Fig. 2.

Total ion chromatograms of the fatty acid compositions (as the methyl esters) of representative pheromone gland (a) and abdominal tissue (b) extracts (HP-1MS capillary column). Fatty acid methyl esters are coded with a number indicating chain length, followed by a number indicating the number of double bonds, with the positions and geometries given if known. Peak numbers correspond to those listed in Table 2. The omega ion at m/z 108, diagnostic for a 3,6,9-triene motif, and the alpha ion at m/z 180, diagnostic for a 5,8,11-triene motif counting from the other end of the chain are indicated in the mass spectrum of the C20:5 acid methyl ester (c). The weak molecular ion at m/z 316 was not detected in full scan mode, but it was detected in the more sensitive selected ion monitoring mode, at a same retention time as the two diagnostic ions at m/z 79 and 108