Spilosoma imparilis

Fig. 12A-C Separation of Type II pheromone components by HPLC with an ODS column (4.6 mm ID X 25 cm) A a crude pheromone extract of Spilosoma imparilis (Arctiidae, 2 FE) including l,Z3,Z6,epo9-21 H (I),Z3,Z6,epo9-21 H (II),Z3,Z6,epo9-23 H (III),Z6,epo9-23 H (IV), and Z3,Z6,Z9-21 H (V) detected by UV 215 nm B a mixture of synthetic standards (ca. 1 pg each of II-V) detected by RID C the same synthetic mixture detected by UV 215 nm. The solvent system is 3.5% water in MeOH (1.0 ml/min)...

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 a parallel study, Wei et al. (2003) showed that the triene precursors to epoxide pheromones were present, along with a variety of other hydrocarbons, in extracts of hemolymph from females of two geometrid (A. selenaria cretacea and II. artilineata) and one arctiid species (Spilosoma imparilis). The epoxides were not found in the hemolymph extracts, nor were the trienes found in extracts of hemolymph from males. When labeled trienes were injected into the abdomens of females, labeled epoxides were later recovered from pheromone glands, demonstrating that the injected compounds had been transported to and taken up by the glands, and that triene hydrocarbons, synthesized somewhere outside the glands (probably in oenocytes), were the direct precursors to the epoxide pheromone components. 

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