Abstract: 【Aim】 This study aims to explore the characteristics of embryonic development of the termite Reticulitermes aculabialis during different developmental stages. 【Methods】 We daily collected eggs of R. aculabialis, fixed their embryonic development status, stained the embryos with DAPI dye, and observed and recorded the morphological characteristics of the embryos at different developmental stages with a laser confocal scanning microscope. 【Results】 Under 25℃, the embryonic developmental process of R. aculabialis takes 25-30 d. The developmental stages of R. aculabialis embryo can be divided into 12 stages according to the developmental characteristics. In the early stage of embryonic development, the yolk cells are evenly distributed in the egg, and cell nuclei are concentrated towards the center of the egg. When cells reach the posterior end of the egg, the concentrated blastocyst cells form the embryonic disc. In the middle stage of embryonic development, the embryo begins “reverse” blastocyst movement with the head along with the anterior and posterior axis reversed from the posterior pole to the anterior pole, and then the germ band shows an obvious “double band” structure. In the middle-late stages of embryonic development, the embryo widens, and the internal organs begin to develop gradually with obvious elongation and segmentation. In the late stage of embryonic development, appendages develop obviously, and the internal organs mature. 【Conclusion】 The embryonic development of R. aculabialis experiences 12 stages, and the germ band of R. aculabialis belongs to the short germ-band type. The germ band has a “double band” structure, and experiences two reversals of blastocyst in the middle stage of embryonic development. This study provides morphological and biological evidence for studying embryonic development of eusocial termites.

Key words: Reticulitermes aculabialis; embryo, development, morphology, developmental stage, laser confocal scanning microscope