Electric signals from power lines discourage bees from landing on nearby flowers, and there is growing concern that this so-called “electric pollution” could be causing widespread disruption to insect behaviour.
Alongside bumblebees, honeybees have been shown to detect and respond to airborne electric fields – which are often caused by static electricity in the natural world – detected through hairs or antennae. Research has shown , and both honeybees and bumblebees are thought to use it to locate nectar-rich flowers.
Other insects have also been shown to make use of these electric fields; caterpillars, for example, use changes in airborne electric fields to . But to date, little is known about how human-made electricity impacts this natural behaviour among pollinators.
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To investigate, Liam O’Reilly at the University of Bristol, UK, and his colleagues team tested how western honeybee (Apis mellifera) behaviour changed when different kinds of electric fields were applied to the air around a catmint plant (Nepeta grandiflora) in an urban meadow in Bristol.
They created an electric field using a weak alternating current (AC), simulating the environment 60 to 100 metres from a high-voltage mains power line, for 2 hours. This reduced honeybee landings on the affected plant by 71 per cent compared with a nearby control plant.
“The first 10 minutes of the AC treatment was a really dramatic difference – there were far fewer landings than the control,” says O’Reilly. “Alternating current is just completely alien to bees.” Landings did increase on the treatment plant as the trial continued, but never reached control levels, O’Reilly notes.
In another test, the team created an electric field using direct current (DC), like the power generated by a battery, which reduced bee landings by 53 per cent compared with the control.
The findings have worrying implications for honeybees, a key pollinator, especially given the ubiquity of electricity infrastructure in most nations. Estimates suggest that in the UK alone, there are almost 70,000 square kilometres of land on which bee colonies forage in the range of high-voltage transmission lines.
“It’s a small study; it’s one species of pollinator,” O’Reilly says. But given previous research looking at honeybees and bumblebees, a “trend of concerning results” is emerging, he says.
Other studies have shown that honeybee behaviour is affected by human-made electromagnetic fields, but this is the first to isolate the impact of electricity, says at the Museum of Natural History Berlin in Germany. The study “confirms a lot of the suspicions we had already about these power lines being able to affect insect behaviour,” he says.
England says the response of honeybees is likely to be similar in regions around the world, and warns other insects are likely to be impacted by human-made electric fields in similar ways. “If I was a betting man, I would probably put money on the fact that many more species, in many other ecological contexts, are also having their natural behaviours interfered with or modified by the electricity coming from power lines,” he says.
More research is needed to determine how power lines and other electricity infrastructure are changing insect behaviour in real-world settings, says O’Reilly, including assessing whether behaviour is altered over the long term.
But options for protecting insects from airborne electric fields are likely to be limited. Burying power lines or adding extra insulation to cables might help, but such measures are expensive. “In the short term, if you’re someone who has an apiary, it would probably be better if you can keep your apiaries further from power infrastructure,” says O’Reilly. “I think you’d have happier bees.”
iScience
