Biological control of rangeland weeds in Australia

Abstract

Weeds of Australian rangelands have been the target for biological control since 1914. There have been several spectacular successes, e.g. prickly pear cactus (Opuntia spp.), with extraordinary ecological and commercial benefits. There have also been projects where no positive outcome has occurred, e.g. prickly acacia [Acacia nilotica (L.) Willd. ex Delile ssp. indica (Benth.) Brenan], parkinsonia (Parkinsonia aculeata L.), and creeping lantana [Lantana montevidensis (Spreng.) Briq.]. Numerous other projects are currently underway and require continuing support to achieve the stated aims. There is considerable potential to increase investment in biological control of rangeland weeds to improve outcomes of current projects and to implement new projects. There is promise of excellent benefits to cost ratios based on past performance. However, there is a worrying trend of loss of capacity in Australia to conduct biological control. Since resources will always be limited, it is important that the weeds that have the greatest impact on ecosystem function and commercial production are identified and targeted for management. Biological control should be part of the management strategies for those priority weeds when conflict over weediness v. commercial value can be resolved in favour of biological control, and when it is considered that biological control could offer benefits.