USE OF CUTICULAR HYDROCARBONS IN BARK BEETLE PARASITOID TAXONOMY - A STUDY OF ROPTROCERUS-XYLOPHAGORUM (RATZEBURG) (HYMENOPTERA, TORYMIDAE)FROM THE UNITED-STATES, EUROPE AND AUSTRALIA

Cuticular hydrocarbons of adult Roptrocerus xylophagorum (= eccoptogas tri) (Ratzeburg) from California and Georgia were isolated and charact erized by combined gas chromatography-mass spectrometry. The hydrocarb on compositions of individuals from both locations were very similar w ith the major components of n-alkanes, midchain-methylbranched alkanes , terminally methylbranched alkanes and 3,7-dimethylbranched alkanes. Hydrocarbons of the females were shorter (average chain length 28.7) t han the hydrocarbons recovered from the males (31.5). Cuticular hydroc arbons of R. xylophagorum females from Belgium, Austria and Switzerlan d were primarily alkenes, n-alkanes and alkadienes, whereas the major components of males from Belgium were n-alkanes, alkenes and terminall y methylbranched alkanes. Cuticular hydrocarbon profiles of R. xylopha gorum collected in Europe were very different from those of R. xylopha gorum from the United States but very similar to Roptrocerus mirus col lected in Switzerland. R. xylophagorum adults from Australia that were progeny of those introduced from the United States had cuticular lipi d profiles similar to to those of the parasitoids collected in North A merica.