Social Communication in the Madagascar Hissing Cockroach: Features of Male Courtship Hisses and a Comparison of Courtship and Agonistic Hisses

Male Madagascar hissing cockroaches (Gromphadorhina portentosa) produce acoustic sounds or 'hisses' during courtship interactions with females. G. portentosa males also hiss during agonistic interactions with other males. In this study we documented intra- and inter- individual variation in male courtship hisses, addressed the possible role of hissing as an indicator of male rank, size or mating success, and determined if individual males produce different hisses during courtship and agonistic interactions. We found inter-individual variation in courtship hisses in dominant frequency and duration. Within males, these characteristics of the courtship hiss were repeatable within a day. Characteristics of courtship hisses and mating success were not related to male rank. However, courtship hisses may convey information about the size of the male: larger males had longer, lower frequency hisses than smaller males. There was a trend for males that mated to be larger than males that did not mate. However, characteristics of the' courtship hiss were not significantly related to mating success after controlling for differences in male weight. Finally, we found that the dominant frequency and duration of courtship and agonistic hisses of males did not differ suggesting that males are using similar signals during both courtship and agonistic interactions. We interpret these results in light of the possible functions of hissing, male-male competition, and female discrimination during courtship interactions.