New research suggests that electromagnetic fields (EMFs) around powerlines could be a factor in the devastating decline in bee populations around the world. Laboratory studies led by Purdue University entomologist Sebastian Shepherd found that when honeybees (Apis mellifera) were exposed to extremely low frequency EMFs at levels comparable to what the insects would be subjected to under power transmission lines, the bees exhibited aggressive behaviour, and were slower to react to introduced threats than a control group was.
There are millions of hectares of land kept relatively clear under powerlines by utility companies across the continent. This semi-wild land often sprouts fields of native plants which in turn attract bees and other pollinator species.
In a series of Pavlovian-style tests, bees were exposed to a floral scent, followed by an electric shock. Bees that were exposed to EMFs were slower to learn to react to the negative stimulus than those that weren’t. The real-world consequences of this delayed reaction to a threat is that colonies may become susceptible to attacks from predators.
The bees exposed to EMFs also displayed overly aggressive behaviour towards bees from other hives. Increased aggression could lead to unwarranted sting reactions, which would be fatal to the bees. Earlier research by the same team found that EMFs also negatively affected bees’ ability to forage after they travel through EMFs.
Other factors, including habitat loss, exposure to pesticides, and invasive pests have all been attributed as potential sources for “colony collapse disorder” – mass die-offs of colonized and wild bees. This new research could be another piece of the puzzle explaining why pollinator species are struggling.
Beyond the loss of the sweet treat they produce, honeybees are an important pollinator species providing billions of dollars in assistance to farmers by pollinating their crops. Honeybees are actually a non-native species, brought to North America from Europe by early settlers. While reluctant to state conclusively that that wild native bees and others he did not specifically test would have similar outcomes, Shepard says that “I would expect the effects to be the same. There’s a lot more work to be done.”