Host specificity, release, and establishment of the gorse spider mite, Tetranychus lintearius Dufour (Acarina: Tetranychidae), for the biological control of gorse, Ulex europaeus L. (Fabaceae), in Australia

The gorse spider mite, Tetranychus lintearius, is widespread on Ulex europaeus in Europe and its foliage-feeding activities can cause severe damage to plants. It has been released as a biological control agent for U. europaeus in New Zealand, the United States, and Chile following tests on over 100 plant species or cultivars confirming its host specificity to Ulex species. The suitability of T lintearius for release in Australia was tested on an additional 32 plant species or cultivars from the family Fabaceae that occur in Australia. The tests confirmed that T. lintearius was a genus-level specialist and would be unable to survive on any plant other than U europaeus in Australia. The first Australian field releases were carried out in Tasmania and Victoria in December 1998. Since then, field releases from laboratory cultures at 116 sites in Tasmania and 90 sites in Victoria have resulted in T. lintearius initially becoming well established in both states. However, examination of T. lintearius colonies in Tasmania and Victoria has shown that predation by the introduced Chilean predatory mite, Phytoseiulus persimilis and the native coccinellid, Stethorus histrio, is already widespread. These predators have the potential to significantly suppress populations of T. lintearius and severely restrict its usefulness as a biological control agent in Australia. (C) 2002 Elsevier Science (USA). All rights reserved.