Evaluating Risks of Introducing a Predator to an Area of Conservation Value: Rodolia Cardinalis in Galápagos

Conservation areas can be highly susceptible to alien species introductions, and therefore extra care should be taken to assess potential interactions between a biological control agent and its new environment. In the Galápagos Islands, biological control was first considered to mitigate the threats posed to flora and specialist phytophagous Lepidoptera by the invasive scale Icerya purchasi Maskell (Hemiptera: Margarodidae). Rodolia cardinalis Mulsant (Coleoptera: Coccinellidae) was selected as a candidate agent, but a risk assessment that included prey range studies was considered necessary to evaluate the threats to Galápagos biota. In this paper important considerations for assessing the potential impacts of introducing an insect predator into a vulnerable ecosystem and for defining test procedures are discussed. These include the assessment of potential ecological impacts at different trophic levels, criteria for identifying and ranking non-target species, and the use of the precautionary principle for assessing acceptable levels of risk. Limitations encountered in conducting tests are also discussed, such as test species availability and the influence of host volatiles.