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A mating duration of more than 6 h was necessary to permanently terminate the production of the sex pheromone (bombykol) in the silkworm moth, Bombyx mori L. (Lepidoptera: Bombycidae), although the female formed a bursa copulatrix including a spermatophore and laid fertilized eggs even after mating for only 0.5 h. The 6-h mated female again produced bombykol if given an injection of synthetic pheromonotropic neuropeptide (PBAN), which is known to activate pheromone biosynthesis in a virgin female. Extracts of brain-suboesophageal ganglion (SG) complexes, which were removed from 6- and 24-h mated females, showed strong pheromonotropic activities. These results indicated that the pheromone gland of the mated female maintained its ability to biosynthesize bombykol; however, it could not produce pheromone due to a suppression of PBAN secretion from the SG. Furthermore, bombykol titers did not decrease after mating in females with a transected ventral nerve cord, even after the injection of a spermatophore extract, suggesting that the suppression of PBAN secretion was mediated by a neural signal and not by a substance in the spermatophore. The mated females accumulated (10E, 12Z)-10,12-hexadecadienoic acid, a precursor of bombykol biosynthesis, in their pheromone glands as did decapitated females. © 1996 Wiley-Liss, Inc.

11,12-メチレンヘキサデク-11-エノイック酸とそのアミド体を, トリブロモシクロプロパン化合物を脱ブロム化後アルキル化する方法 (Baird ら, 1992) を用いて合成した. それら化合物のフェロモン生合成に及ぼす影響をカイコガ処女雌を用いて検討したところ, フェロモン腺への処理はボンビコール含量の低下をもたらした. また, 14C標識あるいは2H標識ヘキサデカン酸を利用した実験において, 上記のシクロプロペン化合物をフェロモン腺あたり1μg前処理すると, 生合成前駆体のボンビコールおよび (Z)-11-ヘキサデセノールへの変換が完全に抑えられ, ヘキサデカノールへの変換は逆に促進された. 以上の結果より, これら11-位にシクロプロペン構造をもつ化合物は, ボンビコール生合成の不飽和化の過程 (11-位とおそらく10,12-位不飽和化反応) を阻害することが明らかになった. 一方, ニトリル誘導体はフェロモン生合成阻害活性を示さなかった.