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Selecting biological control agents

Predicting direct non-target impacts

Selecting agents for safety

Realising the value of New Zealand's databases for biological control

New Zealand's agricultural landscape is remarkable for the fact that it is composed almost entirely of Northern Hemisphere plant taxa and is essentially no more than 150 years old. The majority of species in these new agricultural landscapes are also exotic invaders from the North, although a few intrepid native species have also successfully adapted to these novel landscapes. The exotic invaders include both pests and natural enemies, and the latter include suites of parasitoids and predators, most of which arrived accidentally over time rather than as part of deliberate biological control programmes (Charles 1998).

New Zealand's long history of activity in biological control and ecological research in agricultural ecosystems (Cameron et al. 1989) means that there is an extensive database of many of these species (Ferguson et al. 2007). Some have been here for many decades, others continue to arrive annually at present. Those that have been here for some time provide a valuable resource for risk analysis, in that it is possible to measure the actual, realised extent of their impact on native fauna and compare that with criteria that would be considered or predicted by modern host-range testing in quarantine conditions. This approach can allow direct testing of some of the bullet points posed above (e.g. Charles and Allan 2002 and ongoing research). If and where ecological 'safety' of related natural enemies can be demonstrated, then such empirical data can add confidence to host-specificity predictions of proposed new, biocontrol agents. Improved knowledge of the ecology of New Zealand's exotic natural enemy fauna may hence provide a valuable 'anchor' for future biocontrol theory, host-range testing procedures, and new biocontrol programmes.


Cameron P.J., Hill R.L., Bain J. and Thomas W.P. (1989). A review of biological control of invertebrate pests and weeds in New Zealand 1874-1987. CAB International Wallingford, UK and DSIR, New Zealand.

Charles J.G. (1998). The settlement of fruit crop arthropod pests and their natural enemies in New Zealand: an historical guide to the future. Biocontrol News and Information 19: 47-58

Charles J.G. and Allan D.J. (2002). An ecological perspective to host-specificity testing of biocontrol agents. New Zealand Plant Protection 55: 37-41

Ferguson C.M., Moeed A., Barratt B.I.P., Hill R.L. and Kean J.M. (2007). BCANZ - Biological Control Agents introduced to New Zealand.