Electrostatic facilitation of odorant capture in insects

Summary Olfaction is a sensory modality common to most organisms. In insects, the primary olfactory organ is the antenna, where sensilla house olfactory receptor neurons adapted to detect volatile organic compounds (VOCs). Whilst olfaction is well-understood at molecular and neural levels, questions remain as to how, biophysically, airborne VOCs reach sensilla. Transport through passive diffusion and active antennal motion is empirically supported but cannot entirely explain the remarkably rapid VOC sampling rates. We present evidence that the insect antennae exploits electrostatic forces that amplify VOC transfer from bulk air to sensilla. In effect, charged antennae capture more ambient VOCs than neutral ones, also evoking an enhanced electrophysiological (EAG) response to VOCs. Experimentally altering the charge of isolated antennae modulates EAG responses and olfactory sensitivity. Multiphysics modelling incorporating electrostatic and fluid dynamic mechanisms supports empirical evidence. Altogether, this work reveals the existence of a previously unknown and complementary biophysical mechanism supporting olfaction. Graphical abstract