Developmental regulation of juvenile hormone esterase in Trichoplusia ni: Its multiple electrophoretic forms occur during each larval ecdysis

Juvenile hormone esterase activity has been found during the intramoult period of each larval stadium in Trichoplusia ni. The activity is indistinguishable from that occurring during the final larval stadium, on the basis of its four isoelectric forms and kinetic data. The 4th- to 5th-instar intramoult peak in activity also occurs in other Lepidoptera (Heliothis virescens, Spodoptera exigua, Manduca sexta and Hyphantria cunea). Further, the final species also possessed a peak of activity during the intramoult period to the penultimate larval instar. The findings have important implications for the current concept that the function of juvenile hormone esterase is, by reason of its anti-juvenile hormone action, an enzyme of the last larval instar which enables metamorphosis to begin.