Temporal structure of two call types produced by competing male cicadas

Abstract

Male cicadas vocalize sounds to attract conspecific females. The acoustic traits of calls vary significantly among species and show unique temporal and spectral patterns that dynamically change, even in the same bout. While the calling behavior of a single cicada has been quantified for many species, the acoustic interaction between multiple cicadas and the usage of different call types have not been well studied. In this study, we examined the interaction between male cicadas (Meimuna opalifera) that utilize two types of calls. First, we caught two cicadas in their natural habitat and recorded their calls in the laboratory. Second, we detected the calls of each cicada and classified them into two types: Type I calls with a short duration and high repetition rate and Type II calls with a longer duration and low repetition rate. The analysis of the chorus structure demonstrated that the cicadas vocalized a Type II call immediately after another cicada vocalized a Type I call. Furthermore, we tested the hypothesis that such a timing strategy allowed the cicadas to effectively mask the calls of their competitors. Specifically, we conducted a numerical simulation randomizing the onsets of calls and compared the masking performance with empirical data, which did not support our hypothesis. This study highlights the well-organized structure of cicada calls, even in the choruses with multiple call types, and indicates these calls have a function other than male-male acoustic interaction that requires further investigation.

To Catch a Cicada

“…Despite the often large emission of calls -both in terms of numbers of calling cicadas (referred to as 'chorus centres' 7 (Williams & Simon, 1995)) and overall audio volume -they can also be very hard to pinpoint aurally without substantial training and experience. This is perhaps unsurprising, as cicada songs, in addition to acting as a mating call, are likely to have evolved under selection for their ability to deter predators, due both to simply their volume (Smith and Langley, 1978) and for their effect of auditorily "masking" an individual and blending their call into a chorus preventing effective triangulation 8 (Shieh et al, 2012;Ishimaru et al, 2022). Combined, this presents researchers with a challenging epistemic environment.…”

Difference in the responses of male cicada Meimuna opalifera to the two parts of conspecific calling song

“…1B; Hayashi & Saisho 2015; Ishimaru & Aihara 2022). Although the RC might play an important role in male–male interactions, the biological significance of RC is not clear (Ishimaru & Aihara 2022). We primarily aimed to compare the number of the production of RCs as an indicator of male responses when different types of synthesized sound stimuli were provided.…”

“…In M. opalifera , the male sometimes produces a single short call (named “Ainote” or “Aizuchi” in Japanese, and referred to as a “Type II call” in Ishimaru and Aihara (2022); we refer to the call as “Response Call [RC]” hereafter) when another male is singing nearby (Fig. 1B; Hayashi & Saisho 2015; Ishimaru & Aihara 2022). Although the RC might play an important role in male–male interactions, the biological significance of RC is not clear (Ishimaru & Aihara 2022).…”

“…Therefore, RCs are considered to act as disturbance signals during courtship and/or a variety of choruses (Hayashi & Saisho 2015). Three mutually nonexclusive hypotheses for the roles of RCs are proposed: (i) the competition hypothesis; (ii) the sneaking hypothesis; and (iii) the cooperation hypothesis (Ishimaru & Aihara 2022). With reference to the competition hypothesis, Ishimaru and Aihara (2022) examined the possibility that RCs masked the sounds emitted by other competitive males; however, RCs did not play the role of masking signals.…”

“…In M. opalifera, the male sometimes produces a single short call (named "Ainote" or "Aizuchi" in Japanese, and referred to as a "Type II call" in Ishimaru and Aihara (2022); we refer to the call as "Response Call [RC]" hereafter) when another male is singing nearby (Fig. 1B; Hayashi & Saisho 2015;Ishimaru & Aihara 2022).…”