Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 2, 2001
Publication Date: December 1, 2001
Citation: BARTELT, R.J., COSSE, A.A., ZILKOWSKI, B.W., WEISLEDER, D., MOMANY, F.A. MALE-SPECIFIC SESQUITERPENES FROM APHTHONA AND PHYLLOTRETA FLEA BEETLES. JOURNAL OF CHEMICAL ECOLOGY. 2001. v. 27(12). p. 2397-2423. Interpretive Summary: Pheromones (e.g., chemicals emitted by insects to attract mates) are studied as potential tools for managing insects to the benefit of agriculture. An initial investigation was made into pheromone biology of flea beetles of two genera. Phyllotreta flea beetles are significant pests of crucifers such as canola and rape seed. On the other hand, Aphthona flea beetles are useful biocontrol for the invasive weed species, leafy spurge. Male-specific chemicals were chemically identified from both groups as pheromone candidates, and, interestingly, six of the compounds were identical in both groups. The Aphthona species had two additional compounds that were not present in Phyllotreta. This research is a prerequisite for the eventual testing of the pheromones of these beetles in the field. It is anticipated that the pheromones will be useful for monitoring populations of both the beneficial and pest species.
Technical Abstract: To initiate studies on the chemical ecology of flea beetles, volatiles collected from male and female beetles feeding on host plant material were compared and analyzed. Six male-specific compounds were isolated from Phyllotreta cruciferae, and the same compounds plus two additional ones were isolated from males of Aphthona flava, A. czwalinae, and A. cyparissiae. Structures were studied by mass spectrometry, NMR spectroscopy, UV spectroscopy, polarimetry, chiral and achiral gas chromatography, molecular modeling, and microchemical tests. The compounds were identified as (+)-aromatic-himachalene, (+)-trans-alpha- himachalene, (+)-gamma-cadinene, two other himachalenes known previously only from certain fir tree species, two himachalene alcohols, and one norsesquiterpene ketone with the himachalene ring structure. Except for (+)-aromatic-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 in which the ring system and configurations at two particular asymmetric centers are conserved.