, they show that these fine dust particles can significantly damage the organism of bumblebees if they are permanently ingested through food.
The amount corresponded to the amount of diesel exhaust particles that had already been detected in soils near busy country roads. Analysis of the particles in the Bayreuth laboratories has now shown that they consist partly of elemental carbon, but also contain heavy metals and other organic substances such as polycyclic aromatic hydrocarbons . PAHs are suspected of being toxic to humans and promoting the development of cancer.
"The reduced fat content is an indication that the particles trigger detoxification processes in the bumblebees' bodies, which are associated with increased energy consumption. These studies also suggest the conclusion: the daily intake of exhaust particles through food puts the bumblebees' organism under stress. We observed that their mortality increases significantly," says first author Frederic Hüftlein M.Sc., Ph.D. student at the Animal Ecology research group.
"When the bumblebees were fed the particles once or only several times over the course of 48 hours, there were no measurable significant reactions. There was also little change in the fat content of the bumblebees' bodies. The decisive factor for damage to the bumblebees is that the uptake of the exhaust particles is chronic, i.e. repeated within a longer period of time. If plants and soils are polluted, chronic exposure to the pollutants is conceivable," reports Dr.