A novel acoustic-vibratory multimodal duet

Abstract

The communication strategy of most crickets and bushcrickets typically consists of males broadcasting loud acoustic calling songs, while females perform phonotaxis, moving towards the source of the call. Males of the pseudophylline bushcricket species Onomarchus uninotatus produce an unusually low-pitched call, and we found that the immediate and most robust response of females to the male acoustic call was a bodily vibration, or tremulation, following each syllable of the call. We hypothesized that these bodily oscillations might send out a vibrational signal along the substrate on which the female stands, which males could use to localize her position. We quantified these vibrational signals using a laser vibrometer and found a clear phase relationship of alternation between the chirps of the male acoustic call and the female vibrational response. This system therefore constitutes a novel multimodal duet with a reliable temporal structure. We also found that males could localize the source of vibration but only if both the acoustic and vibratory components of the duet were played back. This unique multimodal duetting system may have evolved in response to higher levels of bat predation on searching bushcricket females than calling males, shifting part of the risk associated with partner localization onto the male. This is the first known example of bushcricket female tremulation in response to a long-range male acoustic signal and the first known example of a multimodal duet among animals.

Response Mode Choice in a Multimodally Duetting Paleotropical Pseudophylline Bushcricket

“…This pattern of male vibrotaxis to the female vibrational signal is also seen in lebinthine crickets described by Ter Hofstede et al (2015). However, the female O. uninotatus can also perform phonotaxis to the male call, after a period of tremulation (Rajaraman et al, 2015). Two possible forms of localization might therefore operate in O. uninotatus: female phonotaxis to the male acoustic call, or male vibrotaxis to the female's tremulation in response to his acoustic call, depending on the female response choice between tremulation and phonotaxis.…”

“…This female tremulation transmits a vibrational signal along the substrate, which the male can detect and use to localize the female by performing vibrotaxis. The male performs vibrotaxis by tracking the vibrational component of the duet, but does not move toward the same vibrational signal if the acoustic component of the duet is missing (Rajaraman et al, 2015). This pattern of male vibrotaxis to the female vibrational signal is also seen in lebinthine crickets described by Ter Hofstede et al (2015).…”

“…The multimodal duetting communication system of the pseudophylline bushcricket Onomarchus uninotatus involves male acoustic and female vibratory signals (Rajaraman et al, 2015). The male's acoustic call elicits bouts of tremulation from the females that have a specific temporal relationship of alternation with the acoustic chirps.…”

A Molecular Basis of Olfaction: Odorant‑Specific Electric-Field Emission

“…Our imposition of an external modulating frequency provided a more coherent and reproducible background carrier and, as a consequence, a more consistently reproducible electric-field signature. In the elasmobranch skate, a voltage-gated calcium channel and calcium-activated potassium channel couple to mediate electrosensory cell membrane voltage oscillations, which are modulated by external weak electrical signals (Lu and Fishman,1995;Ai et al 2017;Rajaraman et al 2015). Virtually all of the thousands of insect species possess mechanisms that produce vibrations.…”

Insect Hearing

“…Predicted outcomes of ( a ) high-cost and ( b ) low-cost scenarios lead to females replying to male calls and passing on some of the risk of movement to the male in the mate search game. That this may be the case is suggested by the recent discovery of an acoustic-vibrational duet in a false leaf (pseudophylline) katydid species Onomarchus uninotatus , in which the male call is answered by a robust tremulation response from the female, with phonotaxis being less frequent and only attempted after a long series of tremulations (Rajaraman et al 2015 ). In some cicada species, females reply to male calls with wing-fl ick responses, and males both call and move toward females (Gwynne 1987 ;Cooley 2001 ).…”