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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 47 (1988), S. 145-152 
    ISSN: 1570-7458
    Keywords: Biological control ; predation ; Eriosoma lanigerum ; Forficula auricularia ; apple orchard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'action prédatrice exercée sur le puceron lanigère par le perceoreille commun, Forficula auricularia, et par d'autres prédateurs, a été comparée dans des parcelles d'un verger expérimental de pommiers adultes aux Pays-Bas. Ces parcelles étaient caractérisées par des densités fortes, intermédiaires, et basses en perce-oreilles. Les colonies de pucerons ont été découvertes et exterminées principalement par les perce-oreilles beaucoup plus rapidement dans les parcelles à forte et moyenne densité de perce-oreilles que dans celles à faible densité. Les pucerons lanigères ont colonisé 30 à 35% des nouvelles pousses lorsque les perce-oreilles étaient exclus par une barrière mécanique (Tanglefoot), alors que moins de 10% des pousses ont été infestées lorsque les perce-oreilles étaient relativement abondants. Plusieurs facterus ont probablement influencé le résultat des expériences de prédation, notamment la présence de proies alternatives (par exemple Aphis pomi), la phénologie du développement des perce-oreilles et le climat. Néanmoins, les perce-oreilles ont joué un rôle important en limitant les populations du puceron lanigère, et constituent potentiellement d'importants agents de contrôle naturel de ce ravageur.
    Notes: Abstract Woolly apply aphid predation by the common earwig, Forficula auricularia L., and other predators was compared in high, intermediate and low earwig density plots of mature apple trees at an experimental orchard in the Netherlands. Aphid colonies were discovered and exterminated primarily by earwigs much more rapidly in the high and intermediate earwig density plots than in the low density plots. Where earwigs were excluded from trees by Tanglefoot bands around the trunks, woolly apple aphids infested 30–35% of new growth shoots whereas less than 10% of the shoots were infested where earwigs were relatively abundant. Several factors including the availability of alternate prey (e.g. Aphis pomi De Geer), earwig developmental phenology and weather probably influenced the outcome of the predation experiments. Nevertheless earwigs play an important role in suppressing woolly apple aphid populations and are potentially important, naturally occurring biological control agents for this pest.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1615-6102
    Keywords: Valonia utricularis ; Protoplast preparation ; Electrorotation ; Microstructures ; Dispersion ; Polarization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protoplasts ofValonia utricularis lacking the large central vacuole can be generated by cutting multi-nucleated, giant “mother” cells into small pieces after short exposure to air. When the protoplasmic content was squeezed out into sea water, irregularly shaped, green coloured aggregates were formed which changed into spherical protoplasts (radius of 20–60 μm) after about 2 h. In these protoplasts the dense internal material (consisting mainly of organelles) was separated from the plasmalemma by a thin transparent layer containing a large number of small lipid vesicles. Cell wall regeneration occurred rapidly after protoplast formation. A central vacuole developed after about 10h. The regenerated cells continued to grow and were viable for several months. Electrorotation studies on 2–3 h old protoplasts at pH 7 in low- and fairly high-conductivity solutions showed one or two anti-field rotation peaks (depending on medium conductivity) between 10 kHz to 1 MHz as well as one cofield rotation peak between 10 MHz to 100 MHz. The rotation spectra could not be fitted on the basis of the single- (or multi-) shell model (i.e., by modelling the cells as a homogeneous sphere surrounded by one or more layers). However, fairly good agreement between the experimental data and theory could be obtained by assuming that the rotational behaviour of the protoplasts depends not only on passive electrical properties of the plasmalemma but is influenced by “mobile charges” of carrier transport systems and/or the dielectric behaviour of the aggregated chloroplasts and vesicles.
    Type of Medium: Electronic Resource
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