Asia bracing for destruction by alien pest: fall armyworms Armyworm on the ground. (uacescomm/Judy Gallagher/Flickr)
Asia bracing for destruction by alien pest: fall armyworms
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Fall armyworms are a longtime American pest. They are munching their way around the globe. They are raising an alarm in Asia. This is after entrenching themselves in Africa.

Experts say the insect was first found outside the Americas. That was in 2016. That was in Africa. It has infested up to half of some crops. Those crops include maize. It includes sorghum. And it includes millet. It's now spread through Yemen. It has spread to South Asia. It has spread to Thailand. And it has spread to China.

This new arrival to her territory worries Uraporn Nounart. She is a specialist on farm pests. She works in Thailand's Agriculture Department.

"We never had this one before. They just were found late last year and in January in this area. It's a big problem." That's what she said while visiting farms recently in Kanchanaburi province. It is northwest of Bangkok.

The worms can cause damage at all stages of a corn crop. What's the worst part? It may be when the larvae, pinky-sized caterpillars turn sweet corn cobs to mush. The incursions of the alien species is a threat. It could upend the balance between costs and returns. That is for farmers in Thailand and elsewhere.

Pesticides are costly. They are toxic. And they don't always work.

The bug's native regions are from Argentina to northern Canada. That depends on the season. Its natural enemies are predators. They are parasites. And they are pathogens. These include bacteria or viruses. They help keep it in check. But the new habitats may lack some of those defenses. That's according to the United Nations' Food and Agricultural Organization. It's convening a conference. It is in Bangkok. It will help share information on battling the pest. It will also share strategies.

Keeping it in check is an urgent priority. Asia is mostly known for rice growing. But maize is an important staple crop. It is a crucial source of feed for poultry. And for livestock.

There were armyworms in all stages of the crop. From seedlings to knee-high to "elephant's eye" high. That was in the cornfields in Kanchanaburi. 

Some local farmers were working hard to limit their losses. They are pulling the tops off stalks grown for baby corn. They are discarding them. This is to help limit how much damage the worms could do. That tactic causes the plant to sprout new ears. These can be harvested later.

Organic farmers don't use the usual farm chemicals. They can sell the waste corn stalks as cattle fodder. Spraying with biomaterials like fungi and thread worms that may be parasites of the worms can help. But some fields still lost about a third of the first baby corn harvest.

"We've never seen anything like this." That is according to one farmer named Sanae.

Thanwa is a younger farmer in another field. He sought help. He had his fields sprayed. He used drones. That's about the only way for the small-scale farmers to get pesticides on taller plants. It has to go up onto the affected parts of the plant once the worms are established.

Uraporn Nournart and her team of young scientists scrambled through the fields. They peeked into corn husks. They pulled apart damaged stalks. They collected worms. And they collected eggs. They collected them for monitoring. They're conducting trials in fields like the one Sanae was working her way through. It is a tranquil plot of waist-high corn ringed by banana trees.

Charuwat Taekul is an entomologist. He works at the Department of Agriculture. He specializes in microscopic parasitic wasps. He was collecting egg clusters. He will use them in his research. He is studying natural enemies of the worms. It's unclear if such wasps would be effective in keeping the fall armyworms under control. But it's one of various strategies being considered.

"Putting into place adequate management measures once a country gets invaded by FAW is important." That's according to Marjon Fredrix. She is an expert with the U.N.'s FAO based in Bangkok. "However, the likelihood of further spread is real."

She notes that the worm's adult moths can fly more than 60 miles a night. They can fly even farther. That is if they're carried by the wind.

The best case scenario would be farmers successfully scouting for and finding the worms early on. That's according to Fredrix. This would enable them to keep them under control. The FAO has developed an app. It teaches the basics. It shows farmers how to find and deal with fall armyworms.

"This new pest needs to be managed in years to come. Farmers will need to develop skills to do so in a sustainable manner," Fredrix said.

The help came a bit too late for Yodsapon. He is a farmer in Tha Muang. He follows Uraporn's team stoically as it winds its way through his wrecked field of sweet corn.

The 6.5-foot-high stalks look vigorous at first glance. They have good-sized ears. They are nearly picking size. But a closer look shows holes in the stalks. This is where the worms have worked their way inside. They have munched ear after ear. They ate them into yellowish brown mush.

The family has other sources of income. They own a small eco-hostel. It is set in their tropical garden. But income from that is unstable. The corn crop will be missed, Yodsapon says.

He's thinking hard about what to do next. Should he switch to another crop? Cassava? Potato?

A good harvest from the field would have netted 2,000-3,000 baht ($65-$100), he says. He expects no income from this one. And spraying repeatedly to try to vanquish the worm could triple his costs.

"In that case, I can't afford it," he says.

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CRITICAL THINKING QUESTION
What do you think people could do to keep the armyworms away from their crops?
Write your answers in the comments section below


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