Abstract
The hemolymph osmotic pressure of male Heliothis virescens last instar larvae and pupae can be correlated with the state of spermatogenesis: intermediate (approx. 325 mOsm/kg) osmotic pressures are found in pre-meiotic animals, low (approx. 300 mOsm/kg) osmotic pressures characterize meiosis and elongation, and high (approx. 370 mOsm/kg) osmotic pressures, characterize the tests of diapausing pupae, where mature sperm have disappeared and only pre-meiotic sperm are found. In vitro studies show that, as the osmotic pressure of the medium is increased, spermatogenesis is inhibited and the survival of pre-meiotic cysts is enhanced. It is proposed that the osmotic pressure of the hemolymph plays a role in spermatogenesis and in the preservation of immature cysts during diapause.