Walter Soares LEAL.* Shigefumi KUWAHARA-1, Mikio ONO-2 and Sakae KUBOTA-3
Laboratory of Chemical Prospecting, National Institute of Sericultural and Entomological
Science, 1-2 Ohwashi, Tsukuba, Ibaraki 305, Japan
1- Faculty of Agriculture, Ibaraki University, Ami-machi, Ibaraki 300-03
2- Fuji Flavor Co. Ltd. 3-5-8 Midorigaoka, Hamura-city, Tokyo 190-11
3- Shizuaka Tea Experiment Station, Kikugawa, Shizuaka 439
The yellowish elongate chafer H. picea is a very important agricultural pest in Japan, which causes tremendous losses in tea and flower productions. In order to explore the feasibility of using semiochemicals for this pest management, its pheromone chemistry was investigated. CC-EAD of the female whole-body extract, using male antennae as sensing element, revealed the occurrence of two EAD-active peaks, one of vvhich was also isolated in the fraction biologically active. Mass spectral data and hydrogenation revealed that this behaviorally active compound was a hexadecadien-4-olide. lt was not possible to determine the double bond positions by direct DMDS derivatization of the pheromone, but partial hydrogenation (diimide) followed by DMDS derivatization showed that the double bonds were lacated in position 7 and 15. FTIR (Tracer) of the pheromone corroborated the lactone structure (1772 cm-1) and showed a band characteristic of a terminal double bond at 3073 cm-1, and one of a double bond in cis-configuration at 3002 cm-1. Chiral resolution of the pheromone, after hydrogenation, demonstrated that the natural lactone had the (R)-stereochemistry.
Synthetic (R,Z)-7,15-hexodecadien-4-olide, prepared from L-malic acid in 14 steps, was identical to the natural product in MS, IR, retention times, and biological activity. T his is the first fatty acid derivative compound found as a sex pheromone of a Melolonthinae species and as far as biosyntl1esis is concerned this is the most complex pheromone constituent of a scarab species identified thus far (Leal, 1996).
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