Honey proteome of the bumblebee Bombus terrestris: Similarities, differences, and exceptionality compared to honey bee honey as signatures of eusociality evolution
Abstract
Although honey bee honey is well studied, information on the characteristics of bumblebee honey is limited. The study goal was to characterize the proteome of Bombus terrestris honey and compare it with the known proteome of Apis mellifera honey.
Honey proteomes could reflect the differences in genetic makeup as well as eusocial organization. Basic characteristics, such as total protein content (0.4 mg/g), pH (4.6), water content (11% lyophilization), and fructose/glucose content (76%) and ratio (1.5), were not unique compared to honey bee honey.
Label-free proteomics enabled reliable identification of 107 bumblebee-derived proteins, and this number is greater than that honey bee honey. In contrast, plant-derived proteins are more abundant in bumblebee honey.
Approximately 40 homologous proteins in B. terrestris and A. mellifera honey were identified. Alpha-glucosidase homologous with A. mellifera Hbg3 was a major protein.
Importantly, MRJPs, alpha-amylase, and glucose oxidase were absent. Yellow-e3-like and carbonic anhydrase are representative bumblebee-specific markers.
Together, these differences reflect the lack of royal jelly production in bumblebees. The bumblebee honey proteome is substantially different from that of honey bees.
These differences can explain the differences in eusocial organization, especially events connected with different nutrient flows and the lack of food-receiving/storing castes in the annual colonies of bumblebees.