The haemolymph juvenile hormone esterase of Manduca sexta (L.)-inhibition and regulation

Thomas C. Sparks, Bruce D. Hammock, Lynn M. Riddiford

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A number of compounds were screened as potential juvenile hormone esterase (JHE) inhibitors, of which O-ethyl-S-phenyl phosphoramidothiolate was found to be the most potent (I50 = 4 × 10-9 M). Gel filtration of the haemolymph resolved only one peak of enzyme activity capable of rapidly hydrolyzing juvenile hormone (JH). JHE titres were monitored during the last instar in wild type and black mutant larvae of Manduca sexta (L.). In wildtype larvae the increase in JHE activity was most rapid during the first 18 h and then became a function of weight until mid-day three. Although the prewandering peak of the JHE activity occurred on day three in both strains, the JHE activity peak was greatly reduced in black mutant and allatectomized larvae. JHE activity was induced in freshly ecdysed final stadium larvae by juvenoid applications. When pharate fifth stadium larvae were either neck- or abdomen-ligated, or when freshly ecdysed larvae were starved, the levels of JHE activity remained low and could not be induced by juvenoids. Thus, JH may complement the action, or stimulate the production of an unknown factor(s) responsible for increasing JHE activity during the prewandering phase. Both strains also possessed a second smaller JHE activity peak of identical size just prior to pupation (day eight). Just prior to pupation the haemolymph JHE activity can be induced by epofenonane to higher than normal levels in black mutant and in allatectomized larvae, as well as in untreated insects, suggesting that JH directly stimulates the second JHE peak.

Original languageEnglish (US)
Pages (from-to)529-541
Number of pages13
JournalInsect Biochemistry
Issue number5
StatePublished - 1983
Externally publishedYes


  • allatectomy
  • gel filtration
  • inhibition
  • juvenile hormone
  • juvenile hormone esterase
  • Manduca sexta (L.)
  • phosphoramidate
  • regulation


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