Abstract
The effects of biodiversity on the transmission of infectious diseases now stand as a cornerstone of many public health policies. The upper Amazonia and Guyana shield are hot-spots of biodiversity that offer genuine opportunities to explore the relationship between the risk of transmission of Chagas disease and the diversity of its triatomine vectors. Over 730 triatomines were light-trapped in four geomorphological landscapes shaping French-Guiana, and we determined their taxonomic status and infection by Trypanosoma cruzi. We used a model selection approach to unravel the spatial and temporal variations in species abundance, diversity and infection. The vector community in French-Guiana is typically made of one key species (Panstrongylus geniculatus) that is more abundant than three secondary species combined (Rhodnius pictipes, Panstrongylus lignarius and Eratyrus mucronatus), and four other species that complete the assemblage. Although the overall abundance of adult triatomines does not vary across French-Guiana, their diversity increases along a coastal-inland gradient. These variations unravelled a non-monotonic relationship between vector biodiversity and the risk of transmission of Chagas disease, so that intermediate biodiversity levels are associated with the lowest risks. We also observed biannual variations in triatomine abundance, representing the first report of a biannual pattern in the risk of Chagas disease transmission. Those variations were highly and negatively correlated with the average monthly rainfall. We discuss the implications of these patterns for the transmission of T. cruzi by assemblages of triatomine species, and for the dual challenge of controlling Amazonian vector communities that are made of both highly diverse and mostly intrusive species.
Highlights
Tropical and sub-tropical countries from all over the globe are vulnerable to two of the major scientific and socio-economic issues faced by today’s human societies; the loss of biodiversity and the burden of infectious diseases
About 68.7% were males and 31.3% females. They belonged to 8 different species, with a dominant species (Panstrongylus geniculatus) representing 62.8% of the community, three secondary species (Rhodnius pictipes, Panstrongylus lignarius, Eratyrus mucronatus) whose abundances add up to 32%, and a set of four other species (Panstrongylus rufotuberculatus, Rhodnius robustus, Rhodnius amazonicus, and Rhodnius paraensis) that collectively account for the remaining 5.2% of the community (Fig 1B)
The low level of equitability in the NC corresponded to a strong dominance of P. geniculatus that represented 74% of the triatomine community, while the intermediate levels of equitability in CP and IC reflected a codominance of P. geniculatus (67.3% in CP and 62% in IC) and the three secondary species
Summary
Tropical and sub-tropical countries from all over the globe are vulnerable to two of the major scientific and socio-economic issues faced by today’s human societies; the loss of biodiversity and the burden of infectious diseases. There are about 30–40 species of Anopheles mosquitoes [16], 30 species of tsetse flies belonging to the Glossina genus [17], more than 20 species of sandflies [18], and up to 70 species of triatomine bugs [19] that are capable of transmitting malaria, African sleeping sickness, leishmaniasis and Chagas disease, respectively. The effect of such insect vector biodiversity has received much less attention despite vector-borne parasites being severely detrimental to human health, and while arthropod diversity is already responding to climate changes [20,21]
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