The Influence of an Electromagnetic Field at a Radiofrequency of 900 MHz on the Behavior of a Honey Bee.

There is little data available on how electromagnetic fields (EMFs) affect the fundamental behavior of honeybees. In laboratory studies, behavioral analysis typically focuses on five behaviors: walking (time spent moving), flight (wing movement), social contact (including mutual grooming), self-cleaning (grooming of body surfaces), and immobility (the time a bee remains motionless). These behaviors – flight, walking, cleaning, social contact, and immobility – are crucial for maintaining the health of bee colonies and the fitness of individual bees. Analyzing flight behavior can provide insight into the cognitive and sensory abilities of honeybees. This study investigated whether 900 MHz EMFs influence these behaviors in honeybees. In addition, the study examined whether potential changes would be visible immediately after exposure or only after some time (delayed effect).

The frames containing the brood were transported to the laboratory and placed in an incubator that mimicked the conditions of a beehive. After emerging, the honeybee workers were transferred to wooden cages and divided into one control group and nine experimental groups. The bees in the experimental groups were exposed to 900 MHz EMFs at intensities of 12 V/m, 28 V/m, or 61 V/m for 15 minutes, 1 hour, or 3 hours. The RF source was a patch antenna connected to an amplifier powered by a 900 MHz radiofrequency (RF) generator modulated with 2G frequency hopping. Immediately after the exposure period ended (and again 7 days later), bees were randomly selected from each group, and their behavior was recorded for six minutes using a camera. Behavioral analysis was performed using Noldus Observer XT 9.0 software (Wageningen, Netherlands). Although one-day-old bees cannot fly, the behavioral analysis assessed flight activity based on wing movements and movements between the walls. The analysis examined two factors: the average duration of a behavior (how much time the bees in the group spent performing a specific behavior) and the average number of occurrences of a behavior (how often individual bees in the group exhibited the selected behavior during the observation period).

Regarding the average time spent on a specific behavior, the effects of acute exposure on "individual contact" were peculiar: partly reduced and partly increased, yet without a clear correlation with field strength or exposure duration. One week later, individual contact decreased slightly in almost all exposure groups, except for the control group. A similar, albeit less pronounced, trend is evident in grooming behavior. The only clear result of this study is the effect of RF exposure on "flight behavior." All exposed groups exhibited less flight behavior than the control group, and the effect was stronger at higher field strengths. Similar trends were observed one week later. All exposed groups continued to exhibit reduced flight behavior compared to the control group by roughly the same percentage (25–68%) as seven days earlier. Groups exposed for three hours appear to be more affected than groups exposed for shorter durations. Similar trends were observed in the number of flight behaviors recorded.

According to the authors, this study shows that 2G-modulated 900 MHz EMFs slightly affect bee behavior compared to the control group. Furthermore, statistically significant differences were found between test groups exposed to RF radiation immediately and seven days after exposure. These results suggest that certain behavioral changes may occur with a time delay following RF exposure. The study found reduced flight activity in bees immediately after exposure and one week later. These results provide further evidence that 2G radiofrequency radiation could weaken bee colonies by reducing their food supply, thereby contributing to increased bee mortality.

Editor’s note:

The study used a new method to automatically categorize bee behavior. Most of the findings were not statistically significant. However, flight behavior, field strength, and exposure duration were clearly and nearly linearly associated with the extent of reduction or disruption of behavior, especially flight behavior. This remained the case even one week after exposure. A larger sample size (about three to four times larger) would reveal statistically significant differences in almost all exposure groups. However, the field strengths used in the study were unrealistically high. The lowest field strength used was 12 V/m, which corresponds to 380 mW/m² (such levels can generally only be measured within ten meters of a base station). This calls into question the generalizability of the findings. Future studies should examine why flight activity is particularly disrupted by 2G radiation and explore this phenomenon at the level of neurotransmitters. (AT)