Figure 2

Propagation of naturally emitted female calling song. (a) Schematic representation of the setup used to measure signal transmission over the stem – stalk node. N. viridula female was calling on the leaf and the emitted signals were recorded with two laser vibrometers (red) from the petioles of the two opposite leaves, approximately at the points where a searching male would place legs after reaching the node (see also Supplementary Video S1). (b) Time differences (Δt) and RMS amplitude difference (ΔA) of vibrational signals simultaneously recorded at positions “ipsi” and “contra”. On y axis, values below 0 indicate signals in which RMS amplitude was higher on the contralateral stalk. Number of pulse trains analysed = 55. The bell-shaped curves at the side of the plot represent distributions of the measurements, obtained with convolution of each point by Gaussian unitary curve. These distributions were later used in the behavioural threshold model (Fig. 6).