Philornis downsi, Dodge & Aitken

Sinclair, Bradley J., 2023, An annotated checklist of the Diptera of the Galápagos Archipelago (Ecuador), Zootaxa 5283 (1), pp. 1-102 : 72

downsi Dodge & Aitken

Philornis downsi Dodge & Aitken, 1968: 138 . Fessl & Tebbich 1998: 55 [conference abstract report]; Fessl et al. 2001: 318 [first records]; Fessl & Tebbich 2002: 445 [threat assessment]; Carvalho et al. 2005: 63 [catalogue]; Fessl et al. 2006 [larval life cycle]; Causton et al. 2006: 125 [introduced species]; Dudaniec & Kleindorfer 2006: 13 [parasitic effects]; Wiedenfeld et al. 2007: 14 [distribution]; Dudaniec et al. 2008, 2009 [genetics]; Sinclair 2009: 113 [remarks]; Bulgarella et al. 2015: 242 [ Ecuador mainland population]; Kleindorfer & Dudaniec 2016: 1 [biology]; Fessl et al. 2018: 213 [colonization]; McNew & Clayton 2018: 369 [biology review].

Philornis isla Couri, 2000: 1 . Carvalho et al. 2005: 12, 63 [as syn. of P. downsi ].

Distribution. Introduced. Neotropical; Galápagos: Baltra, Champion, Daphne Major, Fernandina, Floreana , Gardner, Isabela, Marchena, Pinta, Pinzón, San Cristóbal, Santa Cruz, Santa Fé, Santiago, Seymour ( Causton et al. 2013; Fessl et al. 2018).

Remarks. This species ( Fig. 25 ) has been classified as one of the most highly disruptive invasive species on the islands and one of the most important threats to landbird conservation ( Causton et al. 2006; Fessl et al. 2018). The earliest record of this species was collected during the Galápagos International Scientific Project (housed in the CAS collection), and includes a series of specimens from Santa Cruz (arid and humid zones) collected in January and April, 1964 ( Fessl et al. 2018). Naris deformation in museum preserved specimens of Darwin’s finches also supports a post-1960s introduction of Philornis downsi ( Kleindorfer & Sulloway 2016) .

The larvae are obligate blood-feeding parasites of land birds with the first and second instars living in the nostrils ( Fessl et al. 2006). Older second instars and third instars live in the nest material and feed externally on the blood of nestlings. Biocontrol agents to help control this species are currently being investigated ( Bulgarella et al. 2017). Kleindorfer & Dudaniec (2016) published a review of the impact of the parasite on the Darwin’s finch hosts. Fessl et al. (2018) reviewed the colonization history and conservation challenges, McNew & Clayton (2018) reviewed the general biology of Philornis , and Romine et al. (2022) provided genome sequence data.

Figures

FIGURES 25–26. Galápagos Diptera, lateral view. 25, Philornis downsi Dodge & Aitken (Muscidae); 26, Galopagomyia inoa (Walker) (Sarcophagidae).