Silk moths have been domesticated over a long history and have been improved to allow artificial control of their reproduction.The secret is the "sleep" that occurs during the egg period (embryo stage), and the temperature conditions can be artificially manipulated to control the sleep and regulate the reproductive cycle of the silk moth.On the other hand, wild silk moths (Bombyx mandarin) are dormant by light rather than temperature conditions.Until now, the difference in the dormancy mechanism between silk moths and bombyx mandarins, which should have originated from the same ancestor, was unknown.

　Using a strain called "Kousetsu" of silk moth, the research group created a knockout (KO) strain in which the gene for the silk moth's temperature sensor protein (TRPA1) was deleted using genome editing technology (TALEN system).In this strain, it was found that the dormancy is not determined by the temperature of the embryo stage as in the non-KO strain, but the dormancy is determined by the day length of the larval stage like the larvae.

　Furthermore, it was also found that when the dormancy mechanism due to temperature is cut off, the dormancy mechanism due to the light of the ancestral species appears and "returns".In other words, in domesticated silk moths, some mechanism that connects the temperature sensor and the dormancy mechanism is hidden, and the dormancy mechanism different from that of the ancestral species, Bombyx mandarin, is predominant.

　This is valuable as an elucidation of the molecular mechanism in the environmental response mechanism of organisms such as insects, and with the progress of future research, domestication of silk moths that can not fly, are quiet, and can be bred in large quantities It is expected that the process will be clarified at the molecular level.

Paper information:[Scientific Reports] Comparisons in temperature and photoperiodic-dependent diapause induction between domestic and wild mulberry silkworms