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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 42 (1986), S. 159-167 
    ISSN: 1570-7458
    Keywords: Mediterranean fruit fly ; Ceratitis capitata ; host deprivation ; senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les femelles de C. capitata ont été privées d'hôtes suivant 4 modalités pendant 3 durées (33, 50 et 67% de leur vie) par période de 24 heures. Les modalités se répartissaient de la privation pendant 8 jours après l'éclosion jusqu'à 1 jour sur 3. La survie a été notée chaque jour et la ponte pour tous les jours où il y avait des hôtes. L'effect direct de l'absence d'hôte est d'empêcher la femelle de pondre. Ceci interrompt leur cycle de ponte et réduit leur activité reproductrice totale. Un effort reproductif réduit des femelles jeunes augmente la survie (jusqu'à 2 fois) et la ponte quotidienne (jusqu'à 8 fois) chez les femelles plus âgées. Ainsi, l'effet à long terme de la privation d'hôtes est d'ajourner la sénescence. Les implications de ces observations sur la sénescence de C. capitata sont discutées quant à: (1) la réduction des taux d'extinction des populations pendant les périodes de rareté d'hôtes; et: (2) les stratégies d'obtention de pontes dan les élevages de masse de C. capitata.
    Notes: Abstract Female medflies were subjected to four different patterns of host deprivation at each of three levels for a 24-day period. Treatments ranged from host absence 8 days post-eclosion to host absence 2 out of 3 days. Survival was recorded daily and egg production was recorded on the days in which hosts were present. The direct effect of host deprivation is to deny females the opportunity to oviposit. This disrupts their reproductive cycle and reduces their overall reproductive effort. Reduced reproductive effort at young ages increases survival (up to 2-fold) and daily reproduction (up to 8-fold) at older ages. Therefore, the long term effect of host deprivation is to postpone senescence. The implications of these findings regarding medfly sensescence are discussed in relation to: (i) reduction in population extinction rates during periods of host scarcity and (ii) egging strategies in medfly mass-rearing.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Experimental and applied acarology 5 (1988), S. 151-162 
    ISSN: 1572-9702
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of maternal age on primary sex ratio was determined forTetranychus urticae, T. pacificus andT. turkestani (Acari:Tetranychidae). All females were allowed to mate once.Tetranychus urticae had the highest production of daughters and the lowest production of sons. The sex ratio ofT. urticae was nearly 2∶1 (daughters∶sons), whereas for the other species it was 0.6∶1. Net sex ratios were all shifted in favor of daughters, suggesting that most son-production occurs late in life. Demographic techniques are applied to tetranychid populations, including the concepts of reproductive concentration curves and expectation of future reproduction based on age and previous offspring.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Environmental monitoring and assessment 11 (1988), S. 147-169 
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In earlier work, we found that leeches from an industrially polluted creek bioaccumulated chlorophenols to much higher concentrations than other resident benthic invertebrates and fish. We suggested that leeches may have significant potential as biomonitors for these and other organic contaminants in the environment. In this study, we compared the bioaccumulation and depuration of 16 organic compounds, including eight chlorophenols (CPs), lindane, DDT and four derivatives, benzothiazole (BT) and 2-(Methylthio)benzothiazole (MMBT) for three species of leeches. Dina dubia had the highest bioaccumulation capacity for most contaminants, but residues persisted longest in Erpobdella punctata. Helobdella stagnalis appeared capable of degrading some compounds. Half lives of CPs, DDT and DDT derivatives were generally longer than one month. In contrast, half lives were only 1 day for lindane, 1–2.5 days for MMBT and 7 days for BT despite very high initial tissue concentrations of the latter two compounds. Bioconcentration factors for contaminants in leeches were higher than those reported for other aquatic organisms. Half lives for lindane, DDT and DDT derivatives were consistent with the literature for other organisms, but half lives for CPs were much longer. The results suggest that leeches would be excellent biomonitors of both continuous and intermittent contamination of a waterway with CPs and DDT, as they retain these compounds for long periods after exposure. Their usefulness as a screening tool for lindane and benzothiazoles would be limited to chronically contaminated environments.
    Type of Medium: Electronic Resource
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