The Influence of the Combination of the Thermoperiod with the Photoperiod upon the Growth of the Silkworm Larvae, Bombyx mori, in Artificial-diet-rearing

This paper mainly deals with the influence of the interaction between the thermoperiod having sinusoidal change of temperature (27±4°C) with the 24 hour period, and the photoperiod during larval stages on the body weight, the amounts of food ingested and digested in the 4th and the 5th instar larvae, and the quantitative characters of cocoon.Larval period was divided into such three stages as the 1st to the 3rd, the 4th and the 5th instar, and also each stage was used for the experiments.The data taken were analyzed by the statistical method as follows.1) Effects of the rearing conditions on the growth were remarkable in the 1st to the 4th instar of larvae, but weakened in the 5th instar. And the additive effects were observed between the 1st to 3rd and the 4th stages.2) The growth of larvae under the thermoperiod set up at 2 p.m. of acrophase (31°C) was excellent rather than at 2 a.m.3) The effect of illumination on the larval growth and the productivity of silk substance under the thermoperiod of sinusoidal change of temperature was the most prominent in the continuous light (LL) ; next in order were dark above 27°C (LD 12: 12), continuous dark (DD), and light above 27°C (LD 12: 12) .