Male reproductive maturity and diapause termination in the leaf beetle Gastrophysa atrocyanea

Ojima, Noriyuki; Ishiguro, Shinichi; An, Ying; Kadosawa, Tomohiro; Suzuki, Kōichi

Male reproductive maturity and diapause termination in the leaf beetle Gastrophysa atrocyanea

2015

Ojima, Noriyuki | Ishiguro, Shinichi | An, Ying | Kadosawa, Tomohiro | Suzuki, Kōichi

Male reproductive potential and growth of testes are studied in the leaf beetle Gastrophysa atrocyanea Motschulsky (Coleoptera: Chrysomelidae) that is exposed to mild temperatures after imaginal ecdysis. Continuous administration of the Juvenile Hormone (JH) in artificial diet is highly effective with respect to stimulating testes growth and mating behaviour. Female reproductive diapause can be induced under standard rearing conditions, although optimum reproductive maturity of males is achieved at 15 °C. Treatment of males with a JH analogue accelerates testes development up to the stage of spermiogenesis (the bundling of spermatozoa) but does not promote the formation of cysts with mature sperm. Treatment with 20‐hydroxyecdysone has no influence on diapause termination and testes function. These results suggest that male reproductive maturation in G. atrocyanea is independent of JH, and moderate temperatures may induce an unknown factor that is responsible for the maturation of sperm cysts.

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