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Digitale Medien

Sequestration of cardenolides inOncopeltus fasciatus: Morphological and physiological adaptations (1986)

Scudder, G. G. E. ; Moore, L. V. ; Isman, M. B.

Springer

Journal of chemical ecology 12 (1986), S. 1171-1187

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ISSN: 1573-1561

Schlagwort(e): Hemiptera Heteroptera ; Lygaeidae ; Oncopeltus fasciatus ; Asclepiadaceae ; cardenolides ; sequestration ; morphological adaptations ; physiological adaptations

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Chemie und Pharmazie

Notizen: Abstract The morphological and physiological adaptations associated with sequestration of cardenolides by the lygaeidOncopeltus fasciatus are summarized and discussed. Cardenolides are efficiently accumulated inO. fasciatus; however, the insect does not appear to suffer any physiological cost as a result of handling large amounts of these plant toxins. Morphological adaptations of the insect include a modified integument composed of a double layered epidermis with an inner layer (the dorsolateral space) specialized for cardenolide storage. Special weak areas of the cuticle are found on both the thorax and abdomen, which rupture when the insect is squeezed, resulting in the cardenolide-rich contents of the inner epidermal layer being released onto the body surface in the form of discrete spherical droplets. Physiological adaptations include selective sequestration of food plant cardenolides, concentration of cardenolides in the dorsolateral space, passive uptake of cardenolides at the gut and dorsolateral space requiring little energy output, reabsorption of secreted cardenolides by the Malpighian tubules, high in vivo tolerance to cardenolides, and the presence of cardenolide-resistant Na,K-ATPases.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01639003

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Digitale Medien

Variation in cardenolide content of the lygaeid bugs,Oncopeltus fasciatus andLygaeus kalmii kalmii and of their milkweed hosts (Asclepias spp.) in central California (1977)

Isman, M. B. ; Duffey, S. S. ; Scudder, G. G. E.

Springer

Journal of chemical ecology 3 (1977), S. 613-624

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ISSN: 1573-1561

Schlagwort(e): Variation in cardenolides ; Oncopeltus fasciatus ; Lygaeus kalmii kalmii ; milkweeds ; Asclepias ; chemical defense

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Chemie und Pharmazie

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00988061

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Digitale Medien

Selective sequestration of milkweed (Asclepias sp.) cardenolides inOncopeltus fasciatus (Dallas) (Hemiptera: Lygaeidae) (1985)

Moore, Lynn V. ; Scudder, G. G. E.

Springer

Journal of chemical ecology 11 (1985), S. 667-687

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ISSN: 1573-1561

Schlagwort(e): Cardenolide metabolism ; cardenolide excretion ; cardenolide sequestration ; Hemiptera ; Lygaeidae ; Oncopeltus fasciatus ; milkweed bug ; Asclepias.

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Chemie und Pharmazie

Notizen: Abstract The cardenolide content of the gut, wings, and fat body ofOncopeltus fasciatus was examined. The female fat body contained 4–5% of the total cardenolide content of the insect. The cardenolide content of male fat body, and gut and wings of both sexes was below the detection limit of the cardenolide assay. Thin-layer chromatography was used to determine the cardenolide array of various tissues and secretions ofO. fasciatus reared on seeds of a single species of milkweed (A. Speciosa) and adult extracts and dorsolateral space fluid ofO. fasciatus reared on seeds of two species of milkweed with different cardenolide arrays (A. speciosa andA. syriaca). Our results indicate that cardenolides are not sequestered in the insect simply on the basis of polarity and that metabolism and differential excretion of cardenolides are involved in the sequestration of cardenolides inO. fasciatus. The similarities in the cardenolide profiles ofO. fasciatus reared on different food sources, and tissues ofO. fasciatus reared on a single food source indicates that there is regulation of the cardenolide array inO. Fasciatus.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00988575

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