Intraspecific sexual mimicry for finding females in a cicada: males produce 'female sounds' to gain reproductive benefit

In insects various ways to produce sounds have evolved for communication both within and between species. Cicada males are particularly known for their loud and diverse songs which are produced by tymbal organs. Females of some cicada species can produce sounds by wing flicking in response to male calls. The cicada species Subpsaltria yangi is unusual in that, besides the tymbal organs of males, it has well-developed stridulatory organs that are found in both sexes. Here, we investigated sound production and mating behaviour of this cicada species. We show that, in the context of pair formation, females produced sound signals by stridulation in response to advertisement signals produced by males with tymbal organs. We also found that the sounds produced by male cicadas with stridulatory organs were extremely similar in acoustic structure to those of females, which indicates that males mimic the signals produced by females during pair formation. Acoustic playback experiments suggested that, by producing female-like sound signals, a male could deceive a receptive female into treating him as a rival female, which makes the male more effective in eliciting acoustic responses from the receptive female. Therefore, the males could gain reproductive benefit by mimicking female sound signals, since they rely primarily on females' acoustic responses to find females. Our study provides the first experimental evidence for sound production by a stridulatory mechanism in cicadas, and a novel case of intraspecific sexual mimicry based on acoustic similarity.