Oosorption in the stink bug Plautia stali: role of Juvenile hormone in the induction of oosorption

To clarify the role of juvenile hormone (JH) in the induction of oosorption in females of the stink bug Plautia stali Scott (Heteroptera: Pentatomidae), the effects of extirpation and implantation of the corpus cardiac-corpus allatum complex (CC-CA) are examined in fed and starved adults, respectively. Removal of CC-CA induces oosorption in fed females, whereas CC-CA implantation stimulates ovary development in starved females. Transection of the nervous connections between the brain and CC-CA also exerts a stimulatory effect on ovary development. Uptake of yolk protein by the oocytes, assessed in terms of incorporation of a fluorescence dye, occurs on the day after food deprivation but ceases within 1 day after allatectomy. When females are deprived of food, beginning on day 3 of adult life, and treated with JH III skipped bisepoxide (JHSB(3)) on the same day, their ovaries develop in a dose-dependent fashion. Approximately half of the starved females that received JHSB(3) application on day 5 undergo oosorption in the terminal oocytes. This indicates that the critical starvation period for oosorption induction is approximately 2 days, and the earlier half of this period may reflect the time required for the brain to detect poor nutritional condition. During the latter half, in response to food deprivation, the brain inhibits JH biosynthesis by the corpus allatum through nervous connections, resulting in a low JH titre, which in turn induces oosorption.