The possible role of juvenile hormone esterase in the regulation of juvenile hormone titre in the female cockroach Diploptera punctata.

Juvenile hormone (JH) degradation in vitro and in vivo was studied in the viviparous cockroach Diploptera punctata. In vitro studies with juvenile hormone esterase (JHE) and "general" or l-naphthyl acetate esterase (NAcE) revealed that diethyl-p-nitrophenylphosphate (paraoxon) inhibited both JHE and NAcE activity, but the latter was more sensitive and was completely inhibited at 0.1 mM. NAcE activity was resistant to inhibition with Triton X-100, whereas JHE activity in haemolymph of adult females was inhibited 100% at Triton X-100 concentration of 0.25%. Eighty percent inhibition of JHE activity in vivo was observed following injection of 0.2 microL Triton X-100. In contrast to the previously observed dose-dependant increase in JHE activity. NAcE activity did not increase following treatment of allatectomized females with the JH analogue ethyl-2E,4E-3,7,11-trimethyl-2,4-dodecadienoate (hydroprene). Hydroprene was not catabolized in haemolymph of D. punctata in vitro. The half-life of C16 JH (JH III) in the haemolymph, in vivo, was 1.65 h for day 5 females and 2 h for day 6 females.