INVIVO AND INVITRO BIOSYNTHESIS AND METABOLISM OF METHYL FARNESOATE, JUVENILE HORMONE-III, AND JUVENILE HORMONE-III ACID IN THE MOSQUITO AEDES-AEGYPTI

Biosynthesis and metabolism of juvenile hormone (JH) III in vivo and in vitro were studied in female Aedes aegypti (L.). [12-H-3]Methyl farnesoate was used to follow the synthesis and [12-H-3]-(10R)-JH III to study metabolism. The rate of biosynthesis of [12-H-3]JH III in vivo after adult eclosion increased from 9 fmol/h per female at 1 h to 22 fmol/h per female at day 6. The rate of biosynthesis by exposed corpora allata (CA) in vitro was 23 fmol/h per CA during the 1st d after adult eclosion, then dropped to 4.8 fmol/h per CA on day 3, then increased again to a constant level of synthesis (12 fmol/h per CA) at days 4-6. Immediately after blood feeding, the rate of synthesis of [12-H-3]JH III in vivo and in vitro increased to 27 fmol/h per female and to 23 fmol/h per CA, respectively. The rate of synthesis then decreased in vivo to 12 fmol/h per female at 4 h and in vitro to 6 fmol/h per CA 10 h after the blood meal. After this decrease, the rate of synthesis of [12-H-3]JH III increased again reaching a peak of 25 fmol/h per female at 48-96 h in vivo and 12 fmol/h per CA at 72 h in vitro. These results indicated that the CA of sugar-fed and blood-fed female A. aegypti synthesized JH III in vivo and in vitro from (12-H-3]methyl farnesoate. When [12-H-3]-(10R)-JH III metabolism was followed in vivo in female A. aegypti, the ratio between JH III diol acid:JH III acid:JH III diol was 17:4:1, indicating that JH III was first hydrolyzed by JH III esterase to the acid form, then hydrated to the diol acid by JH III epoxide hydrase. Females treated with [12-H-3]JH III acid converted 46% of the JH III acid in 60 min to the diol acid. These results indicated that the enzyme epoxide hydrase acted on JH III acid 17 times faster than JH III.