Effects of electromagnetic waves on honeybee (apis mellifera L.) physiology and behavior

Honeybees (Apis mellifera L.) are important pollinators that play a critical role in ecosystem balance and agricultural productivity. However, in recent years, increasing stress factors in the environment due to anthropogenic activities have raised concerns about the behavioral and cognitive health of honeybees. One such stressor is electromagnetic fields, which are now widespread in the environment as a result of advancing technology. This thesis study aims to investigate the effect of extremely low-frequency electromagnetic fields on the cognitive abilities and stress levels of honeybees. In this context, honeybees were exposed to electromagnetic fields of different durations (0, 3, 6, 12 hours) and different intensities (0, 100, 1000, and 3000 µT) using a Helmholtz coil that generated a constant electromagnetic field at 50 Hz. The cognitive abilities of honeybees were assessed using the proboscis extension response conditioning paradigm. Learning rates were found to be 92.45%, 75.93%, 64.15%, and 58.82% in the control (0 µT), 100 µT, 1000 µT, and 3000 µT groups respectively. Statistical analyses revealed significant differences between the control group and the 1000 µT (p=0.002) and 3000 µT (p<0.001) groups, while the 100 µT group did not differ significantly from the control group. The stress levels of honeybees were determined by measuring HSP70 levels in brain tissue using the ELISA method. According to the ELISA results, although a relative increase was observed in the 3000 µT group, it was determined that electromagnetic fields did not have a statistically significant effect on the stress levels of honeybees. These findings suggest that exposure to electromagnetic fields may impair the cognitive functions of honeybees by disrupting neural plasticity or synaptic transmission, which likely play a role in learning and memory formation. Given the increasing prevalence of electromagnetic pollution from telecommunications and electrical infrastructure, such impairments may have broader ecological and agricultural implications. Further research focusing on the molecular mechanisms underlying the neurobehavioral changes caused by electromagnetic fields in honeybees is necessary to clarify the potential risks to the sustainability of honeybee populations.