Novel very long-chain methyl-branched alcohols and their esters, and methyl-branched alkanes in pupae of the cabbage looper, Trichoplusia ni (Hubner)

Gas chromatography/mass spectrometry analysis of the cuticular hydrocarbons from parasitic wasps of the genus Muscidifurax

“…The ion pairs at m/z 252/253 in Figure 2a duced at m/z 209 in 11-methylene interrupted hydrocarbons. This ion has been observed previously in published mass spectra [35,36]. Normally, an ion pair would be expected at m/z 210/211 as the primary ion, having weaker intensity than the corresponding secondary ion at m/z 239; however, the observed ion is 1-2 Da lower than expected.…”

“…In this case, a third isomer of weaker intensity has a 7/3-methylene interruption pattern. This pattern was not observed in female trimethylalkanes, but has been observed in the CHCs and cuticular alcohols of other insects as a 5,13,17-methyl branched isomer [26,36]. (Figure 6b) are presented as excellent examples of the unmistakable mass spectra obtained.…”

Waxes of the social spiderAnelosimus eximius(Araneae, Theridiidae): Abundance of noveln-propyl esters of long-chain methyl-branched fatty acids

“…These lipids often contain from one to three methyl groups, and usually contain even numbered carbon chains. They are found internally in the insect and their function is unknown (Nelson and Blomquist, 1995;Nelson et al, 1989).…”