Graded inhibition of cell disintegration of juvenile hormone

The proventriculus of Galleria mellonella larvae consists of 260-300 polyploid cells. The cells grow throughout larval development and at each ecdysis produce a new cuticular lining of the proventriculus. Each cell secretes a large sclerotized plaque covered with thorns. At the end of the last larval instar, the cells disintegrate unless the larvae is treated with juvenile hormone or implanted with active corpora allata. Depending on the time of treatment and the hormone dose, these insects preserve their proventricular cells to graded degrees. In some cases, the cells continue to grow or at least preserve their full function, in other instances they secrete but small plaques with fewer thorns or a smooth cuticle without any thorns. Very late treatments preserve healthy cells incapable of secreting the cuticle.