REACTIVATION OF CORPORA ALLATA IN PHARATE ADULT MANDUCA-SEXTA

The stage at which corpora allata (CA) of Manduca sexta regain the capability for juvenile hormone (JH) biosynthesis during adult development was determined by a transplantation assay and in vitro experiments with CA of adults and pharate adult stages 8 through 11. Stage 10, 11, and adult female CA induced a larval molt when transplanted into allatectomized day 0 4th-instar larvae of M. sexta. Stage 8 and 9 female and ah male CA were inactive. Labelling with [methyl-H-3]methionine showed that female CA in vitro regained the ability to produce JH during stage 11. JH production was substantially increased by allatotropin (Mas-AT, and a synthetic analogue, ATAA) and exogenous farnesoic acid (FA). When [C-14]acetate was used as the tracer, JH acid production in vitro was detected in stage 11 and adult male and female CA; female CA produced also JH. Stage 9 and 10 CA were inactive. With [C-14]propanoate as the labelled precursor and stimulation with ATAA, stage 10 female CA produced (labelled) JH-II acid, and late stage 11 female CA both JH-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 stage 10, [H-3]farnesol to JH-III acid.