Capacity of honeybees to remove heavy metals from nectar and excrete the contaminants from their bodies

Abstract

AbstractWe examined the residues of 13 elements in soil, plant parts, nectar, bee heads, thorax, and abdomens, feces from bee guts, and bee products sampled from two Polish cities (Lublin and Poznań). Our findings indicated that bees have an extraordinary ability to remove metals from nectar when converting nectar into honey. Compared to nectar, honey contained 40-fold lower Fe, 26-fold lower Zn, and eightfold lower Cu and Cd levels, indicating removal of these elements via nectar processing, during which water is evaporated and complex sugars are decomposed into simple ones. The amount of Pb remained unchanged; however, it can also be regarded as a fourfold decrease due to water evaporation from honey, compared to nectar. Some portion of the ingested Fe, Cu, and Zn was used by bees, and the excess amounts were excreted in feces. All analyzed elements were present as biocomplexes transported from the alimentary tract through the abdomen to the thorax and head. Elements transferred in the alimentary tract were partially immobilized/metabolized in the bee fat body, and their residues were excreted with feces from the gut. We postulate that honey is not a good indicator of environmental pollution, as a high amount of elements is removed by bees from their bodies.