Abstract: 【Aim】Domesticating native bumblebees for crop pollination is an effective way to achieve coordinated development of modern agriculture and ecological conservation. This study aims to investigate the effects of inducing queen diapause and diapause-breaking methods on the colony reproductive breeding characteristics of Bombus breviceps, the dominant species in Yunnan Province, southwestern China， so as to optimize key rearing techniques and improve breeding efficiency.【Methods】Through the statistics of the changes in the body weight and survival rates of B. breviceps queens at different diapause stages, as well as the rearing of queens with different body weights, different diapause periods (diapause duration of 30, 60, 90, 120 and 150 d) and different diapause-breaking methods (control group not subjected to any treatment, cold storage at 5 ℃ for 90 d, and CO₂ treatment for 5 and 30 min, respectively), the breeding characteristics such as colony development (pre-oviposition period, duration up to the first worker emergence, duration up to the first progeny queen emergence, duration up to the first male emergence, duration of the colony reaching 6 workers, duration of the colony reaching 30 workers, duration of the colony reaching 60 workers and longevity of foundress queens), colony strength (number of workers and number of progeny queens) and breeding efficiency ［proportion of queens laying eggs, proportion of applicable colonies (proportion of colonies producing 50 or more workers) and proportion of colonies producing progeny queen］ were recorded and compared.【Results】The body weight of mated B. breviceps queens was in a normal distribution, ranging from 0.4513 g to 1.1928 g, with an average of (0.8969±0.1219) g. The most frequent body weight range was 0.8733-0.9788 g, accounting for 61.2%. There was an extremely significantly positive correlation between the survival rate and the body weight of queen at the diapause stage, and both of them decreased with the extension of diapause duration. When the diapause duration exceeded 120 d, the queen survival rate decreased dramatically. There was no significant correlation between the pre-diapause body weight and pre-oviposition period, duration up to the first worker emergence, duration up to the first progeny queen emergence, duration up to the first male emergence, duration of the colony reaching 6 workers, duration of the colony reaching 30 workers, duration of the colony reaching 60 workers, longevity of foundress queens, number of workers or number of progeny queens of B. breviceps, but more colonies with queens of medium body weight (0.8733-0.9788 g) would produce progeny queens. There was no interaction between the effects of pre-diapause body weight and diapause duration on colony development and colony strength. The diapause duration was not significantly correlated with the number of workers and number of progeny queens, but was significantly negatively correlated with the pre-oviposition period, duration up to the first worker emergence, duration up to the first progeny queen emergence, duration up to the first male emergence, duration of the colony reaching 6 workers, duration of the colony reaching 30 workers, duration of the colony reaching 60 workers and longevity of foundress queens. With the extension of diapause duration, the colony developmental duration was shortened. Queens undergoing diapause for 90 d had similar proportion of queens laying eggs to those undergoing diapause for 60 and 120 d, and their colonies produced higher number of workers. Compared with queens undergoing diapause for 60, 120 and 150 d, queens undergoing diapause for 90 d had higher proportion of applicable colonies and proportion of colonies producing progeny queens. The pre-oviposition period, duration up to the first worker emergence, duration of the colony reaching 6 workers, duration of the colony reaching 30 workers, duration of the colony reaching 60 workers of the queens after cold storage at 5 ℃ for 90 d and CO₂ treatments were extremely significantly shorter than that in the control. The number of workers produced in the group of CO₂ treatment for 30 min (496.4±101.1 workers) was the highest, significantly higher than that in the group of CO₂ treatment for 5 min (364.4±132.1 workers), group of cold storage at 5 ℃ for 90 d (398.2±117.2 workers) and the control group (253.0±44.0 workers). The proportion of queens laying eggs (100.0%), proportion of applicable colonies (86.7%) and proportion of colonies producing progeny queens (86.7%) in the group of CO₂ treatment for 30 min were higher than those in the group of cold storage at 5 ℃ for 90 d and group of CO₂ treatment for 5 min, and that in the control group was the lowest.【Conclusion】The mated B. breviceps queens should undergo diapause to initiate colonies. The queens weighing 0.8733-0.9788 g before diapause have better reproductive characteristics. Both cold storage at 5 ℃ for 90 d and CO₂ treatment can induce queens to break diapause and initiate colonies. The results of this study can provide a reference for efficient breeding of B. breviceps, and have important implications for the conservation and their pollination applications of native bumblebees.

Key words: Bombus breviceps, diapause, CO₂ treatment, cold storage, colony development; colony strength, breeding efficiency