Cuticular Hydrocarbon Research1

We have been studying existing taxonomies of forest insects that are based on morphological, genetic and/or behav­ ioral characteristics to evaluate the utility of cuticular (surface) hydrocarbons as taxonomic characters (Haverty and others 1988, 1989, Page and others 1990a, 1990b). Cuticular hydrocarbons are relatively stable metabolic end products that appear to be genetically fixed. Because the insects studied so far synthesize all or most of their hydrocarbon components, hydrocarbon composition and taxonomic grouping should be related. Ideally, we would use these chemical characters much as clas­ sical taxonomists use morphology, behavior or genetics, i.e., to sort the groups of insects on the basis of surface chemical characters first, rather than after groups have already been sorted on the basis of existing (nonchemical) character criteria. However, by comparing our taxonomic separations on the basis of cuticular hydrocarbons with existing taxonomic divisions based on other characteristics, we are broadening the data base of cuticular hydrocarbons as potential taxonomic characters for forest insects. We initially started our studies on the dampwood termites, Zootermopsis, while trying to understand a synonymy of two species of scolytid cone beetles, Conophthorus ponderosae and C. lambertianae. Since these beetles have few useful diagnostic morphological characters, we decided to examine cuticular hydrocarbons as taxonomic characters. To test our understand­ ing of the current methodology, we repeated the results of Blomquist and others (1979) on Z. angusticollis. Our initial investigation produced hydrocarbon profiles that differed from those they had published. Had we made an error in methodol­ ogy? Was their hypothesis about species and caste-specific hydrocarbons correct? Had we observed population or colony variation unreported by them? On the basis of morphological characters, our termite speci­ mens were identified as Z. nevadensis, not Z. angusticollis. Blomquist (personal communication) suggested that both our laboratories reevaluate our termite collections using identical methods and gas chromatography parameters. Surprisingly, Blomquist's and our laboratory data were identical to those in our first trial but different than his published data. Had we discovered a sibling species? Additional collections and analy­ ses led us to identify an "extra" hydrocarbon phenotype of Zootermopsis and to find a morphological character for un­ equivocal identification of the three described species of Zootermopsis (Thome and Haverty 1989). We have separated all species of the dampwood termite by hydrocarbon pheno-