Schwartz, BrettMoore, Christopher JRahm, FredrikHayes, Patricia YKitching, WilliamDe Voss, James Joseph2015-12-070002-7863http://hdl.handle.net/1885/24057The volatile components of the mandibular gland secretion generated by the Giant Ichneumon parasitoid wasp Megarhyssa nortoni nortoni Cresson are mainly spiroacetals and methyl ketones, and all have an odd number of carbon atoms. A biosynthetic scheme rationalizing the formation of these diverse components is presented. This scheme is based on the results of incorporation studies using2H-labeled precursors and [18O]dioxygen. The key steps are postulated to be decarboxylation of β-ketoacid equivalents, β-oxidation (chain shortening), and monooxygenase-mediated hydroxylation leading to a putative ketodiol that cyclizes to spiroacetals. The generality of the role of monooxygenases in spiroacetal formation in insects is considered, and overall, a cohesive, internally consistent theory of spiroacetal generation by insects is presented, against which future hypotheses will have to be compared.Keywords: Biochemical engineering; Biochemistry; Carboxylation; Ketones; Carbon atoms; Chain shortenings; Dioxygen; Diptera; Mandibular glands; Methyl ketones; Monooxygenase; Monooxygenases; Odd numbers; Volatile components; Organic compounds; acetone; oxygen; unsp200810.1021/ja80364332016-02-24