Abstract

The deposition of the eggshell layers in Diatraea saccharalis (Lepidoptera: Pyralidae) ovarian follicles from adult insects were studied by transmission electrón microscopy. The eggshell is composed of the vitelline membrane, the wax layer, and the chorion, which is formed by different layers, recognized as trabecular, lamellate, and outer osmiophilic layers. The deposition oí the eggshell started in ovarían follicles at stage 6 of the vitellogenesis; the first layer to be secreted was the vitelline membrane, being composed of uniformly flocculated material. The thin wax layer is visualized from stage 7 on. The three chorion layers were consecutively secreted up to stage 9 and presented morphological features that allowed their recognition at the ultrastructural level. No exochorion was visualized in the oocyte envelope. The general features of the vitelline membrane, the wax layer and the three chorion layers were similar to the ones described for other Lepidoptera species. The follicle cells were responsible for the different eggshell layers secretion: they assumed different ultrastructural aspects along with the eggshell deposition, especially concerning the morphology of the apical granules, Concomitant with the secretion of the outer osmiophilic layer, the follicle cells start to degeneróte by the autophagic process.