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Cuticular hydrocarbons for species determination of tropical termites
1990 - IRG/WP 1465
Insect species have unique mixtures of cuticular hydrocarbons in the protective wax of their integument. We use hydrocarbons to evaluate similarities among termite populations. Our assumption is that colonies with similar hydrocarbon profiles are closely related. We have collected Reticulitermes in California from areas suspected to have only Reticulitermes hesperus or Reticulitermes tibialis. Their hydrocarbon profiles are similar but different. Colonies of "Reticulitermes tibialis" from distant locations in Arizona have profiles which are extremely different from Reticulitermes hesperus. This implies that there are at least 3 species of Reticulitermes in western North America when only two are described. The Formosan subterranean termite, Coptotermes formosanus, in the United States show no qualitative differences among four geographically distant populations; quantitative differences in hydrocarbon components separate them into different concentration profiles. Our results suggest that Coptotermes formosanus colonies from Florida and Louisiana are not closely related to those from Hawaii. We strongly suspect that the Coptotermes formosanus was introduced into Louisiana at least twice. Hydrocarbon profiles of Coptotermes formosanus from North America and Hawaii are different from Coptotermes from northern Australia, Southeast Asia and the Caribbean. Nasutitermes costalis and Nasutitermes ephratae were collected from five locations in Trinidad. Sixteen major hydrocarbon components were identified; all but one component were common to both species. Nasutitermes costalis has tremendous quantities of 13,17-dimethylhentriacontane whereas in Nasutitermes ephratae this hydrocarbon is insignificant. Furthermore, 12,16-dimethyltriacontane is completely missing in Nasutitermes ephratae. Nasutitermes costalis from Trinidad and Nasutitermes corniger from Panama appear to have cuticular hydrocarbon profiles that are more similar to one another than are those of Nasutitermes ephratae from Trinidad and Panama.
M I Haverty, M Page, B L Thorne, P Escoubas


Chemotaxonomy of the genus Aquilaria (Thymelaeaceae)
2022 - IRG/WP 22-20687
The genus Aquilaria Lam. (Thymelaeaceae) comprises 21 tree species and is mostly found in Southeast Asia. When the tree is infected (fungi, bacteria, etc.), its wood turns brownish or blackish (called agarwood) due to the secretion of an oleoresin in reaction to the infection. The resin is very fragrant and has been sought after and used for centuries by Buddhists, Hindus and Muslims to make incense for religious ceremonies. This oleoresin is mainly found in species of the genus Aquilaria, but also in a few species of the genera Gyrinops Gaertner and Gonystylus Teijsmann & Binnendijk. It is difficult to distinguish between these species and this lack of taxonomic knowledge has led to over-use of the trees, endangering these endemic species listed in CITES Appendix II. We used chemotaxonomy as a discrimination tool to analyse polyphenolic molecules, secondary metabolites, which are known to act as taxonomic markers in other plants. This work showed the possibility of using some very old herbarium samples, which revealed good conservation of its phenolic profile. It is interesting to note that mangiferin, through its high concentration and constant presence in all the species of the genus Aquilaria analysed, constitutes a chemical marker for this genus. Comparative analysis of these phenolic molecules can therefore be very useful when seeking chemotaxonomic markers.
C Zaremski, N Amusant, C Andary, M Ducousso, S Hul, G Michaloud, A Zaremski