THE OVARY IS A SOURCE OF CIRCULATING ECDYSTEROIDS IN BLATTELLA-GERMANICA (DICTYOPTERA, BLATTELLIDAE)

The developmental fluctuations in immunoreactive ecdysteroids in the haemolymph of adult female Blattella germanica (L.) are reported. There is a relatively low titre in freshly ecdysed females, an increase during vitellogenesis to a peak at choriogenesis, and a decrease after ovulation. These fluctuations parallel those of ecdysteroid content in the ovary. In addition, haemolymph ecdysteroid levels are reduced following ovariectomy, and single ovarioles incubated in vitro effectively release ecdysteroids into the medium. The data strongly suggest that the ovaries are a major source of circulating ecdysteroids in adult females of this species. Since the prothoracic gland degenerates shortly after the imaginal moult, the presence of ecdysteroids in the haemolymph of ovariectomized females suggests that there are other tissues that also serve as a source of these circulating hormones during the reproductive cycle of B. germanica.