Model breeding and ecotoxicity study of Eprinomectin on the reproductive performance of Onthophagus hircus (Coleoptera: Scarabaeidae)

This study developed a laboratory rearing model for the dung beetle Onthophagus hircus to evaluate the ecotoxicological effects of eprinomectin (EPM) on its survival and reproductive performance. Adult O. hircus were exposed to increasing EPM concentrations (0-50 ppm) in bovine feces. Survival was significantly reduced at 50 ppm EPM. A reproductive per-formance experiment compared control and 0.05 ppm EPM treatment groups. While adult fecundity was not significantly affected, the EPM treatment resulted in complete failure of progeny development, with no adult emergence. The study demonstrates that environmentally relevant EPM concentrations can negatively impact O. hircus populations through larvi-cidal effects, even when adult survival and reproduction appear unaffected. This highlights the importance of considering long-term impacts when assessing the environmental risks of antiparasitic drugs on beneficial dung fauna. The laboratory rearing model developed provides a valuable tool for further ecotoxicological research on dung beetles.