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Juvenile hormone and methyl farnesoate production in cockroach embryos in relation to dorsal closure and the reproductive modes of different species of cockroaches
Author(s) -
Li Xinyi
Publication year - 2007
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.20207
Subject(s) - cockroach , biology , periplaneta , corpus allatum , juvenile hormone , dictyoptera , farnesol , oviparity , embryogenesis , insect , embryo , endocrinology , anatomy , medicine , botany , biochemistry , zoology , microbiology and biotechnology , ecology
Juvenile hormone (JH), produced by the corpora allata (CA), is first detectable after dorsal closure, a conspicuous event in embryogenesis. The present research found that the timing of dorsal closure was consistently at about 45% of the total embryonic development time across most of the oviparous and ovoviviparous cockroach species examined. These included the ovoviviparous cockroaches Blaberus discoidalis , Byrsotria fumigata , Rhyparobia maderae , Nauphoeta cinerea , Phoetalia pallida , Schultesia lampyridiformis , and Panchlora nivea , as well as the oviparous cockroaches Blatta orientalis , Periplaneta americana , Eurycotis floridana , and Supella longipalpa . However, the only known viviparous cockroach Diploptera punctata completed dorsal closure at 20.8% of embryo development time. Methyl farnesoate (MF), the immediate precursor of JH III, is considered a functional molecule in crustaceans; however, in insects its function is still unclear. To understand the role of JH and MF in cockroach embryos, I compared JH and MF biosynthesis and release in several cockroach species of known phylogenetic relationships. Using a radiochemical assay, the present research showed that cockroach embryos representing all three reproductive modes produced and released both JH and MF, as previously shown for B. germanica , N. cinerea , and D. punctata . Members of a pair of embryonic CA from B. discoidalis , B. fumigata , R. maderae , and D. punctata were incubated with and without farnesol. MF accumulated in large amounts only in CA of R. maderae in the presence of farnesol, which indicates that control of the last step of biosynthesis of JH, conversion of MF into JH by MF epoxidase, is probably a rate‐limiting step in this species. Arch. Insect Biochem. Physiol. 66:159–168, 2007. © 2007 Wiley‐Liss, Inc.