Is genetically modified corn the answer to fall armyworm?

It’s a tiny caterpillar that’s difficult to detect, but for more than a year it’s been having a massive impact on crops in Australia, especially corn. 

Fall armyworm (FAW) has infiltrated six states and territories and is so hard to control farmers are whispering about a method that’s been off the table for almost two decades — genetically modified (GM) corn.

Maize Association of Australia chairman Stephen Wilson said questions were being raised about whether GM corn could manage the armyworm incursion.

“Anecdotally, I am hearing from the field farmers saying we need GM to help us control the insect,” he said. 

“It’s a major discussion point for the industry as a whole because for the last three decades we, as an industry, as the Maize Association, have been working uniformly to say we do not need GM in Australia.” 

Lessons from the US 

Since arriving in Australia in February 2020, fall armyworm has been detected in Queensland, the Northern Territory, Western Australia, New South Wales, Victoria and, most recently, in Tasmania. 

Fall armyworm is native to the United States, where it has devastated multiple agricultural crops, but growers there have different tools to fight it. 

North Carolina State University professor and extension specialist Dr Dominic Reisig said in their industry, corn was genetically modified to produce insecticidal proteins that naturally occured in a bacteria found in soil. It is known as BT corn.

Dr Reisig said while it was not specifically designed to treat FAW it had had an impact. 

“It was first commercially planted in 1996 but that particular crop that was planted did not control fall armyworm,” he said.

“So it wasn’t until different BT toxins were introduced that we really started to see fall armyworm control. 

“But because it’s a sporadic outbreak pest throughout the US it wasn’t like a huge, earth-shattering moment when we were able to control fall armyworm.” 

Are GMO crops the silver bullet? 

According to Dr Reisig, treating FAW across ag industries was a multi-pronged approach with insecticides and a GM crop. 

He said in corn the pest could infest a crop in different stages of its development. 

“Once it gets into the whirl it’s very difficult to control,” he said. 

“But the good thing is when it attacks in those (earlier) stages it’s not that damaging to yield — so the corn looks really bad but it usually pops out of it and it’s not a problem. 

“If fall armyworm attacks later in the season when maize has an ear, then it’s a problem. 

“Once it’s inside that ear you can’t control it and then it’s a really damaging pest in terms of yield and it’s really difficult to control with insecticides so BT (corn) is the way to go.”

He said insecticides were able to control the pest in other crops like soya beans or vegetables because the plants were structured differently.

Weighing up the losses 

Australia only grows three GM crops — cotton, safflower and canola. 

Corn has remained GM-free and, as a consequence, the industry has been able to access different markets including Japan and Korea. 

“End users such as snack food and cornflake breakfast cereal manufacturers have told us the whole time they do not want GM in their raw materials,” Mr Wilson said. 

“It would impact on both the export market and also on all the domestic markets — everything from dairy cows utlising the maize as grain or silage right through to beef cattle and right through to human consumption. 

“It’s a major, major, major impact that would need to be agreed to by all sectors of the industry.” 

A person opens a corn's covering to check if it's ripe.
Australia has been able to access multiple international markets as the corn grown here is GM free.(Pexels: Frank Meriño)

He said any trial would be complicated.

“You have all the regulatory issues of actually bringing germplasm into the country, you have the quarantine issues of having the facilities that could handle the GM product, then you’ve got the issues of field testing,” he said. 

“It would be a long, drawn-out process and we’d have to consider the impact on the industry as a whole because it’s very hard, if not impossible, to have part-GM, part-non-GM. 

“It’s a very expensive process and it makes the non-GM corn being in the minority a very expensive product that people have to pay a premium for.” 

In a statement, a spokesperson from the Federal Department of Agriculture, Water and the Environment said genetically modified maize seeds may only be imported into Australia under an import permit issued by the department, but that no applications had been made. 

Insecticide differences for fall armyworm

NEW research indicates there are variable levels of sensitivity to some insecticides between populations of fall armyworm (FAW) in different geographical areas of Australia.

FAW is a highly migratory, invasive pest that was first reported in Australia in February 2020 and quickly established across parts of northern Australia’s tropical and sub-tropical regions, including northern Queensland, the Northern Territory, and northern parts of Western Australia.

It has been detected in southern WA, New South Wales and Victoria.

The new findings are from two complementary projects, one being a comprehensive research project into FAW’s insecticide sensitivities and genetic make-up being led by Australia’s national science agency CSIRO, with co-investment by the Australian Centre for International Agricultural Research, the Grains Research and Development Corporation (GRDC), Cotton Research and Development Corporation, FMC Australasia and Corteva Agriscience.

CSIRO researcher Wee Tek Tay said the research provided evidence that two geographically separated populations – a WA population from Kununurra in the Kimberley region and a north Queensland population from Walkamin in the Tablelands region – showed variable levels of sensitivity to insecticides.

“Geographic variability in insecticide responses is not unexpected and is commonly observed in the closely related species Helicoverpa armigera,” Dr Tay said.

“The findings don’t necessarily indicate distinct genetic differences in the populations – results of genomic analyses are pending – but they do have implications for growers trying to manage FAW in the field.”

In the absence of a FAW population susceptible to insecticides, bioassays were conducted using H. armigera as a comparison.

Colonies of insects were raised in the laboratory for the tests using individuals sampled from limited areas.

Therefore, they are not necessarily representative of the population in that region, so some caution is needed in interpreting the findings.

NSW Department of Primary Industries (DPI) researcher Lisa Bird said an independent and complementary study of FAW susceptibility in five populations from north Queensland and one population from Kununurra also revealed geographic differences in sensitivity to some synthetic insecticides.

Both the CSIRO and the DPI studies found that FAW populations were between 50 and 150 times less sensitive to the pyrethroid alpha-cypermethrin compared with susceptible strains of H. armigera.

Both researchers found similar levels of variability in sensitivity to methomyl, ranging from three to 11 times less sensitive, in populations from north Queensland compared with susceptible strains of H. armigera.

In contrast, CSIRO found its WA population to be 52 times less sensitive.

Relative tolerance to indoxacarb was found in all FAW populations tested.

Populations from north Queensland were between 11 to 63 times more tolerant to indoxacarb than the susceptible reference strain of H. armigera.

Both researchers included a Kununurra population, with the CSIRO population being 208 times more tolerant and the DPI population being 61 times more tolerant.

This highlights the variability of FAW’s response to an insecticide even from within the same general region.

It is possible FAW has a natural level of tolerance to indoxacarb.

While chlorantraniliprole sensitivity was found to be similar in north Queensland populations compared with H. armigera, the WA colony tested by CSIRO was 15 times less sensitive.

However, there may still be significant variability in sensitivity to this chemistry within the Kununurra region and further work is needed to document the full range of naturally occurring geographic variability between Australian FAW populations.

Sensitivity to emamectin and spinetoram was found to be similar in all FAW populations and H. armigera.

GRDC biosecurity manager Jeevan Khurana said these results provided evidence that geographically different FAW populations in Australia can vary in their responses to insecticide.

“This new knowledge helps to guide insecticide choice,” Dr Khurana said.

“As always, growers are encouraged to judiciously select and rotate products to reduce selection pressure.

“While these studies don’t directly reflect field rates and conditions, it is important for growers to consider insecticide sensitivity when making decisions about product choice.

“Always use the full rate as stated on the label or permit.

“Where a rate range is specified, such as on current FAW permits for indoxacarb and chlorantraniliprole in maize, it is recommended to use the higher rate in accordance with the permit instructions.

“In addition, particular attention should be made to targeting early instar stages (hatchlings to second instar) before FAW entrenchment in the whorl or cobs can occur, and spray coverage (water volume, spray quality etc) should be optimised to ensure the larvae are receiving a lethal dose of the insecticide.”

Pest alert as FAW marches into cane

Cane growers and service providers are being urged to be on the lookout for signs of fall armyworm, following the first confirmed report of the pest in sugarcane.

Identified in a crop on the Atherton Tablelands late last month, the occurrence is thought to be as a result of a heavily-infested maize crop that bordered the cane.

Vigilance is key to managing the threat and responding appropriately, with growers and service providers encouraged to be on the lookout, particularly in blocks near corn/maize or other affected crops.

Early detection coupled with accurate diagnosis will assist with effective pest management decisions for affected crops.

Agrisciences Queensland (DAF) is the main point of contact for identification of potential fall armyworm and they can be contacted on 13 25 23.

The pest is now considered established in Australia, following detection at several sites including the NT, WA, New South Wales and recently in Victoria.

The fall armyworm page on the Sugar Research Australia website has a range of resources including details of the emergency use permits for Permethrin or Chlorantraniliprole to control fall armyworm

iMapPESTS program to help protect sugar cane industry

Moth borers remain one of the highest priority pests for Australian sugar cane production.

For this reason, Australian researchers have taken a proactive approach to clarifying control measures and gathering information about the pest.

While not established in Australia, there are 36 major moth pest species worldwide with seven regarded as high risk to Australia.

The nation’s geographic proximity to Papua New Guinea, Indonesia and South East Asia, where the moths live, mean Australia remains a potential migration point.

Speaking on the first day of the CaseIH Step Up conference in Bundaberg on Tuesday, Sugar Research Australia (SRA) molecular plant pathologist, Dr Nicole Thompson, said significant work had been done to forearm against the threat.

Some of this work included updating species and specimen information in databases and collections; preparing new dossiers based on this research; developing new diagnostic protocols; and updating the geographic distribution of the moth borers.

The pest was just one major concern mentioned by Dr Thompson who also spoke on iMapPESTS, a nationwide research and development collaborative initiative between Australia’s major plant industries with a goal of developing a way to rapidly monitor and report the presence of airborne pests and diseases for multiple agricultural sectors, including viticulture, grains, cotton, sugar, horticulture and forestry.

The project is about advanced surveillance technologies such as automated trapping and sampling for detecting and monitoring a wide range of endemic and exotic pests.

The project will also produce several flexible surveillance hubs with trapping technologies that can be mobilised in response to industry needs such as in response to incursions.TECH: The Sentinel is a custom-designed surveillance trailer unit designed to offer optimal sampling of airborne fungal spores and insects.

 TECH: The Sentinel is a custom-designed surveillance trailer unit designed to offer optimal sampling of airborne fungal spores and insects.

One of the pieces of equipment is the Sentinel.

The Sentinel is a custom-designed surveillance trailer unit designed to offer optimal sampling of airborne fungal spores and insects.

The Sentinel has four different air samplers: two spore samplers which are high-volume, designed to collect airborne spores; a 2m insect suction trap to monitor localised insect dynamics; and 6m insect suction trap, for monitoring of long-distance migratory insect flights.

Each air sampler is automated and collects samples into small vials for fungal spores or larger vials or larger pots for insects.

These are barcoded and read by a scanner onboard and in the labs for complete traceability.

Dr Thompson said sugarcane had many established pests and diseases such as mosaic, Fiji leaf gall, leaf scald, smut, RSD and others.

It’s hoped the iMapPESTS project will assist multiple plant industries in managing these threats.

Farmers say fall armyworm, the ‘coronavirus of agriculture’, could force up food prices

There are fears food prices could rise as a pest caterpillar described as the “coronavirus of agriculture” continues its relentless march across the country.

It has been a year since fall armyworm — not the species that eats lawns — was first detected at Bamaga at the tip of Far North Queensland.

The hungry caterpillar, native to the Americas, is now devouring crops throughout Queensland and has invaded farms and plantations in the Northern Territory, Western Australia, New South Wales and Victoria.

Ray Graham, who owns Queensland’s largest dairy farm, says the pest is the biggest threat to the agriculture industry Australia has ever seen.

“It’s almost a coronavirus for agriculture — we need research and we need money thrown at this quickly,” he said.

‘Never seen anything so vicious’

One of the first areas to be hit by the fall armyworm was the food bowl of Queensland’s Atherton Tablelands, west of Cairns, which produces more than 60 crops in an industry worth more than $500 million a year.

A year on since the grubs were first detected, entire corn crops have been destroyed and experts say the pest is now turning its attention to other crops, including peanuts and avocados.

Corn grower Geoff Riesen, from Yungaburra, said he had been spending more than $2,000 a week on chemicals, to no avail.

“I’ve been farming all my life and I’ve never seen anything so vicious,” Mr Riesen said.

“Every paddock is infected with this on the Atherton Tablelands.

“And it’s not just here, it’s everywhere. It’s in New South Wales, it’s in Victoria, it’s absolutely frightening.”

Mr Riesen’s neighbour, corn grower Bob Lloyd, is in a similar situation. He said pesticide chemicals were proving useless, because the caterpillar hid in the base of the plant, which protected it.

Both men said they were now considering not planting corn again.

Dairy farmers could cut stock

Mr Graham, a fourth generation Queensland dairy farmer, said the grub could have a devastating impact on his operation.

Mr Graham buys 3,500 tonnes of silage — which is fodder made from corn — and a further 2,000 tonnes of grain from local growers to feed his 900 milking cows each year.

“If we aren’t able to source the grain and silage, we will have to get rid of 250 head of cows,” he said.

“We don’t have any alternative but to cut numbers because we’ve got to feed the cattle.

“There isn’t an alternative, there isn’t a fallback situation.”

‘Devastation from the air’

Crop sprayer Hamish Jacob, who is based at Atherton, said he had been struggling to keep up with requests from farmers to spray their fields for fall armyworm.

He said the damage from the air was clearly evident, with patches of yellow and dying crops.

“It is devastation from the air,” Mr Jacob said.

A damaged corn field seen from the air
Atherton Tablelands producers describe the damage caused by the fall armyworm invasion as a “green drought”.(ABC Far North: Brendan Mounter)

“We just don’t have the chemistry to deal with it.

“It’s hard knowing that I still have to charge for what I do.

“I’m providing a service they need but it just takes the shine off to be taking money from someone that is not really going to see anything at the end of it.”

Mr Jacob said the mental toll on farmers had been enormous.

“They’re calling it the green drought,” he said.

“They’ve stuck all that money in the ground and the way it’s looking at the moment, I can’t see how anyone is going to make money out of corn crops this year.”

‘Costs are going to rise’

Local agronomist Paul Keevers said the pest had spread into several states, including New South Wales and Victoria.

He said a looming food shortage was possible.

“The implications for the supply chain especially for the food market can be devastating, the costs are going to rise,” he said.

“They [fall armyworm] attack all sorts of crops and we grow 60 different crops on the Tablelands.

“We’re pretty confident unfortunately that it’s going to take most of those.

“We are already seeing attacks on peanuts and other crops, including avocados.

“All the beef farmers will be impacted, and we will have all the dairy farmers who use grain inside their sheds and silage in their pits so they’re going to run into potentially a feed shortage situation.”

Could a fungus be the answer?

Dr Ian Newton is a senior entomologist with Queensland’s Department of Agriculture based at Mareeba, near Cairns.

He has been investigating the effectiveness of a naturally-occurring fungus that eats the grub from the inside out.

Dr Newton said while laboratory tests were promising, the pest would never be eradicated completely.

“The fungus is not going to be a silver bullet but these biological options would be a good tool because they are very specific and only kill the pest, not the beneficial insects including the pollinators,” he said.

“And they are keen and green, there’s no toxicity problems.”

Dr Newton said the Federal Department of Agriculture, Water and the Environment had also approved the importation of the biopesticide, Fawligen, a naturally occurring caterpillar virus which specifically targets fall armyworm.

“The issue is it needs to be registered in Australia and, to do that, we need to prove that it works and it isn’t detrimental to people, so that is going to take some time.”

Dead grubs in petrie dish
A fungus has shown promising signs of killing the fall armyworm.(ABC Far North: Brendan Mounter)

However, he said that all was not lost.

“It’s here and we are going to have to live with it,” Dr Newton said.

“It’s seen as a bit of a crisis because it’s developed rapidly and we don’t have all the tools or all the knowledge to manage it, but I do believe we will manage it in the end.”

Elders and Maize Australia working on battling Fall armyworm threat

AS the threat of Fall armyworm continues to trend south, agronomists and industry bodies are exploring ways of limiting the pest’s potential damage.

Elders is among those on the frontlines and has enlisted the help of Toowoomba-based technical services manager Maree Crawford to help find an answer to the increasing threat.

Ms Crawford has so far found that drastic measures have failed to prevent damage, but a more integrated approach was preserving crop yields.

“This pest is a serious threat to some crops and there is a tendency for growers and advisors to overuse synthetic pyrethroids up front and this approach is not proving successful,” Ms Crawford said.

“Elders agronomists address Fall armyworm outbreaks in a very structured way, using an integrated pest management approach based on the individual circumstances.

“You have to take a lot of factors into account, like the weather, the lifecycle stage, the crop species and its risk profile, and the extent of the infestation.”

The research comes after Fall armyworm were discovered in a maize trial plot in Georgetown, northern Queensland in February.

Since then, the pest has been spotted in several locations in Queensland, as well as Hillston, Croppa Creek, Breeza, Forbes, Dubbo, Narrabri, Wee Waa, Maitland, Moree and Boggabilla in NSW.

“If you nuke everything, your not going to have the beneficals to clean up new egg lays and hatchings underneath the leaf where your sprays have failed to reach all of the Fall armyworms,” Ms Crawford said.

 Elders Toowoomba agronomist Matt Kenny checks one of the trapview units being used to monitor for early flights of Fall armyworm. Photo: Supplied

Ms Crawford said once the pest got past the past the 10mm-long third instar stage it was almost impossible to prevent large-scale crop damage and in turn it was crucial for farmers to spray in the evening.

“When they are transitioning from the third to the fourth instar, we find them inside the whorl of the plant,” she said.

“They cover themselves down in the whorl with frass, which is their waste, and the chemical can’t get to that, it just sits on top and doesn’t penetrate them.

“It’s critical to spray in the evening, when the largely nocturnal larvae are out feeding.

“It’s a bit of a concern but I think it is manageable with proactive, vigilant practices and the array of chemistry we’ve got access to, we can manage the pest in most crops and limit the damage.”

The threat has Maize Australia executive officer Liz Mann on high alert and urging growers to be vigilant.

“Fall armyworm is moving south and it is a bit of a concern,” Ms Mann said.

“I think it and other pests may be one of the biggest challenges facing producers this season.

“We know producers are usually right on top of these kinds of things and we’re hoping it won’t be too much of a factor ahead of the summer season.”