Substrate-borne Vibrational Signals Research Articles

Effects of heterospecific and conspecific vibrational signal overlap and signal-to-noise ratio on male responsiveness inNezara viridula(L.)

Animals often communicate in environments with high levels of biotic noise that arises from the signals of other individuals. Although effects of background biotic noise on mate recognition and discrimination have been widely studied in air-born sound communication, little is known about incidental interference between signallers that use substrate-borne vibrational signals. In this study we investigated the ability of males of the southern green stink bug Nezara viridula (L.) (Heteroptera: Pentatomidae) to recognize conspecific female song in the presence of biotic noise originating from conspecific and heterospecific vibrational signals. We tested male responsiveness on a bean plant in playback experiments. One leaf was vibrated with conspecific female song, while to the other one we simultaneously applied either heterospecific female signal or various altered conspecific signals with different temporal parameters. We tested males in three levels of biotic noise, ranging from +6 dB to -6 dB and we compared male responsiveness in each treatment with response obtained in unilateral treatment with unaltered conspecific female calling song. Male responsiveness was reduced in the presence of heterospecific signals or when background noise from conspecific signals obscured the species-specific temporal pattern of conspecific female song. By contrast, the presence of two sources of conspecific female songs had a positive effect on male responsiveness, for as long as the signal repetition rate of perceived song did not differ from the species-specific value. In the presence of interfering background signals, searching activity was less affected than male signalling. Increased signal-to-noise ratio restored male responsiveness to the level expressed in unilateral stimulation with conspecific female song. The results are discussed with regard to male behavioural strategies for vibrational communication in a noisy environment.

Substrate-borne Vibrations as a Component of Intraspecific Communication in the Groundhopper Tetrix ceperoi

Substrate-borne vibrational signals used in communication of Tetrix ceperoi (Orthoptera: Tetrigidae) are described for the first time. Among all studied Tetrix species, T. ceperoi use the richest repertoire of vibrational signals. These signals consist of isolated pulses or pulses united into rhythmically repeated or irregularly repeated groups and are used in rivalry, pre-copulation, and copulation behaviour (1st, 3rd, and 4th structural types of signals), and are also used by single males or females (2nd type of signal). A 5th type of vibrational signal is produced by wing tremulation, which was unknown Tetrigidae. Based on the results of this study, the vibrational signalisation seems to play an important role in species-specific mate recognition of T. ceperoi. The significance of individual signals is discussed based on results of manipulative contact experiments.

Characterization of Substrate-Borne Vibrational Signals of Euschistus servus (Heteroptera: Pentatomidae)

Problem Statement: Stink bugs were not major pests of cotton in the southeastern United States until cotton varieties containing Bacillus thuringiensis (Bt) transgenes came into common use, enabling reductions in insecticide applications against highly destructive lepidopteran pests. To maintain the benefits of reduced insecticide applications, it would be advantageous to detect and target isolated populations of stink bugs before they rise to economically important levels. However, detection methods for these pests are less than optimal, and alternative methods are being investigated. One novel method of detection would be to exploit substrate-borne vibrational signals of these bugs. Approach: To develop an effective vibration detection method, substrate-borne vibrational signals produced by different species commonly occurring in the region must be characterized sufficiently to enable detection of these species in the absence of visual observation. In this research, substrate-borne vibrational signals were recorded from the brown stink bug Euschistus servus. These signals were categorized by dominant frequency, duration, and repetition time using a Gaussian mixture model, revealing an assortment of "songs" in an acoustic repertoire. Results: Females of E. servus emitted two distinct songs while males of E. servus emitted four distinct songs. Results indicated that the repertoire of this species differs from that of other species in the same geographical location (southeastern United States) reported in previous literature. Conclusion/Recommendations: In conclusion, detection of pentatomid pests by their substrate-borne vibrational signals must include the parameters of each unique song of each species of stink bug to be detected, including those of the two female and four male songs of E. servus. The characterization of these songs will allow for the development of a monitoring system in the field using strategically placed accelerometers to detect stink bug vibrational communication and thus provide a density map of the location of these pests.

Vibrational Communication Between the Sexes in Diaphorina citri (Hemiptera: Psyllidae)

Abstract We examined the substrate-borne vibrational signals used in communication between the sexes in Diaphorina citri Kuwayama (Hemiptera: Psyllidae), a vector of huanglongbing (an economically devastating disease of citrus), in an anechoic chamber and an olfactometer. Males and females both primarily produced simple, low-amplitude vibrational signals at multiples of 170-250 Hz, ranging in duration from 140 to 700 ms. The vibrational frequencies of males and females were negatively correlated with mass, but the correlation was statistically significant only for males. Females replied to male calls within an interval of 0.3-1.2 s. Such signals are within the ranges of signals observed for other psyllids. Female-female interactions were occasionally observed. Intervals between male calls were not significantly different whether or not females replied. In an olfactometer, calling rate did not differ between virgin males exposed to odors from virgin females on citrus versus those exposed only to clean air. However, the latent period for initialization of calling was significantly shorter for males exposed to clean air, suggesting that in the absence of olfactory cues psyllids might be more inclined to use acoustic signals to communicate with conspecifics. Moreover, calling rate and latency to initialization of calling were positively and negatively correlated, respectively, with male age, suggesting that males are more likely to call the longer they remain unmated.

Reproductive strategy of the Nearctic leafhopper Scaphoideus titanus Ball (Hemiptera: Cicadellidae)

Mating behaviour of Scaphoideus titanus Ball, the vector of the grapevine disease Flavescence dorée, was investigated in order to determine the role of substrate-borne vibrational signals in intra-specific communication and pair formation. Vibrational signals were recorded from grapevine leaves with a laser vibrometer. Signalling activity of single males changed throughout the day and the peak in activity was associated with twilight and early night when 'call and fly' behaviour was observed. Pair formation began with the spontaneous emission of male signals. The male calling signal consisted of a single series of pulses, partially accompanied with a 'rumble'. The male courtship phrase consisted of four consecutive sections characterized by two sound elements, pulse and 'buzz'. Female vibrational signals were emitted only in response to male signals. The female response was a single pulse that closely resembled male pulses and was inserted between pulses within the male signals. All recorded vibrational signals of S. titanus have a dominant frequency below 900 Hz. A unique feature of vibrational communication in S. titanus is well-developed intrasexual competition; males may use alternative tactics, in the form of disturbance signals, or silently approach duetting females (satellite behaviour). While the male-female duet appears to be essential for successful localization of females and copulation, it is also vulnerable to, and easily disrupted by, alternative tactics like masking.

Vibrational Communication of <I>Metcalfa pruinosa</I> (Hemiptera: Fulgoroidea: Flatidae)

Vibrational communication of the Nearctic flatid planthopper Metcalfa pruinosa (Say) (Hemiptera: Flatidae) was investigated to determine the role of substrate-borne vibrational signals in mating behavior. Signaling activity changes throughout the day and vibrational communication in this planthopper begins at night. All recorded male and female signals consisted of a series of single pulses. Most of these signals were classified as calling signals. They were emitted spontaneously or were evoked by playback stimulation with prerecorded conspecific signals. Male calling signals are simple, and the main difference between male and female calls was in the pulse repetition time. Pulse repetition time in the middle section of the calling signal was the least variable property of the vibrational signals. During later stages of pair formation, males emit a phrase that is a sequence of pulse trains that has a distinct time and amplitude pattern, whereas females produce continuing monotonous substrate vibrations that could last for several hours. Males participated in continued exchange of vibrational signals. Signals exchanged during male–male interaction did not differ structurally from male calling signals and males never overlapped their signals.

Substrate-borne vibrational signals of the Consperse stink bug (Hemiptera: Pentatomidae)

AbstractThere is increasing evidence that short-range reproductive behaviors of phytophagous pentatomid bugs are mediated by vibrational signals. These signals have not yet been examined for bugs in the genus Euschistus, which contains several species native to the Americas. Substrate-borne vibrational signals (songs) were recorded from both sexes of the Consperse stink bug, Euschistus conspersus Uhler, an economically important agricultural pest in western North America. Females produced two songs (FS-1 and FS-2), each consisting of a series of frequency-modulated pulses with a pulse duration of 352 ± 105 (mean ± SD) and 163 ± 36 ms, respectively. Males produced four distinct songs, two composed of frequency-modulated pulses (MS-1 and MS-3), one consisting of narrowband pulses (MS-2), and one composed of a series of 1–6 short pulses, many of which were fused to form distinct pulse trains (MS-4). For both males and females, songs consisting of very short, frequency-modulated pulses (FS-2 and MS-3), with a mean pulse duration <170 ms, were emitted when the other member of the pair was silent. Songs made up of longer, frequency-modulated pulses (FS-1 and MS-1) were produced spontaneously and in response to songs from conspecifics. Pulses of MS-2 were produced by a male once a duet with a female had been initiated. This song had no frequency modulation and a longer mean pulse repetition time than MS-1. The two female songs and three of the male songs (MS-1, MS-2, and MS-3) were produced during the calling phase of mating behavior. Pulse trains of MS-4 were emitted during close-range courtship. During copulation males produced intermittent pulses of MS-1, the function of which is unknown. Dominant frequencies of all songs ranged from 102 to 136 Hz, comparable with those of other pentatomid songs. Although there were superficial similarities in the song structures of E. conspersus when compared with those of other pentatomid species, the song repertoire of E. conspersus was distinct and unique.

Comparison of Substrate-Borne Vibrational Signals ofTwo Stink Bug Species, <I>Acrosternum hilare</I> and <I>Nezara viridula</I> (Heteroptera: Pentatomidae)

Substrate-borne vibrational signals (songs) were recorded from the green stink bug, Acrosternum hilare (Say) and the southern green stink bug, Nezara viridula (L.). Female A. hilare emitted one song type in the calling phase of mating behavior, and the production of this song was stimulated by male presence or calling. The temporal characteristics of the pulses and pulse trains of this song were similar to the narrow-band type of pulse trains that constituted the N. viridula female calling song. Male A. hilare produced two different songs, each associated with a different phase of mating behavior. In the calling phase, males produced a song composed of regularly repeated, complex pulse trains whose temporal structure resembled that of the N. viridula male courtship song. In the courtship phase of behavior, males of A. hilare emitted a song that terminated female singing. The pulses of this song had similar temporal characteristics to those of the narrow-band type of the N. viridula male calling song. Immediately after initiating copulation, A. hilare pairs emitted another song, which had no counterpart in the repertoire of N. viridula or other pentatomid species that have been examined. In contrast, males of A. hilare did not appear to produce a song equivalent to the N. viridula male rival song, and neither sex of A. hilare produced songs equivalent to the broad-band pulses and pulse trains found within male and female N. viridula calling songs. Orientation of males toward females was mediated by the female calling song, which had similar spectral and temporal characteristics in both species. Male songs of the two species, although they shared some spectral characteristics, differed in temporal structure and in the contexts in which they were emitted.

Acoustics, context and function of vibrational signalling in a lycaenid butterfly–ant mutualism

Juveniles of the Australian common imperial blue butterfly, Jalmenus evagoras, produce substrate-borne vibrational signals in the form of two kinds of pupal calls and three larval calls. Pupae stridulate in the presence of conspecific larvae, when attended by an ant guard, and as a reaction against perturbation. Using pupal pairs in which one member was experimentally muted, pupal calls were shown to be important in ant attraction and the maintenance of an ant guard. A pupa may use calls to regulate levels of its attendant ants and to signal its potential value in these mutualistic interactions. Therefore substrate-borne vibrations play a significant role in the communication between J.evagoras and its attendant ants and pupal calls appear to be more than just signals acting as a predator deterrent. Similarly, caterpillars make more sound when attended by Iridomyrmex anceps, suggesting that larval calls may be important in mediating ant symbioses. One larval call has the same mean dominant frequency, pulse rate, bandwidth and pulse length as the primary signal of a pupa, suggesting a similarity in function.

Sexual Resonse of a Male Scarab Beetle to Larvae Suggests a Novel Evolutionary Origin for a Pheromone

The tremendous diversity of insect species is paralleled by diverse forms of communication between the sexes (Lewis 1984). A survey of insect fauna would soon reveal that every sensory modality is used in communication, from the obvious visual signals of brightly colored butterflies and acoustic signals of cicadas to the less obvious, but equally important, substrate-borne vibrational signals of leafhoppers and chemical signals used by many moths and beetles. The diversity of these signals has been shaped by evolutionary processes tied to sexual selection and speciation (Otte ' Endler 1989). Though the issues surrounding the role of sexual communication in speciation have not been resolved, studies of the evolution of communication have focused, in large part, on this diversification. An even more elusive evolutionary question concerns how sexual communication originates. The origin of functional communication is enigmatic because, by definition, it involves two parties, the signaler and the receiver. The physiological and behavioral requirements for signal production and signal reception are always different, yet both are necessary. Why would a firefly flash unless other fireflies could respond to that flash? Why would a male cricket sing if females did not have the potential to respond to that signal? How could a chemical signal originate, when the receiver often must have thousands of specialized receptors to respond?

Seismic communication in amphibians

The white-lipped frog, Leptodactylusalbilabris, exhibits the greatest sensitivity to substrate-borne vibrations (seismic stimuli) reported to date for any terrestrial animal. Nerve fibers from the sacculus, the source of this extraordinary sensitivity, show clear responses to sinusoidal seismic stimuli with peak accelerations less than 0.001 cm/s2. In addition, this animal generates substrate-borne vibrational signals during calling. As the male’s vocal sac expands, it strikes the substrate impulsively, generating a vertically polarized surface (Rayleigh) wave that is detected by neighboring males. These Rayleigh waves are used as intraspecific communication signals to coordinate chorus behavior in this species. Recently, a particularly unusual behavior has been described for one species of Malaysian treefrog (Polypedates). During nocturnal courtship, females living in dense mats of floating vegetation perch conspicuously on a reed or blade of grass and tap their rear toes rhythmically. Males on neighboring reeds were observed to quickly locate and mate with the tapping female. Thus it is likely that toe tapping functions as a vibrational signal indicating the female’s presence to neighboring males. It is becoming clear that seismic communication and sensitivity to whole-body vibrations are more ubiquitous among the vertebrates than had been previously imagined. [Work supported by NIH.]

Mate location in the southern green stink bug,Nezara Viridula (Heteroptera: Pentatomidae), mediated through substrate-borne signals on ivy

We observed mate location behavior in Nezara viridulaon the ivy Hedera helix.The female stays motionless on the plant stem, calling with rhythmic repetitions of her calling song. The male walks on the plant, answering with his calling and courtship songs. On encountering petioles or branching points, the male stops and straddles his legs across the fork. Only after another repetition of the female's call does the male proceed to walk again. This behavior may enable the male to compare the vibrations in the two substrates and choose the stronger one to follow. On plants where visual and airborne acoustic communication can be prevented by leaves, substrateborne vibrational signals perceived by receptors in legs would enhance the likelihood of mate location in N. viridula.