Epicuticular hydrocarbons of the sugarcane borer Diatraea saccharalis (Lepidoptera: Crambidae)

Abstract

The epicuticular hydrocarbons of the larval, pupal and adult stages of the sugarcane borer Diatraea saccharalis Fabricius (Lepidoptera: Crambidae)are analyzed. Dramatic changes are observed between the stages studied. Adult hydrocarbons are mostly saturated, with a predominance of 1?4 methyl-branched straight carbon skeletons of 37?47 atoms; the major components are isomeric mixtures of internally branched trimethylderivatives of C39, C37 and C41 carbon backbones. By contrast, very small amounts of methyl-branched components are detected in the pupae, although straight chain hydrocarbons of 23?35 carbons are the prevailing structures (70.7 ± 3.4%) with n-C29 and n-C27 as the major components. Unsaturated hydrocarbons (29.0 ± 3.5%) of similar chain lengths elute by gas chromatography of epicuticular extracts as complex mixtures of mono-, di- and trienes; with the degree of unsaturation increasing with chain length. This is the first report of very long chain unsaturated hydrocarbons in cuticular extracts of a larval lepidopteran (93.3 ± 0.6% of the lipid components), with chain lengths in the range 37?53 carbons and up to four double bonds; the major component being C49:3, which co-elutes with C49:4 and C49:2.