THE CONTROL OF EGG MATURATION BY JUVENILE HORMONE IN THE TOBACCO HORNWORM MOTH, MANDUCA SEXTA

¹ The Biological Laboratories, Harvard University, Cambridge, Massachusetts 02138

1. In Manduca sexta females, follicles develop independently of the corpora allata until they reach a critical stage in late vitellogenesis. In the absence of juvenile hormone (JH), follicles then degenerate. When JH is present, the follicles continue development; they then become independent of JH for the final 12 hours of egg maturation.

2. Allatectomy of the pupa of Manduca sexta or the newly eclosed adult female prevents egg maturation as does extirpation of the brain from the pupa or decapitation of the adult. The ability to develop follicles beyond the vitellogenic phase is restored by injection of synthetic JH or JH mimics.

3. The brain activates the corpora allata close to the time of adult emergence. The glands secrete JH at a constant rate for 48 hours and then become less active in virgin, unfed moths.

4. A female specific protein, identified by SDS gel electrophoresis, is present in adult blood and egg homogenates. Allatectomy has no effect on the concentration of vitellogenin in the blood nor on its incorporation into immature follicles less than one mm long.

5. The action of JH in promoting egg maturation in Manduca sexta appears to be different from that in most other well-studied insect systems in that the hormone is not required for the synthesis and/or uptake of the female-specific yolk protein. Rather it is required for a critical step in development.

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