| Summary: | <p>In many moths, mate-finding communication is mediated by the female sex pheromones. Since differentiation of sex pheromones is often associated with speciation, it is intriguing to know how the changes in female sex pheromone have been tracked by the pheromone recognition system of the males. A male-specific odorant receptor was found to have been conserved through the evolution of sex pheromone communication systems in the genus <i>Ostrinia</i> (Lepidoptera: Crambidae). In an effort to characterize pheromone receptors of <i>O. scapulalis</i>, which uses a mixture of (<i>E</i>)-11- and (<i>Z</i>)-11-tetradecenyl acetates as a sex pheromone, we cloned a gene (<i>OscaOR1</i>) encoding a male-specific odorant receptor. In addition, we cloned a gene of the <i>Or83b</i> family (<i>OscaOR2</i>). Functional assays using <i>Xenopus</i> oocytes co-expressing OscaOR1 and OscaOR2 have shown that OscaOR1 is, unexpectedly, a receptor of (<i>E</i>)-11-tetradecenol (E11-14:OH), a single pheromone component of a congener <i>O. latipennis</i>. Subsequent studies on <i>O. latipennis</i> showed that this species indeed has a gene orthologous to <i>OscaOR1</i> (<i>OlatOR1</i>), a functional assay of which confirmed it to be a gene encoding the receptor of E11-14:OH. Furthermore, investigations of six other <i>Ostrinia</i> species have revealed that all of them have a gene orthologous to <i>OscaOR1</i>, although none of these species, except <i>O. ovalipennis</i>, a species most closely related to <i>O. latipennis</i>, uses E11-14:OH as the pheromone component. The present findings suggest that the male-specific receptor of E11-14:OH was acquired before the divergence of the genus <i>Ostrinia</i>, and functionally retained through the evolution of this genus.</p>
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