Corpus allatum activity in vitro during the reproductive cycle of the viviparous cockroach, Diploptera punctata (eschscholtz)

Abstract

Isolated pairs of corpora allata (CA) from the viviparous cockroach, Diploptera punctata have been shown to synthesize and release C 16JH at a linear rate for at least 5 hr. No storage of C 16JH has been observed at any time during the first oviposition cycle. It is suggested that rate limitation in JH biosynthesis does not occur at the terminal enzymic stage because the immediate precursor, methyl farnesoate, does not accumulate at any level of CA activity. It is concluded that the short-term incubation procedures employed represent an accurate assessment of CA activity in vivo. The synthesis and release of C 16JH by CA has been followed during the first oviposition cycle. High rates of release of JH were observed during rapid oocyte growth—CA became highly active over a 24 hr period as the oocytes were entering vitellogenesis. An analysis of CA activity relative to oocyte length revealed that the release rate of C 16JH was highest when oocyte length was in the range 1.0–1.6 mm. However, it was not possible to ascertain if vitellogenesis was initiated before or after the increase in the JH release rate. C 16JH synthesis of 40 pmol hr −1 is the highest mean rate yet reported for an insect.