Iron-based granules in body of bumblebees

Abstract

The paper deals with the presence of iron-based granules in body parts of bumblebees. Two groups of bumblebees were collected from their natural habitat, industrial landscape, and from a breeding station. Detection of the magnetic particles was performed by a vibratory magnetometer and their morphology and elemental composition was analysed by scanning electron microscopy with EDX microanalysis. By means of the EDX spectra, wild bumblebees were found to have many magnetic and non-magnetic particles on their body, containing Fe, O, Al, Si, Bi, Mg, K, and Ni, likely having origin in the industrial pollution of the environment. In the case of bred bumblebees the presence of iron-rich granules, which occurred more abundantly in subsurface tissues on the head and wings, was observed. Phase analysis based on X-ray diffraction shows that iron-based granules contain magnetite and wuestite and Mössbauer spectroscopy admits a superparamagnetic form of these minerals. Magnetoreception, i.e. the sensory function of these granules, is discussed within the paper.