Abstract: Segmentation is critical to insect embryogenesis, yet little is known about this process in Locusta migratoria manilensis (Meyen) which is an important pest. In this study, the spatio-temporal process of segmentation in L. migratoria manilensis was observed by using immunohistochemical and fuchsin staining methods. The results showed that the zygote nucleus quickly divided and migrated to the egg periphery after fertilization, and then the nuclei were condensing at the posterior end of the egg where a circular blastodisc formed. The blastodisc subsequently differentiated into head lobe and posterior germband. With elongation of the germband, the first segment was observed at thoracic region at about 50 h after egg laid, and then other segments, including 3 head segments, 3 gnathal segments, 3 thoracic segments, and 10 abdominal segments, gradually formed in a sequential pattern within 44 h. The thoracic and gnathal regions were added one or more segments at a time, while only one segment at a time was formed for the abdomen. Our results further confirmed that L. migratoria manilensis is a classic short germband insect with the anterior thoracic region as the morphological differentiation center. Meanwhile, the developmental rates of embryo vary among different locust species, while the segmentation patterns and the relative time required for segmentation are identical.

Key words: Locusta migratoria manilensis, embryogenesis, segmentation, immunohistochemical staining, fuchsin staining