Trophic interactions between mammals and insects and implications for conservation in tropical Asia

Abstract

Forest loss (particularly from agriculture and urbanization), climate change, and wildlife trade are among the largest threats to biodiversity in tropical Asia. The consequences of these threats are numerous and research is needed to understand and manage such environmental changes. Arthropod communities can be especially susceptible to even minor environmental disruptions and given that many arthropods are a primary food source for many other organisms, fluctuations in their communities are likely to affect food web interactions. Ants, as micro-environmental engineers, are particularly important in facilitating and influencing a variety of ecosystem processes, including decomposition, predation, and herbivory. To understand how different trophic interactions (vertebrate and invertebrate) are affected by climate and loss of species, I used a large scale ecosystem manipulation experiment where ants and termites were suppressed during a drought and non-drought year in the Maliau Basin in Malaysian Borneo. I looked at the impacts of suppression on hemipterans – a strictly predacious or herbivorous order of insects. I found a significant effect on hemipteran assemblages and a positive effect on the abundance of herbivorous hemipterans in the drought year in ant-suppressed plots. To further investigate habitat disturbance and its effects on insects, mammals and food webs, I looked at ant community composition in recently burned and unburned hillsides in Hong Kong. The results showed that all sites (burned and unburned) have similar ant species compositions though ant species richness was higher in unburned sites. I then studied pangolin habitat suitability through burrow surveys using a combination of camera traps and “reconnaissance walks”. A subset of suspected pangolin burrows was monitored using infrared camera traps and all were confirmed to be active. Subsequently, eight country parks were surveyed and a total of 25 burrows were recorded. Assessing habitat suitability using locality data and high resolution raster data in the context of a species distribution model, I found that “distance to coast” (potentially a proxy for green space fragmentation or core habitat) consistently correlated positively with high habitat suitability for the species. The results provide important insights into Chinese pangolin habitat suitability in Hong Kong and lay a pathway forward for future research. The results altogether highlight the importance of studying the interactions between insects and mammals for conservation, particularly in Asia where biodiversity threats continue to mount and imperil tropical ecosystems.