Human perturbations reduce dung beetle diversity and dung removal ecosystem function

Biodiversity drives ecological functioning, ultimately providing ecosystem services. Ecosystem processes are favored by greater functional diversity, particularly when groups of functionally different species interact synergistically. Many of such functions are performed by insects, among which dung beetles stand out for their important role in dung decomposition. However, anthropogenic disturbances are negatively affecting their ecological dynamics and ecosystem services. We conducted a manipulative field study, to evaluate the effect of human disturbance on dung beetle diversity (abundance, species richness, and functional group richness) and dung removal rates, comparing perturbed and conserved forests in three regions of Colombia (Caribbean, Andes, and Amazon). We also assess the relationship between dung beetle diversity and dung removal rates. Dung beetle diversity was assessed using pitfall traps, and specimens were measured and assigned to functional groups according to body size and dung relocation strategy. We used exclusion control units and experimental units to assess dung degradation with and without dung beetle activity and evaluate differences in removal rates between two dung removal strategies: paracoprids and telecoprids. Dung removal rates, abundance, and functional group richness were lower in perturbed forests compared to conserved forests. Dung removal increased with abundance, species richness, and functional group richness. Moreover, dung removal performed by telecoprids increased with species richness of telecoprids and paracoprids. Our results evidence a negative effect of human perturbation on dung beetle richness, abundance, and dung removal rates, and also that dung beetle diversity and functional group richness enhance dung removal rates.