Dung beetle trophic ecology: are we misunderstanding resources attraction?

Abstract

Trophic ecology of dung beetles has been widely studied because of the important ecological role of these taxa. However, previous studies have focused on a limited number of potential food items (mainly vertebrate dung and carrion) and have used only one approach (either field or laboratory). Moreover, recent studies showed high abundance of dung beetles in defaunated areas with a low abundance of these resources. In this study, we combined a field and laboratory approach to explore dung beetle trophic attraction to different potential native resources in the Atlantic forest; and we evaluated whether results can explain the high abundance of dung beetles in defaunated areas. Through laboratory olfactometry experiments, we first exposed individuals to vertebrate carrion, omnivorous dung, and decomposing fungi. Then, we exposed species that exhibited a preference for dung to monkey, tapir, and feline dung; and those that preferred carrion and decomposing fungi to chicken, cow meat, and arthropod carcasses. We compared trophic attractions in the field and laboratory conditions with generalised additive models. We found that coprophagous species preferred monkey dung, and all necrophagous and sapro-necrophagous species preferred arthropod carcasses. These results suggest that the importance of arthropods carcasses as an important resource for dung beetles has been largely underestimated. The results of this study might provide an explanation for the high abundance of necrophagous and sapro-necrophagous dung beetles in defaunated areas. In addition, the use of omnivorous dung and arthropod carcasses could be an effective sampling method for dung beetle assemblages.