F. ZHANG, S. TOEPFER, U. KUHLMANN
CABI Bioscience Centre Switzerland, Rue des Grillons 1, CH-2800 Delémont, Switzerland.   F.Zhang@cabi-bioscience.ch

The ability of introduced natural enemies to persist in the environment, to reproduce and to spread gives classical biological control a unique advantage as a pest control method. As an exercise in applied ecology, biological control has always been challenged to predict the outcome of complex population processes.  Despite many proven benefits, classical biological control has recently come under scrutiny because introduced natural enemies may adversely affect native species, especially rare and endangered species.  Concerns should be based on non-target impacts at the population level, rather than attack on individuals but there is debate on which species should be considered when evaluating non-target impacts.

The EU Project DIABROTICA (QLK5-CT-1999-011110) aims to select specific biological control agents of western corn rootworm for potential importation and establishment in Europe. With regard to the safety of biological control the guidelines of the European and Mediterranean Plant Protection Organisation (EPPO) for the importation and release of exotic natural enemies will be followed. Natural enemy surveys carried out in Mexico and Argentina revealed that parasitoids belonging to the genus Celatoria (Diptera: Tachinidae) and Centistes (Hymenoptera: Braconidae) are found to parasitize adults of Diabrotica and Acalymma species (Coleoptera: Chrysomelidae).

Prior to the importation of these adult parasitoids, a literature survey has been conducted to determine the host specificity of these potential biological control agents. In addition, the literature has been scanned to determine Coleopteran species present in the European cultivated agricultural habitats (with emphasis on maize, alfalfa, squash, wheat, sunflower, and grassland habitats) which might be at risk to from being parasitized by exotic parasitoids.  In Hungary, field surveys using sweep net samples were carried out to identify the Coleopteran species present in selected habitats. Simplifying principles have been developed to select potential non-target Coleopteran host species of greatest relevance for assessing the physiological host range of potential biological control agents in quarantine laboratory.