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  • Chemistry  (8)
  • Sitobion avenae  (4)
  • General Chemistry  (2)
  • 1
    ISSN: 1570-7458
    Keywords: Sitobion avenae ; Aphidius rhopalosiphi ; Pandora neoaphidis ; Entomophthorales ; tritrophic effects ; wheat resistance ; natural enemies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of wheat (Triticum aestivumL.) resistance, the parasitoid Aphidius rhopalosiphiDe Stephani-Perez (Hymenoptera: Braconidae) and the entomopathogenic fungus Pandora neoaphidis(Remaudière et Hennebert) Humber (Zygomycetes: Entomophthorales) on the density and population growth rate of the cereal aphid Sitobion avenae(F.) (Hemiptera: Aphididae) was studied under laboratory conditions. Partial wheat resistance was based on hydroxamic acids, a family of secondary metabolites characteristic of several cultivated cereals. The partial resistance of wheat cultivar Naofén, the action of the parasitoid and the joint action of the parasitoid and fungus, reduced aphid density. The lowest aphid densities were obtained with the combination of the parasitoid and the fungus, but wheat resistance under these circumstances did not improve aphid control. Significant reductions of population growth rate (PGR) of aphids were obtained with the joint action of wheat resistance and natural enemies. In particular, the combined effects of parasitoids and fungi showed significantly lower PGR than the control without natural enemies in both wheat cultivars. Our results support the hypothesis that wheat resistance and the utilization of biological control agents could be complementary strategies in an integrated pest management program against cereal aphids.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1570-7458
    Keywords: Sitobion avenae ; Sitobion fragariae ; RAPD ; PCR ; microsatellites ; mtDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A set of molecular markers to differentiate the aphid (Hemiptera: Aphidoidea) species Sitobion avenae (Fabricius) from Sitobion fragariae (Walker), is presented. These markers correspond to (1) a region of the mitochondrial DNA, (2) five species-specific RAPD banding patterns and (3) four microsatellite loci. Each of the markers was able to clearly distinguish between the species. The utility of each molecular marker is discussed. Mitochondrial DNA is best applicable to species determination and relative abundance, RAPDs to the evaluation of genetic diversity, and microsatellites to the assessment of the population genetic structure; the combined use of mtDNA with the other techniques can be of importance when the presence of hybrids is suspected, and RAPDs with microsatellites are best used together in population genetics and host preference studies.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-1561
    Keywords: Sitobion avenae ; aphids ; hydroxamic acids ; DIMBOA ; detoxification ; cytochrome P-450 monooxygenases ; NADPH cytochrome c reductase ; glutathione S-transferases ; esterases ; catalase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Hydroxamic acids (Hx) are wheat secondary metabolites conferring resistance for cereals against aphids. The activity of five enzymatic systems were evaluated in the aphid Sitobion avenae reared on the high-Hx wheat cultivar Chagual and the low-Hx wheat cultivar Huayún for 10 generations. Enzyme solutions were prepared from aphid homogenates and assayed for mixed function oxidases (including cytochrome P-450 monooxygenases and NADPH cytochrome c reductase), glutathione S-transferases, esterases, and catalase. Specific activities per aphid individual of cytochrome P-450 monooxygenases, NADPH cytochrome c reductase, glutathione S-transferases, and esterases were significantly increased in wheat cultivars relative to oat (only marginal increase of esterases in Chagual). Aphids fed on cv. Huayún showed an overall higher induction of enzymatic systems than those fed on cv. Chagual. Comparison of these results with reported effects of Hx on detoxifying enzymes in other insects, including aphids, support the hypothesis that these enzymatic pathways play an important role in the detoxification of toxic host-plant secondary metabolites.
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  • 4
    ISSN: 1573-1561
    Keywords: Aphids ; Sitobion avenae ; feeding deterrents ; antibiotics ; DIMBOA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A total of 25 compounds including benzoxazinones, benzoxazolinones, and N-glyoxylamide derivatives were tested as antifeedants and antibiotics towards the aphid Sitobion avenae in diet bioassays. The antifeedant and mortality indexes increased with the presence of electron-donating groups in the 7 position of the benzoxazinone moiety, the replacement of the oxygen atom by sulfur in the heterocyclic ring, the presence of a hemiacetal instead of an acetal at C-2 of the benzoxazine moiety (and hence the possibility of ring opening), and the presence of a hydroxyl group at C-4 of the benzoxazine moiety (hydroxamic acid) instead of a hydrogen atom (lactam). The results support earlier hypotheses on the chemical bases for the mode of action of these compounds.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 60 (1948), S. 100-108 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1487-1495 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: CNDO/2, MINDO/3 and ab initio molecular orbital calculations are used in a study of conformational isomerism, protonation site and mechanism of protonation of the title compounds.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 59 (1976), S. 1133-1139 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: CNDO/Z, MINDO/3 and ab initio molecular orbital calculations indicate that C-protonated diazomethane is more stable than N(end)-protonated diazomethane. Extrapolation of these results to solution chemistry as well as the kinetic references of protonation of diazomethane are discussed.
    Additional Material: 2 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 33 (1999), S. 380-380 
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 33 (1961), S. 356-358 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Da ein Temperaturgefälle im Meßgerät eine scherabhängige Viscosität vortäuschen kann, wurde bei Überdruck-Kapillar-Viscosimeter nach Umstätter eine genaue Temperaturkontrolle vor und nach der Kapillare angebracht. Außerdem wurde der Meßbereich bis herab auf 0,05 atü Schubspannung erweitert. Auf Grund der Meßergebnisse wurden die Theorien von Bueche und Eyring auf ihre Gültigkeit und ihre Möglichkeit zur Berechnung molekularer Konstanten untersucht.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 405 (1974), S. 315-328 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Catalysis of p-H2 Conversation on Pure and CO-poisoned PlatinumThe reaction has been studied on a Pt foil using u. h. v. cleaning conditions. The rate of the conversion is extremely high on a clean Pt surface, the activation energy being 4.1 kcal/mole. CO/poisons reversibly. After preadsorption of CO on half of the Pt surface the activity descreases to 6% of the original value and the activation energy increases p to 8.4 kcal/mole. In the discussion a direct correlation between the activation energy and the lowest adsorption heats of hydrogen is proposed. The reaction occurs predominantly on centres with lowest bond strength.
    Notes: Die Reaktion wurde an einer Pt-Folie unter UHV-Reinheitsbedingungen untersucht. An reiner Pt-Oberfläche verläuft die Reaktion extrem schnell mit einer Aktivierungsenergie von 4,1 kcal/Mol. CO vergiftet reversibel. Bei Vorbelegung der halben Pt-Oberfläche mit CO fällt die Aktivität auf 6% des Ausgangswertes während die Aktivierungsenergie auf 8,4 kcal/Mol ansteigt. Diskutiert wird ein direkter Zusammenhang der Aktivierungsenergie mit den minimalen Adsorptionswärmen des Wasserstoffs. Die Umwandlung erfolgt bevorzugt an Zentren mit geringster Bindungsfestigkeit.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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