title: Studies of long chain lipids in insects by high temperature gas chromatography and high temperature gas chromatography-mass spectrometry.
abstract: The organic compounds occurring naturally on the cuticles (surfaces) of insects are important for insect communication, help to act as protective water barriers and are useful in chemical taxonomy. Typically the cuticular lipids are only studied by gas chromatography-mass spectrometry (GC-MS) of hexane or pentane extracts, so the normal limitations of GC-MS makes it perhaps unsurprising that compounds with more than about 35 carbon atoms have only rarely been reported. Here we show by high temperature (HT) GC and HTGC-MS of extracts of eleven species of insects from nine genera, that longer chain compounds are actually common. Wax esters and triacylglycerides are virtually ubiquitous in such extracts, but long chain (>C35) hydrocarbons also sometimes occur. Whilst the latter have occasionally been reported previously from mass spectrometry studies, the use of the HTGC combination with MS allowed even some isobaric isomers to be separated and thus more complete lipid distributions to be monitored. Since the physical properties of cuticular compounds depend on this composition of the mixtures, such differences may influence the water loss rates of the insects, amongst other effects. In addition, the high molecular weight compound profiles may allow species to be more easily differentiated, one from another. It would be interesting to apply these methods to examination of the cuticular lipids of insects on a more routine basis, ideally in combination with MALDI-TOF-MS and imaging methods.
authors.affiliation: Petroleum and Environmental Geochemistry Group, Biogeochemistry Research Centre, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Sutton
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wilde
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Martin
authors.forename: Josef
authors.initials: J
authors.lastname: Cvačka
authors.forename: Vladimír
authors.initials: V
authors.lastname: Vrkoslav
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Rowland
mesh_terms: D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006358:Hot Temperature; D007313:Insecta / Q000737:chemistry*; D008055:Lipids / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D008970:Molecular Weight; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D008055:Lipids