Influence of Chilling Duration on Oxygen Consumption and Hatchability in Eggs of the Silkworm, Bombyx mori

The rate of oxygen consumption of the silkworm eggs was measured to set up the barometer for measuring the effect of egg chilling on diapause termination. In diapause eggs, uptake showed a maximum of 79.2 /mg eggs/hr, at one day after oviposition and then gradually decreased to 2.2/mg eggs/hr at 9days. The rates of oxygen uptake of eggs raised immediately after HCl-treatment and reached to a maximal level of 484.5 /mg eggs/hr in 9-day-old eggs, which corresponds to 220 fold that of diapause eggs, and the hatching ability was also over 50％. In order to break diapause, eggs incubated at for 30 days after oviposition had to be kept at least for 45 days at 5, but chilled eggs for 90 days or longer hatched at 10 days as normal hatching periods. We also investigate periods which the value of uptake of eggs chilled during 15 to 120 days at 5 reached at 200 /mg eggs/hr. As a result of that, uptake of eggs chilled during 15 to 45days were not reached at 200 /mg eggs/hr and longer the chilling durations are, the higher the rate of uptake is and the longer the chilling durations are, the shorter the periods up to hatching is. And also, hatch-ability increased rapidly as uptake reaches over 20/eggs/hr.