The effects of juvenile hormone, 20-hydroxyecdysone, precocene II, and ovariectomy on the activity of the corpora allata ( in vitro) in adult female Gryllus bimaculatus

Abstract

Corpora allata from adult female Gryllus bimaculatus exhibit rates of juvenile hormone III synthesis in vitro which are closely correlated with oöcyte maturation. Juvenile hormone III treatments in vivo (injection of 0.5 μg juvenile hormone III) of females reared at 20°C (animals with spontaneously inactive corpora allata) stimulated juvenile hormone synthesis within 12 h. The results could be verified as a de novo biosynthesis, by following the incorporation of radioactivity from [2- 14C]acetate and l-[methyl- 3H]methionine into juvenile hormone III. Addition of juvenile hormone III in vitro (10 −8–10 −4 M) did not stimulate de novo synthesis of juvenile hormone III. In females from a rearing temperature of 20°C a stimulating effect of 20-hydroxyecdysone injection (0.25–5 μg) on juvenile hormone III synthesis became apparent in vivo within 24 h. No stimulation was observed when isolated corpora allata were maintained for 3–4 h in medium containing 5·10 −5 M ecdysone or 20-hydroxyecdysone. Female adult crickets quickly recover from treatment in vivo with precocenes. After incubation of isolated corpora allata in the presence of precocenes, juvenile hormone III synthesis was diminished in a dose-dependent manner. In ovariectomized females juvenile hormone III synthesis was drastically suppressed.