Spectral characteristics of vibrational signals before and after transmission through air.

<p>Frequency spectra (A) (one pulse), sonograms (B) (10 s sequence) and oscillograms (C) (10 s sequence) of abdomen vibration produced signals, recorded simultaneously from the plant where insects were singing (lower traces) and from the neighbouring plant (upper traces). The two plants were separated by an approximately 3 (left) or 6 (right) cm air gap.</p

Parameters of vibrational signals produced by mechanisms other than abdomen vibration.

<p>n = the number of signals analysed, N = the number of individuals analysed, where N is not specified then N = 1. Data are shown as mean ± SD when differences in parameter values between individuals were not significant and as minimal and maximal values when differences in parameter values between individuals were significant. For percussion signals we indicate the statistical test used to compare parameters of signals emitted as independent sequences (I) and parameters of signals emitted as a response to other vibrational emissions (R).</p

Spectral characteristics of tremulatory, buzzing, percussion and abdomen vibration produced signals.

<p>(Above) Vibrational signals produced by tremulation (TR), buzzing (BZ), percussion (PER) and by vibrating the abdomen (AV) on the leaf and recorded on the stem 14–16 cm from the source. Sequence shown is 1 minute long. (Below) Frequency spectra of single tremulatory, buzzing and abdomen vibration produced pulses, and of a 10 s sequence of percussion signals.</p

Comparison of animal activity on a non-vibrated and on a vibrated plant.

<p>Number of individual animals exhibiting different activity levels on the plant in control and in test conditions. Fisher’s exact test for count data was used to compare between control and test conditions the number of individual animals staying on the plant and the number of individual animals emitting vibrational signals. N represents the number of individuals.</p

Architecture of bean plants (<i>Phaseolus vulgaris</i> L.) and experimental setup.

<p>Structure and dimensions of bean plants used, and experimental setup in airborne inter-plant communication experiments (below). See text for detailed description of experimental procedures.</p

Vibrational responses to abdominal vibration produced signals on a neighbouring plant.

<p>Tremulatory (A), percussion (B) and abdomen vibration produced signals (C and D) emitted by a male as a response to abdomen vibrational signals (asterisks) produced on a neighbouring plant. Plants were in contact with the tips of the two closest leaves (A, B and C) or were separated by a 3–7 cm wide gap of air (D).</p

Naturally emitted FS-1 and MS-1 pulses overlapped by continuous pure tones.

<p><b>The relation between interference pulse duration and the difference between MS-1 and pure tone frequencies at different frequency and velocity levels</b>. a,b, c: naturally emitted FS-1 and MS-1 signals overlapped by (a) 100 Hz/0.69 mm/s, (b) 125 Hz/1.13 mm/s and (c) 150 Hz/0.60 mm/s pure tones. d: mean interference pulse duration (SD<40% of the mean value, N = 3–23, n = 6) of naturally emitted MS-1 signals overlapped by 100 Hz/0.22 mm/s (black diamonds), 125 Hz/0.22 mm/s (open squares) or 150 Hz/0.22 mm/s (grey triangles) pure tone vibration. Means were determined in 1000 ms sections beginning from start to end of the MS-1 signal, e: mean pulse duration (SD<40% of the mean value, N = 3–26, n = 9) of naturally emitted MS-1 signals on soybean masked by 150 Hz/0.343–1,151 mm/s pure tone vibration. Black markers: MS-2 signals with FM decreasing from a starting dominant frequency below 150 Hz; open markers: MS-2 signals with starting frequency of FM above 150 Hz. Means were determined in 1000 ms sections beginning from the start to the end of the MS-1 signal. Time bar 5 seconds.</p

Interference induced on a soybean plant by overlapping pure tones and playback MS-1 signals.

<p>Oscillograms of a continuous 150 Hz/1.26 mm/s vibration masking (a) a 150 Hz/5.29 mm/s pulse and (b) fused 125 Hz/3.85 mm/s (left), 150 Hz/2.69 mm/s (middle) and 200 Hz/3.49 mm/s (right) pulses. Oscillograms (left) and sonograms (right) of MS-1 (dominant frequency = 111 Hz, velocity = 7.46 mm/s) playback overlapped by (c) 100 Hz/1.47 mm/s, (d) 125 Hz/1.48 mm/s and (e) 150 Hz/1.88 mm/s continuous vibration. f: mean (N = 2–24) pulse duration of MS-1 signals (n = 12) (SD<40% of the mean) masked by 125 Hz/1.16 mm/s pure tone and recorded on soybean (diamonds), <i>C</i>. <i>cayan</i> (squares) and bean (triangles); pulse duration was determined in 12 play-back signals in 1000 ms sections starting from the beginning to the end of the MS-1 signal. g: mean (N = 2–24) pulse duration of two artificially induced MS-1 signals (SD<40%) masked by 125 Hz pure tone of different velocities and determined in 1000 ms sections, starting from beginning to of the MS-1 signals recorded on soybean.</p

Spectra (upper), sonograms (middle) and oscillograms (lower) of <i>Eushistus heros</i> vibratory communication signals.

<p>a: FS-1 and MS-1 pulses in a calling duet, b: FS-1 pulses and MS-2 pulse trains in a courtship duet, c: MRS pulse train.</p

Temporal and frequency properties of <i>Eushistus heros</i> FS-1, MS-1, MS-2 and MRS signals.

<p>Minimal and maximal means with standard deviations are shown when differences among individuals were significant: FS-1a (One-way ANOVA, F>11.27, df = 4, P<0.0001), FS-1b (One-way ANOVA, F>3.389, df = 4, P<0.05), MS-1 duration (One-way ANOVA, F = 2.055, df = 7, P = 0.0521), MS-1 others (One-way ANOVA, F>8.59, df = 7, P<0,0001), MS-2 (One-way ANOVA, F>8.598, df = 3, P<0.0001), MRS (One-way ANOVA, F>6.71, df = 4, P<0.0001). N, number of signals analyzed for each individual; n, number of animals; FS-1a = female first song in duet with MS-1; FS-1b = female first song in duet with MS-2; MS-1 = first male song; MS-2 = second male song; MRS = male rival song; Freq = frequency, FM = frequency modulation.</p><p>Temporal and frequency properties of <i>Eushistus heros</i> FS-1, MS-1, MS-2 and MRS signals.</p