Über Arthopoden-Abwehrstoffe XLIV.

Schildknecht, H.; Birringer, H.

doi:10.1515/znb-1969-1209

Cited by 11 publications

(1 citation statement)

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“…There are, however, other defensive steroidal agents found in insects. Cardenolides have been isolated from certain danaid butterflies, grasshoppers, chrysomelid beetles, and other insects (17)(18)(19)(20)(21), and a diversity of steroids is secreted by dytiscid beetles (22). It is of interest that the vertebrate counterpart of the lucibufagins, the bufadienolides from toads, also serve as defensive agents.…”

Section: Discussionmentioning

confidence: 99%

Lucibufagins: Defensive steroids from the fireflies Photinus ignitus and P. marginellus (Coleoptera: Lampyridae)

Eisner

Wiemer

Haynes

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

107

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Feeding tests with thrushes (Hylocichia spp.) led to the isolation of three novel steroid pyrones from fireflies (Photinus ignitus and P. marginellus) responsible, in part at least, for the unpalatability of these insects to the birds. The term lucibufagin is coined for these steroidal pyrones. The closest known relatives of lucibufagins are the familiar cardiotonic bufadienolides, found in certain toads and plants. It had previously been suspected that fireflies-the familiar luminescent beetles of the family Lampyridae-contain noxious substances that protect them against vertebrate predators. A diversity of lizards, birds, and mammals was said to reject these insects, but the defensive substances responsible, presumed to be present in the blood and tissues of the beetles, had not been characterized (2-4).Pursuant to our finding that fireflies of the genus Photinus are rejected by birds (thrushes of the genus Hylocichla), we developed a bioassay with these predators by which the feeding deterrency of extracts of Photinus, and that of fractions of the extracts, could be evaluated. The procedure led to the isolation of three novel steroidal pyrones, deterrent to the birds, and present in the beetles at defensively effective concentrations. We here describe the isolation and partial characterization of these compounds, for which we propose the term lucibufagins. Steroidal pyrones, or bufadienolides, are of restricted occurrence in nature. They have been found in some well-known toad venoms as well as in a small group of plants (ref. 5, pp. 469-476). However, no examples have been reported from invertebrates. MATERIALS AND METHODSThe two species of Photinus studied, P. ignitus and P. marginellus, are common in the northeastern United States. They were collected at night with nets in the environs of Ithaca, New York, and immediately brought to the laboratory for feeding tests or chemical extractions. Because the fireflies were taken in flight, they can be assumed to be virtually all males. Thrushes were chosen for the feeding tests because they adapted well to captivity and were known to be broadly insectivorous in their habits. A single Swainson's thrush (Hylocichla ustulata, male) and five hermit thrushes (H. guttata, three females and two males) were used. All had been taken months beforehand in mist nets during the migratory season. They were caged singly in the laboratory and were "experienced" at the time of experimentation, having previously been offered palatable and unpalatable insects in connection with other studies. They were sexed at autopsy.The initial tests with the single Swainson's thrush were in-The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact. 905tended to provide preliminary data on the food preferences of such a bird. These tests extended over a period of 23 days, during which the thrush was offered, in daily feedi...

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