Observations on the Settling Behaviour of Larvae of the Tubeworm Spirorbis borealis Daudin (Polychaeta)

1960 ◽  
Vol 11 (1) ◽  
pp. 55 ◽  
Author(s):  
B Wisely
Keyword(s):  
Natural Conditions ◽  
Searching Behaviour ◽  
Laboratory Conditions ◽  
Direct Observations ◽  
Settling Behaviour ◽  
Surface Contour ◽  
North Wales ◽  
Nearest Neighbours ◽  
Fucus Serratus ◽  
Settlement Behaviour

Aspects of natural and experimental settling of Spirorbis borealis on the seaweed Fucus serratus L. were compared. Under natural conditions S. borealis appeared to settle preferentially in the concave grooves flanking the midribs, and less commonly on the flatter parts of the fronds. Settlement seldom took place on the convex midrib. The centres of individuals of dense populations, which were spaced along the grooves, were 1-2 mm from those of their nearest neighbours; none of the 2582 examined were closer than 0.5 mm. Experiments showed that larvae tended to avoid settling on P. serratus bearing adults of their own species, or similar shaped objects, when the density of these exceeded 10 per cm² and if alternative settling surfaces of Fucus were provided. Direct observations showed that larvae tended to explore concave areas of the fronds more intensively than other areas and turned away from nearby round, protruding objects during their final settling movements. However, larvae withheld from suitable settling surfaces for increasing periods of time showed a successive abbreviation of the pattern of searching behaviour. When they had been prevented from settling for 8 hours or more they settled on or very close to the point where they first alighted, apparently regardless of the surface contour or the presence of nearby objects. The most densely settled populations encountered naturally in the area (Menai Straits, North Wales) ranged from 12 to 33 individuals per cm² and averaged 21, but experimental densities of 64 to 322 individuals per cm² were obtained readily when larvae competed for limited settling spaces on F. serratus under laboratory conditions. Analysis of the settlement behaviour and its modification with the passage of time indicated how the pattern of settlement observed in nature could result.

Genetics of Gibberella fujikuroi. IV. Natural occurrence of compatibility alleles at the mating locus

1983 ◽  
Vol 25 (6) ◽  
pp. 605-608 ◽  
Author(s):  
Gurmel S. Sidhu
Keyword(s):  
Genetic Control ◽  
Gibberella Fujikuroi ◽  
Natural Occurrence ◽  
Mating Types ◽  
Natural Conditions ◽  
Field Isolates ◽  
Laboratory Conditions ◽  
Sexual Compatibility

Gibberella fujikuroi is a heterothallic bipolar fungus and both mat+ and mat− mating types are found in nature but, they rarely cross under natural conditions. However, mat+ and mat− field isolates cross with the two tester strains under laboratory conditions and show variable degrees of sexual compatibility as measured in terms of number of fertile perithecia. Fifteen mat+ and fifteen mat− field isolates were crossed with the two tester strains. Variable degrees of compatibility, ranging from 2.2 to 47.7 perithecia when crossed with 223 (mat−) and 1.1 to 39.9 perithecia when crossed with 80 (mat+), were obtained. The genetic control of six easily distinguishable degrees of compatibility were studied from testcrosses made with the tester strains using random and unordered tetrad analyses. Three alleles in mat+ and three alleles in mat− were distinguished. Frequency of natural occurrence of mat+ and mat− was found to be 27 and 73%, respectively.

scholarly journals Frazil Measured in the Laboratory and in the Field

1986 ◽  
Vol 17 (2) ◽  
pp. 115-128
Author(s):  
Gee Tsang
Keyword(s):  
Experimental Data ◽  
Fresh Water ◽  
Sea Water ◽  
Flowing Water ◽  
Natural Conditions ◽  
Water Research ◽  
Laboratory Conditions ◽  
National Water ◽  
Research Institute

Using an instrument that was recently developed at the National Water Research Institute, the concentration of frazil in flowing water was measured under laboratory conditions for both fresh water and sea water and under natural conditions in the Beauharnois Canal. Experimental data and their analysis are reported in this paper.

Two methods of estimating competitiveness of chemosterilized males of Musca domestica (Diptera: Muscidae)

1992 ◽  
Vol 82 (4) ◽  
pp. 521-524 ◽  
Author(s):  
M. Saiful Islam ◽  
Gordon R. Port
Keyword(s):  
Musca Domestica ◽  
Test Methods ◽  
House Fly ◽  
Test Method ◽  
Ratio Test ◽  
Mating Competitiveness ◽  
Laboratory Conditions ◽  
Direct Observations ◽  
Hexamethyl Phosphoramide

AbstractMating competitiveness and sexual or total competitiveness of males of the house fly, Musca domestica Linnaeus, treated with 1.0% hexamethyl phosphoramide (hempa) were measured quantitatively from direct observations and ratio test methods, respectively. From direct observations, treated males of Cooper and Boxted strains of M. domestica were found to obtain more first matings than untreated males (P <0.01 and P <0.05, respectively) when competing for untreated females, whilst by using the ratio test method under laboratory conditions, total competitiveness values (C) of treated males of the two strains were estimated to be 0.72–0.89 and 0.75–0.97, respectively, at three different ratios from 1:1:1 to 3:1:1.

scholarly journals The growth-rate of juvenile Asterias rubens L.

1951 ◽  
Vol 30 (2) ◽  
pp. 381-385 ◽  
Author(s):  
H. Barnes ◽  
H. T. Powell
Keyword(s):  
Growth Rate ◽  
Natural Population ◽  
Otter Trawl ◽  
Asterias Rubens ◽  
Natural Conditions ◽  
General Biology ◽  
Direct Observations ◽  
The Common ◽  
Large Animals

The general biology of the common starfish, Asterias rubens L., has recently been studied by Vevers (1949), whose investigations included observations on the growth-rate of this species. His material was collected in the Plymouth area largely by means of an otter trawl, supplemented by a few Agassiz and dredge hauls, and there are therefore few records in his data of the growth-rate of juvenile A. rubens under natural conditions. Vevers also made observations on the growth-rate of individuals kept in laboratory tanks, but again the results apply mainly to fairly large animals. The only other direct observations on growth-rate appear to be those of Bull (1934), who dealt with three small individuals kept in aquarium tanks, while Orton & Fraser (1930) give measurements made on a natural population taken, after one year's growth, from a buoy.

Observations on the Viability of Bacterium salmonicida

1940 ◽  
Vol 5a (1) ◽  
pp. 1-7 ◽  
Author(s):  
D. C. B. Duff ◽  
M. Isobel MacArthur ◽  
Helen G. Thompson
Keyword(s):  
Natural Waters ◽  
Domestic Sewage ◽  
Natural Conditions ◽  
Laboratory Conditions ◽  
Laboratory Procedures

Under laboratory conditions Bact. salmonicida multiplies in unaltered domestic sewage and survives therein for 15 days. Removal, destruction or diminution of the original sewage flora resulted in marked multiplication of B. salmonicida inocula, and in survival periods of from 13 to 67 days. Viability figures derived from laboratory procedures may not be directly applicable in interpreting the fate of B. salmonicida released under natural conditions into natural waters.

scholarly journals The development of trial questionnaire on social exclusion

2016 ◽  
Vol 7 (4) ◽  
pp. 132-146 ◽  
Author(s):  
I.Yu. Suvorova
Keyword(s):  
Social Exclusion ◽  
Social System ◽  
Personal Exposure ◽  
External Factors ◽  
Natural Conditions ◽  
Psychological Experience ◽  
Laboratory Conditions ◽  
External Conditions ◽  
The Creation

The article describes the evolution of the phenomenon of social exclusion and methods of its investigation in laboratory conditions. To the best of our knowledge, the diagnostic of social exclusion has been primarily based on external factors till now. This article is devoted to the creation of questionnaire aimed to reveal the psychological experience of social exclusion in natural conditions. Such tool is necessary because it is insufficient to refer only to external conditions of personal exposure to the periphery of social system in order to estimate psychological exclusion, as physical and psychological exclusion do not always coincide. The reliability of our questionnaire is α = 0,952. The validity of the tool was checked through the correlation with Leontiev’s Test of Sense of Life Orientations. As a result, strong links were found between scales of both tests (0,462&lt; r &lt; 0,725; 0,01&lt; p&lt; 0,05).

scholarly journals Phenotypic plasticity in an ant with strong caste–genotype association

2018 ◽  
Vol 14 (1) ◽  
pp. 20170705 ◽  
Author(s):  
Alexandre Kuhn ◽  
Hugo Darras ◽  
Serge Aron
Keyword(s):  
Phenotypic Plasticity ◽  
Environmental Factors ◽  
Juvenile Hormone ◽  
Hormone Treatment ◽  
Caste Determination ◽  
Developmental Pathway ◽  
Natural Conditions ◽  
Social Hymenoptera ◽  
Laboratory Conditions ◽  
Genetically Determined

Caste determination in social Hymenoptera (whether a female egg develops into a reproductive queen or a sterile worker) is a remarkable example of phenotypic plasticity where females with highly similar genomes exhibit striking differences in morphology and behaviour. This phenotypic dichotomy is typically influenced by environmental factors. However, recent studies have revealed a strong caste–genotype association in hybridogenetic ants: workers are all interlineage hybrids while queens are all purebred, suggesting that female caste fate is genetically determined. Using the hybridogenetic ant Cataglyphis mauritanica , we show that under laboratory conditions, purebred offspring develop into reproductive queens but occasionally give rise to workers. Moreover, while hybrids typically become workers, juvenile hormone treatment can switch their developmental pathway to the reproductive caste. These results indicate that phenotypic plasticity has been retained in an ant with a strong caste–genotype association, despite its lack of expression in natural conditions.

scholarly journals Enterococcus faecalis Gene Transfer under Natural Conditions in Municipal Sewage Water Treatment Plants

1998 ◽  
Vol 64 (2) ◽  
pp. 626-632 ◽  
Author(s):  
Herbert Marcinek ◽  
Reinhard Wirth ◽  
Albrecht Muscholl-Silberhorn ◽  
Matthias Gauer
Keyword(s):  
Water Treatment ◽  
Sex Pheromone ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Sewage Water ◽  
Municipal Sewage ◽  
Natural Conditions ◽  
Laboratory Conditions ◽  
Sewage Water Treatment ◽  
Different Strains

ABSTRACT The ability of Enterococcus faecalis to transfer various genetic elements under natural conditions was tested in two municipal sewage water treatment plants. Experiments in activated sludge basins of the plants were performed in a microcosm which allowed us to work under sterile conditions; experiments in anoxic sludge digestors were performed in dialysis bags. We used the following naturally occurring genetic elements: pAD1 and pIP1017 (two so-called sex pheromone plasmids with restricted host ranges, which are transferred at high rates under laboratory conditions); pIP501 (a resistance plasmid possessing a broad host range for gram-positive bacteria, which is transferred at low rates under laboratory conditions); and Tn916 (a conjugative transposon which is transferred under laboratory conditions at low rates to gram-positive bacteria and at very low rates to gram-negative bacteria). The transfer rate between different strains of E. faecalis under natural conditions was, compared to that under laboratory conditions, at least 105-fold lower for the sex pheromone plasmids, at least 100-fold lower for pIP501, and at least 10-fold lower for Tn916. In no case was transfer from E. faecalisto another bacterial species detected. By determining the dependence of transfer rates for pIP1017 on bacterial concentration and extrapolating to actual concentrations in the sewage water treatment plant, we calculated that the maximum number of transfer events for the sex pheromone plasmids between different strains of E. faecalisin the municipal sewage water treatment plant of the city of Regensburg ranged from 105 to 108 events per 4 h, indicating that gene transfer should take place under natural conditions.

scholarly journals Pathogenicity of Beauveria bassiana strains isolated from Ostrinia nubilalis Hbn. (Lepidopte­ra: Pyralidae) to original host and to ladybirds (Coleoptera: Coccinelidae)

1999 ◽  
Vol 35 (No. 3) ◽  
pp. 108-112 ◽  
Author(s):  
C. Cagáň ◽  
V. Uhlík
Keyword(s):  
Fungal Infection ◽  
Beauveria Bassiana ◽  
Ostrinia Nubilalis ◽  
Coccinella Septempunctata ◽  
Spore Suspension ◽  
Natural Conditions ◽  
Laboratory Conditions ◽  
Original Host

B. bassiana strains isolated from 0. nubilalis were tested against the larvae of 0. nubilalis and coccinellid beetles in laboratory conditions (25°C). The first dead 0. nubilalis larvae were observed 48 hours after the application. During the first five days after the application, the efficiency of spore suspension was significantly higher than the efficiency of dry spore formulation. Spore suspension killed more than 50% of larvae after 72, or 96 hours. After dry spore formulation was used, more than 50% of larvae were killed during 96, or 120 hours. B. bassiana killed 50% of coccinellid larvae during 48 hours. After anot her 24 hours 83.3% (strain SK78), or 100% (strain SK99) coccinellid larvae were killed by fungus. More than 50% of dead adults of Coccinella septempunctata L. and Propylea quattuordecimptmctata (L.) was found 72-120 hours after application of fungus. This mea ns that B. bassiana was not adapted specifically to original host and killed effectively the adults and larvae of Coccinellidae. Different behaviour probably allows the coccinellids to escape from fungal infection in natural conditions

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