Frog-biting midges (Corethrella spp) as vectors of Trypanosoma sp. and Batrachochytrium dendrobatidis

Frog-biting midges use the mating call of male frogs to localize them and obtain a blood meal. As many hematophagous species, these midges can potentially transmit parasites and infectious diseases to their vertebrate host. In this study we examine the role of frog-biting midges as vectors of two common anuran pathogens: (i) Trypanosoma sp, a unicellular flagellate protozoa, and (ii) Batrachochytrium dendrobatidis (Bd), a chytrid fungus implicated in the decline or extinction of hundreds of amphibian species. In particular, we investigate the interaction of the midges with the túngara frogs, Engystomops pustulosus in Gamboa, Panama. Blood samples of túngara frogs revealed sexual differences in trypanosome infections consistent with the transmission of this parasite by the midges. Blood smears revealed that forty percent of the males were infected with trypanosomes while less than one percent of the females were infected; higher prevalence values were obtained using molecular tools. We identify the trypanosome species as a new lineage, phylogenetically related to other frog trypanosomes. We also examined frog-biting midges attracted to the calls of túngara frogs and quantified their Bd levels using qPCR. About ten percent of the midges were positive for Bd. We discuss the implications of the transmission of trypanosomes and Bd by the midges regarding its potential fitness consequences and role on population dynamics.