Permissive action of juvenile hormone on vitellogenin production by the mosquito, Aedes aegypti

Abstract

The timing of Aedes aegypti fat bodies' responsiveness to 20-hydroxyecdysone was determined in females with or without a previous blood meal. Fat bodies removed and cultured at different times of development were exposed to medium containing 10 −6M 20-hydroxyecdysone. Competency to this hormone started at 56–60 h after eclosion in newly emerged females and 96 h after a blood meal in 5–6-day-old females. Fat bodies that were cultured immediately after eclosion did not respond to 20-hydroxyecdysone. However, prior juvenile hormone treatment of these fat bodies permitted the development of competence to respond to the ecdysteroid. In a similar set of experiments with fat bodies cultured from females 48 h after blood feeding, addition of juvenile hormone restored the fat bodies' response to 20-hydroxyecdysone at 96 or 112 h. Our conclusions from these in vitro studies is that while juvenile hormone alone cannot initiate vitellogenesis, it is a prerequisite for the development of competence to 20-hydroxyecdysone which in turn is the main stimulus for vitellogenin synthesis and production.