Sexual Selection Of The Cicada Platypleura Kaempferi(Hemiptera:Cicadidae)

The cicada Platypleura kaempferi is a common species distributed in East Asia.The males of this species produce loud sounds using the timbals to attract conspecific females,and females locate and find males according to sounds and finally select suitable match.Previous studies on this species were mainly focused on morphological and taxonomic study,and simple description of acoustic signals of males has been provided.But sexual selection in this species has not been investigated.In the present study,we conducted the following analyses to reveal the sexual selection mechanism in P.kaempferi: 1)the relationship between the female's choice for males and the features of male's calling songs and courtship songs was analyzed based on behavioural observation and acoustic analysis;2)the correlation between the morphological characters and sexual selection was studied using methods of capture-mark-recapture/resight and morphometric analysis;3)the size-assortative mating between paired male and female individuals was explored using the Pearson correlation analysis;4)the correlation between the calling song and the courtship song was analyzed using the Pearson correlation analysis;and 5)the correlation between the acoustic features and morphological characters of successfully mated males was analyzed using the Pearson correlation analysis.1)Female's choice for males based on features of male's calling songs and courtship songsThe results of the Mann-Whitney U test revealed significant difference in three calling song features(i.e.,CR,PD,IP)between the males who were succeeded in attracting females and those failed in attracting females.It was also significantly different in two courtship song features(i.e.,CSR,IE)between the males who were succeeded in courtship and those failed in courtship.The results of linear regression analysis show that the male mating success rate was significantly correlated with three calling song features(i.e.,CR,PD,IP)and two courtship song features(i.e.,CSR,IE).The relationship between the five acoustic features and the mating success rate was further revealed by the cubic curve regression analysis: the higher the calling song rate,the shorter the single pulse duration and the interval between pulses,the lower the courtship song rate,the longer the interval between echemes,the higher the mating success rate.Conversely,the lower the mating success rate.The above results indicated that the greater the male's ability of change song rate in the course of courtship(switching the higher calling song rate to lower courtship song rate),the higher the mating success rate.2)The correlation between the morphological characters and sexual selectionThe results of the Mann-Whitney U test show that there was no difference in morphological characters between the males who were succeeded in attracting females and those failed in attracting females;there was no difference in morphological characters between the males who were succeeded in courtship and those failed in courtship;there was no difference in morphological characters between mated females and unmated females.Linear regression analysis further revealed that there was no correlation between mating success rate and four morphological characteristics(i.e.,body length,body size PC1,wing length/body length,abdomen length/body length).3)The size-assortative mating between paired male and female individualsThe results of the Pearson correlation analysis show that there was no significant correlation between the five morphological characteristics(i.e.,BL,body size PC1,wing length/body length,abdomen length/body length and body weight)between the male and female individuals who were succeeded in pair-formation.The mating pattern of a large male mating with a large female and a small male mating with a small female was not detected in P.kaempferi.This suggests that mate choice in terms of size is random in this species.4)Correlation analysis of calling song and courtship song of same male individualThe results of the Pearson correlation analysis show that there was no significant correlation between the four temporal features(i.e.,CL and CSL,CR and CSR,PD and ED,IP and IE)of the calling song and the courtship song of same male individual.5)Correlation analysis between songs and morphologyThe results of the Pearson correlation analysis showed that there was no significant correlation between the nine acoustic features(i.e.,CL,CR,PD,IP,CSL,CSR,ED,IE,DF)and the four morphological characteristics(i.e.,body length,body size PC1,timbal cover length and timbal cover width)of males who got success in pair-formation.This indicates that the songs(including calling song and courtship song)do not convey the morphological information of males.In summary,in the sexual selection process of the cicada P.kaempferi,male songs are the main basis for females to choose males.Female preference for male song reveal the unique sexual selection mechanism of this species: females prefer males who can produce the higher singing rate of the calling song and the lower singing rate of the courtship song.That is,the male with the greater ability to change their song rate is more likely to mating success.The above results enrich the sexual selection mechanism of cicada insects,extend our understanding of the diversity of singing behaviors of cicada insects,and provide new information for subsequent studies on the behavior of other cicada insects.