Abstract: 【Aim】 To clarify the dynamic changes of reproductive system of queens of the Chinese honeybee (Apis cerana cerana) after emergence, and to explore the effects of CO₂ narcosis on the ovarian development of their virgin queens. 【Methods】 Through artificial breeding technology and storage of the queens, we obtained different day-old virgin queens of A. cerana cerana, observed the morphological characteristics of their reproductive system after emergence, and determined the morphological indexes of their reproductive system including the body weight, ovarian weight, diameter of spermatheca, and number of ovarioles. After the virgin queens were narcotized with different concentrations (50%, 75% and 90%) of CO₂ in two consecutive days (at the 5- and 6-d-old, respectively) for 8 min, and different day-old virgin queens were respectively narcotized with 75% CO₂ for 1-3 times (each time for 8 min), the morphological characteristics of the ovaries of the 10-d-old queen were observed by paraffin section and HE staining, and their ovarian weight and the length of the largest oocyte of ovaries were detected. Meanwhile, the relative expression level of vitellogenin gene (Vg) in the head of the 10-d-old queens was measured by real-time fluorescence quantitative PCR (RT-qPCR). 【Results】 The number of ovarioles and the diameter of spermatheca of the queens of A. cerana cerana did not fluctuate obviously with the age increasing. However, the ovarian weight of queens increased obviously during the 6-12-d-old and then tended to be stable. As compared to the control (not subjected to CO₂ narcosis), narcosis with 50%, 75% and 90% CO₂ resulted in the increase of the ovarian weight and the length of the largest oocyte of queens of A. cerana cerana and the upregulation of the relative expression level of Vg gene in the queen head. Moreover, narcosis with 75% CO₂ twice significantly promoted the ovarian development of A. cerana cerana queens. 【Conclusion】 The ovaries of A. cerana cerana queens present obvious developmental changes after emergence, and CO₂ narcosis can accelerate their ovarian development.

Key words: Apis cerana cerana, queen, CO₂ narcosis, reproductive system, ovary; vitellogenin