FIGURE 1.

Interaction of key factors in diapause. Insulin signaling profiles change in diapause, caused by the activity of different insulin-like peptides (ILPs). The ILP profile must remain dynamic in diapause to support the diapause-associated metabolism over time and changing conditions. Other factors, such as the nutrient-sensitive adipokinetic hormone (AKH) and the pro-reproductive juvenile hormone (JH), influence insulin signaling and are themselves influenced in turn. JH opposes the metamorphic action of ecdysone and its upstream regulators. FoxO is typically inhibited by insulin signaling, but is disinhibited during diapause. Conversely, the pro-growth transcription factor Myc is typically promoted by insulin signaling, but becomes inhibited during diapause. Many features of diapause physiology are regulated through interactions between insulin signaling, JH, ecdysone, and nutritive feedback signals from the fat body. The extended lifespan of insects in diapause is likely a product of these features’ combination.