A review of factors influencing diapause in bumble bee queens

Bumble bees are insect pollinators that play important roles in agricultural and natural ecosystems. They are social insects, but at the end of the colony’s life cycle, the next-generation queens depart from the nest, mate with drones, and enter diapause. After diapause, the queen finds a suitable location to build a nest, collect food and reproduce. During the diapause period, the queen was alone, and environmental variables and intrinsic traits could affect the success of queens’ diapause. Here, we review on the environmental factors (nutrients, temperature and diapause duration, pesticide and parasites) and intrinsic traits (body weight, age, mating behavior, energy metabolism and hormone regulation) that influence bumble bee queen diapause. All these elements affect the queen diapause process. Additionally, the changes in the queen's intrinsic traits were influenced by environmental factors. According to the results of previous studies, we discuss the existing knowledge and shortcomings and suggest future research directions. The regulatory mechanisms of environmental factors that affect nutrient reserves and metabolism during queen diapause initiation and diapause itself could be investigated in depth by means of molecular biology techniques. This review can serve as a theoretical foundation for future research on the bumble bee queen diapause and will help to explore their regulatory mechanisms.