The electromagnetic fields used for mobile telephony and data transmission have been referred to as a possible cause of bee mortality. Antennas are located everywhere in the country and 'non-irradiated' air is no longer available for bees to fly in. Even beekeepers use their mobile phone while tending their bees. Although it does not seem to be a likely cause of bee mortality, it cannot be excluded entirely until research tests this hypothesis.
To obtain a picture of the possible effects of electromagnetic fields on bees, we first reviewed identified available literature on this topic. Bees appear to be sensitive to magnetic fields (also to the magnetism of the earth) and to electric charge; a recent article in Science showed that bumblebees can use the electrostatic charge of a flower to detect whether it has just been visited or is still fresh. It appears that something is indeed known about the effects on bee colonies of electromagnetic fields around power lines, but very little is known about more recent applications such as mobile telephony and data traffic.
Because so little research on this topic is available, in 2011-2012 we conducted a study into the effect of exposing bee colonies to the radiation from an antenna for mobile telephony and data traffic. Beehives were placed 200 m from an antenna. To also ensure ‘non-radiated’ colonies for comparison, these control colonies were placed in a Faraday cage constructed of two layers of wire mesh. When placed in the field, this cage damped the field to such an extent that no signal was available for a mobile phone. To make the conditions as comparable as possible, the ‘radiated’ colonies were also placed in a similar cage, but one made of plastic mesh, which allowed the radiation to pass unhindered. Adult bees from both groups could fly in and out of the hives freely, so they were always exposed when they left the hive. Therefore, we focused on the phases when the bees were still inside the hives: the egg, larva and pupa phases. But also, what is the result of these early life stage effects in later life?
Bees from both groups who had gone through these phases inside the hives were compared according to their life span, physiological characteristics, flight capacity and other characteristics.
Bees did develop equally well under both treatments. We demonstrated this by photographing a piece of comb with just laid eggs on day 1, and the same spot again one week later: successful eggs then have turned into a larva, unsuccessful eggs have been removed (empty cell). Again one week later successful larvae have become pupae.
On the day of emergence of young worker bees we took them from the colonies of origin, marked them by painting a coloured (colony specific) dot on their thorax, and then introduced them into a host colony. By checking regularly their presence, we were able to determine the longevity of the bees. Bees from exposed and non-exposed colonies had similar longevity, which also indicates that orientation was not affected, since this would have caused a faster dwindling of the bees.
Also in a host colony marked bees were brought to Graz in Austria, where after reaching the age of ~20 days they were tested in a carrousel for their flight capacity. There were no differences between exposed and non-exposed reared bees.
Finally we also checked how many of the 10 colonies in both cages survived the winter: more non-exposed colonies than exposed seemed to survive. However we could not statistically test this seeming difference, since we had only 1 cage with and 1 cage without electromagnetic field exposure and due to far too low colony numbers. Therefore this should still be tested in a new experiment.