BENEFITS FROM BIOLOGICAL CONTROL OF WEEDS IN AUSTRALIA

Australia has a long and successful history in weed biological control, second only to the usa. a new book reviews all 73 weeds targeted in australia, listing the >200 insect and pathogens released as biocontrol agents. biocontrol programs have targeted agricultural, pastoral, rangeland, aquatic, and environmental weeds in tropical and temperate australia. despite so many releases over more than 100 years, there has been very little damage to non-weedy plants. in an economic impact assessment done in 2006 on the 36 programs for which there was economic data, only nine gave few or no economic benefits. thirteen programs resulted in very large economic benefits, including those against blackberry and lantana which had been considered failures. biocontrol against parthenium started in 1977 and cost over $11 million, but benefits from reduced control costs and increased pasture production exceed $39 million. parthenium is still abundant in central and north queensland but is now much easier for landholders to manage, and the economic benefits are very great. overall, biocontrol has returned annual benefits of $95.3 million from an annual investment of $4.3 million. the australian experience demonstrates that weed biocontrol is very cost-effective, most programs are successful and the risks are very small. costs and risks are even smaller when using biocontrol agents already successful in another country. asian countries could benefit from proven agents against weeds of importance in this region, such as parthenium, chromolaena, mikania, and mimosa, to gain the economic benefits already captured by australia.