Identification and Field Evaluation of Sex Pheromone Components of the Pear Barkminer Moth, Spulerina astaurota
The pear barkminer moth, Spulerina astaurota Meyrick (Gracillariidae: Gracillariinae), is a harmful pest of the Asian-pear tree. Pheromone components of the female were analyzed by gas chromatography (GC) with an electroantennographic (EAG) detector and GC coupled with mass spectrometry. The analyses of a crude pheromone extract and those of a fractionated extract on a Florisil column indicated three EAG-active components, tetradecadien-1-ol, its acetate, and an aldehyde derivative. Characteristic fragment ions in the mass spectra of the dienyl compounds and derivatives with 4-methyl-1,2,4-triazoline-3,5-dione revealed double bonds at the 9- and 11-positions. By comparing the chromatographic behaviors to those of four authentic geometrical isomers, which were synthesized by three different routes starting from 1,8-octanediol or 1,9-nonanediol, the configuration of each natural component was assigned to be 9Z,11Z; i.e., it was concluded that the S. astaurota females secreted (9Z,11Z)-9,11-tetradecadien-1-ol (Z9,Z11-14:OH) as a main pheromone component, and the acetate and aldehyde derivatives (Z9,Z11-14:OAc and Z9,Z11-14:Ald) as minor components. This identification was confirmed by a field evaluation of the synthetic pheromone. While the male moths could be attracted to a lure baited with Z9,Z11-14:OH alone, Z9,Z11-14:OAc showed a strong synergistic effect on the attraction. Among the lures tested, the mixture of alcohol and acetate in a ratio of 7:3 exhibited the strongest attraction. Addition of Z9,Z11-14:Ald in the mixture did not significantly increase the number of males attracted. Furthermore, the field test indicated that some contamination of a geometrical isomer of the alcohol did not impair the activity of the binary mixture with the 9Z,11Z configuration.
Key WordsFemale sex pheromone Lepidoptera Gracillariidae Gracillariinae (9Z,11Z)-9,11-Tetradecadien-1-ol 9,11-Dienyl compounds Conjugated dienes Male attraction Asian pear Insect pest monitoring
We thank the Asian-pear growers, especially T. Ikuhashi, Y. Kaigo, Y. Nakahara, H. Ohta, S. Okabe, K. Takeuchi, and I. Tokuyama, who participated in this research and contributed their farms and time to the effort. We are grateful to T. Ishiko and S. Toita of the Tottori Prefectural Agriculture and Forest Research Institute. We also thank Drs. F. Tamura, A. Itai and M. Azuma for offering important information, and Ms. A. Oda and students of the Laboratory of Applied Entomology in Faculty of Agriculture at Tottori University for their help with field experiments and rearing insects.
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