New crop-destroying pest enters China amid devastating swine fever epidemic

By Jessie Higgins
A Chinese farmer tills a rice field in a remote village in Jiayang, a small mountainous city in Sichuan Province, in 2016. A new pest has entered China that could threaten the production of rice, corn and other cash crops this year. File Photo by Stephen Shaver/UPI
1 of 4 | A Chinese farmer tills a rice field in a remote village in Jiayang, a small mountainous city in Sichuan Province, in 2016. A new pest has entered China that could threaten the production of rice, corn and other cash crops this year. File Photo by Stephen Shaver/UPI | License Photo

May 16 (UPI) -- A new pest that threatens key agricultural commodities is spreading through China as the nation is reeling from an African swine fever epidemic that may wipe out hundreds of millions of hogs.

The new pest is called the fall armyworm, a moth native to Central America that feeds voraciously on many commodity crops while in its caterpillar phase.


The pest "has no natural predators in China and its presence may result in lower production and crop quality," the U.S. Department of Agriculture's Foreign Agricultural Service said in an advisory. "Experts report that there is a high probability that the pest will spread across all of China's grain production area within the next 12 months."

The moth has arrived as China is losing a large percentage of its food supply to the rapid spread of African swine fever, which has spread to hogs throughout the country.


At the same time, a trade war with the United States limits China's ability to import food to fill the gap. And China had planned to increase production of the very commodities the fall armyworm feeds on.

Impact uncertain

The combined impact of all these factors is difficult to predict, experts say.

"Certainly, the simultaneous occurrence of these two elements are very unfortunate," said Keith Cressman, a forecasting officer with the United Nations Food and Agricultural Organization.

Unchecked, the pest has been shown to reduce corn yields elsewhere in the world up to 20 percent. It is unclear how China's yields will be affected.

"It is a bit too early to say with any precision what could happen," Cressman said. "We're waiting to see what kind of impact it will have on crop production."

The Chinese government is taking the threat seriously.

Officials implemented an emergency trapping and scouting program soon after the pest was detected in southern China in January. On March 18, the Chinese Ministry of Agriculture and Rural Affairs deployed a Fall Armyworm Prevention and Control Technology Plan, which is considered a pilot program, according to the USDA report.

Judging by how the moth has affected food production in other parts of the world, the impact could be significant.


Corn favorite food

The fall armyworm is endemic across much of North, Central and South America. It feeds on many crops, including rice, wheat, sorghum, sugarcane, cotton, soybeans and peanuts. But its favorite food is corn.

Growers of corn and other crops in the Western Hemisphere have long battled the bug.

"There was a report about it [in North America] in 1795," said Rangaswamy Muniappan, director of the Integrated Pest Management Innovation Lab at Virginia Tech. "Fall armyworm is native to the New World."

The moth originated in the tropical regions of Central America and has since spread throughout the Americas. It is a warm-weather species.

In the United States, it thrives in the hot, humid southern regions. Farmers in Florida, Georgia, Alabama, Texas and California must contend with the insect year-round.

During the summer, the moth flies north in search of the fertile corn and soy fields planted across the Midwest, Plains, Mid-Atlantic region and East Coast. They've even made it as far north as Canada. The moth can't survive in cold weather, though, so in the fall, it heads south.

China has a similar range of climates as the United States. Its central and northern regions have hot summers and cold winters, and a majority of the nation's grain is grown there. So it is likely the fall armyworm will behave similarly in that country, Muniappan said.


Moth kept at bay

Over the centuries, farmers in the Western Hemisphere have developed increasingly sophisticated techniques to keep the moth at bay. Some try to plant early so their corn can be harvested before the caterpillars are at peak levels, according to the University of Florida.

Today, genetically modified versions of most cash crops in the United States no longer are vulnerable to the insect. Most American farmers grow a type of corn called Bacillus thuringiensis, or BT corn, that is genetically engineered to kill the fall armyworm by emitting a bacterial toxin deadly to its larvae.

That toxin kills many kinds of larvae and caterpillars that otherwise would feed on the harvest.

"In the Northeast, the fall armyworm is not a problem because of BT corn," said John Tooker, an associate professor of entomology at Pennsylvania State University. "It is controlled very well here."

This is not the case outside the Western Hemisphere where, until recently, the fall armyworm did not exist.

Moth spreads

That changed in 2016, when the moth accidentally was brought to Africa. Lacking natural enemies in that part of the world, it became an invasive species, decimating millions of acres of crops as it spread quickly across the continent.


Within two years, the insect was everywhere in sub-Saharan Africa. It then moved up into South Asia, across Southeast Asia, and now has arrived in China.

"Farmers in these countries didn't have any good way of managing that pest," Cressman said.

Most of the impacted farmers in these areas of the world are not commodity crop growers, he said. They are small groups and families growing just a few acres of food to feed themselves.

"If you're a small-holder farm, and this is your only crop that you're relying on for income and existence, this can be quite damaging," Cressman said.

Several national and international groups and organizations are working with farmers in Africa to develop techniques to control the insect.

The United Nations organization is teaching small farmers to hunt manually for and remove egg clusters, which attach to the undersides of leaves, among other labor-intensive techniques for killing the caterpillars by hand.

Long-term solutions

Other groups are seeking more long-term solutions. Muniappan's lab at Virginia Tech is looking for native African parasites and bacteria that will kill the caterpillars (in the same way BT corn does in the United States) that farmers could spread across their fields.

But all these solutions will take time. And as the moth continues its spread, each new region will need to develop its own methods. This process has just started in China, and experts predict it could take some time to implement.


"It is important to note that most farmers in China do not have the financial resources and training needed to effectively manage" the fall armyworm, the USDA report said. "Even if a mitigation program is employed, costly control measures [mainly chemical sprays] will drag production margins into negative territory for farmers of most crops that could be affected."

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