New Tech Fights Fall Armyworm by Letting Offspring Die

Mar 04, 2022

Scientists have developed a new technology that could control the devastating fall armyworm crop pest by releasing genetically controlled males that suppress populations as subsequent offspring cannot survive, a study says.

The fall armyworm, Spodoptera frugiperda, which was detected in Sub-Saharan Africa for the first time in 2016, could lead to one-third maize yield losses in some countries and up to US$6.3 billion loss annually, according to the study published in the journal BMC Biotechnology.

The gene technology developed by Oxitec, a UK-based biotechnology company that genetically modifies insects to assist in insect control, enables production of male-only cohorts of the friendly fall armyworm that when released into farmer fields will mate with pest female fall armyworms, and their female offspring cannot survive, resulting in fewer pests on the crops and therefore less damage.

"Crop pests continue to spread disease and devastate food production. Current management of these pests is highly reliant on just few tools, many of which have off-target ecological impacts, are vulnerable to resistance developing in the pest population, and are often limited in their effectiveness," says Kelly Matzen, a co-author of the study, and Oxitec's chief technology officer.

"There is, therefore, an urgent need for new pest management options that offer greater effectiveness and sustainability, and a lighter environmental footprint," Matzen adds.

The pest is native to the Americas but has since spread rapidly across Africa, Australia, India and South-East Asia.

An initial three-year research phase, according to Matzen, enabled the early development of the friendly fall armyworm, and testing the competitiveness of the genetically modified male-only cohorts of the pest against wild-type males.

"We are continuing the work and the current research phase is focused on conducting product development trials and product stewardship activities, conducting field trials in Brazil, and piloting scale-up of the technology," she explains.

"For now, our focus with fall armyworm is on assessing the performance of the friendly fall armyworm in Brazil. When we have completed further product development, we will explore how we can make the product available to farmers in other regions."

Improving control of fall armyworm could improve harvests for local farmers and protect their livelihoods, and has the potential to improve food security through the availability of corn grain for countries around the world, the study says.

But Ivan Rwomushana, a senior scientist and an invasive species management specialist based at the regional center for Africa of CABI, the parent organization of SciDev.Net, says that it will be difficult to deploy the Oxitec technology in Sub-Saharan Africa without the support of governments.

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Video: Turning Plant Defense Into a Management Strategy

Turning Plant Defense Into a Management Strategy

Understanding how a plant responds to stress is one thing.

Using that knowledge to make better management decisions is another.

Systemic acquired resistance, or SAR, is the plant's more direct defense response. When stress or infection occurs, the plant begins signaling throughout its system and preparing defensive compounds.

But if we know that response exists, can we help prepare the plant before the stress arrives?

The answer starts with understanding what triggers the response and what the plant needs to carry it out.

The Trigger and the Fuel

Salicylic acid plays an important role in triggering the SAR pathway.

Think of it as turning the truck on.

The engine may be running, but it still needs fuel to do the work.

In this case, manganese plays an important role in supporting the enzyme systems involved in the plant's defensive response.

This makes manganese status an important part of the conversation. Whether a producer is using tissue testing, sap analysis, or simply scouting for visible deficiency symptoms, the goal is to make sure the plant has adequate manganese available.

Manganese is required in relatively small amounts, but that does not make its role small.

If the plant receives a signal to defend itself but lacks the nutrition needed to support that response, it may struggle to carry out the process efficiently.

The trigger matters.

The fuel matters too.

Prepare Before the Stress Arrives

The best time to think about stress management is before the plant is overwhelmed.

Once a crop is already struggling, management can quickly turn into a game of catch-up.

This is similar to nitrogen management. Once a plant becomes severely deficient, correcting the problem does not necessarily erase the time and yield potential already lost.

Plant defense can work the same way.

Low-rate, targeted approaches designed to support the SAR pathway may fit best ahead of an expected stress event rather than after significant damage has already occurred.

That requires producers to think about predictable stress.

We may not know exactly what the weather will do tomorrow, but we generally know summer heat is coming. We know certain field conditions increase disease pressure. We know a herbicide application can temporarily stress a crop as the plant processes the chemistry.

Even a properly timed and labeled herbicide application can create a temporary response in the plant.

That does not mean the herbicide is bad.

Weeds can create significantly more yield loss than the temporary stress caused by controlling them.

The question is not whether we should eliminate every stressor.

The question is whether we can better prepare the plant to manage necessary and predictable stress.

Not All Stress Is Bad

Stress is a normal part of plant growth.

A perfectly stress-free environment does not exist in the field.

In fact, some stress is necessary for normal plant development. A plant responds to wind, temperature, moisture, sunlight, and countless other environmental signals throughout the season.

The environment is stress.

The plant's job is to manage it.

Problems begin when the stress load becomes greater than the plant's ability to respond.

Extreme heat, drought, high salt concentrations, disease pressure, and even certain management practices can add to that load.

This is where understanding SAR becomes useful.

Instead of waiting until the plant is visibly struggling, producers can begin identifying periods when stress is likely and make management decisions around those windows.

ISR Starts With the Soil

While SAR is a more direct defense response, induced systemic resistance, or ISR, brings the conversation back to soil health.

The longevity of a farm is closely connected to the health of its soil.

Carbon plays a major role because it supports biological life within the soil. Bacteria, fungi, and other organisms interact with plant roots and influence how the plant grows, accesses nutrients, and prepares for stress.

This is why soil health cannot be reduced to one product or one application.

It is a system.

Keeping living plants in the field longer can support biological activity. Cover crops may fit some operations. Better water management can improve soil conditions.