Rearing dung beetles (Coleoptera: Scarabaeidae): Identifying knowledge gaps and future challenges

Insect rearing systems are widely used in biological control, experiments, and for food supply including single, multiple, and mass rearing from small to large scales. An example of a reared taxon is the dung beetles, a speciose cosmopolitan group that provides essential ecosystem services to the environment. Dung beetle species have been translocated into several countries, such as Australia, United States, and Brazil, in ongoing efforts to fill niches not occupied by native fauna. The success of these programs depends on the capacity to rear sufficient numbers for successful field release, establishment, and experimental information; a task that needs to consider its reproductive biology. Many species of dung beetle are univoltine, long-lived, exhibit parental care, and produce small numbers of progeny. Rearing conditions need to promote the production of large, well-nourished, and fecund individuals. In this review, we synthesize the scarce literature on dung beetle rearing and appraise the abiotic and biotic factors that influence rearing initiatives. We identify major research priorities that allow the optimization of these programs. The published data focus on a restricted range of taxa. Further, the influence of factors such as soil moisture and composition, rearing media, temperature, and biotic interactions are poorly understood. Consequently, even for large-scale and well-funded projects, there is heavy reliance on institutional knowledge and anecdotal reports, with few published experimental evaluations. The most imperative goal for optimizing progeny is to conduct rigorous experiments with a wider range of taxa that lead to establishing efficient and specific rearing strategies and programs.