BIOLOGICAL CONTROL OF WEEDS

l Weeds cost Tasmanian agriculture alone $58 million annually l The cost to the Tasmanian environment has not been estimated l In Tasmania, some weeds such as gorse each contribute industry production losses exceeding $1million annually SOME WEED FACTS

TIAR Weed Biological Control Programmes l Gorse l Ragwort l Horehound l Boneseed l Brooms l Slender thistles Current Programmes Targeting:

TIAR Weed Biological Control Programmes l 1.5 million during last 10 years l Sources: - Commonwealth Government - CRC for Australian Weed Management - Australian Weeds Research Centre Research Funding

What is weed biological control? The use of a living species, usually an insect, mite or pathogen, to regulate host plant densities The use of a living species, usually an insect, mite or pathogen, to regulate host plant densities Biological Control on Weeds

Classical Biological Control Generally involves introduction of natural enemies from their native range into an exotic range where their host plant has become a weed Generally involves introduction of natural enemies from their native range into an exotic range where their host plant has become a weed

Concept of Classical Biological Control To introduce natural enemies of a target weed that will reduce the density of the weed to a level that is acceptable and that will maintain the weed density at that level To introduce natural enemies of a target weed that will reduce the density of the weed to a level that is acceptable and that will maintain the weed density at that level

Features of Weed Biological Control l Environmentally friendly l Relatively cheap - initial research cost high but long term costs low as the agents are self sustaining and not restricted to one area l Projects may take 20 years or longer to complete

TIAR Weed Biological Control Programmes l Introduction, mass rearing, establishment and dispersal of biocontrol agents l Conducting agent efficacy studies l Developing integrated management strategies l Liaising with national and international organisations, local weed experts and weed management groups Focussed on:

Biological Control of Ragwort

Ragwort Control in Tasmania (Results) l Now substantial in many areas since the establishment of the ragwort flea beetle

Ragwort Control in Tasmania (Results) l The benefit-cost ratio of the biological control program has been estimated at 32:1 l Benefits to increase through the continuing spread of two additional biological agents l Benefits to increase through the application of integrated control strategies

Biological Control of Gorse

Biological Control of Gorse in Australia Gorse spider mite, Tetranychus lintearius (released 1998) Gorse thrips, Sericothrips staphylinus (released 2001) Gorse soft shoot moth, Agonopterix umbellana (released 2007) Gorse pod moth, Cydia succedana (pending) Gorse seed weevil, Exapion ulicis