Ultrastructure and distribution of antennal sensilla of Bombus terrestris (Hymenoptera: Apidae)

Bombus terrestris (Hymenoptera: Apidae) is an efficient pollinator that is widely used in agriculture. High-efficiency pollination is closely related to antennae. As sensory organs, antennae are of great significance in sensing and perceiving the external environment and information exchange between individuals. However, there remains a lack of comprehensive and systematic research on the antennae of B. terrestris. Therefore, we analysed the morphology and distribution of antennal sensilla (chemoreceptors) of B. terrestris using scanning electron microscopy (SEM). The total antennal length of B. terrestris was 7.0657 ± 0.0388 mm for queens, 5.9113 ± 0.0712 mm for workers, and 6.9727 ± 0.1211 mm for males. Queens and males were found to have seven different sensilla types, whereas workers had only six. Furthermore, the ultrastructure and putative functions of each sensilla type in B. terrestris, other bumblebees, and honeybees are described and discussed. These results provide a useful reference and guidance for the study of the pollination behaviour of B. terrestris and may explain the preference for some flower visits.