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  • Springer  (257)
  • Elsevier  (230)
  • Nature Publishing Group  (63)
  • Wiley-Blackwell  (23)
  • American Association for the Advancement of Science (AAAS)
  • 1985-1989  (517)
  • 1955-1959  (62)
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 44 (1987), S. 177-185 
    ISSN: 1570-7458
    Schlagwort(e): spotted alfalfa aphid ; Therioaphis trifolii ; aphid-resistant plants ; lucerne = alfalfa ; Medicago sativa ; variation ; bioassay ; antibiosis non-preference ; inter-plant movement
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé L'étude de la multiplication initiale des effectifs de T. trifolii, élevés au laboratoire sur pousses de différents pieds de luzerne, a servi de test d'antibiose pour les cultures en plein champ. La distribution de l'antibiose, dans des échantillons importants de plantes appartenant à des cultivars sélectionnés pour leur résistance aux pucerons, a présenté une forme en J, c'est-à-dire que la majorité des plantes était très résistante, quelques unes apparemment sensibles, et un certain nombre intermédiaires entre ces deux extrêmes. Pour un niveau donné d'antibiose, la reproduction, la mortalité et ainsi la distribution initiale en âges dans les populations de pucerons ont été généralement identiques. La multiplication végétative de plantes présentant un gradient de résistance à l'intérieur d'un cultivar et l'utilisation d'un plan de distribution des boutures ont permis l'étude de ce qui semble être l'effet de l'hétérogénéité spatiale sur la résistance des cultures aux attaques de pucerons. La simulation d'une invasion de la culture par les pucerons en plaçant des adulte sur toutes les boutures d'un rang ne pouvait donner une explication de la croissance de la population que si les pucerons se déplacaient le long du rang pour découvrir et exploiter les pieds les plus sensibles. Une distribution par taches, comme on peut l'envisager dans un champ, ne devrait pas gêner les pucerons, car bien que les mouvements d'évasion soient stimulés par les niveaux de résistance élevés (de non-préférence), on peut en déduire que les pucerons se déplaceront sur des plantes très résistantes, eventuellement pour atteindre des plantes moins résistantes placées derriere.
    Notizen: Abstract Initial population growth of spotted alfalfa aphid reared on shoots cut from individual lucerne plants, was tested and used as a realistic bioassay of antibiosis. Within cultivars selected for aphid-resistance there was a J-shaped distribution of antibiosis between plants of the crop, the majority being highly resistant, a few apparently susceptible and a proportion partly-resistant. For a given level of antibiosis, reproduction, mortality and thus initial age distribution of aphid populations were generally similar. Vegetative cloning of plants from the range of resistance available in a cultivar has allowed studies of the likely effect of spatial variation of resistance in crops on aphid infestations, using experimental arrays of cut shoots. Simulation of aphid invasion of crops by the placement of adults on all shoots of an array gave results explicable only if the aphids moved through the array to find and breed on the more susceptible plants. A patchy arrangement of these, as might be expected in a field crop, would not hinder the aphids, for although movement off a plant is stimulated by higher resistance (non-preference) levels, it was inferred that aphids will move onto higher resistance plants, eventually to reach lower resistance plants beyond.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 49 (1988), S. 75-82 
    ISSN: 1570-7458
    Schlagwort(e): aphid-resistance ; lucerne ; alfalfa ; Medicago sativa ; spotted alfalfa aphid ; Therioaphis trifolii f. maculata ; antibiosis ; bioassay
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In autumn 1981 there were widespread reports of a reduced level of antibiosis in lucerne crops and field trials where cultivars selected for resistance to the aphid, Therioaphis trifolii f. maculata, had been used. On our field trial, the plot of ‘CUF 101’ lucerne was infested to a level about 40% of that on the aphid-susceptible ‘Hunter River’, compared with an average of about 3% over the two years before and the two years after. An experimental study of possible causes using a bioassay technique on cloned plants representing the spectrum of resistance in CUF 101 indicated that loss of resistance was temporary and occurred apparently randomly among the tests, but that certain treatments increase the frequency of its occurrence. Lowered temperatures and the use of either young regrowth or senescent lucerne, each increased the frequency of loss of resistance. Inundation of lucerne by large numbers of aphids did not affect the expression of resistance directly, but the few progeny that survived to adulthood on partly-resistance lucerne were habituated and were then able to interact with the plants to increase the apparent frequency of breakdown of resistance. Plants which showed the loss of resistance developed aphid populations between 4x ad 25x those when they expressed their normal resistance level. Investigations suggest that the situation in autumn 1981 may have been the result of a prolonged and massive immigration of aphids into lucerne crops, which, on the aphid resistant cultivars allowed surviving aphids to exploit maximally the combined effects of factors causing some loss of resistance.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Behavioral ecology and sociobiology 17 (1985), S. 385-387 
    ISSN: 1432-0762
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Adult female whitespotted sawyers Monochamus scutellatus (Coleoptera: Cerambycidae) were placed on succeeding days with two males differing visibly in size. Females showed a significant preference for the larger of two males. The rate of oviposition was significantly higher when the female was paired with the larger male. Both the rate of movement by the paired female and her rate of indicating non-receptivity were significantly lower when the female was paired with the larger male. This species exhibits resource defense polygyny, and females appear to choose mates mainly on the basis of the quality of resources defended. This study suggests, however, that when resource quality is constant, females choose mates on the basis of their size.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 326 (1987), S. 210-210 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Astronomical Methods and Calculations. By Agnes Acker and Carlos Jaschek. Wiley: 1986. Pp.343. Hbk$34.95, £38.50; pbk$26.35, £14.95. SCIENCE is quantitative and astronomy is no exception. But astronomy has a special piquancy because the problem of measuring such fundamental ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 184 (1959), S. 1644-1645 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Crossbred ewe and wether lambs, 5-8 months old and weighing between 40 and 124 lb., were used. They were kept on pasture and each, with the exception of the black sheep, had been infected experimentally with 200 metacercarise of Fasciola heptica obtained from a laboratory colony of infected Limncea ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 183 (1959), S. 603-604 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Table l. REFRACTIVE INDEX OF AMMONIUM SULPHATE SOLUTIONS Temperature Molarity 30-60 24-90 20 -50 13-25 0 10 Water 1-3316 1 -3321 1-3327 1-3332 1-3338 0-4138 1 -3401 1-3410 1 -3414 1 -3420 1 -3430 0-9658 1 -3508 1-3514 1-3518 1-3526 1-3539 1-5118 1 -3602 1-3610 1-3617 1 -3625 1 ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 183 (1959), S. 250-250 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Olefines are cleanly separated from the saturated hydrocarbons on a column packing consisting of a saturated solution of silver nitrate in ethylene glycol supported on graded 'Celite'1. The C3 gases are separated from the C3 by a tri-isobutylene/*Celite' column2. Attempts to achieve separations by ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 182 (1958), S. 63-64 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Owen1 has stated necessary and sufficient conditions for such an equilibrium (when it exists) to be stable for the case of three alleles, and in attempting to generalize these conditions to the case of n alleles and to derive reasonably concise and illuminating proofs we have been led to consider ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 181 (1958), S. 1281-1282 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Absolutely fresh herring flesh (from fish taken alive from the drift net and frozen in solid carbon dioxide) contained ammonia (20 mgm./100 gm. flesh) and trimethylamine (1 mgm./100 gm.). No mono- or di-methylamine was present. No higher aliphatic amines were found under conditions which would have ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 181 (1958), S. 1482-1483 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The specimen of Simpson's Fig. 2a labelled Nelum-bium type has been re-examined and is interpreted as Zonalapollenites close to Z. dampieri Balme1, which species has recently been described (1957) from Western Australia. Several closely allied forms have been recorded (N. F. H.) from the British ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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