Biological control: An essential component of the toolbox for managing invasive species in the Galapagos Islands

Invasive species are the greatest threat to the long-term conservation of the Galapagos Islands and the well-being of its residents, and are the focus of a multinstitutional effort to reduce their impacts on these iconic ecosystems. Invasive insects and plants are especially challenging to control because of their ability to disperse and cover extensive areas. Importation biological control offers one of the few options for their permanent and sustained control. To date, biological control has only been used once in Galapagos with the release of the vedalia beetle, Rodolia cardinalis, against the invasive cottony cushion scale, Icerya purchasi. This likely saved several of the unique plant species from local or archipelago-wide extinction. The success of that project paved the way for the consideration of biological control as an important component in the toolbox for managing invasive species in the region. Biological control is now being considered for use against the avian vampire fly (Philornis downsi) and blackberry (Rubus niveus), both of which are having significant effects on biodiversity as stand-alones, which, in the case of the fly, is exacerbated when their ranges overlap. We discuss the importance of biological control for the protection of World Heritage sites and other protected areas, how biological control interacts with other control tools in the tool box, and some of the challenges associated with evaluating these options in areas of high conservation value.