Defined exposure of honey bee colonies to simulated radiofrequency electromagnetic fields (RF-EMF): Negative effects on the homing ability, but not on brood development or longevity.

Urbanization and the increasing use of wireless technologies lead to higher emission rates of radiofrequency electromagnetic fields (RF-EMF) in populated areas. This anthropogenic electromagnetic radiation is a form of environmental pollution and a potential stressor on bees or other flying insects. Cities often have a high density of wireless devices operating on microwave frequencies, which generate electromagnetic frequencies e.g. in the 2.4 and 5.8 GHz bands commonly used by the wireless technologies. To date the effects of nonionizing electromagnetic radiation on the vitality and behavior of insects are poorly understood. In our experiment we used honey bees as model organisms and analyzed the effects of defined exposures to 2.4 and 5.8 GHz on brood development, longevity and homing ability under field conditions. To generate this radiation, we used a high-quality radiation source which generates a consistent, definable and realistic electromagnetic radiation, engineered for this experiment by the Communications Engineering Lab (CEL) at the Karlsruhe Institute of Technology. Our results show significant effects of long-term exposures on the homing ability of foraging honey bees, but no effects on brood development and adult worker longevity. Using this novel and high-quality technical set-up, this interdisciplinary work provides new data on the effects of these widely used frequencies on important fitness parameters of free-flying honey bees.