Declining Dung Beetle (Coleoptera: Scarabaeidae) Abundance and Diversity in the Neotropics: Causes and Conservation Strategies

Dung beetles are one of the best-studied insect groups in the Neotropics. Their fundamental role in ecosystems as recyclers of organic material produced by vertebrates contributing to nutrient turnover in biogeochemical cycles make them a well-known insect group in the Neotropics. They are distributed in both native and agroecosystems and are sensitive to changes in land use. Dung beetles can be used as bioindicators of change in the biological diversity (e.g., taxonomic, phylogenetic, and functional) of a site, to assess the impact of changes from original vegetation to that from other land uses, including shifts in soil quality. Such changes can help support decisions such as land-use practices that should be avoided or preserved. We identify the main threats to the diversity and anthropogenic drivers of declines in Neotropical dung beetle communities and functions (habitat fragmentation, deforestation, agricultural management, defaunation, hunting, fire, invasive species, urbanization, and global environmental change). Most studies in dung beetle ecology are related to each driver, resulting in reduced species richness, abundance and biomass, changes in community composition, increases of generalist species, and homogenization of assemblages. There are also descriptions of the primary constraints and limitations of dung beetles and their ecological functions, and for some factors, these constraints affect their survival, reproduction, and persistence over space and time. We identify gaps and needs in research in the population dynamics and natural history of dung beetle species and in studies that analyze the synergistic effects of identified drivers. Monitoring recent declines in population size or geographical range of some species is vital to understanding the mechanisms promoting extinction and the effects of anthropogenic influence, and this type of data is vital when detecting declines in population sizes and their causes. A tremendous information gap remains regarding dung beetle species inclusion on the IUCN Red List, a widespread situation for all invertebrates. We propose some topics for future research and draw conclusions on the consequences of human activities on dung beetles. We conclude formulating some suggestions for the maintenance and conservation of populations and communities of these beetles.