Influences of food web dynamics on multi-host vector-borne pathogen transmission: Using chagas disease as a model system

Background/Question/Methods

The study of food webs incorporates community and ecosystem ecology in a quantitative framework to understand species relationships within an ecosystem. Therefore, food webs can provide information on how species community structure influences the transmission of infectious disease agents. The zoonotic multi-host vector-borne pathogen, Trypanosoma cruzi, cycles between triatomine vectors and a variety of mammalian hosts, including humans, throughout the Americas. In Panama, T. cruzi is transmitted  between the sylvatic vector, Rhodnius pallescens and mammalian arboreal hosts within the royal palm tree, Attalea butyracea. Research suggests that abundance of R. pallescens increases within palms in disturbed landscapes. This pattern in vector abundance may be a response to changes in intra-palm species communities along gradients of microhabitat and landscape disturbance across a matrix of land use change in central Panama. Eleven palm crown communities were sampled in peridomicile, pasture, and secondary forest habitat sites in La Chorrera and Trinidad de Las Minas, Panama. Palm dissection techniques and invertebrate and vertebrate observation and collecting methods were used to determine intra-palm crown community. Species community structure was analyzed and compared across palms using the food web network modeling program, Network 3D.  Rhodnius pallescens abundance was compared alongside community measurements and across each palm.

Results/Conclusions

Similar to previous findings, there was an increase in vector abundance within palms in peridomicile habitats. Furthermore, palms with higher vector abundance contained a greater number of trophic species compared to the palm sampled from early secondary forest. However, species community structure did not vary significantly across all palms sampled. It is suspected that communities within disturbed habitats contain habitat tolerant species (i.e. cockroaches) and lack habitat sensitive species (i.e. tarantulas) which serve as primary predators and are integral in vector control. A greater number of palms (N=50) needs to sampled and is currently underway. Food web analysis is a novel approach to understanding multi-host vector-borne dynamics and can be applied to determining natural methods of vector control. Results from this study can be further applied to the prediction, prevention, and management of Chagas disease in Latin America and understanding similar zoonotic disease systems.