Cuticular Hydrocarbons as Chemotaxonomic Characters of Pine Engraver Beetles (Ips spp.) in the grandicollis Subgeneric Group

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

“…may be the first genus reported with a 3,15-isomer as a significant or sole 3,X-substituted dimethylalkane within the peak, rather than a predominant 3,7-dimethylalkane, as found typically at KI XX10 in other insects, such as Blatella cockroaches [16]. Additional 3,X-isomers with large methylene interruptions (greater than 3 methylene units) have been reported previously as 3,13- [14,23,30], 3,17- [14,29], and 3,19- [33] dimethylalkanes. Muscidifurax spp.…”

“…Insects of the genus Muscidifurax are one of the two genera reported to-date which have a clearly definable 3,7,15-trimethylalkane series as well as corresponding 4,8,16-trimethylalkanes on even carbon backbone chains. The only other insects reported to produce a 3,7,15-trimethylalkane are lps pine engraver beetles [14]. Although not presented in these figures, 3,7,11-and 4,8,12-trimethylalkanes were observed in Muscidifurax; however, these are present at low levels and have been found in several other insects [12,26,29,37].…”

“…Previously, isomers of 4,8-, 4,10-, 4,12-, and 4,14-dimethylalkanes have been reported [12,26,29,34]. However, there is only one report of 4,16-dimethylalkanes, found in peaks containing 4,14-and 4,18-isomers [14]; it is not known whether the 4,16-isomer is the major component of this peak as is the case for Muscidifurax. Figure 2 displays the EI mass spectra of 11-methylene interrupted 3,X-and 4,X-branched dimethylalkanes for backbone chain lengths from 33 to 35 carbons.…”

“…These represent tetramethylalkanes on carbon backbone chains of C 29 to C 37 . Only two other insects have been reported to contain 3,7,11,15-tetramethylalkanes; these are the tsetse fly Glossina brevipalpis [13] and the pine engraver beetle lps paraconfusus [14].…”

“…Additionally, CHCs have been used to differentiate species of beetles [14], mosquitoes [15], cockroaches [16], grasshoppers [17,18], termites [19,20], bees [21,22], fruit flies [23], tsetse flies [11][12][13]24], and others. The identification of CHCs by gas chromatography/mass spectrometry (GC/MS) allows the differentiation of four species of Muscidifurax by examining not only the gas chromatograms but also the mass spectra which clearly contain different compounds that demonstrate the sexual dimorphism in this species.…”