Stridulation and Its Significance in the Genus Cenocorixa (Hemiptera, Corixidae)

Abstract

Abstract1) In the genus Cenocorixa both males and females are able to produce stridulatory signals by rubbing specialized stridulatory pegs (pars stridens), located anterobasally on the fore femora, against sharp edges of the head (plectrum). 2) The stridulatory signals of Cenocorixa are species and sex specific. The main differences between the signals of various species are in the temporal pattern of pulse-trains and in the amplitude of the signals. 3) The male signal functions as an agonistic signal serving to space out individuals. Males in most species will answer to almost any stridulatory signals, and will usually approach the source of the sound, nudge the other stridulating specimen, and often chase the pursued specimen. Both intraspecific and interspecific, as well as inter-generic interactions between the males were observed. 4) Stridulation is important in behavior leading to successful copulations. Male stridulation, besides functioning as an agonistic signal, also functions as a calling signal facilitating pair-formation. Receptive females respond to the stridulatory signals from a conspecific male by remaining stationary and stridulating (= agreement signal). The males orientate directly towards the female according to the agreement signal; successful copulations were only observed after such signal recognition. No courtship display was observed in any of the species. 5) Both males and females of Cenocorixa are able to discriminate between the signals of the conspecific opposite sex and all other signals. Females answer only to the conspecific male call and males show both stridulatory response and directly oriented searching behavior only when induced by a conspecific female call. Thus, stridulation functions in the premating isolation of the species in this genus.