Beyond phoresy: symbioses between dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) and mites (Acari)

Decomposers are an essential component in any ecosystem and excrement represents one of the most abundant resources. Dung beetles and mites are important taxa in this microhabitat and interact in complex ways. Usually, a phoretic association is assumed, with mites merely being transported by beetles, but the extent of this relationship is poorly under-stood. We performed a comprehensive literature search and identified 245 relevant articles from which we recognised three major forms of symbiosis: i) commensalism, constituting phoresy with no cost to the host, ii) parasitism, in which preda-tion, competition, or antagonism feature to the detriment of one partner, and iii) mutualism, in which both beetle and mite derive benefit. We examine the evidence for commensal phoresy, negative effects (parasitism, predation, or competition), and mutualism. Further, we identify as research priorities the exploration of ecological succession and seasonal dynamics, the effect of introduced mite species on ecosystem services, and co-evolution. In conclusion, the association and potential success of a hypothetical "phoresy" between mites and dung beetles depend on several variables that need to be evaluated. Finally, there is a lack of empirical data regarding dung beetle-mite interactions, with a large knowledge gap in several aspects, mainly because phoresy remains understudied.