Platyptilia pica

Many species of Castilleja (Scrophulariaceae) contain iri-doid monoterpenes (Arslanian et al, 1985) as well as pyrrol-izidine, quinolizidine, and monoterpene iridoid alkaloids (Stermitz et al., 1986a). Both pyrrolizidine and quinolizidine alkaloids appear to be taken from the hosts of these hemipar-asitic plants see Chapter 30). The larvae of Platyptilia pica (Pterophoridae) excrete but do not sequester iridoids. The adult moths contained rhexifoline, an iridoid monoterpene alkaloid (Stermitz et al, 1986a). 

Stermitz, F. R., G. H. Harris, and W. Jing, Iridoids and alkaloids from Castilleja host plants for Platyptilia pica. Rhexifoline content of P. pica, Biochem. Syst. Ecol, 14, 499-506 (1986a). 

The stems and leaves of Castilleja rhexifolia (Scrophula-riaceae) contain senecionine (5) and its A -oxide (obtained from Senecio triangularis) as their main alkaloids. The major alkaloid of the blossoms and seeds is rhexifoline, an iridoid-monoterpene-derived alkaloid, which is found in many Castilleja species. These plants serve as a host for the plume moth, Platyptilia pica. The larvae primarily eat the green seeds. Both the larvae and the adults of this insect contain rhexifoline (Roby and Stermitz, 1984). Plants of C. hispida contain quinolizidine alkaloids, and occasional plants of C. sulphurea contain quinolizidine alkaloids, whereas those of C. occidentalis do not contain alkaloids other than rhexifoline. The iridoid monoterpene content of all these alkaloids is similar. The larvae were found to excrete the monoterpene iridoids (Stermitz et al., 1986). 

McCoy, J. W. and F. R. Stermitz, Alkaloids from Castilleja mini-ata and Penstemon whippleanus, two host species for the plume moth, Ambryptilia (Platyptilia) pica, J. Nat. Prod., 46,902-907 (1983). 

---