BioClay developed by University of Queensland researchers a big win for farmers

Silverleaf whitefly (Bemisia tabaci) is a big concern for Australia's cotton industry as it can contaminate and downgrade lint quality.

It is also a problem for pulse producers and the horticultural industry, attacking more than 500 plant species.

The pest produces a honeydew when feeding that causes sooty mould to grow on leaves, damaging cotton lint as well as fruit and vegetable produce.

Controlling silverleaf whitefly has proven difficult due to its ability to quickly develop resistance to traditional chemical pesticides.

That's why scientists at The University of Queensland have spent the past decade developing BioClay, an environmentally friendly spray able to target and kill this pest.

Research team leader Professor Neena Mitter said BioClay would be a game-changer for crop protection.

"Silverleaf whitefly is considered an invasive species in the United States, Australia Africa and several European countries and attacks more than 500 plant species including cotton, pulses, chilli, capsicum, and many other vegetable crops," Professor Mitter said.

"The insect lays eggs on the underside of the leaves and the nymphs and adults suck the sap from the plant resulting in reduced yields."

Silverleaf whitefly also poses a threat to otherwise healthy crops as it can transmit a variety of viruses.

So how does BioClay work?

It is a spray that uses degradable clay particles to carry double-stranded RNA, which enters and protects the plant without altering the plant's genome.

Professor Mitter said this was the first time the BioClay platform has been used to target sap sucking insect pests.

"When whiteflies try to feed on the sap, they also ingest the dsRNA, which kills the insect by targeting genes essential to its survival," she said.

"The world of RNA is not just responsible for COVID-19 vaccines, it will also revolutionise the agricultural industry by protecting plants from viruses, fungi and insect pests."

Not all insects are harmful though and that's why PhD candidate Ritesh Jain went through the global database of genome sequences to identify suitable gene targets.

"Initially, we had to screen hundreds of genes specific to SLW to see which ones would affect their growth," Mr Jain said.

"Importantly, the dsRNA proved harmless when fed to other insects, such as stingless bees and aphids."

Bioclay was developed by UQ's Queensland Alliance for Agriculture and Food Innovation and the Australian Institute for Bioengineering and Nanotechnology.

The research has been supported by the Horticulture Innovation Australia grant and has also received funding from the Cotton Research and Development Corporation and Nufarm.

Researchers will now partner with Nufarm to test the whitefly BioClay formulation in real-world production systems.

Read more:

CRDC senior research and development manager Susan Maas said this innovation would support the industry to maintain Australia's reputation for producing uncontaminated, high-quality cotton in a safe and environmentally friendly way.

Hort Innovation research and development manager Dr Vino Rajandran said the spray could give the industry another tool in its biosecurity armoury.

"It has the potential to save growers time and money and is a great example of industry levy investment in action," Dr Rajandran said.

The research is being published today in the scientific journal, Nature Plants.