Abstract

Silk glands obtained from Diatraea saccharalis (Lepidoptera: Pyralidae) along the last larval instar were conventionally prepared for transmission electron microscopic observation. The first ultrastructural sign of the cellular degenerative process was observed in day  4 after last-instar ecdysis, mainly in the basal cytoplasm of the posterior glandular region. The cells presented many autophagic vacuoles and concentric rough endoplasmic reticulum. The degenerative process extended to the basal cytoplasm of the anterior glandular región later on (day 6 after the last ecdysis). The apical cytoplasm of the posterior región was affected by the degenerative process in day 8 after last-instar ecdysis The degenerative process of the glandular región in D. saccharalis silk gland did not occur synchronously throughout the gland, starting at the posterior glandular región. The sub-cellular alterations are initially concentrated at the basal cytoplasm. the apical cellular región being affected later on.