Dung beetles primarily rely on mammal dung as a food resource, and are thus affected by declines in mammal populations as a result of large-scale anthropogenic disturbances in tropical rainforests. Interactions between dung beetles and mammals have been little explored in Southeast Asia's forests, and especially in terms of assessing changes in network structures across an environmental gradient.
In a recent publication in Biotropica, titled "Dung beetle-megafauna trophic networks in Singapore's fragmented forests", we present the first trophic networks for Southeast Asia, and investigated the changes in network structures across five Singapore forest fragments that differ in size, isolation, and megafauna diversity. We also used dung baits from both extant and extinct megafauna species to determine whether present-day dung beetle communities are generalist in their feeding preferences.
Dung beetle-mammal interaction networks across the five study sites. Image 2022 Ong Xin Rui.
We found similar network structures and dung beetle communities among sites that were more connected, and a reduced network structure in the most isolated site. Our networks also revealed that Singapore's dung beetle communities displayed high nestedness (i.e. rare dung beetle species feed on a subset of dung types used by common dung beetle species) and high generalism. We see that dung beetles were attracted to both extant and extinct dung types, and even found that one species used dung from the reticulated python. This shows that certain species can display increased resilience during periods of low mammalian dung availability by exploiting a wider variety of food resources.