Reliability of detection of the tremulation signal.

<p>(A) Tremulation signal in the background noise of a leaf of <i>A. magdalenae</i>. (B) Action potential activity of the frontal leg nerve carrying fibres of the subgenual and hearing organ. (C) Instantaneous spike rate analysis of the recording shown in (B). Stippled line indicates threshold for detection (2 times SD of spontaneous activity). (D) Result of signal detection (arrows indicate “hits”).</p

Signalling with air-borne sound and tremulations.

<p>(A) A female <i>Docidocercus gigliotosi</i> producing a series of tremulations on a plant by strong up and down movements of its abdomen; a single airborne sound pulse of a male is shown for comparison. (B) Rate of production of tremulations (blue) and air-borne sound signals (red) of a single male over the course of about 6 hours after sunset (halve moon conditions). The number of either of these two signals for a total of 11 males is shown in (C) (airborne sound) and (D) (tremulations).</p

Summary of the costs and benefits of the public and private mode of communication in <i>D. gigliotosi</i>.

<p>Summary of the costs and benefits of the public and private mode of communication in <i>D. gigliotosi</i>.</p

Summary of two matched filters.

<p>Whereas the average AN1-neuron is tuned to 4.9 kHz (blue), the peripheral directionality is tuned to 4.5 kHz (red). The calling song frequencies of males vary from 4.3 to 5.3 kHz (horizontal bar; mean 4.7 kHz; broken line), indicating that the combined action of both receiver biases exerts a stabilizing selection pressure on this male trait.</p

Interaural intensity differences exhibit optimum functions and determine the degree of lateral steering in no-choice paradigms.

<p>In a single female, the amount of IID provided by the peripheral directionality (A) correlates with the degree of steering (B). (C) On average, the peripheral directionality is tuned to 4.5 kHz, i.e. provides the highest IIDs (blue; mean±SE; N = 20), although optima in single females vary from 4.0 to 5.1 kHz. The lateral steering in no-choice paradigms (red; mean±SE; N = 20) also peaks at 4.5 kHz and exhibits a rather similar optimum function. The correlation of mean values between IIDs and lateral steering (n = 20) is high (D).</p

Comparison of “hits” (A) and “false alarms” (B) achieved in the two modes of communication.

<p>The air-borne sound stimulus was either 10 dB or 20 dB above threshold at the position of the receiver (white and black bars, respectively). The tremulation signal amplitude was about 20 dB above threshold. For further explanation see text.</p

Tuning of AN1-interneuron and its relevance for the preference of females in two-choice tests.

<p>(A): Variance of tuning curves (red = average tuning; N = 20) in relation to the range of variation of carrier frequencies of male calls (black bar). (B): Tuning of AN1 in a single female and (C) the degree of lateral steering in a two-choice situation towards a calling song at a CF providing the stronger stimulation (right speaker).</p

AN1-tuning is highly predictive for female choice.

<p>(A): Strength of lateral steering towards or away (positive and negative values, respectively) four calling song frequencies of 4 kHz, 4.5 kHz, 5 kHz and 5.5 kHz in a choice with calling songs ranging from 3.5 to 6 kHz. For example, 5 kHz is preferred against all CFs except 4.8 kHz, and a CF of 4 kHz is rejected in all choices except 3.5 kHz (mean±SE; N = 20). (B) The average tuning of AN1 (blue; mean±SE; N = 20) correlates strongly with the behavioural preference (lateral steering towards a CF of 5 kHz in a choice with alternative CFs from 3.5 to 6 kHz, and (C) the degree of lateral steering increases with the intensity difference due to the threshold difference in AN1 for the two alternative CFs.</p

Transmission and perception of substrate-borne vibrations along <i>Aechmea magdalenae</i>, the roost plant of the katydid <i>D. gigliotosi</i>.

<p>When one leaf of the plant is stimulated with a sinusoidal stimulus at 10 Hz (at the position indicated by the large arrowhead), the induced vibrations of the plant differ substantially close to the source (distance 5 cm) and at a distance of 150 cm. Note the slow increase of acceleration amplitude after stimulus onset, and corresponding decrease at the end, indicative of resonant properties of the plant at this frequency. Three PST-histograms of responses of vibration receptors are shown for three positions on the plant (arrows), when the stimulus was a male tremulation induced at the position of the arrowhead. The receptor response was largest for the position at the end of the same leaf, where the acceleration amplitude was high, but suprathreshold responses were also observed on other leaves. For further information see text.</p

Phonotaxis and female motivation: CP 1.0s vs 2.0s

Mecopoda elongata females were given the possibility to approach one of two speakers. One is broadcasting a song model with a chirp period (CP) of 1.0 s and the other a song model with a CP of 2.0 s. Data show female choices and how often females were motivated to approach either speaker. A data summary of female motivation is shown in Fig. 7