Ulex europaeus L. - Gorse

Gorse, Ulex europaeus, is one of the most invasive weeds in south-eastern Australia and is difficult to control by traditional methods. The annual cost of gorse management to agricultural industries alone has been estimated at $7 million. Biological control is being investigated as a cheaper and long-term control option to reduce the spread and impact of gorse, particularly in areas where it is widespread or inaccessible. Three foliage-feeding agents and a seed-feeder have now been released for its biological control in Australia. The gorse seed weevil Exapion ulicis, released in 1939, and the gorse spider mite Tetranychus lintearius, released in 1998, are now widespread across south-eastern Australia. The gorse thrips Sericothrips staphylinus, released in 2001, is now established and although initially slow to spread, populations have started to disperse exponentially in Tas. Establishment of the gorse soft shoot moth Agonopterix umbelana was confirmed in Tas in 2010 following its release in 2007. These four agents are expected to reduce plant vigour and seed output in the long term. Release of a second seedfeeding agent, the gorse pod moth Cydia succedana, will be dependent on the outcome of host-specificity tests. In combination with the gorse seed weevil, this species has the potential to reduce gorse seed banks below critical replacement levels in some areas. European surveys have found no new agents worth pursuing. Integrated control techniques offer the best prospects for long-term control in areas where gorse is actively managed, but the extent to which biological control will play a role will only be determined by future research once the complete guild of available agents is established.