Fall Armyworm’s Arrival in India Sparks Fear of its Spread Through Asia

Two-and-a-half years after the fall armyworm, an invasive crop pest native to the Americas, was first reported in Africa, it has now been officially confirmed for the first time on the Asian continent, first in the southern state of Karnataka in India and more recently in the adjacent states of Telangana and Tamil Nadu as well.

photo courtesy of M. DeFreese/CIMMYTA farmer at work weeding in a maize field in the Indian state of Bihar. The fall armyworm has already been detected in three Indian states — Karnataka, Telegana, Tamil Nadu.

The pest, which is a voracious eater of maize along with at least 80 other plant species, was found on a maize plant in Karnataka and according to a pest alert from the Indian Council of Agricultural Research (ICAR) has already been shown to have a 70 percent infestation rate there.

As I wrote in March of the Armyworm in Earth Island Journal’s summer issue, most experts believed that since the pest reached Africa, it was only a matter of time before it spread further throughout the eastern hemisphere. The fall armyworm is a strong flyer and can reach distances of hundreds of miles in one night with the right winds. It is already confirmed or reported in every country in sub-Saharan Africa and given the continent’s proximity to the Middle East and the rest of Asia, its further spread was inevitable. Although it is unknown where the pest will go next, a recent paper by Regan Early from Exeter University says, “current trade and transportation routes reveal Australia, China, India, Indonesia, Malaysia, the Philippines and Thailand face high threat of fall armyworm invasions originating from Africa”.

The Centre for Agriculture and Bioscience International (CABI), one of the organizations leading the fight against the fall armyworm, was already preparing for this eventuality. “We had been planning a regional meeting in Pakistan on emerging invasive threats including fall armyworm before it arrived in India,” says Roger Day, program executive for CABI’s Action on Invasives program. “We’ll be going ahead with that in September. We’re in discussion with various partners about what other meetings might be useful in Asia.”

Muni Muniappan of the USAID-funded Feed the Future Innovation Lab for Integrated Pest Management was also looking ahead. In July of 2017, he invited a Nepalese researcher to a fall armyworm meeting in Ethiopia, with the knowledge that the pest would likely reach Asia and it was best to be prepared. Muniappan is now planning to hold an awareness workshop in Nepal in the fall as well.

The fall armyworm’s arrival in Asia, which is home to some of the world’s biggest maize producers, poses a big risk for the food security of the continent. India, for example, has 25 percent of the world’s hungry population. It produces over 20 million tons of maize each year as well as other staple crops favored by the fall armyworm, such as rice and sorghum.

Although Asia grows more maize than Africa, it is less of a subsistence crop on this continent, with more of it going to other uses such as livestock feed, but it is still a vital crop. China produces around 20 percent of the world’s maize, second only to the United States, and India and Indonesia produce around 2 percent each, roughly double what Nigeria, the largest producer of maize in Africa, grows.

“In Asia, the yields per unit area of maize are generally higher than in Africa. This means the potential value of the crop loss is higher,” Day says.

It is still unclear how the fall armyworm got from Africa to India. Although the pest is known to fly far distances under the right wind conditions, a flight from even the easternmost point of Africa all the way to India would be an extremely long one, over 1,500 miles.

“It’s likely fall armyworm arrived in India from Africa through human-aided transport, although natural migration is also a possibility since it’s able to fly hundreds of kilometers in one night on prevailing winds,” said Gopi Ramasamy, CABI’s Country Director for India in a press release. In addition, although the pest has not been officially sighted in the Middle East, it is possible that it flew there first before moving onto India and just has not been reported there yet.

As in Africa, now that the pest is in Asia, there is very little hope of eradication, only control. In Africa, farmers used chemical pesticides to try and combat the fall armyworm, but the pesticides were not generally very effective and have negative repercussions when it comes to environmental and human health. Farmers have also used more traditional methods, such as using fish soup to attract ants to predate the fall armyworms or putting ash or soil in the whorl of the maize plant to suffocate the pests. These have shown more promise but can be difficult to implement on a large scale.

Biological control, such as the rearing and release of natural enemies, is also being explored in Africa and will likely be in Asia as well. Muniappan has been working with the egg parasitoids Trichogramma and Telenomus remus in Africa, so finding local predators of the fall armyworm in Asia will be an important step.

In the United States, the fall armyworm’s native home, genetically modified corn is a common tool in the fight to control the pest. And Asia, unlike Africa, widely uses genetically modified crops. South Africa is the only African country that grows genetically modified maize, and there are very few countries on the continent with any commercial GM crops. Asia’s broader acceptance of these crops could allow for the adoption of transgenic resistant maize varieties in hopes of controlling fall armyworm.

As with Africa, it will take a host of actions to keep this pest under control, and there is no time to spare.

“A fast response is important as this pest spreads quickly,” Ramasamy says.