Short- and long-term management options for an introduced parasite of Darwin’s finches in the Galápagos Islands

Mariana Bulgarella *1, George E. Heimpel 2

1 School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
2 Department of Entomology, University of Minnesota, St. Paul, Minnesota, USA

Philornis downsi is a bird-parasitic muscid fly native to mainland South America. It has invaded the Galápagos Islands where it is seriously diminishing populations of most species of Darwin’s finches. We studied and compared the rates of bird parasitism by P. downsi in its native range in mainland Ecuador with those found in their introduced range in Galápagos. Parasitism rates were much lower in mainland Ecuador than those found in the islands. We uncovered four parasitoid species attacking P. downsi in mainland Ecuador and conducted host-specificity tests on them. One parasitoid species, Conura annulifera, exhibited high specificity in quarantine experiments in the laboratory and is being considered as a candidate for importation biological control of P. downsi in the Galápagos Islands pending further study. In addition, we are assessing the feasibility of a short-term, stop gap solution to help the Galápagos birds until a more permanent solution is found and implemented.

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