Submitted to: International Society of Chemical Ecology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 12, 2001
Publication Date: N/A
Technical Abstract: As part of a project on the chemical ecology of flea beetles (Coleoptera: Chrysomelidae), volatiles were collected from males and females feeding on host plant material and were compared and analyzed. Six male-specific compounds were isolated from Phyllotreta cruciferae, a pest of canola and other crucifers. The same six compounds plus two additional ones were isolated from males of Aphthona flava, A. czwalinae, and A. cyparissiae, which are biocontrol agents of leafy spurge, a serious weed pest. Structures were studied by mass spectrometry, NMR spectroscopy, UV spectroscopy, polarimetry, chiral and achiral gas chromatography, molecular modeling, and microchemical tests. Three of the compounds were identified as the bicyclic sesquiterpenes, (+)-ar-himachalene, (+)-trans-alpha-himachalene, and (+)-gamma-cadinene. Two others were himachalene hydrocarbons which were known in general structure from certain fir tree species but with ambiguous stereochemistry. Finally, there were two himachalene alcohols and one norsesquiterpene ketone that is a himachalene analog. Except for (+)-ar-himachalene and (+)-gamma- cadinene, the compounds are either new natural products or new enantiomers of previously described natural products. Electrophysiological activity was demonstrated for five of the compounds. All of the active compounds (two hydrocarbons, two alcohols, and one ketone) have one particular portion of the ring system in common, including identical configurations at two asymmetric centers. The compounds likely have a pheromonal function.