Exposure to Magnetic Fields Changes the Behavioral Pattern in Honeybees (Apis mellifera L.) under Laboratory Conditions

Abstract

Earth’s magnetic field (MF) plays an important role for many species, including the honeybee, in navigation. Nowadays, much larger alternating fields are emitted by miscellaneous electric infrastructure components, such as transformers and power lines, and the environment is therefore polluted by an anthropogenic electromagnetic field, though little is known regarding its impact on living organisms. The behavior of animals is the first and easiest way to establish the impact of stress. It shows if the animal can detect the exposure and react to it. To investigate this, one-day-old bees were exposed to a 50 Hz magnetic field of induction at 1 mT and 1.7 mT for 10 min, 1 h, and 3 h under laboratory conditions. All groups exposed to the magnetic field showed differences in behavioral patterns. What is more, they presented a behavior absent in the control: loss of balance. There were differences, both in the ratio of behaviors and in the number of bouts—exposed bees more often changed behavior. Occurrence of differences is an indication of the reaction of the honeybee organism to the magnetic field. Loss of balance is a disturbing symptom, and behavior changes indicate a disturbance of the honeybee by the electromagnetic field.

Electromagnetic fields disrupt the pollination service by honeybees

“…This requires a highly sensitive magnetoreception system based on light-independent, ferromagnetic-based proteins and radical pair–based chemical magnetoreceptors, such as the photosensitive cryptochrome 2 (Cry2), which is involved in sensing the directional component of EMF ( 23 ). Thus, honeybees are adapted to fluctuations of the natural EMF emitted by lightning, animals, and extraterrestrial sources, such as sunspot solar cycles and solar geostorms ( 20 , 24 ).…”

“…These negative effects of EMF could cascade into a number of additional effects on insects’ physiology and behavior, including less pollen and honey harvested ( 26 , 27 ), impaired learning ability, flight dynamics, foraging, and feeding ( 28 ), as well as increased piping in the colony ( 29 ). Hence, perturbations in terms of EMF from anthropic sources would disrupt the pollination services provided by honeybees, as they would avoid places exposed to EMF ( 24 ). However, no previous studies have addressed the consequences of honeybees’ exposure to EMF in terms of (i) plant pollination and reproduction and (ii) biochemical and molecular mechanisms underlying honeybee behavioral and antioxidant stress responses.…”

Extremely Low-Frequency Electromagnetic Field Impairs the Development of Honeybee (Apis cerana)

“…Additionally, ELF-EMF exposure was found to reduce learning ability, alter behaviors and flight dynamics, reduce the success of foraging flights towards food sources and feeding, and induce the cognitive impairment of honeybees [ 27 , 28 ]. This causes numerous foraging bees to lose their ability to return home [ 29 ]. Electromagnetic fields were therefore taken as one of the factors responsible for honeybee colony collapse disorder (CCD) [ 30 ].…”