Philornis downsi (Diptera: Muscidae), an Avian Nest Parasite Invasive to the Galapagos Islands, in Mainland Ecuador

A recent study reveals that the avian nest parasite Philornis downsi, native to mainland South America, has extended its invasive reach to the Galápagos Islands, where it targets Darwin’s finches and other land birds. The research identifies mainland Ecuador as a potential route for this invasion, based on the first documented presence of P. downsi in the region. Analyzing 20% of nests in 2013 and 27% in 2014 from western Ecuador, scientists found that P. downsi accounted for 74% (2013) and 40% (2014) of dipteran puparia, with lower parasitism rates than those observed in the Galápagos. Additionally, two new bird hosts—streak-headed woodcreeper and fasciated wren—were recorded for the genus Philornis. The study also documents a parasitoid wasp (Brachymeria) preying on P. downsi puparia, with emergence holes noted in 9% (2013) and 19% (2014) of samples. This research underscores the ecological impact of invasive species and highlights the need for monitoring to mitigate threats to native bird populations.

Bulgarella, M., Quiroga, M. A., Brito vera, G. A., Dregni, J. S., Cunninghame, F., Mosquera Munoz, D. A., Monje, L. D., Causton, C. E., & Heimpel, G. E. (2015). Philornis downsi (Diptera: Muscidae), an Avian Nest Parasite Invasive to the Galapagos Islands, in Mainland Ecuador. Annals of the Entomological Society of America, 108(3), 242–250. https://doi.org/10.1093/aesa/sav026