Pyrrolizidine alkaloids: different acquisition and use patterns in Apocynaceae and Solanaceae feeding ithomiine butterflies (Lepidoptera: Nymphalidae)

摘要: Pyrrolizidine alkaloids (PAs) often serve as chemical mediators of plant-herbivore-predator interactions. Butterflies (Danainae and Ithomiinae) moths (Arctiidae) usually acquire PAs from plant sources (larval host plants, flowers or withered leaves visited by adults — pharmacophagy) thereby become chemically protected against predators; they also use pheromone precursors. Study GC-MS in three species Ithomiinae butterflies, their larval plants adult alkaloid showed different acquisition patterns: (1) larvae the primitiveTithorea harmoniasequester food plantPrestonia acutifolia(Apocynaceae: Echitoideae), may these sources; (2) more derivedAeria olenafeed onPrestonia coalita, whose no were detected, but freshly emerged sometimes contain males intensively seek sequester (3) still advancedMechanitis polymniafeed on several PA-freeSolanumspecies, various sources. Males females all mostly two PAs, diastereoisomeric retronecine monoesters lycopsamine intermedine, stored N-oxide form. Larval a large array PA structures, most abundant frequent being its diastereoisomers echinatine, rinderine indicine, deoxy-analogues supinine amabiline. Bioassays with wild caught suggest that protection predation orb weaving spiderNephila clavipesmay be dependent concentration maybe some spider idiosyncrasies, emergedAeria olenawithout are liberated byNephila, suggesting other protective compounds. The role this selective pressure for ithomiines is not clear.