Pyrrolizidine alkaloids in the arctiid mothHyalurga syma

Abstract

The arctiid mothHyalurga syma (subfamily Pericopinae) sequesters pyrrolizidine alkaloids (PAs) from its larval food plantHeliotropium transalpinum (Boraginaceae). Colorimetric quantification of total PAs in the larvae, pupae, and adults ofHyalurga revealed mean values of about 286-445μg per individual (1.4-2.6% of dry weight). The PA mixtures found in the moth and its larval food plant were evaluated by GC-MS. Food-piant leaves were found to contain the diastereoisomeric retronecine esters indicine (IIIa), intermedine (IIIb), and lycopsamine (IIIc), and the heliotridine ester rinderine (IIId) only as minor constituents, whereas 3'-acetylrinderine (IVc) (68% of total PAs) and the respective 3'-acetyl esters of indicine (IVa) and intermedine (IVb) (both 17%) were the major alkaloids. Supinine (IIa) is detectable in traces only. The PA mixtures in eggs, larvae, pupae, and imagines ofHyalurga were identical: indicine, intermedine, and lycopsamine accompanied by considerable amounts of supinine and amabiline or coromandalinine (IIb/IIc) were the major components. Only larvae were found to store small quantities of a 3'-acetyl derivative. Rinderine and its 3'-acetyl ester were never found in the insects. Low concentrations of the arctiidspecific PA callimorphine (I) were present in larvae, pupae, and imagines. The differences in the PA patterns of the insects and their larval food plant suggest thatHyalurga is capable of modifying plant-derived PAs by inversion of the 7-OH configuration (conversion of the necine base heliotridine into retronecine), and perhaps the inversion of the 3'-OH [conversion of (+)-trachelanthic acid into (-)-viridifloric acid], although the possibility of a selective sequestration of the respective retronecine esters cannot be excluded. Some trials with the orb-weaving spiderNephila clavipes, a common neotropical predator, showed that both freshly emerged and field-caught adults ofHyalurga syma are liberated unharmed by the spider. The liberation could be related to the presence of PAs in the moths.

Detoxification of pyrrolizidine alkaloids by the harvestman Mitopus morio (Phalangidae) a predator of alkaloid defended leaf beetles

“…The giant tropical orb spider, Nephila clavipes, is an important predator of butterflies. PA-protected lepidopterans such as the moths Utetheisa (Eisner 1982) and Hyalurga (Trigo et al 1993) and various Ithomiinae butterflies (Brown 1984;Masters 1990) are rejected by the spider; they are cut out of the web and liberated unharmed.…”

Uptake and metabolism of [ 14 C]rinderine and [ 14 C]retronecine in leaf-beetles of the genus Platyphora and alkaloid accumulation in the exocrine defensive secretions

“…PA-storing neotropical ithomiine butterflies are well protected against predation by the tropical orb spider Nephila. Butterflies containing PAs are immediately cut out of the web by the spider and liberated unharmed, whereas insects devoid of PAs are eaten (Eisner & Meinwald 1987, Masters 1990, Trigo et al 1993, Trigo et al 1996. Arctiid moths protect their eggs by endowing them with PAs against predators such as coccinellid beetles (Dussourd et al 1988), larvae of the green lacewing (Ceraeochrysa cubana, Neuroptera) (Eisner et al 2000), and ants (Hare & Eisner 1993).…”

Pyrrolizidine Alkaloids in the Pericopine MothScearctia figulina(Erebidae: Arctiinae): Metabolism and Chemical Defense

“…11 In the second, larvae are generally monophagous, feeding on a single PA-host plant genus, from which they sequester the alkaloids; subtribes Callimorphina and Pericopina shared this syndrome. 11,14 The third syndrome comprises polyphagous larvae, feeding both on non-PA and PA-host plants. 5,11 Species from the subtribe Arctiina showed this syndrome.…”

“…11 Other interesting PA pathways in arctiine moths are the de novo biosynthesis of insect ester alkaloids (insect PAs) and the stereochemical inversion of 7R configuration to 7S pyrrolizidine rings. [14][15][16] Both biochemical mechanisms are involved in the biosynthesis of dihydropyrrolizine male sexual pheromones. [16][17][18][19] Insect PAs are esters biosynthesized from plant-acquired necine bases with necic acids of insect origin, and it has been suggested that they are biosynthesized via transesterification of plant PAs.…”

“…16,20 Callimorphine type PAs were found in the Arctiina Arctia caja, Creatonotos transiens, Estigmene acrea, and Grammia geneura, in the Callimorphina Callimorpha dominula and Tyria jacobaea, and in the Pericopina Gnophaela latipennis and Hyalurga syma. [14][15][16] PAs of the creatonotine type were found in the Arctiina Creatonotos transiens, Estigmene acrea, and Grammia geneura, and in the Callimorphina Utetheisa ornatrix. 16 Insect PAs were not found in the Callimorphina Nyctemera annulata.…”