Can the host density rescue the viral transmission?: Effects of the avian-mosquito communities on the St. Louis encephalitis virus activity

Abstract

Arbovirus represents an ecological clustered of arthropod borne viruses. They depend of the interaction among vectors and hosts, and those might be driven by the variations at community, population and individuals vector-host level. Dilution effects predicts an scenario, where the transmission risk, on multi-host systems, is reduced as host diversity increases. Here, we focused on the effects of the structure and composition of the avian-mosquito community on the activity of St. Louis encephalitis virus (SLEV, Flavivirus). Avian and mosquito communities and the frequency of SLEV infection in Culex mosquitoes were prospected during three transmission seasons across the periurban-urban landscape in Cordoba city, central area of Argentina. Hypothesis related at community structure and density avian-mosquito level were represented and analyzed by general linear mixed models, when environmental and temporal viral activity heterogeneity were explicitly considered. Then, models performance were ranked following the Information Theory framework. The presence and the transmission of SLEV were not explained by neither of the diversity measures explored. Although, Eared Dove and mosquito density were related with at least two-folds increases in the number of SLEV infected Culex. Dilution effect exerted by biodiversity might not be driving the SLEV activity in the Cordoba city, meanwhile viral trait as the generalist host use could provide resilience to transmission when the composition of host and vector change. Finally, the results support an amplification effect by the density of particular community members on the transmission and amplification of SLEV such as Eared Dove.