Physiology, ecology, and evolution of a successful colonizer: the horned dung beetle, Euoniticellus intermedius

Abstract

Insects are intentionally introduced to various regions out of their native ranges to perform fundamental functions, such as pest control, and some keep dispersing from introduction sites to become cosmopolitan and even invasive. The African horned dung beetle, Euoniticellus intermedius (Reiche) (Coleoptera: Scarabaeidae), has been intentionally introduced on multiple continents to bury cattle dung and control livestock pests, but has naturally dispersed and became very abundant at various latitudes and elevations out of its native and original introduction ranges. This beetle has been considered invasive, but there is no direct evidence of its effects on displacing native species. As it is highly fecund, E. intermedius has been an important model in experimental studies performed in nature and in the laboratory in multiple fields. In evolutionary biology, it serves as a model for sexual selection, given the sexual dimorphism characterized by the presence of a horn in males which is correlated with individual condition and strength, and which is absent in females. In ecotoxicology, it has been studied regarding physiological mechanisms of responses to contaminants, population declines, and evolutionary responses to challenging toxic conditions. Given its importance in burying dung in cattle pastures, experiments have also determined environmental conditions that limit this ecological function. Despite being unique in its tolerance to a wide variety of stressors and environments, this species is sensitive to current conditions of global change, including warming and pollution. We identify the most promising questions to be solved in physiology, ecology, and evolution, for which E. intermedius would be an ideal study system.