Differences in dung beetle (Coleoptera: Scarabaeinae) assemblages in different habitat types and habitat patches within the Verde Sumaco forest, Ecuador

Abstract

Scarabaeinae, the dung-eating beetle subfamily, comprises keystone species that perform a host of ecological functions. They are easily surveyed and respond to habitat change, making them suitable indicators of effects of land use conversion on biodiversity. I set baited pitfall traps in mature forest, secondary forest, and chakras, traditional home gardens, in Verde Sumaco, Orellana, Ecuador. I investigated the effects of habitat type and edge type (mature forest adjacent to river, secondary forest adjacent to river, and secondary forest adjacent to open farm) on Scarabaeinae diversity. I found significant effects on dung beetle capture on both habitat type (F(2, 21) = 3.38, p = 0.05) and edge type (F(1, 21) = 4.23, p = 0.05). Total captures of Eurysternus beetles (F(1, 12) = 21.73, p = 0.001), endocoprid species (F(1, 17) = 16.61, p = 0.001), and telecoprid species (F(1, 17) = 5.37, p = 0.033) were significantly greater when the edge was a transition between forest types or chakra, compared to when forest was adjacent to rivers or farms. Capture of the telecoprid group was significantly greater in secondary forest than mature forests (F(1, 17) = 13.91, p = 0.002). These differences may be explained by a combination of natural history, ecological adaptation, and human influence. Alterations in dung beetle assemblage will modify the ecological functions being mediated by these keystone species. Within terrestrial entomofauna, dung beetles are proportionally the most affected taxa, with the primary driver of decline being habitat conversion. Losing the ecological functions that these species provide could have appreciable deleterious impacts on moist tropical forests.