Problem Statement: Attempts to control the invasive weed Salvinia molesta D.S. Mitchell in Africa, India, Sri Lanka and Fiji, using a weevil, Cyrtobagous singularis Hustache, collected from Salvinia auriculata Aublet in Brazil failed.

Methods: In 1978, the native range of S. molesta was discovered in Brazil. A hunt began for a pest that could be introduced as a biocontrol agent in countries where S. molesta has become an invasive alien species. A weevil, thought to be C. singularis, and found on S. molesta, successfully decimated a large population of S. molesta in Queensland, Australia. The dramatic success of this biocontrol operation was reported by Room, Harley, Forno & Sands in 1981. In 1983, however, it was reported that, in fact, the weevil was not C. singularis as originally thought, but was a new species, later described as C. salvinae.

Outcomes and Impacts: The weevil has now been introduced in Africa, New Guinea, the US and elsewhere to successfully control this pest that was choking precious waterways.

Lessons: Knowledge of taxonomy and distributions of the two Salvinia species was critical to this important biocontrol project. Without taxonomy, funds would have been wasted on ineffective control projects.