THE CONTROL OF REPRODUCTION IN DIPLOPTERA PUNCTATA (BLATTARIA)

Abstract

1. In the viviparous roach, Diploptera, the factors controlling the maturation of the eggs were studied during an interval encompassing the first pre-oviposition, first pregnancy, and second pre-oviposition periods. During egg maturation the corpora allata become active as judged by histological criteria (increase of cytoplasmic content); they become and stay inactive during pregnancy. Ovarian inactivity after allatectomy also demonstrates that active corpora allata are responsible for the deposition of yolk in the oocytes. In addition, the corpora allata control the activity of the accessory sex glands, and of an as yet unknown type of cell presumably located in the bursa copulatrix, the secretion of which facilitates the extrusion of the spermatophore.2. In virgins, the brain inhibits the function of the corpora allata by way of the nervi corporis allati, and thus prevents or delays the maturation of the eggs. Severance of these nerves results in a sustained activity of the corpora allata with the result that several successive batches of eggs mature.3. In females which have not yet borne young, mating is essential for a normal rate of egg maturation. The effect of mating can be replaced by parturition which provides adequate stimuli to induce egg maturation. Thus, in an animal that has just given birth, mating does not step up the growth rate of the eggs. The stimuli exerted by mating or parturition are transmitted to the corpora allata by way of the ventral nerve cord and the brain.4. Artificial mating (mechanical stimulation with a small glass spermatophore) also results in activation of the corpora allata and in subsequent maturation of the eggs. Similarly, excision of the gonapophyses induces egg maturation, presumably because the afferent nerves are stimulated by this procedure. It seems likely that sensory receptors on the gonapophyses and possibly on other parts of the genital apparatus receive the stimuli exerted by mating and parturition.5. The corpora allata of adult females of Diploptera are restrained to the extent that egg maturation occurs only after considerable delay unless this inhibition is eliminated by appropriate afferent stimuli. Complete inhibition of the corpora allata, and thus of the ovaries, during pregnancy is achieved by the eggs developing in the brood sac.6. Ovariectomy does not result in sustained activity of the corpora allata as is the case in some other insect species.