Sequestration of pyrrolizidine alkaloids in several arctiid moths (Lepidoptera: Arctiidae)

Abstract

Sequestration of dietary pyrrolizidine alkaloids (PA) by larvae and adults of six European arctiid moth species (Spilosoma lubricipeda, Arctia caja, Phragmatobia fuliginosa, Callimorpha dominula, Diacrisia sannio, andTyria jacobaeae) was investigated for comparison with the well-studied Asian arctiidCreatonotos transiens. Larvae of all species metabolized free PA bases into the respectiveN-oxides. Only adults ofA. caja, P. fuliginosa, andS. lubricipeda, but not their larvae, converted dietary 7(S)-heliotrine to 7(R)-heliotrine, a direct precursor of a male pheromone in some arctiids, 7(R)-hydroxydanaidal. The larval integument figures as the main storage site for resorbed alkaloids; only minor amounts were found in other tissues. In addition, a significant amount of alkaloid is deposited in the cocoon ofArctia caja; only traces of alkaloids could be found in the meconium and the exuviae of this species. A substantial part of the alkaloids fed was degraded to unknown, nonalkaloidal products.

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

“…Members of the plant families Asteraceae, Boraginaceae and Fabaceae, which represent the major sources of PA containing plant species, synthesize and store PAs exclusively as N-oxides (Hartmann & Witte 1995;Hartmann 1999). Most PA-sequestering insects also handle and accumulate the alkaloids as N-oxides, including Lepidoptera such as several arctiid moths (Ehmke et al 1990;Hartmann et al 1990;Nickisch-Rosenegk et al 1990;Nickisch-Rosenegk & Wink 1993) and ithomiine butterflies (Trigo et al 1996), Orthoptera such as the aposematic grasshopper Zonocerus (Biller et al 1994) and leaf-beetles of the genus Oreina Hartmann et al 1997;Hartmann et al 1999). Tertiary PAs with certain structural features (e.g., 1-2 double bond and esterification of the allylic hydroxyl group at C-9) are potentially toxic.…”

Diversity of Pyrrolizidine Alkaloids in the Boraginaceae Structures, Distribution, and Biological Properties

“…Several insects are PA specialists which not only tolerate PAs of their host plants but use them for their own chemical defence against predators, as morphogens and even as pheromones [101,144,[225][226][227][228][229][230][231]. Defensive PAs can be obtained as larvae from food plants and as adults via nectar.…”

Evidence for two genetically and chemically defined host races of Tyria jacobaeae (Arctiidae, Lepidoptera)

“…Maidak et al 1996) and ND1 gene (B; from position 123 to 585 according to the reference sequence of Papilio machaon, Aubert et al 1999) In 1988 and 1989 we had transferred larvae, which were collected from Petasites plants, experimentally to containers with PA-rich Senecio or Adenostyles leaves. The larvae started feeding on the plant material and PA sequestration could be confirmed by GLC measurements (Von Nickisch-Rosenegk & Wink 1993). This indicates, that although the alpine larvae naturally prefer PA-free Petasites plants they have maintained the capacity to tolerate PA plants and to accumulate PAs.…”

“…As several studies have shown, larvae of T. jacobaeae, reared on Senecio jacobaea take up the plant alkaloids and partially convert them into callimorphine and other PA derivates (Aplin & Rothschild 1972;Edgar et al 1980;Ehmke et al 1990;Hartmann 1995;Lindigkeit et al 1997;Von Nickisch-Rosenegk & Wink 1993). Two reference samples (Bu1 and Bu2) collected from low elevation areas show substantial amounts of pyrrolizidine alkaloids (110 and124 ng PAs per mg insect, respectively).…”

“…Adults are capable of ejecting noxious secretions from their thoracic glands. These alkaloids obviously serve as chemical defence compounds, because this moth is unpalatable and almost invariably rejected by vertebrate predators (Aplin & Rothschild 1972;Edgar et al 1980;Ehmke et al 1990;Hartmann 1995;Lindigkeit et al 1997;Von Nickisch-Rosenegk & Wink 1993;Vrieling & De Boer 1999;Van Zoelen & Van der Meijden 1991;Watson & Whalley 1983).…”