Searching for putative avian malaria vectors in a Seasonally Dry Tropical Forest in Brazil.

Background: Haemosporidian parasites of the genera Plasmodium and Haemoproteus can have detrimental effects on individual birds and populations. Despite recent investigations into the distribution and richness of these parasites and their vertebrate hosts, little is known about their dipteran vectors. The Neotropics has the highest diversity of mosquitoes in the world, but few studies have tried to identify vectors in this area, hampering the understanding of the ecology of avian malaria in the highly diverse Neotropical environments.
Methods: Shannon traps and active collection were used to capture 27,110 mosquitoes in a Seasonally Dry Tropical Forest in southeastern Brazil, a highly endangered ecosystem.
Results: We screened 17,619 mosquito abdomens from 12 different species and several unidentified specimens of Culex, grouped into 1,913 pools, for the presence of haemosporidians. Two pools (out of 459) of the mosquito Mansonia titillans and one pool (out of 29) of Mansonia pseudotitillans were positive for Plasmodium parasites, with the detection of a new parasite lineage in the former species. Detected Plasmodium lineages were distributed in three different clades within the phylogenetic tree revealing that Mansonia mosquitoes are potential vectors of genetically distant parasites. Two pools of Culex spp. (out of 43) were positive for Plasmodium gallinaceum and closely related lineages. We found a higher abundance of these putative vectors in pasture areas, but they were also distributed in areas at intermediate and late successional stages. One pool of the mosquito Psorophora discrucians (out of 173) was positive for Haemoproteus.
Conclusions: The occurrence of different Plasmodium lineages in Mansonia mosquitoes indicates that this genus encompasses potential vectors of avian malaria parasites in Brazil, even though we did not find positive thoraces among the samples tested. Additional evidence is required to assign the role of Mansonia mosquitoes in avian malaria transmission and further studies will add information about evolutionary and ecological aspects of avian haemosporidia and untangle the diversity of their vectors in Brazil.