The effect of electromagnetic fields (EMFs) on certain behavioral and physiological characteristics of honeybees (Apis mellifera L.)

Although the exact causes are not fully explained, researchers accept that several factors, such as increased pesticide use, honeybee diseases and pests, and global climate change, contribute to colony losses. Technologies influenced by the growing population, such as mobile phone base stations and high-voltage power lines, have led to the emergence of electromagnetic fields. These developments have raised discussions about whether there is a relationship between electromagnetic fields and the colony losses observed in honeybees, which are entirely dependent on nature. In this study, which aimed to determine the effects of low-frequency electromagnetic fields generated by electrical sources on honeybees under producer conditions, groups exposed to effects produced with copper coils at levels of 20 μT, 50 μT, 100 μT, and 300 μT were compared with a control group in terms of brood production, the number of frames with brood, the number of frames with bees, flight activity, flight altitude, navigation, orientation to food sources, and memory. The study was conducted at the Beekeeping Business of Van Yüzüncü Yıl University Beekeeping Research and Application Center Directorate, with five colonies in each group. Using negative binomial regression to evaluate the data, no differences were observed in brood production among groups exposed to 20 μT, 50 μT, 100 μT, and 300 μT. However, considering the number of brood and bee-covered frames and flight activity, it was revealed that colony development characteristics were negatively affected as the magnetic effect increased. The aggression test showed that, compared to the control group, the number of stings on black balls increased by 63.9%, 17.1%, and 38.9% in the groups exposed to 50 μT, 100 μT, and 300 μT, respectively. Regarding the flight distance of honeybees from magnetic field-emitting coils, foraging worker bees generally exhibited a tendency to fly farther away from the magnetic influence starting from the 100 μT group, reaching the highest level in the 300 μT group. As part of the study, which was conducted in different work packages, the findings from navigation tests showed a significant decrease in the ability of bees exposed to varying magnetic fields to return to their hive. Worker bees preferred food sources with lower magnetic effects, and exposure to electromagnetic fields significantly reduced the learned behavior of the proboscis extension reflex (PER) depending on the level of exposure.