Scanning electron microscope observations of pollen food bolus in the alimentary canal of honeybees (<i>Apis mellifera</i> L.)

Abstract

A new cryomicrotomy technique which preserved the spatial relationships of pollen within the alimentary canal of the honeybee (Apis mellifera L.) was used during preparation for scanning electron microscopy. With this technique it was possible to demonstrate that the food bolus of the gut of the honeybee was not homogeneous. Layers of alcohol-insoluble colloidal suspensions were found in the form of a slurry containing no pollen. In other areas, mixtures of pollen and colloids and pollen with no surrounding colloids were found. Both intact and ruptured pollen grains were observed, and the protoplasm was found to be completely empty or intact or partially removed, depending on the species of pollen and location in the alimentary canal. The observations lend support to the proposal that pollen grains are digested by bursting the cell walls to release protoplasm or by gradual removal of the protoplasm from the pollen pores.