Tabata Jun, Ichiki Ryoko T, Moromizato Chie, Mori Kenji
Division of Applied Entomology and Zoology, National Agriculture and Food Research Organization, 3-1-3 Kannondai, Tsukuba-city, Ibaraki 305-8604, Japan
Crop, Livestock and Environment Division, Japan International Research Center for Agricultural Sciences, Ohwashi 1-1, Tsukuba-city, Ibaraki 305-8686, Japan.
J R Soc Interface. 2017 Mar;14(128). doi: 10.1098/rsif.2017.0027.
Sex pheromones play a central role in intersexual communication for reproduction in many organisms. Particularly in insects, reproductive isolation that leads to speciation is often achieved by shifts of pheromone chemistries. However, the divergence and evolution of pheromones remain largely unknown. This study reveals a unique evolutionary consequence for terpenoid pheromones in coccoid insects. Coccoids, such as mealybugs, show clear sexual dimorphism: males are dwarf and short-lived, whereas females are wingless and almost immobile. Female pheromones are therefore indispensable for males to navigate for sexual reproduction, but some females can reproduce asexually. Interestingly, a derived asexual lineage that reproduces by parthenogenesis coexists with its ancestral lineage that reproduces sexually in a population of the pineapple mealybug, Here, we isolated, characterized and synthesized a novel monoterpene, (-)-(-1,2-dimethyl-3-methylenecyclopentyl)acetaldehyde, as a pheromone of the sexual females of This monoterpene aldehyde, with an irregular linkage of isoprene units, is notable, because all mealybug pheromones previously reported are carboxylic esters of terpenols. This compound was, however, never produced by the asexual females. As a consequence of acquiring parthenogenetic reproduction, the asexual females appear to have abandoned the production of the sex pheromone, which had been essential to attracting males in their ancestors.
性信息素在许多生物体的两性间繁殖交流中起着核心作用。特别是在昆虫中，导致物种形成的生殖隔离通常是通过性信息素化学组成的变化来实现的。然而，性信息素的分化和进化在很大程度上仍然未知。本研究揭示了球蚧类昆虫中萜类性信息素独特的进化结果。球蚧类昆虫，如粉蚧，表现出明显的两性异形：雄性体型矮小且寿命短暂，而雌性无翅且几乎不动。因此，雌性性信息素对于雄性进行有性繁殖的导航至关重要，但有些雌性能够进行无性繁殖。有趣的是，在菠萝粉蚧种群中，通过孤雌生殖进行繁殖的衍生无性谱系与其有性繁殖的祖先谱系共存。在这里，我们分离、表征并合成了一种新型单萜，（-）-（-1,2-二甲基-3-亚甲基环戊基）乙醛，作为有性繁殖雌性的性信息素。这种单萜醛具有异戊二烯单元的不规则连接，这很值得注意，因为之前报道的所有粉蚧性信息素都是萜醇的羧酸酯。然而，这种化合物从未由无性繁殖的雌性产生。作为获得孤雌生殖的结果，无性繁殖的雌性似乎已经放弃了性信息素的产生，而性信息素在其祖先中对于吸引雄性至关重要。
