Abstract: 【Aim】 This study aims to compare the foraging preferences of the honeybee Apis mellifera and the bumblebee Bombus lantschouensis  when visiting greenhouse peach flowers in relation to the viability of pollen and the pollen/nectar collection rates of the two bee species. 【Methods】 The frequency of visits by the two bee species to flowers at the early, peak and late stages was recorded in greenhouses. The viability of pollen from flowers at different stages was tested, together with the viability of pollen carried by the two bee species, and the collection rate of pollen foragers and nectar foragers was counted. The numbers of trees and of branches visited by the two bee species were also recorded. 【Results】 Pollen viability varied widely among flowers of different stages, no pollen was released from flowers at the early stage, and the viability of pollen in flowers at the peak stage (58.3%) was significantly higher than that in flowers at the late stage (34.2%)(P<0.01). A. mellifera specialized more in a high frequency of visits to flowers at the peak stage (75.3%). B. lantschouensis also had a preference for flowers at the peak stage, but its frequency of visits (49.2%) was lower than that of A. mellifera(P<0.01). Viability of pollen carriedby A. mellifera (92.1%) was significantly higher than that of pollen carried by B.lantschouensis(72.9%), but A.mellifera had a lower collection rate both for pollen foragers and for nectar foragers than B. lantschouensis (P<0.01). When visiting a fixed number of peach flowers, B.lantschouensis was distributed more widely (visiting more branches and more trees) than A.mellifera in the greenhouse (P<0.01). 【Conclusion】 Compared with the bumblebee B.lantschouensis, the honeybee A. mellifera prefers foraging from flowers with pollen with higher viability, but this greater specialization reduces its pollen and nectar collection rate during visits.

Key words: Apis mellifera, Bombus lantschouensis, peach, pollination, foraging preference, flower stage, pollen viability