Risk assessment of biodiversity impacts from release of biocontrol agents in livestock facilities in Norway

Summary

VKM assessed the potential risks to biodiversity in Norway associated with the import and release of biocontrol agents for management of house flies and stable flies in poultry farms, pig or sheep barns, cattle feedlots, and horse stables. Effective control of filth flies requires repeated releases of up to one million mass-reared individuals, but recent permits have restricted releases to lower numbers. Risk assessments were completed for the dump fly Hydrotaea aenescens, the parasitoid wasps Spalangia cameroni, S. endius, Nasonia vitripennis, Muscidifurax raptor, M. raptorellus and M. zarapator, and the hister beetle Carcinops pumilio. Nasonia vitripennis is a native species in Norway, C. pumilio is a non-native species that is widely established in Norway, and S. cameroni occurs on pig farms in southern Norway. Hydrotaea aenescens and M. raptor have been detected in low numbers, whereas S. endius, M. raptorellus and M. zaraptor have not been reported in Norway. The biological control agents are generalist predators and parasitoids that could affect native species through six impact mechanisms from the Environmental Impact Classification for Alien Taxa: competition, predation, hybridization, disease transmission, parasitism, and indirect effects. No impacts on native biodiversity have been documented where the non-native species occur in Norway or elsewhere. The potential for establishment and spread is low because the non-native species are associated with manmade habitats, have poor dispersal ability, and are warm-adapted species unlikely to cope with cold winters. Mitigation measures can reduce risks during import from commercial suppliers and releases in farms and stables, whereas surveillance programs could detect unexpected changes in insect communities. VKM concludes that the risks to native biodiversity in Norway are likely to be low from use of these biocontrol agents for management of pest flies in animal production facilities.