Philornis Downsi Interactions With Its Host In The Introduced Range And Its Parasitoids In Its Native Range

Abstract

The study of ecological interactions is important for the management of invasive species. In the Galapagos Islands, an invasive parasitic fly, Philornis downsi Dodge & Aitken (Diptera: Muscidae), is causing high rates of mortality among endemic avifauna. Long-term management of this invasive fly is not yet available, and research is needed to further understand the interactions among its host and its natural enemies to further consider management strategies. My research examines the interactions of Philornis downsi with one of its hosts in the Galapagos Islands and with its natural parasitoid enemies in mainland Ecuador. I studied the interactions between the fly and one of its hosts, the Galapagos flycatcher (Myiarchus magnirostris) in the Galapagos Islands, as well as with the fly’s natural parasitoid enemies in mainland Ecuador. My studies in the Galapagos Islands showed that Philornis downsi is mainly vespertine (active at dusk) and that its activity was higher when adult birds were more active around nests. And, my studies in mainland Ecuador showed that almost all parasitoids that emerged from Philornis pupae encountered in mainland Ecuador did not emerge from experimentally deployed pupae of non-Philornis fly species. The results of my thesis will provide information on P. downsi interactions which could aid in its management. Additionally, understanding these interactions should simplify the efforts to mitigate the impact of the fly and avoid the possibility of future extinctions of endemic avifauna in the Galapagos Islands.