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By Fiona McFarlane Helen Paynter 29 June 2022 3 min read

We have a knack – it’s a sort of super-power. While we can't fly, we know how to harness fungi and insects to help us manage weeds as part of Australia's biosecurity.  

Australia's biosecurity system is incredibly important. Therefore, we need these super-powers to help us protect our environment and way of life. 

The cabomba weevil is about the size of a grain of rice.

But what is biosecurity exactly? 

Biosecurity is the way we stop the introduction and spread of harmful organisms into our country. This also extends to how we manage the impacts of those already here. 

These harmful organisms can be insects, animals, plants, viruses, bacteria and other pathogens (pathogens are organisms that cause disease).

Australia maintains a strong biosecurity system. We apply biosecurity measures to help prevent, respond to, and recover from pests, weeds and diseases that threaten the economy and environment. 

Accordingly, the system operates across multiple levels of government, industry, research and community.  

Biosecurity is everyone’s responsibility. Declaring goods you wish to bring into the country is a common responsibility for example. This can also extend to looking for signs of unusual disease in our crops, animals or the broader environment. 

But what does this have to do with insects and fungi? 

As your national science agency, we are committed to finding solutions to challenges facing Australia's health and biosecurity systems. 

And invasive weeds are a major biosecurity challenge. Weeds are among the top three threats to the natural resources and biodiversity of Australia. 

Moreover, they cost Australia’s economy more than $5 billion per year. Grain growers alone spend more than $2.5 billion per year on weed control. 

We've been researching the use of biological control agents to manage our unwanted weeds for many years now.  

Insects and fungi can be excellent biological control agents. They can help us manage many of Australia's most pressing agricultural and environmental weeds in the long-term. 

The cabomba weevil is the first biological control agent used against cabomba, and doesn’t pose risks to native plant species.

How does biological control of weeds work? 

Biological control, often called biocontrol for short, uses a weed's specialised natural enemies (called biocontrol agents) to help suppress it. 

Doing this isn't as straightforward as it may sound. There is a rigorous and regulated process to follow before releasing a biocontrol agent to manage a problem weed. 

We have a lab in Montpellier, France. Many of our biocontrol agents originating in Europe and North Africa are taken to this lab before travelling to Australia. Once the biocontrol agent has been studied in the field, many make their way to our lab in France. Once there, they will be studied further for biosecurity processing.  

What about biocontrol agents from other locations? We work with local collaborators and institutions to undertake similar research to that in our French lab. 

These processes culminate to help us ensure that any new biocontrol agent will not cause harm to our nativre and desirable plants. However, it can take several years for a new biocontrol agent to be ready for release into the field. 

So this timeframe means our researchers can be working on solutions for several different weeds over time.

Wonderful weevils and fighting fungi  

Our researchers are investigating fungal biocontrol agents in the fight against two major environmental weeds.

The scourge of sea spurge 

Our scientists have found a fungus, Venturia paralias, that is highly specific to sea spurge. Sea spurge, Euphorbia paralias, is a major plant invader of our beautiful southern beaches.  

Controlling it with smut 

Our scientists have been releasing the leaf smut fungus, Kordyana brasiliensis, as a biocontrol agent. The smut fungus is targeted to help control a weed called wandering trad, Tradescantia fluminensis. This weed is smothering our forests and clogging waterways.  

Watery weevils 

Cabomba (Cabomba caroliniana) is a submerged aquatic weed of slow-moving water bodies. It affects water quality, recreational activities, public safety, and aquatic biodiversity.  We are studying the cambomba weevil, Hydrotimetes natans, as a biocontrol agent.

Your experts in biocontrol 

We are one of the leading global exponents of risk-analysis based biocontrol. This makes us one of the few agencies capable of providing biocontrol research and management support for several weeds. This includes those of national significance. 

Lastly, our researchers have successfully demonstrated that different biocontrol agents can reduce weed populations with no adverse effects on native Australian wildlife and plant, livestock and crops, or human health.  

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The above video shows the Larva of the cabomba weevil seen hollowing out the stems and leaves of the plant.

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