BIOSYNTHESIS AND RELEASE OF JUVENILE-HORMONE DURING THE REPRODUCTIVE-CYCLE OF THE RING-LEGGED EARWIG

Corpora allata of adult female Euborellia annulipes, incubated in medi um containing H-3-methionine, synthesized and released juvenile hormon e III. Labelled material co-migrating with methyl farnesoate was also found, suggesting this as an intermediate in the pathway of juvenile h ormone 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 mu M farnesoic acid. The rate of juvenile hormone III biosynthesis/release in vitro remained c onstant for at least 8 hr for glands of different activities, The rate of juvenile hormone production was closely correlated with the gonado trophic cycle, In females with previtellogenic ovarian follicles (0.26 +/- 0.004 mm), hormone production was only 0.59 +/- 0.13 fmol hr(-1)/ corpus allatum; production increased to 1.52 +/- 0.25 fmol hr(-1)/corp us allatum when basal follicles were growing rapidly, and remained hig h during the period of oviposition, By 3 days following oviposition wh en females were brooding clutches, hormone production had declined to 0.46 +/- 0.13 fmol hr(-1)/corpus allatum, The addition of 60 mu M farn esoic acid to the medium enhanced juvenile hormone biosynthesis at eac h stage examined, Lastly, elevating the level of L-methionine in the m edium also enhanced hormone biosynthesis. Maximal hormone production w as 32.8 +/- 10.9 fmol hr(-1)/corpus allatum, at an L-methionine concen tration of 51 mu M.