Islands for the first time. This also constitutes the first record of the genus Sympherobius from the islands. Comparisons have been made between the Galápagos specimens, the type specimen of the species, and specimens from Peru, Mexico, and the southern United States of America. Illustrations of habitus and genitalic structures, as well as a diagnosis and a discussion of the species are also given. Additional distributional data and illustrations are provided for Chrysopa wollebaeki Esben-Petersen, Megalomus darwini Banks, and Myrmeleon perpilosus Banks. A lectotype is designated for Megalomus darwini Banks. Keys for identification are given for all species known from the islands.
Composition of the soil fauna in forested and grassy plots at Delhi, Ontario
Authors: Tomlin A. D. , Miller J. J.
Published: March 2009

There were several differences between invertebrate fauna collected from 15 cm deep cores taken from previously cultivated soil (now in grass) and fauna of a similar Fox loamy sand series in a nearby woodlot at Delhi, Ontario (42°51′ N, 80°30′W). Soil invertebrate populations in the grassy field were less dense (931 × 103 vs. 1853 × 103 animals/m2) and less diverse, had less than half of the biomass (1.2 vs. 2.9 g dry wt./m2), and exhibited little significant decrease in invertebrate densities with increasing soil depth compared with woodlot soil cores; woodlot soils exhibited significant decreases in invertebrate densities with increasing soil depth. The litter layer (LFH) of the woodlot provided the highest invertebrate densities and biomasses of any soil horizon tested over the 5-month sampling period. Percent abundances at both sites for most taxa were relatively similar; nematodes, protozoans, and mites were most abundant and earthworms, least abundant. The category "other arthropods" (including hexapods, myriapods, and araneids) was the largest contributor at both sites when taxa were ranked according to biomass. Earthworms were virtually nonexistent in the grassy field and were represented by only two species, Dendrobaena octaedra (Savigny) (which was dominant in both abundance and biomass) and Aporrectodea tuberculata (Eisen), in woodlot soil. Woodlot faunal densities and biomasses for most taxa were similar to comparable Eurasian sites of similar climate and vegetation.
Cycle de développement, écologie et succès d'Hippomedon propinquus (Amphipoda, Gammaridea) dans deux écosystèmes du golfe du Saint-Laurent
Authors: Lamarche Gabriel , Brunel Pierre
Published: March 2009

Bimonthly quantitative day and night samples from one monitoring station located in the St. Lawrence Estuary (in silt–clay, at a depth of 119 m), with a constant yearly temperature (1–4 °C), reveal that densities of the detrivorous and necrophagous lysianassid amphipod Hippomedon propinquus were similar (0.4–9.7 individuals/100 m3 in 1970, 1971, and 1973) to densities at another station in Chaleur Bay with comparable sediments, temperature, and depth (4.2–7.5 individuals/100 m3 in 1969 and 1971). However, its rank among the gammaridean community (10th to 15th in the bay, 3rd to 5th in the estuary) and a faster growth in the estuary suggest better "success" in the latter. Vertical migrations are mainly diurnal and of higher amplitude in the bay than in the estuary, where these are mostly nocturnal, except in June and July. Life expectancy is over 2 years with a maximum of 13 molts, 4 to 5 of which occur in the adult stage. Growth is slower, life expectancy is shorter, but rank is higher (third) at another Chaleur Bay station where H. propinquus also displays increased swimming activity. In both ecosystems, reproduction is mostly a continuous, year-round process, but juvenile recruitment is more important in spring and summer, conforming to our prediction that life cycle is more independent of primary production and seasonal sestonic fallout when species occupy higher positions in the food web. Average size of ovigerous females decreases while fecundity increases in summer. Females produce larger eggs in Chaleur Bay. Poorer and less predictable primary production in the St. Lawrence Estuary gives opportunistic species like H. propinquus an advantage over more strictly detrivorous crustacean species.