Relationship between DNA Synthesis, Juvenile Hormone and Metamorphosis in Galleria Larvae
Epidermal cells in holometabolous insects exhibit progressive differentiative changes. At hatching from the egg, the larval epicells have already secreted a characteristic larval cuticle. In Galleria mellonella, the greater wax moth, the larval cuticle is untanned, soft and pliable with hexagonal plaques on the surface. In insects, each epidermal cell secretes the cuticle that is overlying it. Thus, each hexagonal plaque represents the boundary lines of the cuticle secreted by the epidermal cell underlying the plaque. The larva passes through several morphologically and anatomically similar instars. At each of these succeeding larval molts the epidermal cells secrete a morphologically and chemically similar cuticle. After a definite number of larval molts, usually seven in Galleria, the larva metamorphoses into a pupa. At this molt the epidermal cells secrete a pupal cuticle characterized by its tanned exocuticle and knob-like elevations on the outer surface. Acquisition of the ability to secrete a pupal cuticle by the larval epidermal cells has been regarded as a differentiative event.
KeywordsEpidermal Cell Juvenile Hormone Wing Disc Larval Cuticle Molting Hormone
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