History, opportunities and challenges for biological control in Australia, New Zealand and the Pacific islands

Abstract

Biological control of weeds has a history spanning over a century; projects began on lantana in Hawaii (1902), and on cactus in Australia (1912). Many projects have been initiated in Australia and New Zealand, while the Pacific Islands have depended on the transfer of agents from elsewhere. There are 26, 12, and four weeds currently biological control targets in these regions, respectively. Projects vary from native range surveys for potential agents, to distribution of established agents, assessment of their impacts and potential for non-target effects. Many opportunities exist for biological control in the region. For example, the Australian flora includes 2000 species of naturalised plants and 20 new exotic plant species are recorded annually. Of a national list of 71 weed species, less than a third have been targeted by biological control including 11 that are current. Similarly, New Zealand has 2108 naturalised plant species, a new species naturalises every 39 days and 500 species are currently classed as weeds, of which 200 are controlled by legislation. Only a small fraction of these are currently targets for biological control. New avenues of research include the biological control of grass weeds, and integrating biological control with other management tools. There are considerable challenges ahead such as selecting the best agents, accurately predicting host ranges and predicting distributions. There are problems maintaining support to work in the vast, sparsely populated, low economic value, lands of Australia, and the scattered islands of the Pacific, which may have high cultural and biological diversity and endemicity. For the longer term, biological control will need to expand its focus ensuring that it contributes to broader goals in natural resource management. After a brief introduction to the history of biological control of weeds in the Australian, New Zealand and Pacific Island regions, this paper examines current and potential activities, the opportunities they offer to improve our understanding and our ability to manage weeds, and the challenges weed researchers face while ensuring that the potential of biological control in sustainable weed management is realised.