Galapagos Invasive Species:
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Black fly - a candidate for biocontrol?

Black fly bites Simulium ocraeceum, locally known as “carmelito” or black fly, is one of the introduced insects affecting the Galapagos, especially San Cristobal Island. This species was first recorded in 1989 in San Cristobal, and it has been occasionally reported in a few other archipelago islands such as Santiago, Floreana and Isabela.

Adults are abundant during the rainy season and produce bothersome bites on vertebrates and humans. Simulium ocraeceum is an Onchocerciasis known vector, and is the cause of economic loss as it reduces harvest efficiency due to the annoyance it causes to the farmers. Black flies also impact seriously on cattle farming as the bites of flies distract animals from foraging adequately, which brings as result, a reduction of milk and meat yield. The presence of these annoying flies could also deter tourists to the island. Annoyance produced by insects can be so intense as to prevent outdoors recreational activities.

A number of chemical products have been applied in order to control black fly, which have been very effective. However, eventual resistence and the long length of time that the chemicals remain in the environment have led to the replacement of  these products with less polluting compounds. The best means of control is with the use of a biological control method, which is regarded as less dangerous for the environment. In the search for a biological control agent Bacillus thuringiensis var. israeliensis (B.t.i.) has proven the most effective as it kills the larva and has less impact upon other macro vertebrates from freshwater ecosystems.

However, before developing a control program some previous studies have been studied to evaluate which factors determine success in a control program. Since 1999, the Charles Darwin Foundation has developed projects with the principal aim of:


Since 1999 most of the objectives in the project have been achieved, although it is necessary to continue monitoring at some study zones in order to obtain reliable data for evaluating the use of B.t.i. to control this invasive species.

Source: Charles Darwin Foundation and the Galapagos National Park.

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This website was created on 25 October 2004 by PT and JK