Very long-chain methyl-branched alcohols and their acetate esters in pupae of the Southern armyworm, Spodoptera eridania: Identification and biosynthesis

Abstract

Homologous series of very long-chain methyl-branched primary alcohols and their acetate esters comprise a major lipid class in pupae of the Southern armyworm, Spodoptera eridania, and were characterized by capillary gas chromatography-mass spectrometry as their acetate esters and their chloride and deuterated derivatives. The major components contain between 38 and 42 carbons in the alkyl chain, and have 1, 2 or 3 methyl branches. The four components, 22,26- and 22,34-dimethyloctatriacontanol, 24,28-dimethyltetracontanol and 26,30-dimethyldotetracontanol, comprise over 50% of the free alcohols and over 75% of the acetate esters. Radiolabeled acetate and propionate were incorporated at high levels into the acetate esters from 24 to 90 h after pupation and into the free alcohols from 120 to 160 h after pupation. Both microsomal and soluble enzyme preparations from the tissue associated with the pupal cases incorporated labeled methylmalonyl-CoA into lipid. The data show that very long-chain methyl-branched primary alcohols and their acetate esters are a major lipid class synthesized by S. eridania pupae, and indicate that these unusual methyl-branched alcohols are characteristic of lepidopteran pupae.