Co-occurrence or dependence? Using spatial analyses to explore the interaction between palms and triatomines (Chagas disease insect vectors)
Authors: Calderón Johan M. , González Camila 
Published: May 2019

Background

Triatomine kissing bugs are responsible for the vectorial transmission of the parasiteTrypanosoma cruzi,etiological agent of Chagas disease, a zoonosis affecting 10 million people and with 25 million at risk of infection. Triatomines are associated with particular habitats that offer shelter and food. Several triatomine species of theRhodniusgenus have close association with palm crowns, where bugs can obtain blood from the associated fauna. TheRhodnius- palm interaction has been reported in several places of Central and South America. However, the association in the distributions ofRhodniusspecies and palms has not been quantitatively determined.

Methodology/Principal Findings

Broad distributions of eightRhodniusspecies and 16 palm species withRhodnius-infestation reports were estimated using Ecological Niche Models.Rhodniusspecies distributions in their total range were compared to their distributions in areas with palms.Rhodniusspecies presence was found to be higher in areas with palms. However, that tendency notoriously depended on palm species.Rhodniusspecies presence increased several times in areas with particular palm species. Moreover, a possible relationship was found betweenRhodniusand palm species richness, indicating the Amazon region as the convergent region where severalRhodniusand palm species intersected. Finally, palm distribution was evaluated as predictor ofRhodniusspecies distributions, but their inclusion in the distributions models did not improve their performance.

Conclusions/Significance

The distributions of someRhodniusand palm species showed a high spatial association, which can be based on species interaction or niche similarity. Based on distribution convergence, the Amazon region appear to be the origin of theRhodnius-palm association. The direct relationship between palms andRhodniusspecies richness could be based on the habitat heterogeneity offered by different palm species. Despite spatial association, palm presence would not be a relevant predictor ofRhodniusspecies distributions in comparison to other environmental variables. Inclusion of other input data as hosts’ distribution could help to increase model predictability.

Author summary

The infestation of palms withRhodniusgenus kissing bugs (Chagas disease vectors) is important from the public health perspective, since insects living in palms can infest nearby houses. The migration of these bugs to households could threaten vector control programs since reinfestation of treated dwellings can occur. Association betweenRhodniusand palms species distributions has been previously suggested but never quantitatively determined. The strong association between one palm species and oneRhodniusspecies can be used as a factor to predict the presence ofRhodniusbugs in definite areas. In this study, we estimated by models the distributions of eightRhodniusspecies and 18Rhodnius-infested palm species.Rhodniusdistributions models showed a biased presence toward areas with certain palm species. That specific association was very strong in some cases; however, the presence of associated palm species was used inRhodniusdistributions models, but that did not improve the predictability of the models. Palm presence appear to be not essential for theRhodniuscurrent distribution because they could inhabit other habitats; but that association could be relevant to theRhodniusevolutionary and biogeographic history.