The enemy release hypothesis underpins classical (or importation) biocontrol as a management technique for invasive species. Classical biocontrol has had resounding success when prospective control agents have been subject to appropriate screening before release. Occasionally, however, natural enemies have been reunited with their hosts accidentally. Such adventive agents may provide effective control but have also avoided the...

Pre-release efficacy assessments (PREA) can be used to prioritise the most damaging candidate agents for further studies in biological control programmes against invasive alien plants. This study assessed the efficacy of various potential enemies of Trichocereus spachianus (Riccob.) (Caryophyllales: Cactaceae), an invasive cactus in South Africa, in order to prioritise the most damaging candidates for further studies, includin...