title: Two genera of Aulacoscelinae beetles reflexively bleed azoxyglycosides found in their host cycads.
abstract: Aulacoscelinae beetles have an ancient relationship with cycads (Cycadophyta: Zamiaceae), which contain highly toxic azoxyglycoside (AZG) compounds. How these "primitive" leaf beetles deal with such host-derived compounds remains largely unknown. Collections were made of adult Aulacoscelis appendiculata from Zamia cf. elegantissima in Panama, A. vogti from Dioon edule in Mexico, and Janbechynea paradoxa from Zamia boliviana in Bolivia. Total AZG levels were quantified in both cycad leaves and adult beetles by high performance liquid chromatography (HPLC). On average, cycad leaves contained between 0.5-0.8% AZG (frozen weight, FW), while adult beetles feeding on the same leaves contained even higher levels of the compounds (average 0.9-1.5% FW). High AZG levels were isolated from reflex bleeding secreted at the leg joints when beetles were disturbed. Nuclear magnetic resonance and mass spectroscopy identified two AZGs, cycasin and macrozamin, in the reflex bleeding; this is the first account of potentially plant-derived compounds in secretions of the Aulacoscelinae. These data as well as the basal phylogenetic position of the Aulacoscelinae suggest that sequestration of plant secondary metabolites appeared early in leaf beetle evolution.
authors.affiliation: Department of Plant Science, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
authors.forename: Alberto
authors.initials: A
authors.lastname: Prado
authors.forename: Julieta
authors.initials: J
authors.lastname: Ledezma
authors.forename: Luis
authors.initials: L
authors.lastname: Cubilla-Rios
authors.forename: Jacqueline C
authors.initials: JC
authors.lastname: Bede
authors.forename: Donald M
authors.initials: DM
authors.lastname: Windsor
mesh_terms: D000818:Animals; D005075:Biological Evolution; D012634:Bodily Secretions / Q000737:chemistry*; D001838:Bolivia; D002851:Chromatography, High Pressure Liquid; D001517:Coleoptera / Q000737:chemistry*; D003492:Cycasin / Q000302:isolation & purification; D005260:Female; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D013058:Mass Spectrometry; D008746:Methylazoxymethanol Acetate / Q000031:analogs & derivatives / Q000302:isolation & purification; D008800:Mexico; D010176:Panama; D018515:Plant Leaves / Q000737:chemistry*; D032481:Zamiaceae / Q000737:chemistry*
chemical_list: D008746:Methylazoxymethanol Acetate; C008305:macrozamin; D003492:Cycasin