Management of an invasive avian parasitic fly in the Galapagos Islands: is biological control a viable option?

Abstract

The bird-parasitic fly, Philornis downsi, was first recorded in the Galápagos Islands in 1964 where it likely invaded from mainland Ecuador. This muscid fly is now the leading cause of recent declines in endemic landbird populations as its larvae feed on the nestlings of at least 19 bird species in the Galápagos, including many species of Darwin’s fi nches. As yet, no long-term control method has been implemented for P. downsi, but importation (also known as classical) biological control may be a viable option. Due to historically high-profiLe examples of biological control agents attacking non-target species, some consider biological control to be too risky to be compatible with conservation aims.