Programmed cell death in the wing of Orgyia leucostigma (Lepidoptera: Lymantriidae)

Programmed cell death is an integral and ubiquitous phenomenon of development that is responsible for the reduction of wing size in female moths of Orgyia leucostigma (Lymantriidae). Throughout larval and pupal life, cells of the wing epithelium proliferate and interact to form normal imaginal discs and pupal wings in both sexes. But at the onset of adult development, most cells in female O. leucostigma wings degenerate over a brief, 2-day period. Lysosomes and autophagic vacuoles appear in cells of the wing epithelium shortly after it retracts from the pupal cuticle. Hemocytes actively participate in removing the resulting cellular debris. By contrast, epithelial cells in wings of developing adult males of O. leucostigma do not undergo massive cell death. Wing epithelium of female pupae transferred to male pupal hosts behaves autonomously in this foreign environment. By pupation, cells of the female wing apparently are committed to self-destruct even in a male pupal environment. Normal interactions among epithelial cells within the plane of a wing monolayer as well as between the upper and lower monolayers of the wing are disrupted in female O. leucostigma by massive cell degeneration. Despite this disruption, the remaining cells of the wing contribute to the formation of a diminutive, but reasonably proportioned, adult wing with scales and veins.