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  • Demography  (2)
  • Tephritidae  (2)
  • DNA-protein cocrystallization  (1)
  • Ganzin I  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Molecular Biology 234 (1993), S. 496-498 
    ISSN: 0022-2836
    Keywords: DNA sequence context ; DNA-protein cocrystallization ; biased random search ; cooperativity
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 63 (1992), S. 135-142 
    ISSN: 1570-7458
    Keywords: Anastrepha obliqua ; A. ludens ; A. serpentina ; Tephritidae ; body size ; reproduction ; insect demography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Individuals of three Anastrepha species: A. obliqua, A. ludens, and A. serpentina (Diptera: Tephritidae), were sorted according to pupal weight in cohorts of large and small flies. Demographic parameters and reproductive patterns and heterogeneity were determined for each cohort. Large flies of the three species presented greater expectation of life and gross fecundity rates. A. ludens was the species with the longest life span (expectation of life of large adults was 110 days) and the greatest gross fecundity rates (1597 eggs/female for the large flies). While, A. obliqua had the shortest mean age of reproduction (33 days), and the greatest daily egg production (14 eggs/female/day). Net fecundity was similar in these two. A. serpentina had lower fecundity rates. Reproductive information for each size and each species include: age-by-parity relations, fraction of sexually mature life in which females lay eggs, and frequency distribution of individual egg production. Results demonstrate that even under constant laboratory conditions and using standard artificial hosts, there is a great deal of life history variation among these Anastrepha species and among other tephritid fruit flies.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 50 (1989), S. 209-214 
    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
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 34 (1983), S. 13-19 
    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
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 47 (1988), S. 73-80 
    ISSN: 1570-7458
    Keywords: Tephritidae ; Mexican fruit fly ; Anastrepha ludens ; clutch size ; host selection ; insect demography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'examen a porté sur l'influence du polymorphisme et des modifications dues à l'âge des mouches sur la fécondité et la taille des pontes de A. ludens Loew (Dipt. Tephritidae). L'étude a concerné aussi l'influence de la dimension, de la couleur et de la densité des hôtes sur la taille des pontes. Des mouches isolées ou par groupes ont reçu des hôtes artificiels formés de sphères d'agar enveloppées dans du parafilm. La fécondité brute de femelles isolées a été de 1000 oeufs/femelle et de 165 pontes/femelle, avec une variation de 1 à 40 oeufs/ponte. La taille moyenne des pontes des différentes femelles isolées s'étalait de 4,5 à 10,6 oeufs/ponte. Le nombre d'oeufs/ponte des femelles groupées était fortement liée à la dimension de l'hôte, s'étalant de 4,4 oeufs/ponte pour des hôtes de 2 cm de diamètre à 12,7 oeufs/ponte pour ceux de 11 cm de diamètre. Ni la couleur et la densité des hôtes, ni la densité et l'âge des mouches n'ont influé sur la taille des pontes. Ces résultats suggèrent que les variabilités du comportement des femelles et de la dimension des hôtes déterminent par priorité la taille des pontes de A. ludens.
    Notes: Abstract We document individual and age-specific variation in reproductive output and clutch size of Anastrepha ludens Loew. (Diptera: Tephritidae). The influence of host size, color, and density on clutch size are also examined. Individual and groups of flies were offered artificial hosts composed of agar spheres wrapped in Parafilm. The gross reproduction rate of individual flies was 1000 eggs/female and 165 clutches/female with a range of 1 to 40 eggs/clutch. Mean clutch sizes for these females ranged from 4.5 to 10.6 eggs/clutch. The number of eggs/clutch laid by females held in groups was highly correlated with host size, ranging from about 4.4 eggs/clutch in 2 cm diameter hosts to 12.7 eggs/clutch in 11 cm hosts. Host color, host density, fly density, and fly age did not affect clutch size. This study suggests that variation among females and host size are the principal determinants of clutch size in A. ludens.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 82 (1990), S. 417-423 
    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
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