How do regeneration stages of Caatinga forests influence the structure of dung beetle (Coleoptera: Scarabaeidae) assemblage?

The Caatinga is a semiarid ecosystem that undergoes continual environmental disturbances through outdated production technologies and deregulated use of its natural landscapes. Bioindicators, such as dung beetles, are successfully used to understand processes of forest disturbance and subsequent regeneration. The aim of the present study was to evaluate the dung beetle assemblage of a region of the Caatinga with fragments at initial, intermediate, and late stages of regeneration. Sampling was conducted in forest remnants of northeastern Brazil between 2011 and 2013 during the dry and rainy seasons, using traps baited with dung and carrion. There were no differences in beetle richness and abundance according to stage of regeneration. However, there was higher abundance in carrion traps and during the rainy season, which also presented higher richness compared to the dry season. There was a difference in species composition among the fragments in late regeneration. Deltochilum irroratum (Laporte) and Canthon aff. simulans Martínez occurred predominantly in fragments with late regeneration. The harsh conditions and scarcity of resources in Caatinga during the dry season seem to be important factors that limit the activity of these beetles. As this ecosystem has high evapotranspiration rates, carrion, which is less ephemeral than dung, could be an important resource for the beetles, justifying the higher abundance attracted to this resource. Our results suggest that D. irroratum and C. aff. simulans have a strict distribution in conserved habitats and could be evaluated as indicator species of this ecosystem in future studies.