Ovarian inhibition of juvenile hormone synthesis in the viviparous cockroach, Diploptera punctata.

The mature ovary can actively prevent increases in rates of juvenile hormone (JH) synthesis by corpora allata (CA). This was unequivocally shown in two ways. (1) By combining in a single host female one ovary known to be stimulatory and one known to be nonstimulatory. Since the combination of a stimulatory and nonstimulatory mature ovary resulted in rates of JH synthesis intermediate between those found following implantation of either of these ovaries alone, it is concluded that the nonstimulatory mature ovary is indeed inhibitory (a nonstimulatory immature ovary had no such inhibitory effect). (2) By implanting nearly mature ovarioles and female CA into males. The ovarioles prevented the increase in rates of JH synthesis by the implanted CA that occurs in the absence of implanted ovarioles. This ovarian-elicited difference in rates of JH synthesis by CA implanted into males was not accompanied by differences in hemolymph ecdysteroid titers. Also, following removal of nearly mature ovaries from normal females the rates of JH synthesis remained above those of control females for only 24 hr and then declined to rates of controls. This suggests that there is an additional factor regulating the decline in JH synthesis at the end of the gonadotrophic cycle.