Australian researchers are tracking a notorious crop-destroying pest around the world as it spreads from continent to continent.
Fall armyworm (FAW) has been referred to as the “coronavirus of agriculture” and the devastation the moth causes has been likened to that caused by a bushfire.
It is known to feed on more than 350 plant species from maize to cotton and vegetables.
Growers in Queensland have been dealing with the worst incursion of the pest since it arrived in Australia in 2020.
Global food trade culprit
The fall armyworm, here in moth form, has decimated food and plant crops across the world. (Supplied: Biosecurity Queensland)
Like human ancestry tracing, analysing the moths’ genetics across the world allows the team from Australia’s chief science agency, the CSIRO, to determine the global path it has taken.
Principal research scientist Wee Tek Tay said they found it did not spread from its native home in tropical regions of the Americas to Africa, then onto Asia, and then to the Pacific, like once thought.
Dr Tek Tay said by analysing the genetics of the moths in each continent they found it invaded Africa and Asia in multiple areas around the same time.
“These multiple introductions were the result of human activities such as international trade,” he said.
“Anywhere in the world that is importing agricultural crops, as well as cut flowers, is a major trade pathway for invasive pests.”
Like other continents, FAW reached Australia’s shores on multiple fronts when it arrived in 2020, Dr Tek Tay said.
Very hungry caterpillar
Central Queensland sorghum grower Rhys Daniels said he had seen FAW in crops for four years, but this was the first time his farm was badly impacted.
“The crops just looked lethargic, they were yellow,” he said.
“There was all this chewing on the leaves, there were leaves missing. It just didn’t thrive.”
Scientists have mobilised to attack on numerous fronts using insecticides, beneficial bugs, and gene technology. (Landline)
Mr Daniels said the amount of sorghum he grew last summer was drastically reduced due to the pest.
Determining the path the different FAW populations had taken not only identified weaknesses in global biosecurity efforts, Dr Tek Tay said it gave growers tools to treat the pest by understanding the genetics of the one they were dealing with.
He said the pest in its caterpillar stage was the most damaging as it ate the crops.
Mr Daniels knows this well, as he sprayed insecticide on his crop to kill the FAW but said it was difficult because it hid in the whorl of a plant where the leaves and grain form.
“You can’t physically get the chemical onto it very easily,” he said.
“We mucked around with different nozzle selection … but you just don’t get very good control.”
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Dr Tek Tay said the different populations were genetically different enough that they had different resistance to different treatment options.
“We were able to demonstrate that they were resistant to different chemical insecticides and biological compounds such as BT,” he said.
BT crops are genetically modified to produce insecticidal proteins that naturally occur in bacteria found in soil.
In some parts of the world, such as the US, BT crops are grown to combat the devastation of FAW.
Fall armyworm decimated Queensland sorghum crops this year. (Supplied: Terry Staib)
Future tracking
The CSIRO team is continuing its work tracing the insect’s genetics.
In one project they are collaborating with the Rural Development Administration of South Korea to help understand how the pest is moving between neighbouring regions in Asia.
“That will be a resource that we can build to understand future introductions of potentially new populations coming to Australia,” Dr Tek Tay said.
He said they had not started the genome sequencing in Australia yet.
A fall armyworm is known to feed on more than 350 crops worldwide. (ABC Rural: Daniel Fitzgerald)
Meanwhile, growers like Mr Daniels are concerned whether this year is an indication of what is to come for their summer crops in the future.
He said sorghum in central Queensland was known as “captain reliable” as growers could get good yields most years.
“I hope it’s not the new normal because it’s going to devastate the industry,” he said.
Mr Daniels said he would plant sorghum this summer, but not as much as he had previously, and would have to further evaluate if the pest was bad again this coming season.
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