As a natural method, biocontrol doesn’t require the use of chemicals and machinery which can have a negative impact on the environment. It’s also economically efficient and sustainable, as once self-replicating and co-evolved natural enemies are established, they should provide control indefinitely without further cost or intervention.
Environmental – Biological control is natural and doesn’t rely on the use of man-made chemicals that can adversely impact an ecosystem. It also allows the amount of herbicides required for weed control to be reduced.
Cost – After the initial research costs, once the agents are established and having an impact on the weed the only further expenditure required would be that used for monitoring activities.
Sustainability – It’s permanent, and therefore completely sustainable. The weed is continually under attack from an army of natural enemies.
Spread – The control agents, be they insects or pathogens, locate and affect most – if not all – populations of a weed until they’re stopped by physical, environmental or chemical barriers, just as they would in their native range.
Safety – Biocontrol agents pose no threat to human health, crop production or beneficial organisms.
Landscape – While the agents are doing their job, previously out-competed native species can gradually recover and recolonize areas without the need for extensive replanting.
Control not eradication – A successful agent should not eradicate the weed on which it depends, but reduce it to acceptable levels instead. There may be costs associated with alternative control methods.
Timescale – It takes time. It can take between five to 10 years from release to achieve successful control.
Impacts – The complete impact on the target weed is not always predictable.
Other management options
Doing nothing – Invasive weeds will continue to have a devastating effect on native flora and fauna, damage the built environment and national economies, and affect people’s health.
Chemical control – Chemical herbicides can be effective where permitted, but using this method of control on a large scale is costly and could impact on biodiversity. Many of the worst invaders are aquatic or grow beside rivers where use of chemicals is banned or severely limited.
Manual control – Manual control methods are available for most invasive weeds, but are rarely viable on large scale invasions because they are labour-intensive and costly.