Asia Bracing for Destructive Armyworms 03/19 07:42
THA MUANG, Thailand (AP) -- Fall armyworms, a longtime American pest, are
munching their way around the globe, raising alarm now in Asia after
entrenching themselves in Africa.
Experts say the insect was first found outside the Americas in 2016, in
Africa, where it has infested up to half of some crops of maize, sorghum and
millet. It's now spread through Yemen and South Asia to Thailand and China.
This new arrival to her territory worries Uraporn Nounart, a specialist on
farm pests at 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," she said while visiting farms
recently in Kanchanaburi province, northwest of Bangkok.
The worms can cause damage at all stages of a corn crop, but the worst may
be when the larvae, pinky-sized caterpillars turn sweet corn cobs to mush. The
incursions of the alien species threaten to upend the balance between costs and
returns for farmers in Thailand and elsewhere.
Pesticides are costly, toxic and don't always work.
In its native regions, from Argentina to northern Canada depending on the
season, the bug's natural enemies --- predators, parasites and pathogens such
as bacteria or viruses --- help keep it in check. But the new habitats may lack
some of those defenses, the United Nations' Food and Agricultural Organization
says. It's convening a conference in Bangkok this week to help share
information and strategies on battling the pest.
Keeping it in check is an urgent priority: Even though Asia is mostly known
for rice growing, maize is an important staple crop and crucial source of feed
for poultry and livestock.
In the cornfields in Kanchanaburi, there were armyworms in all stages of the
crop, from seedlings to knee-high to "elephant's eye" high.
Some local farmers were working hard to limit their losses by pulling the
tops off stalks grown for baby corn and discarding them to limit how much
damage the worms could do. That tactic causes the plant to sprout new ears that
can be harvested later.
Organic farmers don't use the usual farm chemicals so 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," said one farmer, Sanae.
In another field, Thanwa, a younger farmer, sought help and had his fields
sprayed using drones. For taller plants, that's about the only way for the
small-scale farmers to get pesticides up onto the affected parts of the plant
once the worms are established.
Swaddled against the burning sun, Uraporn Nournart and her team of young
scientists scrambled through the fields, peeking into corn husks and pulling
apart damaged stalks to collect worms and eggs for monitoring. They're
conducting trials in fields like the one Sanae was working her way through, a
tranquil plot of waist-high corn ringed by banana trees.
Charuwat Taekul, an entomologist at the Department of Agriculture who
specializes in microscopic parasitic wasps, was collecting egg clusters to use
in his research into 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," said Marjon Fredrix, 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 100 kilometers (60
miles) a night, even farther if they're carried by the wind.
The best case scenario, says Fredrix, would be farmers successfully scouting
for and finding the worms early on, so they can keep them under control. The
FAO has developed an app that teaches the basics of how to find and deal with
"This new pest needs to be managed in years to come, and farmers will need
to develop skills to do so in a sustainable manner," Fredrix said.
The help came a bit too late for Yodsapon, a farmer in Tha Muang. He follows
Uraporn's team stoically as it winds its way through his wrecked field of sweet
At first glance, the 2-meter-high (6.5-foot-high) stalks look vigorous, with
good-sized ears that are nearly picking size. But a closer look shows holes in
the stalks where the worms have worked their way inside, munching ear after ear
into yellowish brown mush.
The family has other sources of income, a small eco-hostel set in their
tropical garden. But income from that is unstable, and the corn crop will be
missed, Yodsapon says.
He's thinking hard about what to do next: switch to another crop? Cassava?
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.