Is Philornis pici the only one parasite harming Ridgway's hawks

HAYES, C.; HAYES, T.; CORDERO-RODRIGUEZ; QUIROGA, M.

La Fortuna

Conferencia; IV Neotropical Raptor Conference. La Fortuna, Costa Rica.; 2016

The Peregrine Fund

Philornis (Diptera: Muscidae),is a genus of Neotropical bird-parasitic flies. Little is known about thebiology of Philornis species, as general information is limited to 28 of the 49described species. Although adult Philornis flies are non-parasitic andfeed on decaying organic matter, fruit, or flowers; their larva do parasitizebirds. Where known, the larval habits of Philornisspecies are divided into three groups: coprophagous (9%), semi-haematophagous(9%) and subcutaneous (82%). Dissimilar effects of infections with Philornisspp. have been found varying from light to lethal; and such variation depend onseveral host (body size, nest temperature, immune system), environmental(temperature, food availability) and parasite (larval habits, virulence) characteristics.As a consequence, an accurate identification of parasite species is of vitalimportance since many traits of the host-parasite association depend on theparasite species involved; in particular since multiple species of Philornismay be found parasitizing the same host. Unfortunately Philornis taxonomy is anissue of concern for ecoepidemiologists and taxonomists since the analysis ofexternal morphological characters proved to present some weaknesses. Somecharacters used to distinguish between Philornis species are based incoloration (that varies with the age of the parasite, its conservation methodand the light of the stereoscopes) or their values overlap (i.e.: equal number ofsetae on hind tibia anterodorsal surface). Furthermore, some of the knownspecies were described based on a single individual, thus not representing thefull spectrum of species variability. The Peregrine Fund has recorded Philornis pici infestation rates of70-80% of first nesting attempts by Ridgway?s Hawk, and rates of almost 100% insecond and third nesting attempts. Since infestations by Philornis are asignificant cause of mortality for Ridgway´s Hawk nestlings and infestations bydifferent species of Philornis may differ in form and severity, it is necessaryto identify the different species attacking the birds. This will ultimatelyhelp us in seeking different methods to control this parasite.Until now, P. pici was the only species of fly confirmed as a parasiteof Ridgway?s Hawks; however our survey indicated at least two more species: P. angustifrons and P. glaucinis are parasites of this endangered hawk; reason why their identification is amajor discovery. Our findings, besides sheddinglight on the parasites threatening Ridgway?s Hawks, highlight the need tocombine morphological, ecological and molecular studies to unveil the yetunclear taxonomy of the genus Philornis.