Syntomoides imaon

In contrast, the hemolymph of females of the arctiid moth Spilosoma imparilis were found to contain significant levels of the polyunsaturated hydrocarbons corresponding to the epoxide pheromone components produced by this species (Wei el al., 2003). In a biosynthetic study with the arctiid Syntomoides imaon, the pheromone of which consists of a blend of 3Z,6Z,9Z-21 H and 1,3Z,6Z,9Z-21 H (Matsuoka el al., 2008), the lipids extracted from oenocytes and peripheral fat bodies associated with the abdominal integument contained both (llZ,14Z,17Z)-eicosa-ll,14,17-trienoic acid and (13Z,16Z,19Z)-docosa-13,16,19-trienoic acid, the intermediates predicted by elongation of linolenic acid by one or two cycles of 2-carbon chain extension (Ando et al., 2008). The latter acid is likely to be the direct biosynthetic precursor to 3Z,6Z,9Z-21 H (Ando et al., 2008). 

In the final installment of this story to date, Matsuoka et al. (2008) determined that female A. selenaria cretacea contained (llZ,14Z,17Z)-eicosa-ll,14,17-trienoic acid but not the longer-chain (13Z,16Z,19Z)-docosa-13,16,19-trienoic acid, in line with the fact that the pheromone of this species consists of 3Z,6Z,9Z-19 H and a corresponding monoepoxide (Matsuoka et al., 2008). That is, this geometrid only requires a C20 fatty acid precursor to decarboxylate to its C19 pheromone compounds. In contrast, as mentioned above, the arctiid species Syntomoides imaon, which produces C2i triene and tetraene pheromone components, was found to contain both (llZ,14Z,17Z)-eicosa-ll,14,17-trienoic acid and the longer-chain (13Z,16Z,19Z)-docosa-13,16,19-trienoic acid (Matsuoka et al., 2008). That is, the arctiid species requires the C22 precursor in order to produce its C21 pheromone components by decarboxylation, whereas the geometrid species only requires the C20 precursor, because its pheromone is composed of the shorter-chain C19 compounds. These data suggest that the chain elongation of linolenic acid and related precursors is under precise control. 

Ando, T., Matsuoka, K., Yamamoto, M., Muramatsu, M. and Naka, H. (2008). Identification of C21 Type n sex pheromone components and novel C20 and C22 trienyl biosynthetic precursors from a wasp moth, Syntomoides imaon (Arctiidae Syntominae). In Abstracts of the 25 th Anniversary ISCE Meeting, International Society of Chemical Ecology,... 

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