Mechanosensory hairs may explain how bumblebees sense electric signals transmitted by flowers, says a team of scientists at the University of Bristol, UK.

Bumblebees use information from surrounding electric fields to make foraging decisions.

However, how they detect these fields has been a mystery – until now.

Focusing on the buff-tailed bumblebee (Bombus terrestris), Bristol scientists tested two potential mechanisms that would allow the insects to detect electric fields through the insulating medium of dry air: deflections of either the antenna or hairs.

Using a laser to measure vibrations, they found that both the antenna and mechanosensory hairs deflect in response to an electric field, but the hairs move more rapidly and with overall greater displacements.

They then looked at the bumblebees’ nervous system, finding that only the hairs alerted their nervous system to this signal.

“This ability may arise from the low mass and high stiffness of bumblebee hairs, the rigid, lever-like motion of which resembles acoustically sensitive spider hairs and mosquito antennae,” the researchers said.

Noting that mechanosensory hairs are common in arthropods, they suggest that electroreception could be a widespread phenomenon that provides insects with a variety of currently unrecognized abilities.

“We were excited to discover that bumblebees’ tiny hairs dance in response to electric fields, like when humans hold a balloon to their hair,” said lead author Dr. Gregory Sutton from the University of Bristol’s School of Biological Sciences.

“A lot of insects have similar body hairs, which leads to the possibility that many members the insect world may be equally sensitive to small electric fields.”

“Scientists are particularly interested in understanding how floral signals are perceived, received and acted upon by bees as they are critical pollinators of our crops,” he added.

“Research into these relationships has revealed the co-evolution of flowers and their pollinators, and has led to the unraveling of this important network which keeps our planet green.”

The team’s findings have been accepted for publication in the Proceedings of the National Academy of Sciences.

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Gregory Sutton et al. 2016. Mechanosensory hairs in bumble bees (Bombus terrestris) detect weak electric fields. PNAS, in press