An analysis of time-varying dynamics in electrically sensitive arthropod hairs to understand real-world electrical sensing

Abstract

With increasing evidence of electroreception in terrestrial arthropods, an understanding of receptor level processes is vital to appreciating the capabilities and limits of this sense. Here, we examine the spatio-temporal sensitivity of mechanoreceptive filiform hairs in detecting electrical fields. We first present empirical data, highlighting the time-varying characteristics of biological electrical signals. After which, we explore how electrically sensitive hairs may respond to such stimuli. The main findings are: (i) oscillatory signals (elicited by wingbeats) influence the spatial sensitivity of hairs, unveiling an inextricable spatio-temporal link; (ii) wingbeat direction modulates spatial sensitivity; (iii) electrical wingbeats can be approximated by sinusoidally modulated DC signals; and (iv) for a moving point charge, maximum sensitivity occurs at a faster timescale than a hair’s frequency-based tuning. Our results show that electro-mechanical sensory hairs may capture different spatio-temporal information, depending on an object’s movement and wingbeat and in comparison with aero-acoustic stimuli. Crucially, we suggest that electrostatic and aero-acoustic signals may provide distinguishable channels of information for arthropods. Given the pervasiveness of electric fields in nature, our results suggest further study to understand electrostatics in the ecology of arthropods and to reveal unknown ecological relationships and novel interactions between species.

Prey can detect predators via electroreception in air

“…This may be advantageous if one sensory modality is contextually more reliable than another. However, our experimental evidence presented here, alongside previous theoretical calculations ( 15 , 43 , 45 , 46 ), clearly demonstrates that electroreception alone is sufficient to detect the presence, location, and wingbeat, of a charged predator at ecologically useful distances.…”

“…Furthermore, while we expect that electroreception can be utilized synergistically with acoustic sensing to improve overall sensitivity via constructive interference, this polarization-based mechanism also allows for electrical and acoustic stimuli to be distinguished from each other despite being sensed by the same sensory structures, an ability predicted previously ( 15 , 27 , 40 , 43 , 44 ). This may be advantageous if one sensory modality is contextually more reliable than another.…”

“…The wasp was assigned a charge of +10 pC, based on the mean charge measured for V. vulgaris , and the caterpillar assigned a charge of −2 pC, based on the mean charge measured for A. io . The plant was defined as electrically grounded ( 5 , 12 – 16 ). Electrical material properties were based on values from the literature ( SI Appendix , Table S2 ).…”

“…For all caterpillars, electric stimuli were presented that mimicked the electric field emanating from a common wasp intermittently flying nearby, modulated by its 180 Hz wingbeat frequency ( 13 , 14 ). This modulation exists because the wings are charged, and as they flap, oscillating closer and further from the prey, the electric field strength will increase when the wings are closer, and decrease when the wings are further, creating an oscillation in the electric field ( 15 ). Stimuli consisted of 2-s bursts of 180 Hz sinusoidal electric field at ecologically relevant magnitudes, followed by 2 s of electrical silence; a regime repeated until the end of each trial.…”