we have demonstrated that ASR significantly affects contest and courtship behaviour in the dung beetle Onthophagus taurus. ASR is an accurate predictor of the intensity of contest and courtship competition, with the male-biased treatment exhibiting higher levels of these behaviours. In addition, we found no significant difference in the weight of brood balls among the different ASR treatments. The mean number of broods per male was lower in the male-biased treatment compared to the female-biased and unbiased treatments, while the mean number of brood balls per female did not differ significantly among ASR treatments. These findings suggest that ASR may impair the breeding success of dung beetles by influencing their fecundity, but not parental care.