Bumblebee hair motion in electric fields

Bees have been observed to detect and learn the presence of weak electric fields in various behavioural experiments in the lab. The electro-sensitivity of bumblebees has also been suggested to be important for pollination. However, the structure and function of electro-sensory organs are yet to be described. Bees, like other arthropods, are known to have evolved various mechanoreceptors. Antennae and hairs have mechanosensory functions and have been shown to respond to weak electric fields. Current proposals posit that hairs and antennae can act as electromechanical sensors. To investigate this hypothesis, the mechanical response of bumblebee hairs stimulated by an electric field was measured using microscanning laser Doppler vibrometry. Hair vibration velocity is shown to be proportional to charge triboelectrically deposited on the bee and the effect of polarisation charge is seen to be negligible. Hair motion due to acoustic stimuli is also measured and compared to hair electromechanical response. Preliminary results show that the electro-sensitivity of charged bee hairs is comparable to hair sensitivity to acoustic stimuli.