Figure 7. Schematic representation of Har-HK regulation during insect diapause and development.

Long day lengths trigger increased ecdysone (20E) levels, stimulating Har-POU and -c-Myc expression, and leading to high HK expression for development. In contrast, short day lengths repress ecdysone levels, resulting in low Har-POU and -c-Myc expression levels that lead to low Har-HK expression levels. Low HK expression levels cause low metabolic activity and increased ROS accumulation in diapause individuals. As a key diapause regulator, ROS induces entry into developmental arrest or lifespan extension.