Abstract: 【Aim】 To study the anatomical structure of the labial gland of Reticulitermes chinensis and its differentiation in individuals of different castes so as to provide a reference for further exploring the mechanism of stomodeal trophallaxis and caste differentiation. 【Methods】 The anatomical structure of the labial gland of R. chinensis and its differentiation among individuals of different castes were observed by microdissection, the structure and nerve innervation of the labial gland of worker were observed by scanning electron microscope, and the drinking water habit of workers and the water storage function of the labial gland reservoir were investigated by water drinking test. 【Results】 The labial gland of R. chinensis consists of a pair of symmetric structures, each consisting of a labial glandular acinus, a labial gland reservoir and relevant ducts. Each side duct respectively opens at the base of the hypopharynx. The labial gland of the termite queen was the most developed among various castes. The four parameters, i.e., the sizes of the labial gland and the labial gland reservoir, the size of acinus and the number of acini in labial gland, of termite queen were significantly higher than those of other castes of individuals. The labial gland of soldier, worker and alate were also rather developed, but the differences in the above four parameters among them were not significant. Revealed by scanning electron microscope, the acini of the labial gland of workers are connected by branch ducts and common ducts, and the nerves are distributed on the lateral side of the acini. Workers had the ability to drink water, and the obtained water was stored in the labial gland reservoir. 【Conclusion】 Among different castes, the termite queen of R. chinensis has the most developed labial gland, and the alate also has rather developed labial gland, suggesting that in addition to performing reproductive function, the termite queen also undertakes other jobs such as stomodeal trophallaxis and breeding larva. R. chinensis workers have the ability to drink water, and the labial gland reservoir has the function of storing water.

Key words: Reticulitermes chinensis, labial gland, anatomical morphology, scanning electron microscopy observation, drinking water habit for workers