Females prefer males producing a high-rate song with shorter timbal-stridulatory sound intervals in a cicada species

Abstract

Uncovering mate choice and factors that lead to the choice are very important to understanding sexual selection in evolutionary change. Cicadas are known for their loud sounds produced by males using the timbals. However, males in certain cicada species emit 2 kinds of sounds using respectively timbals and stridulatory organs, and females may produce their own sounds to respond to males. What has never been considered is the mate choice in such cicada species. Here, we investigate the sexual selection and potential impact of predation pressure on mate choice in the cicada Subpsaltria yangi Chen. It possesses stridulatory sound-producing organs in both sexes in addition to the timbals in males. Results show that males producing calling songs with shorter timbal-stridulatory sound intervals and a higher call rate achieved greater mating success. No morphological traits were found to be correlated with mating success in both sexes, suggesting neither males nor females display mate preference for the opposite sex based on morphological traits. Males do not discriminate among responding females during mate searching, which may be due to the high energy costs associated with their unusual mate-seeking activity and the male-biased predation pressure. Females generally mate once but a minority of them re-mated after oviposition which, combined with the desirable acoustic traits of males, suggest females may maximize their reproductive success by choosing a high-quality male in the first place. This study contributes to our understanding mechanisms of sexual selection in cicadas and other insects suffering selective pressure from predators.

Keywords: Cicadidae; female choice; mating success; predation pressure; sexual selection.

Figure 1.

Acoustic analyses of the calling song of S. yangi. (A) Oscillogram of a sequence of the calling song. (B) Power frequency spectrum of the calling song. C) Power spectrum showing the distribution of energy in a call with most of the energy accumulated around a single frequency (the dominant frequency).

Figure 2.

Demography and pair-forming in S. yangi. (A) Oscillogram of a sequence of duets of S. yangi. (B) A copulating pair of S. yangi. (C) Frequency distribution of the number of re-sighted males observed in field investigation. (D) Number of matings of S. yangi males observed in field investigation. “0” represents that no mating was observed in the field investigation, including the males without re-sighting. “1,” “2,” “3,” “4,” and “5” represent mating once, twice, 3 times, 4 times, and 5 times, respectively. FS, female stridulation, MS: male stridulation.

Figure 3.

Non-parametric estimates of male mating success in relation to call acoustic properties: (A) TSI, (B) CR, (C) the FSD, and (D) the FSP.

Figure 4.

Predators of S. yangi and the differences of the character between the marked males preyed and not preyed upon by the robber fly P. albiceps. (A) A male captured by the robber fly P. albiceps. (B) The ratio of wing length/body length. (C) The ratio of wing length/body weight. Data are presented as mean ± SD.