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  • 1
    Electronic Resource
    Electronic Resource
    Distribution ofBathyplectes curculionis andBathyplectes anurus [Hym.: Ichneumonidae] fromHypera [Col.: Curculionidae] on alfalfa in Egypt, Iraq, and Iran (1980)
    Springer
    BioControl 25 (1980), S. 111-121 
    Details
    ISSN: 1573-8248
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé La répartition géographique desHypera spp. (Col.: Curculionidae) et de ses parasites larvaires,Bathyplectes curculionis (Thomson) etB. anurus (Thomson) (Hym.: Ichneumonidae) a été étudiée de 1973 à 1975 en Irak et en Iran, dans les régions où sont cultivées les espèces deMedicago, et en Égypte surTrifolium alexandrinum L. LesHypera spp. ont été trouvés en plus grand nombre là où la moyenne quotidienne des températures était inférieure à 25°C ou supérieure à 15°C.B. curculionis était largement répartie dans l’ensemble des 3 pays, mais plus abondante dans les régions à étés chauds et secs et à hivers modérément froids. B. anurus était moins abondante et moins largement répartie géographiquement queB. curculionis. B. anurus était dominante dans les régions à étés modérément chauds et à hivers froids ou très froids. Là où les 2 espèces étaient présentes,B. anurus était abondante 2 à 4 semaines avantB. curculionis. Les hyperparasitesMesochorus spp. ont été abondants surBathyplectes spp., leur répartition couvrant largement l’Égypte, l’Irak et l’Iran.
    Notes: Abstract A survey forHypera postica (Gyllenhal) and their larval parasites,Bathyplectes curculionis (Thomson) andB. anurus (Thomson) was conducted from 1973 through 1975 in Egypt, Iraq, and Iran. The search was concentrated in Iraq and Iran in areas having cultivated species ofMedicago, and in Egypt onTrifolium alexandrinum L. Hypera were most abundant where mean daily temperatures were below 25°C or above 15°C.B. curculionis were widely distributed throughout all 3 countries, but were most abundant in the regions having hot, dry summers, with moderately cold winters.B. anurus were less abundant and less widely distributed geographically thanB. curculionis. B. anurus were prevalent in regions having moderately warm summers and cold, to very cold, winters. In localities containing both parasites,B. anurus reached peak levels about 2–4 weeks beforeB. curculionis. Mesochorus spp. were the predominant hyperparasites obtained fromBathyplectes spp. They were widely distributed in Egypt, Iraq, and Iran.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02374313
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Study of an approximate relation between the energy of an atom and the electronic potential at the nucleus (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 22 (1982), S. 989-997 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper provides an analysis of the reasons for the approximate validity of the relation \documentclass{article}\pagestyle{empty}\begin{document}$ E = \frac{3}{7}NV(0) $\end{document}, between the total energy E of a neutral atom, the number N of electrons, and the electronic potential at the nucleus V(0). Using the density functional formalism we find that the right-hand side of the above equation also appears (and is the leading term) in density functional approximations more sophisticated than the Thomas-Fermi (TF) approximation (the above equation is exact in the TF approximation). Systematic improvements to the equation appear to be difficult because the main corrections come from those terms which are more difficult to handle in the density functional formalism. After this analysis we propose a kinetic energy functional for neutral atoms in the Hartree-Fock approximation. The first term of this new functional is a rescaled Thomas-Fermi term \documentclass{article}\pagestyle{empty}\begin{document}$$ T_0^\gamma = (1 + \gamma)\int {\frac{3}{{10}}(3\pi ^2){}^{2/3}\rho ^{5/3} d{\rm r}} $$\end{document}, where γ = -0.0063 for light atoms and γ = 0.0085 for the others. The second term is the first gradient correction due to Kirzhnits \documentclass{article}\pagestyle{empty}\begin{document}$$ T_2 = \frac{1}{{72}}\int {\frac{{(\nabla \rho)^2 }}{\rho }d{\rm r}} $$\end{document}.For lithium to krypton atoms, this new functional gives an average error of 0.22%.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560220510
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  • 3
    Electronic Resource
    Electronic Resource
    Heterozygosity and effective size in laboratory populations ofAphidius ervi [Hym.: Aphidiidae] (1983)
    Springer
    BioControl 28 (1983), S. 245-258 
    Details
    ISSN: 1573-8248
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé La diminution de la variabilité des allozymes dans 7 populations de laboratoire deAphidius ervi Haliday montre que l'importance des effectifs des populations correspond approximativement à la moitié du nombre d'individus utilisés pour renouveler l'élevage à chaque génération. Une participation inégale à la reproduction des individus femelles aux générations successives est la cause la plus probable de ce phénomène.
    Notes: Abstract Decline of allozyme variability in 7 laboratory populations ofAphidius ervi Haliday demonstrates that the effective population size is approximately one half the number of individuals used to renew the cultures each generation. Unequal reproductive contribution by individual females to subsequent generations is the most likely cause for this phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02372175
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A food-web approach to economic thresholds: A sequence of pests/predaceous arthropods on California cotton (1982)
    Springer
    BioControl 27 (1982), S. 31-43 
    Details
    ISSN: 1573-8248
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary Our findings indicate that guidelines for the assessment of pests on cotton should consider also their essential role as primary food sources at all population levels, as well as their potential for yield reduction. The value of an adequate food base for predaceous arthropods as provided byTetranychus is relevant for the development of economic thresholds not only for this group, but also for pests that may occur later in the season. A higher predaceous potential was reflected in the greater levels ofGeocoris and ofOrius found on untreated plants with abundant food, as compared with a much lower (O+K treatment) or higher (MP treatment) food (mite) level on insecticide-treated plants. The increased potential for regulation of pest numbers through higher numbers of predators was especially significant, because the higher numbers were present over an extended period, including July–August. In the San Joaquin Valley, an increase in predation potential during this period is highly beneficial, becauseLygus and lepidopterous worms also occur on cotton at this time. We strongly urge that policy guidelines on effects from chemicals on arthropods be re-evaluated. The long-standing concern over disruptive effects of chemicals must be extended to include their impact on the arthropods that constitute the principal sources of food for predaceous arthropods. It is not sufficient to know the direct mortality impact of chemicals against beneficial-predaceous insects. The indirect effect against them via disruption of their food chain is more significant because a considerably longer timeinterval is required to replenish the food supply than is needed for beneficial-predaceous adults to reinvade a field. Results from this study support our contention that at least four components must be considered seasonally in developing economic thresholds for pest management programs: 1) the plants, 2) the complex of key pests, 3) the complex of beneficial arthropods, and 4) sources of food in the form of minor «pests» required to support significant numbers of predaceous arthropods in agricultural crops.
    Notes: Abstract The value of an adequate food base for predaceous arthropods as provided byTetranychus is relevant for the development of economic thresholds for this group and also for pests that occur later in the season. A higher predaceous potential was reflected in greater levels ofGeocoris and ofOrius on untreated plants with abundant food, as compared with lower predator numbers on insecticide-treated plants having lower food levels. The higher numbers ofGeocoris andOrius were significant because they persisted through July–August. In the San Joaquin Valley, an increase in predators during this period is highly beneficial, becauseLygus and lepidopterous worms may damage cotton at this time. Policy guidelines on effects from chemicals on arthropods need re-evaluation. The assessment of disruptive effects of chemicals must include their impact on the arthropods that constitute the principal sources of food for predaceous arthropods. The indirect effect of chemicals against beneficial-predaceous insects via disruption of their food chain is highly significant because a considerably longer time-interval is required to replenish the food supply, than is needed for beneficial-predaceous adults to reinvade a field. Results from this study support our contention that at least four components must be considered seasonally in developing economic thresholds for pest management programs: 1) the plants. 2) the complex of key pests, 3) the complex of beneficial arthropods, and 4) sources of food in the form of minor «pests» required to support significant numbers of predaceous arthropods in agricultural crops.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02371853
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    Paper (German National Licenses)
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