Genetic diversity and geographic distribution of parasitic flies of the Philornis torquans complex in Argentina.

Philornis Meinert 1890 (Diptera: Muscidae) is a genus of flies that parasitize birds in the Neotropical region. The characteristics of the host-parasite interactions and its consequences may depend on the Philornis species involved, and thus precise identification of these parasites is crucial for the interpretation of ecological and epidemiological studies. However, morphological identification of Argentine Philornis species is elusive while molecular evidence points towards the existence of a complex of cryptic species or lineages undergoing a speciation process, which were named the 'Philornis torquans complex'. Herein the authors extended the current knowledge on the systematics and biogeography of parasitic Philornis flies from Argentina, analysing samples collected in several ecoregions, including the Atlantic Forest, Iberá Wetlands, Open Fields and Grasslands, Espinal, Pampa, Dry Chaco, Humid Chaco, Delta and Paraná River Islands, Monte of Plains and Plateaus. The results of the present study strengthen the evidence on previously described Philornis genotypes using four genetic markers (ITS2, COI, ND6, 12S rRNA). The authors report new patterns of occurrence and describe the presence of a novel genotype of subcutaneous Philornis. In addition, the present study unveils ecological niche differences among genotypes of the Philornis torquans complex in southern South America.

Environmental variables determining the distribution of an avian parasite: the case of the Philornis torquans complex in South America.

Philornis flies are the major cause of myiasis in nestlings of Neotropical birds, being of major concern in geographically-restricted and endangered bird species. Despite its relevance for the conservation of birds, there is little information about the environmental dimensions determining Philornis spp. geographical range. By using maximum entropy, we identified for the first time the macro-environmental variables constraining the abiotic niche of the P. torquans complex in South America, and provided a model map of its potential distribution based on environmental suitability. We identified the minimum temperature of the coldest month as the most relevant variable, associated with the largest decrease in habitat suitability in Brazil and northern South America. Furthermore, the mean temperature of the warmest quarter limited suitability mostly along with the Andean range. In addition, humidity and moisture are influential factors in most of Argentina, northern Chile, and coastal Peru. The geographical projection suggests that environments in most of central-eastern Argentina, and in a broad area in central Chile, are suitable for the presence of the P. torquans complex. Besides providing information about the ecology of Philornis spp., this study represents a tool for bird conservation and a reference for future work on the distribution of this genus.