Abstract
In order to synchronize the molting of silkworm larvae reared on an artificial diet in a large scale, the application of the scotophase was investigated.
1. Induction of larval apolysis and the following ecdysis depended closely upon the time of switch-off from the photophase, but was not observed by the way of switch-on at all.
2. The scotophase could be received by larvae as a stimulus after the middle time of each instar. The critical stage for the reception was dependent on the larval body weight, being effective at about 60% of the maximum weight in each instar.
3. Scotophase had to be continued for at least 4hr for the effective response.
4. From these results, an induction mechanism of larval molting by scotophase was discussed in relation to insect hormones. Further, a proposal was made concerning the photoperiodic control in mass rearing of silkworm larvae by the artificial diet.
