Invader’s success: behavioural and reproductive plasticity of interacting exotic dung beetles

Dung beetles have been introduced to non-native sites to perform dung removal function in cattle pastures. Despite some species becoming invasive, their behavioural and reproductive strategies remain to be elucidated in detail. Here we evaluated the shift in behaviour and reproduction of two species of dung beetles, Euoniticellus intermedius and Digitonthophagus gazella, when they interact with the same or other species out of their native range. Under natural conditions, E. intermedius brood masses were lighter in traps (i.e., field enclosures) with more total brood masses. In the laboratory, D. gazella induced faster dung colonization by E. intermedius and conspecifics. The presence of conspecifics or heterospecifics reduced reproductive success in D. gazella, revealing intense competition for dung. In the offspring, E. intermedius females emerged larger in the presence of D. gazella, revealing differential maternal investment triggered by competitors. In conclusion, behavioural and reproductive plasticity are fundamental for dung beetles to become successful invaders.