Effects of ovariectomy and mating on the activity of the corpora allata inadult female Blattella germanica (L.) (Dictyoptera : Blattellidae)

In adult female cockroaches, the ovary greatly affects the synthesis of Juv enile Hormone (JH) by the corpora allata, and in females of some cockroach species, removal of the ovaries results in a permanent depression of JH syn thesis. We report that the corpora allata in ovariectomised, adult virgins of the German cockroach, Blattella germanica (L.), increase and then decrea se in activity, as they do in intact females. Moreover, the distal tubules in the left colleterial glands of ovariectomised females accumulate abundan t protein, the production of which is regulated by JH. In both ovariectomis ed and sham-operated females, the activity of the corpora allata more than tripled between days 1 and 4 of adulthood, during which the oocytes of sham -operated females grew considerably in length. The corpora allata of sham-o perated females produced even more JH on day 7, but very little on day 10, by which time all females had oviposited. The glands of ovariectomised fema les, by constrast, produced a similar amount of JH on day 7 as on day 4, bu t much less on day 10. Beginning on day 13, the activity of the corpora all ata increased again in ovariectomised females, an increase that did not occ ur until day 22 in sham-operated females. Mating of ovariectomised females on day 6 resulted in a significant increase in the activity of the corpora allata by day 10. We conclude that both the ovary and mating stimulate the synthesis of JH early in the reproductive cycle, but that neither is needed for the occurrence of a complete cycle of JH synthesis.