Effects of Pharmacological Agents on Ecdysteroid Synthesis in vitro in Ovaries and Abdominal Integument from Female Adult Crickets, Gryllus bimaculatus de Geer (Ensifera, Gryllidae)

In female adults of Gryllus bimaculatus, ovaries as well as the abdominal integument pro­ duce free and conjugated ecdysteroids in vitro (Hoffmann et al., 1992). The aim of the current study was to determine the influence of various potential ecdysteroid biosynthesis effectors (RH 5849, KK 42, diflubenzuron, ketoconazole, azadirachtin, acetylenic and allenic cholesteryl derivatives B l, B6, AL2), and also of the protein synthesis inhibitor cycloheximide, on net release of moulting hormones in vitro by the adult ecdysteroid sources. All the com ­ pounds examined can be divided into four groups due to their different effectiveness on both the ecdysiosynthetic tissues. The non-steroidal ecdysteroid agonist RH 5849 (group 1) enhanced ecdysteroid synthesis in ovaries, but inhibited hormone production in the abdomi­ nal integument. Treatment in vitro with diflubenzuron (dimilin) and cycloheximide (group 2) strongly reduced ovarian ecdysteroid synthesis whereas they were hardly effective on integumental hormone production. The group 3 compounds (ketoconazole, B l, B6, AL2, azadirachtin A ) demonstrated a stronger inhibitory effect on the abdominal integument than on the ovary. The imidazole compound KK 42 (group 4) was a very potent effector of ecdy­ steroid biosynthesis in both hormone sources.