Pyrrolizidine alkaloids in arctiid moths (Lep.) with a discussion on host plant relationships and the role of these secondary plant substances in the Arctiidae

Abstract

Pyrrolizidine alkaloids (PA) have been identified in six species of Arctiidae reared on Senecio and Crotalaria. These include senecionine, seneciphylline, integerrimine, jacobine, jacozine, jacoline, jaconine and a metabolite (C,,H,,NO,) from Senecio, and monocrotaline, trichodesmine and crispatine from Crotalaria.The all-red aberration of Tyriajacobaeae (var. conyij contained much less of the metabolite than normal examples of this species. Female Spilosoma lutea reared on the same plants of S. Jhcobaea contained markedly more jacobine and jacoline than the males.Host plant relationships and secondaly plant substances are discussed. It is suggested that the Arctiid moths' own deterrent secretions, directed against vertebrate predators, pre-adapts them for reeding on foliage likewise protected against large herbivores by toxic secondary plant substances such as cardenolides and pyrrolizidine alkaloids. These latter substances are more toxic to vertebrate than to insect herbivores, and their dual function of deterrent and insect aphrodisiac puts a premium on their sequestration and storage once a species has achieved the initial steps, and occupied the plant niche concerned. It is further suggested that the polyphagous habits of the Arctiidae result in a more equitable distribution of the secondary plant substances within the Miillerian complex concerned, thus providing a generalized warning message for the potential vertebrate predator.KEY WORDS:-arctiid moths -host plant relationships -pyrrolizidine alkaloid storage.

Differences in Effects of Pyrrolizidine Alkaloids on Five Generalist Insect Herbivore Species

“…PAs are known to deter generalist insect herbivores (Bentley et al, 1984;Dreyer et al, 1985;van Dam et al, 1995;Hägele and Rowell-Rahier, 2000). Specialist herbivores can detoxify (Hartmann, 1999;Naumann et al, 2002) and sequester PAs (Rothschild et al, 1979;Dobler, 2001;Pasteels et al, 2003). Larval performance of the specialist moth Tyria jacobaeae L. was not affected by different PA profiles in its host plant S. jacobaea (Macel et al, 2002).…”

On the reproductive ecology of Suaeda maritima, S. monoica and S. nudiflora (Chenopodiaceae).

“…These butterflies apply from their proboscides a fluid capable of dissolving alkaloids and then re-imbibe it. Both sexes of these butterflies store alkaloids apparently for defense (Edgar et al 1976;1979;Rothschild et al 1979;Conner et al 1981). Owen (1971) reported that danaine butterflies use withered and damaged plants and floral nectar as sources of alkaloids.…”

Time course of pyrrolizidine alkaloid sequestration in Longitarsus flea beetles (Coleoptera, Chrysomelidae)

“…The vast majority of arctiid moths for example, sequester PAs as larvae and transfer them through the pupa to the adult stage (Boppré 1990;Hartmann & Witte 1995). Well studied species include the moths Utetheisa ornatrix (Eisner 1980;Eisner & Meinwald 1987) and Tyria jacobaeae (Aplin et al 1968;Ehmke et al 1990;Rothschild et al 1979). Some butterflies in contrast take up PAs only in the adult stage.…”