Observations of Embryonic Changes in Middle and Late Stages of the Greater Wax Moth, Galleria mellonella (Lepidoptera: Pyralidae)

Abstract

The embryogenesis of lepidopteran insects has morphogenetic events accompanying the blastokinesis movements (anatrepsis and katatrepsis) in early and late stages, respectively. Katatrepsis is related to embryonic movement with yolk mass and regression of amnioserosa folds in the second half of the development cycle. The whole mount method and differential interference contrast microscopy (DIC) were used for analysing the embryonic developmental changes. Those changes in the middle and late embryonic periods were described and divided into eight stages: 1) Completion of segmentation and differentiation of cephalic and thoracic appendages (32-40 hours post-oviposition h. PO); 2) Expanded growth of cephalo-gnathal and abdominal parts (41-60 h. PO); 3) Completion of thoracic appendages and appearance of pleuropodia, katatrepsis (60-70 h. PO); 4) Pre-revolution morphogenetic movement of the cephalo-gnathal region (71-80 h. PO); 5) revolution of the embryo (81-100 h. PO); 6) Beginning of dorsal closure (101-115 h. PO); 7) completion of dorsal closure (116-120 h. PO); and 8) full-grown embryo just before hatching (121-144 h. PO).