Biosynthesis and release of juvenile hormone during the reproductive cycle of the ring-legged earwig

Abstract Corpora allata of adult female Euborellia annulipes , incubated in medium containing 3 H-methionine, synthesized and released juvenile hormone III. Labelled material co-migrating with methyl farnesoate was also found, suggesting this as an intermediate in the pathway of juvenile hormone III production. Juvenile hormone was not appreciably stored in the glands, but was released into the medium. In normal medium, 93.6 ± 1.6% of the total juvenile hormone III synthesized was released and 96.5% ± 0.3 in medium supplemented with 60 μM farnesoic acid. The rate of juvenile hormone III biosynthesis/release in vitro remained constant for at least 8 hr for glands of different activities. The rate of juvenile hormone production was closely correlated with the gonadotrophic cycle. In females with previtellogenic ovarian follicles (0.26 ± 0.004 mm), hormone production was only 0.59 ± 0.13 fmol hr − /corpus allatum; production increased to 1.52 ± 0.25 fmol hr −1 /corpus allatum when basal follicles were growing rapidly, and remained high during the period of oviposition. By 3 days following oviposition when females were brooding clutches, hormone production had declined to 0.46 ± 0.13 fmol hr −1 /corpus allatum. The addition of 60 μM farnesoic acid to the medium enhanced juvenile hormone biosynthesis at each stage examined. Lastly, elevating the level of l -methionine in the medium also enhanced hormone biosynthesis. Maximal hormone production was 32.8 ± 10.9 fmol hr −1 /corpus allatum, at an l -methionine concentration of 51 μM.