REACTIVATION OF CORPORA ALLATA IN PHARATE ADULT MANDUCA-SEXTA

The stage at which corpora allata (CA) of Manduca sexta regain the cap ability for juvenile hormone (JH) biosynthesis during adult developmen t was determined by a transplantation assay and in vitro experiments w ith CA of adults and pharate adult stages 8 through 11. Stage 10, 11, and adult female CA induced a larval molt when transplanted into allat ectomized day 0 4th-instar larvae of M. sexta. Stage 8 and 9 female an d ah male CA were inactive. Labelling with [methyl-H-3]methionine show ed that female CA in vitro regained the ability to produce JH during s tage 11. JH production was substantially increased by allatotropin (Ma s-AT, and a synthetic analogue, ATAA) and exogenous farnesoic acid (FA ). When [C-14]acetate was used as the tracer, JH acid production in vi tro was detected in stage 11 and adult male and female CA; female CA p roduced also JH. Stage 9 and 10 CA were inactive. With [C-14]propanoat e as the labelled precursor and stimulation with ATAA, stage 10 female CA produced (labelled) JH-II acid, and late stage 11 female CA both J H-II acid and JH-II. Adult male CA produced only JH-II acid. At stage 8, female CA were able to convert [C-14]FA to JH-III acid, and at stag e 10, [H-3]farnesol to JH-III acid.