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  • Coleoptera  (1)
  • Lygaeus kalmii kalmii  (1)
  • Springer  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Variation in cardenolide content of the lygaeid bugs,Oncopeltus fasciatus andLygaeus kalmii kalmii and of their milkweed hosts (Asclepias spp.) in central California (1977)
    Springer
    Journal of chemical ecology 3 (1977), S. 613-624 
    Details
    ISSN: 1573-1561
    Keywords: Variation in cardenolides ; Oncopeltus fasciatus ; Lygaeus kalmii kalmii ; milkweeds ; Asclepias ; chemical defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A colorimetric assay was used to quantify the amount of cardenolides in the lygaeid bugsOncopeltus fasciatus andLygaeus kalmii kalmii and their milkweed host plants (Asclepias spp.) in central California. The cardenolide content of individual insects, determined in microgram equivalents of digitoxin, varied from zero to over 300 μg per insect. Sources of variation of cardenolide content in the insects include interspecific and intraspecific differences in the content of the host plant species and also differences in the content of plant organs on which insects were feeding. This last source of variability may explain temporal variation in the cardenolide content of the insects. Adults ofO. fasciatus, which migrate into California in the late spring and early summer, and adults ofL. k. kalmii, which emerge from winter hibernacula in the early spring, contained small to immeasureable amounts of cardenolides. The colonization pattern ofO. fasciatus on species ofAsclepias in north central California suggests that this species does not maximize its opportunities to sequester large quantities of cardenolides from potential hosts. The emetic potential of lygaeids in California to vertebrate predators is briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00988061
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  • 2
    Electronic Resource
    Electronic Resource
    Avoidance of antinutritive plant defense: Role of midgut pH in Colorado potato beetle (1992)
    Springer
    Journal of chemical ecology 18 (1992), S. 571-583 
    Details
    ISSN: 1573-1561
    Keywords: Leptinotarsa decemlineata ; Coleoptera ; Chrysomelidae ; Colorado potato beetle ; Helicoverpa zea ; Lepidoptera ; Noctuidae ; phenolics ; poly-phenol oxidase ; peroxidase ; chlorogenic acid ; Lycopersicon esculentum ; tomato ; host-plant resistance ; midgut pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The fate of the tomato foliar phenolic, chlorogenic acid, in the digestive systems of Colorado potato beetleLeptinotarsa decemlineata (Coleoptera: Chrysomelidae) andHelicoverpa tea (Lepidoptera: Noctuidae) is compared. In larvalH. zea and other lepidopteran species previously examined, approximately 35–50% of the ingested chlorogenic acid was oxidized in the digestive system by foliar phenolic oxidases (i.e., polyphenol oxidase and peroxidase) from the tomato plant. The oxidized form of chlorogenic acid, chlorogenoquinone, is a potent alkylator of dietary protein and can exert a strong antinutritive effect upon larvae through chemical degradation of essential amino acids. In contrast, inL. decemlineata less than 4% of the ingested dose of chlorogenic acid was bound to protein. In vitro experiments to determine the influence of pH on covalent binding of chlorogenic acid to protein showed that 30–45% less chlorogenic acid bound to protein at pHs representative of the beetle midgut (pH 5.5–6.5) than at a pH representing the lepidopteran midgut (pH 8.5). At an acidic pH, considerably more of the alkylatable functional groups of amino acids (−NH2, −SH) are in the nonreactive, protonated state. Hence, polyphenol oxidases are unlikely to have significant antinutritive effects against the Colorado potato beetle and may not be a useful biochemical source of resistance against this insect. The influence of feeding by larval Colorado potato beetle on foliar polyphenol oxidase activity in tomato foliage and its possible significance to interspecific competition is also considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00987820
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