Is the pupal stage truly inactive?

Pupae seem inactive but are dynamically reorganizing internal structures. This requires organization of bodily parts and active metabolism. The larval tissues dissolve into nutrient fluid. The imaginal discs develop features of the adult insect. The oxygen consumption remains high to sustain this important phase of its life.

The illusion of dormancy of the puparium is due to exterior quiescence. Within the chrysalis or cocoon, however, the cells are actively engaged in function. Biochemical stimuli are active in initiating both the degeneration of tissues and their subsequent reformation. This activity requires more energy than does the feeding of the larva, but there is no external evidence of activity.

Temperature has a direct effect on the metabolism of pupae. Warmer temperatures accelerate metabolic activities, thereby speeding up development. Cooler temperatures slow metabolic processes, prolonging pupation. Some species will enter diapause, a state that suspends development throughout the winter months. Metabolic rates decrease dramatically during these periods of dormancy.

Pupae display avoidance behaviors indicating awareness of their surroundings. Many species can wiggle if disturbed. Some species can produce a loud clicking sound to surprise a potential predator. These behaviors suggest that their nervous system is functioning during this stage of metamorphosis, despite the dramatic physical changes that occur internally.

Understanding pupal activity aids research applications. Scientists study metamorphosis to gain insights for tissue engineering. Medical researchers examine histolysis as a potential model for cancer treatment. Conservationists track the timing of development affected by climate change.

Read the full article: Insect Life Cycles: Types, Stages, and Facts