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  • aphid  (2)
  • aphids  (2)
  • Epiphyas postvittana  (1)
  • 1
    ISSN: 1573-1561
    Keywords: Nothofagus ; faunal abundance ; herbivory ; bioactivity ; leafroller antifeedant activity ; aphid deterrency ; pinosylvin ; galangin ; Ctenopsteustis obliquana ; Epiphyas postvittana ; Acyrthosiphon pisum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Nothofagus species from Chile and New Zealand were surveyed in the field for invertebrate abundance and leaf feeding damage and in the laboratory for antifeedant activity against leafrollers (Ctenopsteustis obliquana, Epiphyas postvittana), deterrent activity against pea aphid (Acyrthosiphon pisum), insect growth regulatory activity (Oncopeltus fasciatus), nematicidal activity (Caenorhabditis elegans), antibiotic activity (Pseudomonas solanaciarium), and general toxicity. A data matrix indicated that N. alessandri and N. pumilio most likely have a chemical barrier to insect attack as leaves showed low faunal abundance, low herbivory, and activity in the leafroller antifeedant, aphid deterrent, and nematicidal assays. A chemical examination of N. alessandri that used the leafroller antifeedant test to guide the separation yielded an active fraction containing the flavonoid, galangin, and the stilbene, pinosylvin, which appear to act in concert to deter leafroller feeding. The discovery of the phytoalexin, pinosylvin, in the leaves, raises the possibility that Nothofagus in general, and N. alessandri in particular, may have induced chemical defense mechanisms.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-1561
    Keywords: Spacing pheromones ; olfactometry ; aphids ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Olfactometry using an apterous individual of Rhopalosiphum padi (L.) showed an arresting effect by volatiles from a wheat seedling and a repellent effect by volatiles from a wheat seedling infested with aphids at a high population density (ca. 9 aphids/cm2). Four compounds, 6-methyl-5-hepten-2-one, (−)- and (+)-6-methyl-5-hepten-2-ol, and 2-tridecanone, were identified by GC-MS in air entrainments from the wheat seedlings with high aphid density but not from the wheat seedlings alone. The mixture of the four compounds in the natural proportion counteracted the attractivity of the volatiles from the intact uninfested wheat seedling. The likely role of these compounds in the spacing behavior of this aphid species, when present in high densities on wheat, is discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 24 (1998), S. 361-370 
    ISSN: 1573-1561
    Keywords: Sulcatol ; aphid ; spacing pheromone ; enantiomeric synergism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract GC-MS analysis of volatiles released from wheat infested with a high density of aphids showed the presence of 6-methyl-5-hepten-2-ol (sulcatol). The proportion of enantiomers present in the volatiles was determined by esterifying the mixture with (1S)-( − )-camphanic chloride and quantifying the esters. The mixture consisted of 75% (R)-( − ) and 25% (S)-( + ). The mixture of enantiomers as well as the racemate showed significant repellency towards apterous Rhopalosiphum padi in an olfactometer (15.7% and 14.4%, respectively, with 10 ng of stimulus). Single enantiomers or a mixture containing 25% (R)-( − )- and 75% (S)-( + )-enantiomers were inactive. The results are discussed in relation to the achievement of specificity by aphids in different pheromone-mediated behaviors.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-1561
    Keywords: Tritrophic interaction ; aphid ; Sitobion avenae ; parasitoid ; Aphidius rhopalosiphi ; oviposition ; defensive behavior ; DIMBOA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The influence of hydroxamic acids (Hx), plant secondary metabolites associated with aphid resistance in wheat, on the host acceptance and suitability of the aphid Sitobion avenae to the cereal aphid parasitoid Aphidius rhopalosiphi was evaluated. Aphids showed a reduction in mean relative growth rate and in body size in the wheat cultivar with higher Hx level. Reduction in aphid size was related to a decreased success in avoiding parasitoid oviposition. A minor increase in A. rhopalosiphi developmental time was observed in aphids feeding on the higher Hx cultivar. Experiments with different concentrations of DIMBOA glucoside, the main Hx in wheat, in artificial diets showed an increase in parasitoid developmental time at the highest concentration, with no change in other performance variables. The evidence is discussed in relation to the compatible utilization of host-plant resistance and biological control in integrated pest management.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-1561
    Keywords: Sitobion avenae ; Aphididae ; aphids ; hydroxamic acids ; DIMBOA ; catalase ; cytochrome c oxidase ; peroxisomes ; mitochondria ; xenobiotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract 2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), a hydroxamic acid involved in the resistance of cereals to aphids, was administered to adult individuals of the aphid Sitobion avenae in artificial diets. Effects on the cellular metabolism were inferred from the evaluation of several organelle marker enzymes. Catalase from peroxisomes and cytochrome c oxidase from mitochondria increased their activities about twofold when aphids were fed with 2 mM DIMBOA. The role of these enzymes in the metabolizing of xenobiotics by aphids is discussed. Biochemical and cytochemical evidences for the presence of peroxisomes in aphids are reported here for the first time.
    Type of Medium: Electronic Resource
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