Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Demography  (2)
  • Cabernet Sauvignon  (1)
  • Cerebral blood flow  (1)
  • Ganzin I  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Reproductive limits and heterogeneity of male twospotted spider mites (1989)
    Springer
    Entomologia experimentalis et applicata 50 (1989), S. 209-214 
    Details
    ISSN: 1570-7458
    Keywords: Demography ; male population biology ; sex ratio ; Tetranychus urticae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La reproduction est un processus qui nécessite généralement un mâle et une femelle. Cependant la biologie des populations ne s'est traditionnellement intéressée qu'à la contribution des femelles dans ce processus. Un effet de cet accent sur les femelles est que l'activité reproductrice des mâles a été très ignorée. Cet article examine, dans un contexte démographique, l'activité reproductrice des mâles de T. urticae, acarien arrhénotoque et phytophage. Trois séquences de l'activité reproductrice des mâles ont été examinées: 1) la copulation, 2) l'insémination, 3) la reproduction. En moyenne un mâle de 1 jour a copulé 15 fois, inséminé 15 femelles et a eu 336 filles. Pendant les 8 premiers jours, le mâle moyen a inséminé 70 femelles et a eu 1145 filles. Ces résultats suggèrent que le nombre de spermatozoïdes transférés à chaque insémination, plus que le nombre d'inséminations, est le facteur limitant d'une forte contribution du mâle à la reproduction.
    Notes: Abstract This paper determines reproductive limits and variation in performance of male twospotted spider mites Tetranychus urticae Koch when virgin females are provided ad libitum over the first eight days of adult life. Theree phases of male reproduction were studied: copulations, insemination and reproduction. An average one day old male copulated 15 times, inseminated 15 females, and contributed to 336 daughters. All parameters declined with age. The average male inseminated 70 females and contributed to 1145 daughters in the first days. Variability between males was small for all parameters considered. These data suggest that the number of sperm transferred at each insemination, rather than the number of inseminations, is the limiting step to higher male reproductive output.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341169
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Life tables of phylloxera on resistant and susceptible grape rootstocks (1983)
    Springer
    Entomologia experimentalis et applicata 34 (1983), S. 13-19 
    Details
    ISSN: 1570-7458
    Keywords: Grape phylloxera ; Viteus vitifolii ; Resistant rootstocks ; Life tables ; Cabernet Sauvignon ; Muscat of Alexandria ; Ganzin I ; St. George
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le Phylloxera de la vigne, Viteus vitifolii Shimer, a été élevé sur des racines coupées en boîte de Pétri. Les tables de vie ont été établies en utilisant deux variétés sensibles de Vitis vinifera L. (Cabernet—Sauvignon et Muscat d' Alexandrie) et deux variétés résistantes de Vitis rupestris (Saint Georges en Ganzin I). Sur les variétés résistantes, le Phylloxera avait des taux de fixation du premier stade plus faibles (24 et 9.5%) que sur les variétés sensibles (57 et 36%). De la même façon, les taux bruts (G.R.R.) et nets (R0) de la reproduction étaient plus bas sur les variétés résistantes que sur les variétés sensibles. La durée moyenne d'une génération (T) était variable (19 à 49 jours) et ne paraissait pas liée à la sensibilité des variétés. Le taux net d'accroissement (λ) était inférieur à 1 sur les variétés résistantes, contre 1,06 et 1,10 sur les variétés sensibles. Sur Cabernet—Sauvignon, le Phylloxera avait des valeurs de G.R.R., R0 et T supérieures sur les tubérosités que sur les nodosités. Cependant les valeurs de λ étaient à peu près égales (1,05 et 1,07, respectivement) sur les tubérosités et les nodosités.
    Notes: Summary Grape phylloxera, Viteus vitifolii Shimer, were reared on excised grape roots maintained in petri-dish chambers. Life tables were constructed using 2 susceptible rootstocks, Vitis vinifera L. Cabernet Sauvignon and Muscat of Alexandria, and 2 resistant rootstocks V. rupestris St. George and Ganzin I. Phylloxera on the resistant varieties had lower rates of 1st-instar establishment (24% and 9.5%) than on the susceptible varieties (57% and 36%). Similarly, gross reproductive rates (GRR) and net reproductive rates (R0) on the resistant varieties were lower than on the susceptible varieties. Mean generation times (T) were variable (19–49 days) and appeared not to be related to rootstock susceptibility. Finite rates of increase (λ) were less than 1.0 on the resistant varieties, and 1.06 and 1.10 on the susceptible varieties. Phylloxera on Cabernet Sauvignon tuberosities had higher GRR, R0 and T-values than on the nodosities. However, λ-values were nearly equal, 1.05 and 1.07 on the tuberosities and nodosities, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00300894
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Cerebral blood flow mapping using stable Xenon-enhanced CT in sickle cell cerebrovascular disease (1990)
    Springer
    Neuroradiology 32 (1990), S. 289-295 
    Details
    ISSN: 1432-1920
    Keywords: Brain infarctions ; Sickle cell disease ; Cerebral blood flow ; Xenon-CT ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cerebral blood flow (CBF) of 25 patients with sickle cell cerebrovascular disease (SCCVD) was examined using a Xenon-CT flow mapping method. Brain CT and MR findings were correlated with those of the Xenon-CT flow studies. CBF defects on Xenon-CT correlated reasonably well with the areas of cortical infarctions on the MR images, but in 27% of the cases, flow defects were slightly larger than the areas of infarctions on the MR images. In deep watershed or basal ganglia infarctions, abnormal CBF was noted about the cerebral cortex near infarctions in 72% of the patients, regardless of infarction sizes on the MR images. However, decreased CBF was recognized in 4 of the 9 children whose MR images were virtually normal. Thus, the extent of flow depletion cannot be predicted accurately by MR imaging alone. Xenon-CT flow mapping proved a safe and reliable procedure for evaluation of the CBF of patients with SCCVD. Although this study is preliminary, it may have a potential in selecting patients for hypertransfusion therapy, as a noninvasive test and for following children with SCCVD during their therapy. Careful correlation of results of CBF with those of MR imaging or of CT is important for objective interpretations of flow mapping images.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00593047
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Male demographic constraints to extreme sex ratio in the twospotted spider mite (1990)
    Springer
    Oecologia 82 (1990), S. 417-423 
    Details
    ISSN: 1432-1939
    Keywords: Sex ratio ; Twospotted spider mite ; Demography ; Male reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Twospotted spider mites, Tetranychus urticae Koch are arrhenotokous. As a result of this genetic structure, primary and secondary sex ratios diverge from the 1:1 female:male ratio commonly found in diploid systems. Ratios vary, but 3:1 is the most common. The influence of life history parameters on spider mite sex ratio is unclear, although maternal genetic effects, resource quality and maternal age are known to play a role. An area that has not been studied is the relationship between male reproductive capabilities and spider mite sex ratio. A prior study on male reproduction in spider mites suggests that males have far too high a reproductive capacity to explain sex ratio patterns, but that study was not conducted under realistic mating conditions. Thus, this study was conducted to determine if there is a link between male reproduction and spider mite sex ratio. This was done by exposing males to various exposure regimes of females and recording the number of copulations, inseminations and daughters fathered by each male. Results include the following: i) males are most virile when one day old; ii) virgin males become nearly completely devoid of sperm (or other copulatory products) after about 15 matings and then take about four days to recover; and iii) the optimal number of matings per day (defined as that which produces the greatest number of daughters in the least number of inseminations) is four females per day. The principle conclusion is that although males have a high potential reproductive output, insemination quality is only high for the first four or five matings each day. Therefore, to ensure full inseminations of all daughters by sons, females are constrained to producing primary sex ratios of about 5:1 or less.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317492
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...