bluuebunny/crossref_metadata_2025 huggingface dataset:
VARIATION IN NUMBER OF DORSAL SPINES IN THE BROOK STICKLEBACK, EUCALIA INCONSTANS
Authors: Lawler G. H.
Published: April 2011

The brook stickleback, Eacalia inconstans (Kirtland), is usually described as possessing five or six dorsal spines and the species is commonly called the five-spine stickleback. In Homing Lake, Manitoba, fish with six dorsal spines predominate. The occurrence of sticklebacks with a high number of dorsal spines is noted from other Manitoba lakes and to a lesser extent in samples from some Ontario lakes. Indications are that the dorsal spines are more numerous in fish from the Hudson Bay drainage than from the Great Lakes region. An increase in the number of dorsal spines with increasing latitude is apparent.
EVOLUTION IN THE FIELD CRICKET, ACHETA ASSIMILIS FAB.
Authors: Bigelow R. S.
Published: April 2011

Progeny of northern spring field cricket adults lay non-diapause eggs, undergo nymphal diapause, and overwinter as nymphs. Progeny of northern fall adults lay diapause eggs, do not undergo nymphal diapause, and overwinter as eggs. The two populations cannot interbreed freely in the field owing to a temporal difference in breeding seasons; they did not interbreed in the laboratory. Rearing experiments show that the developmental differences are genetically based rather than environmentally conditioned, and it is, therefore, unlikely that hybrids would be viable even if they were produced in the field. Consequently these two populations behave as good species. Field crickets from Virginia developed much more rapidly than did spring crickets from Quebec. Quebec spring males and Virginia females produced hybrids with developmental rates intermediate between those of their parents. More female than male hybrids were produced, and the females developed more rapidly than did male hybrids. Offspring were produced by hybrid females and Quebec spring males, but not by hybrid females and Virginia males. Partial, but incomplete reproductive isolation exists between Quebec and Virginia field crickets. A possible mechanism of sympatric speciation in insects is discussed.
PARASITES OF SOUTH PACIFIC FISHES: II. DIPLECTANUM MELANESIENSIS N. SP., A MONOGENETIC TREMATODE FROM FIJI AND THE NEW HEBRIDES
Authors: Laird Marshall
Published: April 2011

Thirty-six immature examples of the serranid Epinephelus merra Bloch were collected from coral pools at Aneityum (New Hebrides) and Makuluva Islet (Fiji), on four occasions from 1952 to 1954. The gills of all of them were infected with Diplectanum melanesiensis n. sp., the closest known relatives of which parasitize allied hosts in Japan (D. epincpheli Yamaguti) and Celebes (D. serrani Yamaguti). The South Pacific species resembles D. serrani but differs from D. epinepheli in lacking a conspicuous ejaculatory bulb and in having a transversely positioned ovary the elongate terminal portion of which enfolds the right caecum. It is distinguished from both these species by its markedly smaller size (217 to 500 μ by 66 to 117 μ, av., 366 by 92 μ) and the structure of the squamodiscs, which have nine concentric rows of rodlets, the four innermost ones forming complete circlets.
MONHYSTERA CAMERONI N. SP.—A NEMATODE COMMENSAL OF VARIOUS CRUSTACEANS OF THE MAGDALEN ISLANDS AND BAY OF CHALEUR (GULF OF ST. LAWRENCE)
Authors: Steiner G.
Published: April 2011

The known cases of monhysterid nematodes showing commensalism with crustaceans are reviewed and a new one, that of Monhystera cameroni n. sp., described. Its relationship to M. socialis Bütschli, 1874 and M. chitwoodi n. sp. (= M. socialis Bütschli of Chitwood, 1951) is discussed. M. chitwoodi is established as a separate species. It is proposed to replace the term "caudal" glands by that of "foot" glands for reasons of clarity and comparative morphology. The reduction of the foot gland system from a three to a two cell complex as here observed is interpreted. Its possible significance for the concept that the phasmids are modified foot glands is expounded. The occurrence of microsporidial parasites in M. cameroni is mentioned.
THE NORMAL BLOOD CHEMISTRY OF THE BEAVER (CASTOR CANADENSIS): A. PACKED-CELL VOLUME, SEDIMENTATION RATE, HEMOGLOBIN, ERYTHROCYTE DIAMETER, AND BLOOD CELL COUNTS
Authors: Kitts W. D. , Robertson May C. , Stephenson B. , Cowan I. McT.
Published: April 2011

Packed-cell volume, sedimentation rate, hemoglobin, red blood cell count, white blood cell count, differential count, and red cell diameter have been determined on blood samples taken from 22 beavers. The various values obtained are in general comparable with those reported for the other rodents. Exceptions to this general agreement were noted in the much higher sedimentation rate and slightly larger red cell diameter of beaver blood.
STUDIES ON STRONGYLOIDES OF PRIMATES: III. OBSERVATIONS ON THE FREE-LIVING GENERATIONS OF S. FÜLLEBORNI
Authors: Premvati
Published: April 2011

There is only a single generation of free-living adults in the life cycle of S. fülleborni. The free-living mature female lays a batch of eggs after each mating, thus increasing the number of infective larvae. Unfertilized females of the exogenic generation are unable to lay viable eggs.
LA TOXICITÉ DU DDT POUR LE SAUMON DE L'ATLANTIQUE (SALMO SALAR LINNÉ) ET LES ALEVINS DE TRUITE (SALVELINUS FONTINALIS MITCHILL)
Authors: Gagnon André
Published: April 2011

The relative sensitivity of brook trout fry, salmon fry, and 1- and 2-year-old parrs to known quantities of DDT was studied in hatchery-trough experiments with larger numbers of specimens than were used by previous workers. In troughs, in which part-time water circulation was achieved and DDT used at the rate of 0.5 lb./acre (0.32 p.p.m.), high mortality rates (93–100%) were recorded for salmon fry, trout fry, and 1-year-old parrs. Moreover, it was shown that group susceptibility decreases in the following manner: salmon fry > 1-year-old parrs > trout fry. In another series of experiments, under identical conditions, it was shown that sensitivity in salmon decreases with age. Using salmon fry, in troughs deprived of water circulation, a study was made of the effects of various concentrations of DDT: 0.33, 0.18, 0.072, and 0.036 p.p.m. corresponding to 0.5, 0.25, 0.1, and 0.05 lb. of DDT/acre, respectively. The average lethal dose (L.D. 50) was found to be 0.072 p.p.m. A comparison between two series of experiments shows how mixing of the DDT with water makes the poison more deadly than when used as a DDT–oil solution on the surface of water.
NEW RECORDS AND SPECIES OF CALANOID COPEPODS FROM SASKATCHEWAN AND LOUISIANA
Authors: Wilson Mildred Stratton
Published: April 2011

Diagnoses are given for three new species of the fresh-water calanoid copepod genus Diaptomus (subgenera Hesperodiaptomus and Aglaodiaptomus) from Saskatchewan and Louisiana. A check list of the calanoid copepods of Saskatchewan includes 23 species, of which 8 were previously reported in the literature, and 15 are new additions resulting from examination of collections from various types of water bodies.
STUDIES ON STRONGYLOIDES OF PRIMATES: IV. EFFECT OF TEMPERATURE ON THE MORPHOLOGY OF THE FREE-LIVING STAGES OF STRONGYLOIDES FULLEBORNI
Authors: Premvati
Published: April 2011

The optimum temperature for the complete development of the free-living and the infective larvae of Strongyloides fülleborni is 25 °C. Morphological changes are seen at higher or lower temperatures.
METHODS FOR STUDYING FORCIPOMYIA MIDGES, WITH SPECIAL REFERENCE TO CACAO-POLLINATING SPECIES (DIPTERA, CERATOPOGONIDAE)
Authors: Saunders L. G.
Published: April 2011

The known pollinators of cacao are shown to belong to the subgenera Proforcipomyia and Thyridomyia of the genus Forcipomyia. Characters are presented for the recognition of larvae, pupae, and adults of members of these groups. The breeding grounds are reported for four potential pollinating species, which are described and figured in all stages. Methods of collecting, rearing, and studying these insects are given, including rearing on artificial cultures.
ROLE OF GLYCEROL IN THE COLD-HARDENING OF BRACON CEPHI (GAHAN)
Authors: Salt R. W.
Published: April 2011

Concentrations of glycerol as great as 5 molal are built up in larvae of Bracon cephi (Gahan) after hibernation begins in the fall, and are lost again in the spring. The source of the glycerol was not determined, but is not glycogen. Large solute concentrations, composed mostly of glycerol, depress the melting points of the haemolymph to as low as −17.5 °C. Supercooling points of the intact larvae are lowered even more than their melting points, and this excess is proportional to the melting point depression.Glycerol is directly responsible for the cold-hardening of the larvae in two separate ways: by increasing supercooling, it increases the ability of the larvae to avoid freezing, and by its protective action it allows the larvae to survive even if they do freeze.
Migration departures from starling roosts
Authors: Richardson W. John , Haight Murray E.
Published: April 2011

Migration departures from Southern Ontario roosts of the European starling (Sturnus vulgaris) have frequently been observed by radar. Departures occurred at the normal time for roost dispersals. The birds usually moved northeast in spring and southwest in autumn, but occasional reverse movements were detected. Most of the sites from which departures were recorded produced normal dispersals and departures on more than one morning. In both spring and autumn, departures in both normal and reverse directions occurred with following winds. In spring, departures in the normal direction occurred with above normal temperatures; in autumn, they occurred with below normal temperatures. When only cases with following winds were considered, these temperature correlations were maintained. No correlation between incidence of departures and temperature change, wind speed, amount of cloud, or relative humidity was detected.
Natural British infestations of Diplozoon paradoxum Nordmann, 1832 (Trematoda: Monogenea) with respect to levels of infestation, size of the host, and condition of the host's blood
Authors: Wiles Michael
Published: April 2011

Frequency distributions of different levels of infestation for the monogenetic trematode Diplozoon paradoxum Nordmann, 1832 did not resemble the Poisson distribution when present in the cyprinid fishes Abramis brama L., Gobio gobio L., Phoxinus phoxinus L., and Rutilus rutilis L. A significant relationship was found between host size and incidence in P. phoxinus and R. rutilus and between host size and the level of infestation in P. phoxinus. In A. brama an inverse relationship was found between the level of infestation and host size. No correlation was observed between the level of infestation with D. paradoxum and the packed red cell volume (PCV) or serum haemoglobin (Hb) value of the blood of P. phoxinus or R. rutilus. No differences in these haematological parameters were detected between the blood of infested and non-infested fish. However, individual values of PCV and Hb were well correlated for both host species. As the parasite caused no perceptible damage to the gill epithelium of the four cyprinids studied, it is thought to be well adapted to its hosts.
Photoreception in the nauplius eye of Pandalus borealis Kröyer: Decapoda, Crustacea
Authors: Eaton Peter B. , Boyd Carl M.
Published: April 2011

On the basis of past morphological studies the nauplius eye of Pandalus borealis has been regarded as a simple photoreceptor. This is the first physiological study on its light-sensing capabilities. Small extracellular metal electrodes were used to measure the eye's response (electroretinogram, ERG) to intensity and wavelength controlled light stimuli. Responses demonstrated characteristics similar to responses of other invertebrate photoreceptors. This leads to the conclusion that the nauplius eye of P. borealis is a functional photoreceptor.
Seasonal metabolic organization in the muskrat (Ondatra zibethica). I. Changes in growth, thyroid activity, brown adipose tissue, and organ weights in nature
Authors: Aleksiuk M. , Frohlinger A.
Published: April 2011

Ten muskrats (Ondatra zibethica) per month were removed live from the natural environment for the duration of 1 year, in a preliminary study of seasonal metabolic organization. Growth in total body weight and skeletal dimensions occurs during the spring, summer, and autumn, but is absent during the winter. Thyroid activity, as reflected by 24-h I-125 conversion ratio, 24-h thyroidal uptake of injected I-125, and relative thyroid weight, is low during the winter relative to other seasons. The mass of interscapular brown adipose tissue, plus weights of water, lipids, and protein therein, are inversely related to seasonal changes in temperature. Percentage lipids in the tissue increases from August to April, and decreases from April to July; percentage water follows an opposite pattern. Percentage protein increases slightly during the winter. Dynamics of DNA content in the tissue suggest DNA synthesis occurs during the summer, rather than in the autumn when the tissue is enlarging. Adrenal weights increase slightly during the winter, and greatly during the spring and summer when the animals are about 1 year old. The liver and kidneys decrease in weight during the winter, while heart weight, lung weight, hematocrit, and blood hemoglobin increase considerably during that period. Thyroid activity and the mass of interscapular brown adipose tissue are inversely correlated from August to April (5% level).A number of hypotheses regarding seasonal metabolic organization are set forth on the basis of the above data.
Aggressive behavior of Apis mellifera L. workers towards introduced queens. II. Role of the mandibular gland contents of the queen in releasing aggressive behavior
Authors: Yadava R. P. S. , Smith M. V.
Published: April 2011

Removal of the mandibular glands from virgin queens eliminated the balling response of workers towards them. Worker bees coated with the contents of queen mandibular glands elicited aggressive behavior in sister workers; the aggression increased with an increasing amount of gland contents. The contents of glands removed while the queen was under complete anaesthesia appeared to provoke less worker aggression.
Metamorphosis of the perirectal Malpighian tubules in the mealworm Tenebrio molitor L. (Coleoptera, Tenebrionidae). II. Ultrastructure and role of autophagic vacuoles
Authors: Byers J. R.
Published: April 2011

The perirectal Malpighian tubules of T. molitor are highly specialized for ion and fluid transport. Although they survive metamorphosis, being similar in structure and function in both larva and adult, they undergo a sequence of dramatic alterations in subcellular organization. In the early stages of metamorphosis there is a phase of dedifferentiation during which the perirectal tubule cells undergo degenerative changes. The highly specialized brush border, which in the larva is formed of closely packed microvilli containing mitochondria, is partially broken down and a large number of mitochondria undergo autophagic isolation and digestion. A conspicuous result of the autophagic processes is the accumulation of membrane lipid within autophagic vacuoles which are eventually transformed into 'osmiophilic bodies.' During the later stages of metamorphosis the cells progressively redifferentiate and the brush border is reconstituted. The number of osmiophilic bodies declines markedly, concomitant with an apparent increase in the number of mitochondria.
The northern flying squirrel: a mycophagist in southwestern Oregon
Authors: Maser Chris , Maser Zane , Witt Joseph W. , Hunt Gary
Published: April 2011

Fecal samples were collected over 27 months from the northern flying squirrel (Glaucomys sabrinus (Shaw)), a mycophagist in the Pacific Northwest portion of its range. Nine genera of hypogeous Basidiomycetes, 10 of hypogeous Ascomycetes, and 1 of hypogeous Zygomycetes were identified from fecal samples (hypogeous fungi fruit underground). The squirrel food habits generally paralleled the seasonal availability of the hypogeous fungi, but with notable exceptions. Our data demonstrate the functional diversity an individual species lends to its habitat when viewed in a functional context.
Effect of parasitism by Anaphes sp. (Hymenoptera: Mymaridae) on the cold hardiness of Listronotus oregonensis (Coleoptera: Curculionidae) eggs
Authors: Hance Thierry , Boivin Guy
Published: April 2011

The cold hardiness of egg parasitoids is critical to their survival in winter because these organisms have little control in the choice of their overwintering site. The supercooling points of Listronotus oregonensis eggs increased from −24.9 to −22.1 °C as eggs matured. When these eggs were parasitized by Anaphes sp., their supercooling point remained stable at −22.9 °C throughout the development of the parasitoid. Anaphes sp. maintained its cold hardiness by increasing its levels of glycerol and fructose. When the parental generation was exposed to a combination of low temperature and short photoperiod, the supercooling point of the daughter generation (F1) was significantly decreased. A further decrease in the supercooling point was observed when F1 individuals were stored at 3 °C for 14 or 20 days. These data show that local extinction of populations overwintering in nonsheltered habitats is probably common in southwestern Quebec.
Morphological responses of white-tailed deer to a severe population reduction
Authors: Ashley E Paul , McCullough Gary B , Robinson Jeffrey T
Published: April 2011

We document responses, in terms of mass, hind-foot length, and antler beam diameter, of white-tailed deer (Odocoileus virginianus borealis) to an approximate 85% population reduction achieved by means of a series of public hunts in Long Point National Wildlife Area (LPNWA), Lake Erie, Ontario. Dressed weights and yearling antler beam diameters of LPNWA deer are among the lowest on record for this subspecies. Notable increases between 1989 and 1990 and in 1994 were common, especially in younger animals. Most significantly (P <<= 0.05), from 1989 to 1994, mean mass of male fawns increased by 44%, that of yearling males by 96%, and that of 2.5-year-old bucks by 75%. Significant increases in mean hind-foot length were also noted in male and female fawns and 2.5-year-old bucks. Antler beam diameters increased by 93% in yearlings and 35% in 2.5-year-old bucks between 1989 and 1994. The significant and immediate responses to decreased density and competition demonstrate that the herd was under extreme environmental stress and show the exceptional resiliency of this species in withstanding severe environmental pressure. Long Point deer are not genetically smaller than adjacent mainland deer as some had thought, but their growth has been restricted by environmental conditions.
Applying difference equations to wolf predation
Authors: Eberhardt L L
Published: April 2011

Parameters for generalized Lotka-Volterra equations, expressed as difference equations, have been estimated from actual data on wolves and their prey. The functional response is represented by a single constant, while the numerical response is expressed as a ratio-dependent limitation on predator abundance. Parameters for the Lotka-Volterra equations were estimated by multiple-regression fits to data on moose (Alces alces) and wolves (Canis lupus) on Isle Royale, and from other sources. Observed prey-predator ratios are highly variable, but much of the variability may arise from nonequilibrium conditions. A multiple-prey model has been developed by assuming that utilization rates vary in proportion to relative current biomass. If analyses are to be useful, the dynamic, nonlinear nature of predator-prey systems requires that a system of equations be developed, along with extensive series of observations of actual abundances of predator and prey.
Divergent cytogenetic evolution in Nearctic and Palearctic populations of sibling species in Chironomus (Camptochironomus) Kieffer
Authors: Kiknadze Iya I , Butler Malcolm G , Aimanova Karlygash G , Andreeva Evgenya N , Martin Jon , Gunderina Larissa I
Published: April 2011

Chromosomal polymorphism is described for natural populations of Chironomus pallidivittatus in both the Palearctic and Nearctic regions. The Palearctic populations studied exhibit 24 banding sequences, whereas 10 banding sequences have been recorded from Nearctic C. pallidivittatus. In total, 29 sequences and 37 genotypic combinations have been found. Of the 29 sequences known, only 5 are Holarctic (common to both the Nearctic and Palearctic), 19 are exclusively Palearctic, and 5 are Nearctic. The karyotype of Nearctic C. pallidivittatus is characterized by specific, homozygous Nearctic sequences in arms B and G and fixed Holarctic inversion sequences in the other arms. Only two chromosome arms in C. pallidivittatus, but all seven arms in the sibling species Chironomus tentans, differ between Palearctic and Nearctic forms by the presence of unique, homozygous sequences in the Nearctic karyotype. This indicates a great difference in the cytogenetic histories of these closely related species; much less karyotypic divergence between continents has occurred in C. pallidivittatus than in C. tentans. The cytogenetic distance between Palearctic and Nearctic populations of C. tentans is higher (DN = 1.62) than in C. pallidivittatus (DN = 0.27). Thus, Palearctic and Nearctic C. tentans should be regarded as sibling species, but Palearctic and NearcticC. pallidivittatus are best viewed as strongly divergent races of the same species. A photomap of polytene chromosomes of C. pallidivittatus is presented in which banding sequences are mapped by using C. tentans as a standard.
Mitochondrial DNA polymorphism in a black fly, Simulium vittatum (Diptera: Simuliidae)
Authors: Zhu X , Pruess K P , Powers T O
Published: April 2011

Mitochondrial DNA (mtDNA) was extracted from pooled field-collected samples representing six species of black flies (Cnephia dacotensis, Simulium bivittaum, S. johansenni, S. luggeri, S. piperi, S. vittatum) and compared by restriction fragment length polymorphism (RFLP) analysis. Morphospecies were molecularly distinct, with few shared restriction fragments. Eleven populations of S. vittatum were found that appeared to be homogeneous for a single mitochondrial haplotype. Ten other populations of S. vittatum showed extensive mitochondrial heterogeneity. In part, these samples contained mixtures of two cytologically recognized siblings: IIIL-1 and IS-7. About 70% of the mitochondrial genome of a population pure for sibling IIIL-1 was cloned as five HindIII fragments, which were used as hybridization probes to examine individual black flies. Thirteen mtDNA haplotypes involving permutations of 10 HindIII restriction sites were identified in individual black flies examined from 26 populations. DNA from 168 larvae cut with both EcoR1 and HindIII revealed five additional haplotypes. One HindIII haplotype was present in 84% of 390 larvae examined and predominated in every population examined from New York to California and in both the IIIL-1 and IS-7 siblings. Nebraska populations had individuals with nearly all known haplotypes. The most common haplotype was usually the only form present in warm, silty streams with organic enrichment. Rarer haplotypes were found in cool, spring-fed streams but without clear geographic or phylogenetic components.
Do small voles require less food than large voles?
Authors: Bronson F H
Published: April 2011

Many small mammals lose body mass in the fall and winter. Laboratory studies suggest that the cause of this varies from individual to individual, at least in meadow voles, Microtus pennsylvanicus. The short day lengths of fall induce this adaptation in some individuals, presumably to promote winter survival. Other individuals, side-by-side neighbors, are insensitive to this cue; they enter winter with a larger body mass that they may not be able to maintain if conditions become too harsh. A long-held assumption is that the photoregulated loss of mass allows energy to be conserved by decreasing the amount of food required for survival and, thus, decreasing foraging time. The present experiment tested the hypothesis that smaller, photoresponsive meadow voles do indeed consume less food and spend less time feeding than larger individuals, which are not photoresponsive. This hypothesis was tested in conditions meant to simulate some of the energy challenges faced by voles at the onset of winter. Representatives of each phenotype were housed in cages in which they had to leave their nests in order to feed, and in which food intake and time spent feeding could be monitored. At 25°C the two groups did not differ in either food intake or time spent feeding; the smaller animals required more food per gram of body mass. Food quality was reduced and, later, ambient temperature was decreased to 3°C. Food intake and feeding time were again almost identical in the two groups. It is suggested that the hypothesis failed to find support in this experiment because it does not take into account the higher thermoregulatory costs associated with a decrease in size.
On the genus Eclipidrilus Eisen, 1881 (Lumbriculidae, Clitellata), including a description of Eclipidrilus ithys sp.nov.
Authors: Brinkhurst R O
Published: April 2011

The genus Eclipidrilus is recongnized from the unique apomorphy of elongate of elongate atria with spiral muscles. The spermathecae are in segment IX, the male pores, in X, and female pores in 10/11;tests are found in IX-X or X and ovaries in XI. The seven North American species, one of which has been recorded from wales, differ in regard to the presence or absence of a proboscis, the median unpaired or lateral paired gonopores, the form of the penes, and the number of spermathecae and (or) atria. The primary characteristics of Eclipidrilus ithys sp.nov. are that it lacks a proboscis, it ha a small penis, and while there may be one or two atria, the atrial pores are ventrolateral (not median), the ejaculatory duct forms an upright structure in X, and the spermathecal and male pores are not enclosed in massive glands.
Preroosting aggregations in the American crow,Corvus brachyrhyncos
Authors: Moore Jeffrey E , Switzer Paul V
Published: April 2011

Preroosting aggregations (PRAs), or site-specific gatherings of individuals made prior to flying into a night roost, are frequently associated with avian roosting behavior. We investigated PRAs in the American crow (Corvus brachyrhyncos) in order to describe preroosting behavior and test possible hypotheses concerning their function. Crows were aggregated among the available fields and within a field. Although crows in PRAs in fields commonly foraged, in previous studies crow PRAs have been found in the area at sites where little foraging probably took place, such as large rooftops. As the evening progressed, individuals shifted to PRA sites closer to the location of night roosts. Crows left PRAs for night roosts in a highly aggregated fashion, but prior to arriving at a night roost, individuals often separated from those with whom they left the PRA. Those individuals that were still together upon arriving at the night roost rarely settled next to each other. This pattern of behavior, along with characteristics of crow night roosts, is inconsistent with functional explanations based on crow PRAs being information centers for location of either daytime foraging areas or night roosts, nor does it support hypotheses solely related to foraging benefits. Rather, the results suggest that while crow PRAs are probably associated with multiple benefits, lowering predation risk may be a primary function.
The forewing tegulae: their significance in steering manoeuvres and free flight inLocusta migratoria
Authors: Gee Christine E , Shoemaker Kelly L , Robertson R Meldrum
Published: April 2011

The flight system of Locusta migratoria is widely used to investigate the principles of sensory-motor control. The four tegulae are proprioceptors of the flight system that are active during the downstroke and provide afferent input to flight-system neurons. While the role of the hindwing tegulae in the flight motor pattern has been well characterized, the role of the forewing tegulae is unclear. We tested whether the forewing tegulae may be more important for the generation of intentional steering manoeuvres than for generation of the basic flight motor pattern. Following ablation of the forewing tegulae, tethered flying locusts continued to generate characteristic intentional steering manoeuvres in open-loop conditions. In contrast, we found that locusts were less likely to sustain unrestrained free flight following ablation of the forewing tegulae. We also found that the number of spikes in a forewing depressor muscle increased, as did the hindwing to forewing delay in elevator-muscle activation after ablation of the forewing tegulae. We conclude that the forewing tegulae promote free flight in locusts and we discuss the role they may play in locust flight.
Spatial distribution of zooplankton biomass size fractions in a bog lake: abiotic and (or) biotic regulation?
Authors: Masson Stéphane , Pinel-Alloul Bernadette
Published: April 2011

Although spatial heterogeneity of zooplankton has been explained by variations in abiotic and biotic factors as well as their cascading interactions, few studies have paid attention to the relative importance of these processes in structuring the vertical and horizontal distribution of zooplankton within a lake. The main objective of this study was to determine the relative importance of abiotic and biotic processes in the regulation of the vertical and horizontal distribution of four size fractions (53-100, 100-202, 202-500, and >500 µm) of the zooplankton biomass in a bog lake (Lake Geai, Quebec). Spatial heterogeneity of zooplankton biomass was found in both the horizontal and the vertical dimensions of the lake, and spatial patterns were quite similar for all size fractions. On the horizontal axis, spatial heterogeneity was stronger in the epilimnetic stratum. Zooplankton biomass was mainly aggregated in the east side of the lake in an area of higher conductivity and greater density of small chaoborid larvae. On the vertical axis, zooplankton biomass was concentrated in the epilimnetic waters and decreased with depth. This vertical pattern of distribution might be due to the avoidance of cold and anoxic waters and a high density of large chaoborid larvae in the hypolimnion. In general, invertebrate predation has been identified as the primary factor regulating zooplankton biomass distribution in Lake Geai. However, the size structure of chaoborid predators was more important than their density in the control of the spatial distribution of zooplankton.
Seasonal occurrence, body composition, and migration potential of army cutworm moths in northwest Montana
Authors: White, Jr. Don , Kendall Katherine C , Picton Harold D
Published: April 2011

Grizzly bears (Ursus arctos horribilis) consume adult army cutworm moths (Euxoa auxiliaris) from late June through mid-September on alpine talus slopes in Glacier National Park (GNP), Montana. As part of a study carried out to better understand the ecological interactions between grizzly bears and army cutworm moths in GNP, we studied temporal abundance patterns, body mass and composition, and migration potential of moths collected from alpine moth aggregation sites throughout the summer of 1994 and 1995. Army cutworm moths arrived in the alpine zone of GNP in late June or early July and departed by late August or early September. While moths were in the alpine zone, their body mass and moisture, lipid, and gross energy contents markedly increased and crude protein decreased. The absence of moths from the alpine zone coincided with the presence of moths on the Great Plains. Using published estimates of the cost of transport in flying animals, we calculated that an army cutworm moth flying in late summer through still air could fly 140 km using body lipid reserves alone.
Euphausiids as intermediate hosts of Anisakis simplex in the St. Lawrence estuary
Authors: Hays Réjean , Measures Lena N , Huot Jean
Published: April 2011

To determine abundance of larval Anisakis simplex in euphausiids of the St. Lawrence estuary, Meganyctiphanes norvegica and Thysanoessa raschii were collected at seven sites from the mouth of the Saguenay River to Baie des Outardes. Larvae were removed from euphausiids by means of a modified Baermann apparatus filled with a pepsin-HCl digest solution. Abundances of larvae in euphausiids ranged from 0 to 58.2 × 10-5. Larvae (N = 100) were in the third stage (bearing one cuticle) or moulting from the second stage to the third stage (bearing two cuticles). Euphausiids, particularly T. raschii, which represented 98% of the total euphausiids sampled, are important intermediate hosts of A. simplex in the St. Lawrence estuary. These data indicate the importance of the St. Lawrence estuary as an enzootic zone for A. simplex and thus a valuable area to study the biology and the transmission of this parasite.
Ambophthalmos, a new genus for "Neophrynichthys" angustus and "Neophrynichthys" magnicirrus, and the systematic interrelationships of the fathead sculpins (Cottoidei, Psychrolutidae)
Authors: Jackson Keith L , Nelson Joseph S
Published: April 2011

The new genus Ambophthalmos is recognised for "Neophrynichthys" angustus and "Neophrynichthys" magnicirrus, two southern Pacific psychrolutids. A hypothesis of psychrolutid phylogenetic relationships based on parsimony analysis of osteological characters is presented. Two synapomorphic characters suggest that A. angustus and A. magnicirrus form a monophyletic group: the supratemporal is posteriorly fused to the posttemporal and arch 2 is medially fused to its antimere. Four characters suggest that Cottunculus is monophyletic and five synapomorphic characters suggest that Ambophthalmos is sister to Cottunculus. A cladistic classification of the Psychrolutidae includes five subfamilies sequenced as Dasycottinae, new; Eurymeninae, new; Cottunculinae, redefined; Malacocottinae, new; and Psychrolutinae, unchanged.
A genetic and morphological comparison of shallow- and deep-water populations of the introduced dreissenid bivalve Dreissena bugensis
Authors: Claxton W Trevor , Wilson Anthony B , Mackie Gerry L , Boulding Elizabeth G
Published: April 2011

The discovery of a morphologically distinct dreissenid mussel in the profundal zone of Lake Erie suggests the presence of either a third dreissenid mussel species in the Great Lakes or a previously unknown morphological phenotype of an existing dreissenid species. We examined the morphometrics and molecular systematics of the zebra mussel (Dreissena polymorpha) and the profundal and epilimnetic forms of the quagga mussel (Dreissena bugensis) from Lakes Erie and Ontario. In an attempt to resolve the taxonomic status of the profundal form of the quagga mussel, we sequenced a 710 base pair fragment of the cytochrome oxidase subunit I mitochondrial gene of the two forms of the quagga mussel. No nucleotide differences were found, supporting the hypothesis that the profundal form of the quagga mussel is a phenotype of D. bugensis, not a separate species. In contrast, the second and third principal component scores from an analysis of the morphological variables shell length, shell width, shell height, and shell mass separated the epilimnetic and profundal forms of the quagga mussel into two groups, but grouped zebra mussels from all depths together. The most parsimonious explanation for our results is that D. bugensis shows plasticity in shell morphology with respect to depth, whereas D. polymorpha does not.
Ingestion of trace metals by the opossum shrimp, Mysis relicta, determined by laser ablation sampling - inductively coupled plasma mass spectrometry
Authors: Lasenby David C , Veinott Geoff
Published: April 2011

Differences in the diet of individual mysids can be determined by analysing the elemental composition of the gut contents of individual mysids with laser ablation sampling - inductively coupled plasma mass spectrometry. Two groups of the opossum shrimp, Mysis relicta, were cultured in the laboratory for a 2-week period. One group was fed a diet of Daphnia magna and the other lake sediment. Although the element:Sr ratios within the gut were highly variable, mean element:Sr ratios of several elements (V, Pb, Ca) in the gut of mysids fed D. magna were significantly different from those in the gut of sediment-fed mysids.
Water vapour uptake and drought resistance in immobile instars of Parasitengona (Acari: Prostigmata)
Authors: Wohltmann Andreas
Published: April 2011

Eggs and protonymphs of a number of terrestrial Parasitengona were tested for drought resistance and their ability to take up atmospheric moisture. Species of the Erythraeoidea display higher drought resistance in both instars than species of the Trombidioidea. This is achieved by evolutionary modifications of the ground plan of the Parasitengona, including reduction of body openings and additional sealing of others with lipids, resulting in reduced water loss. Water vapour uptake is not evident in erythraeoid eggs or protonymphs but has been observed in the Trombidioidea and probably constitutes a characteristic of at least the stem species of the terrestrial Parasitengona. The resulting increase in fresh mass is about 50% before the protonymph stage begins; its role is probably not related to drought resistance or osmotic regulation. Instead, it presumably serves to extend the cuticle and thus provides more space for the development of the subsequent instar.
Diet choices made by free-ranging moose in northern Sweden in relation to plant distribution, chemistry, and morphology
Authors: Shipley L A , Blomquist S , Danell K
Published: April 2011

Understanding how large herbivores select their diet requires accurate measurements of the nutritional costs and benefits of food items and the composition of plants in the diet relative to the composition of plants in the habitat. We followed moose (Alces alces) tracks in the snow and measured bites of browse plants taken and the number and mass of twigs of the 10 browse species available within the moose's reach and measured morphological and chemical characteristics of browse plants. The diets of 41 moose in northern coastal Sweden contained 75% Scots pine (Pinus sylvestris) and willow (Salix spp.), with the remaining proportion equally divided among five deciduous browse species and common juniper (Juniperus communis). The moose used approximately 20% of the bites available along the foraging patch, usually taking only one or two bites on each plant selected for browsing. Moose selected rowan (Sorbus aucaparia), willow species, and aspen (Populus tremula) in winter, used gray alder (Alnus incana), silver birch (Betula pendula), and Scots pine in proportion to their availability, and avoided pubescent birch (Betula pubescens) and Norway spruce (Picea abies). Selection was correlated with plant morphology but not with digestibility or nitrogen, fibre, or phenolic content. Moose selected browse species offering fewer, larger stems over those with many, smaller stems. Moose made slight adjustments in their food selection and foraging intensity as abundance of browse plants declined, thereby presumably maintaining higher harvesting rates.
Selection of blue mussels, Mytilus edulis, by common eiders, Somateria mollissima, by size in relation to shell content
Authors: Bustnes Jan Ove
Published: April 2011

The blue mussel, Mytilus edulis, is the most important food item for the common eider, Somateria mollissima, but the mussels eaten by eiders vary in length between both areas and seasons. The aim of this study was to experimentally test the hypothesis that common eiders try to minimize shell intake when selecting among mussels of different lengths. Two types of experiments were conducted using wild common eiders in captivity. Experiment 1 tested whether eiders could seek out the mussels with least relative shell content and highest flesh content from among mussels of an array of lengths. They selected the shortest mussels (<20 mm), which had the lowest shell content. In experiment 2, the eiders were given mussels of the same length class (26-31 mm), but with different shell morphology and shell mass, from the subtidal and upper intertidal zones. The birds only ate the subtidal-zone mussels with the lowest shell mass. The results of this study strongly indicate that reducing the amount of indigestible shell is an important factor for eiders selecting among mussels of different lengths.
The genus Carabodes (Acari: Oribatida: Carabodidae) of North America, with descriptions of new western species
Authors: Reeves R Marcel , Behan-Pelletier Valerie
Published: April 2011

Four new species of the oribatid mite genus Carabodes from western North America are described, based on adult specimens: Carabodes california known from California, C. colorado from British Columbia, Alberta, Idaho, Wyoming, Colorado, Arizona, and New Mexico, C. dickinsoni from British Columbia, Washington, Oregon, and California, and C. hoh from British Columbia, Washington, Oregon, and California. We provide an expanded diagnosis of the genus, including information on integumental birefringence, chaetotaxy, palptarsal setation, and position of lyrifissure iad. We present a table of character states and a diagnostic key for the 28 species, as well as a summary of their distributions.
Use of time, space, and food by the gymnophthalmid lizardPrionodactylus eigenmanni from the western Amazon of Brazil
Authors: Vitt Laurie J , Sartorius Shawn S , Avila-Pires Teresa Cristina S. , Espósito Maria Cristina
Published: April 2011

The gymnophthalmid lizard Prionodactylus eigenmanni lives in leaf litter of terra firme forest in the western Amazon. Lizards are active during sunny and cloudy periods and body temperatures are 27.2 ± 0.19°C (mean ± SE). Body temperatures did not correlate with substrate or air temperatures: P. eigenmanni apparently gain heat by seeking temporary patches of relatively warm microhabitat. Two populations (Rio Ituxí in Amazonas and central Rondônia) were compared with respect to diet and morphology. The diet consists of a wide variety of invertebrates, but spiders, homopterans, orthopterans, and roaches constitute the majority of food items. Prey types and sizes in the two localities were similar. Females are larger than males and there is no apparent sexual dimorphism in head size as is found in many other lizards. Even though the two populations were studied in different seasons, there was no indication that wet versus dry season affected the ecology of these lizards.
Influence of weasel (Mustela nivalis Linnaeus, 1766) odour on spatial behaviour of root voles (Microtus oeconomus Pallas, 1776)
Authors: Borowski Zbigniew
Published: April 2011

Findings concerning the influence of the odour of the specialized predator Mustela nivalis Linnaeus, 1766, the weasel, on the behaviour of Arvicolidae (voles) suggested that there is an impact on voles' utilization of space. This question was addressed by studying the influence of weasels and their scent on the utilization of space by free-living root voles, Microtus oeconomus Pallas, 1776. Eleven captured voles (6 males and 5 females) were selected for telemetric monitoring over 10 days. After the first 5 days a weasel in a cage was exposed, along with samples of its odour in the form of urine and faeces, at the determined "centre of activity" within the home range of these voles. The sizes of home ranges were compared between experimental and control voles and the former were found to be smaller than the latter following introduction of the predator. However the centres of activity did not shift, and the probabilities of individuals being encountered at them before and after were the same. To try to account for these reactions, a series of laboratory experiments with the same vole species (n = 50) was carried out to study the influence of weasel odour on locomotory activity and on distances from, and numbers of contacts with, the source of the odour. Voles recognized the predator's scent and responded with a level of locomotory activity that was lower, as well as by fewer contacts being made with the source, in the experimental group than in the control group. However, the distances kept from sources of predator odour were no greater than from control sources, and in fact, voles spent more time close to the source than at greater distances. The reaction of a root vole to the presence of a weasel in the home range is therefore not to escape from the range but to reduce the probability of an encounter with this predator by decreasing locomotory activity.
Perceived predation risk, parasitism, and the foraging behavior of a freshwater snail (Potamopyrgus antipodarum)
Authors: Levri Edward P
Published: April 2011

Foraging behavior can be influenced by such factors as predation risk, individual size, and parasite infection. Snails (Potamopyrgus antipodarum) placed in tanks with large rocks were exposed to four types of water: (1) water with crushed snails, (2) water from a tank in which fish (Gobiomorphus cotidianus) were fed only trout chow, (3) water from a tank where the fish were also fed snails, and (4) plain water. Snails could respond by moving to the top of rocks (where algal food was present) or to the bottom of rocks (where the predation risk was lower). The snails responded to fish chemicals by moving to the bottom of rocks. The response was dependent on snail size and fish diet. Smaller snails moved to the bottom of rocks more than larger snails did. Trematode-infected snails were found on top of the rocks more than other classes of snails, but infected snails still moved to the bottom of rocks in response to the fish predator. Snails eaten by fish in the field tend to be smaller than snails in the overall available population. Thus, snails that are more vulnerable to predation respond more intensely to the odor of fish by moving to the bottom of rocks. This size-dependent response to fish appears to be independent of the occurrence of trematode infection.
Response of neighboring coyotes (Canis latrans) to social disruption in an adjacent pack
Authors: Gese Eric M
Published: April 2011

Territoriality is an important mechanism by which social carnivores limit or exclude potential competitors from mates, food, and space. The response of neighboring conspecifics to social disruption in an adjacent social unit has been rarely documented, owing to the difficulty of observing secretive or nocturnal carnivores. We observed 54 coyotes (Canis latrans) from five resident packs, plus five transient animals, for 2507 h from January 1991 to June 1993 in the Lamar River Valley, Yellowstone National Park, Wyoming. We documented the spatial response of three neighboring coyote packs to the social disruption in an adjacent fourth pack caused by the death of the alpha male and subsequent temporary abandonment of the territory by the alpha female. One of the three packs shifted its space-use pattern into part of the adjacent pack's territory and maintained occupancy of the newly acquired area even when the alpha female returned with a new mate. Neither food shortage nor prey availability was a contributing factor. The absence of the alpha pair maintaining territorial boundaries allowed the adjacent pack to take over part of the unoccupied area.
Effect of a plant-derived spider toxin analogue on crayfish neuromuscular junctions
Authors: Mercier A J , Farragher S , Schmor B , Kamau M , Atkinson J
Published: April 2011

N8-Coumaroyl spermidine (N8-CS) is an example of hydroxycinnamic acid - polyamine conjugates found in certain plants. Because of its structural similarity to some spider toxins, N8-CS was tested for its ability to block arthropod neuromuscular synapses. It inhibited chemical synaptic transmission at crayfish (Procambarus clarkii) neuromuscular junctions, the IC50 being approximately 200 µM. Its effect was at least partially reversed by washing with physiological saline. Joro spider toxin, a structurally similar compound, also blocked crayfish neuromuscular synapses but its effect was irreversible. These results suggest that plant-derived cinnamoyl spermidines might have paralytic properties similar to those of spider toxins.