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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 61 (1991), S. 117-122 
    ISSN: 1570-7458
    Keywords: Cockroach ; insect growth regulators ; Blattella germanica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Late instar German cockroach male and female nymphs were exposed continuously for two weeks to surfaces treated with fenoxycarb, diflubenzuron, and pyriproxyfen, singly and in combination. Concentrations were determined that eliminated or nearly eliminated reproduction in matings with untreated mates, either through mortality, effects on reproduction, or a combination of mortality and ‘sterility’ (no hatch). The major effect of fenoxycarb, pyriproxyfen, and pyriproxyfen plus fenoxycarb was on reproduction. The major effect of diflubenzuron was mortality. No hatch occurred in matings of females that were exposed to low concentrations of pyriproxyfen and fenoxycarb (2 ng/cm2 and 6 ng/cm2, respectively); sterility was incomplete when females were exposed to 600 ng/cm2 of diflubenzuron. Mortality and sterility acted together to eliminate productive matings (matings that produced nymphs) when relatively high concentrations of diflubenzuron were combined with one or both of the other insect growth regulators (IGRs). In the triple combination, very small amounts of fenoxycarb and pyriproxyfen (total 1.1 ng/cm2) combined with 200 ng/cm2 of diflubenzuron eliminated productive matings of treated females, but similar results with treated males were found only at higher concentrations of each IGR.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 67 (1984), S. 123-129 
    ISSN: 1432-2242
    Keywords: Interchange quadrivalents ; Disjunction ; Chiasma frequency ; Blattella ; Cockroach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A stock of Blattella germanica bearing the interchange T(3; 12)/3;12 was subjected to close inbreeding with selection for random disjunction at metaphase I. After 3–4 generations of selection, interchange quadrivalent chiasma frequency decreased, variability in free bivalent chiasma frequency increased sharply, and individuals with either random or directed disjunction were present in the stock. Random disjunction was modified from a ratio of 2∶1∶1∶2 (adj.-1; alt.-1; adj.-2; alt.-2) to a ratio of 1∶1∶1∶1. After 7–8 generations of selection, chiasma frequency appeared to stabilize at lower than normal levels and variability decreased for both quadrivalents and free bivalents. Directed disjunction was modified from a ratio of 2∶1∶1∶4 to 1∶1∶1∶2, and no individuals with the original high level of directed disjunction were detected. Chains-of-four tended to orient randomly, especially in individuals where the ring quadrivalents showed directed disjunction. Relaxation of inbreeding, but not selection, produced an increase in chiasma frequency and variability in both free bivalents and quadrivalents, but the modified ratios for both random and directed disjunction were retained. These results are discussed with respect to inbreeding effects and genetic control of chiasma frequency and metaphase I disjunction in interchange quadrivalents.
    Type of Medium: Electronic Resource
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