REMODELING OF NEUROMUSCULAR SYSTEMS DURING INSECT METAMORPHOSIS

During metamorphosis in the hawkmoth, Manduca serta, the larval thorac ic legs are replaced by a new set of adult legs that include new senso ry neurons and muscles, and participate in new patterns of locomotor a ctivity. Larval leg motoneurons persist to innervate the new adult leg muscles, but undergo striking changes in dendritic morphology that ar e regulated by the insect steroid, 20-hydroxyecdysone. In the peripher y, the motor terminals regress as larval muscles degenerate, and expan d as new adult muscles form from myoblasts. Evidence obtained both in vivo and in vitro suggests that the proliferation of myoblasts during metamorphosis is dependent upon innervation.