How IITA discovered the fall armyworm

31 January 2020

Isn’t it interesting how seemingly unrelated events in two countries can lead to the same outcome? The story of identifying the fall armyworm in Africa is as intriguing as the pest itself.

In 2015 Ylva Hillbur, IITA’s former Deputy Director General (DDG) Research for Development was in talks with a Swedish team of researchers at the Swedish University of Agricultural Sciences who were interested in studying the African armyworm. Hillbur requested for samples of the moth from Georg Goergen, the entomologist who heads IITA’s insect Biodiversity Center in Cotonou, Benin. “I kept an open eye so that if ever we saw the moths, we’d send some to the DDG,” Georg says. We knew it would only be a matter of time since the African armyworm is a seasonal insect, which only appears in the first rains after a very long dry spell. We were also aware that it never stays long in the same place, usually a week or two, and it leaves behind only one generation in any given place before moving to the next location,” says Georg an entomologist with ample field experience.

How IITA discovered the fall armyworm

March 2016

While the team in Cotonou was on the lookout, the farm manager at IITA-Ibadan, Nigeria was going on about his daily work of inspecting maize fields and spraying any pests. This was in March 2016. After the usual spraying, the farm manager noticed that this particular insect was not dying. The more they sprayed, the more the insects multiplied, and they fed audaciously. This strange insect that didn’t respond to pesticides alarmed the farm manager, so he alerted Lava Kumar, IITA’s virologist. Kumar informed an entomologist—Abou Togola based at IITA’s Kano Station in northern Nigeria. Togola went to Ibadan and immediately recognized that this moth was different from other native African species. This is when samples were sent to IITA’s biocontrol center in Cotonou for Georg to identify.

Georgen was excited to receive the samples thinking it must the African armyworm that the DDG had asked for. However, when the specimen arrived, he was surprised. “It was different from what I knew! Surely, it was a species belonging to Spodoptera but there are over 30 species of Spodoptera although Africa had eight species by then,” he says. “We first received caterpillars (larvae) and the adults (moths) came later. Based on the genitalia, we identified the moths as the fall armyworm—at this point excitement reached fever pitch.” Why were you excited, I asked? “New information is always exciting. We knew it to be an important pest that required us to move fast. However, you can only publish such information when you are 200% sure. If one is wrong, one can ruin their own and the institute’s reputation,” Georgen responded. In ensuring that he was 200% sure, Georg asked Kumar, the virologist, to DNA barcorde the samples and they matched the barcodes of genomic databases in the US. By early June 2016, they were absolutely certain that it was indeed the FAW. The scientists notified the Nigerian Agricultural Quarantine Service (NAQS) about new pest, and with their consent, made this information public by publishing it in a journal in October 2016. It took 16 months from when the paper was published to the first major outbreak on the continent. “The first outbreaks were seasonal and contained. However, we knew that this would be a long-lasting problem—when the fall armyworm gets a foothold on the continent, there is nothing you can do to stop it because it’s a migratory insect, which can fly over 50 km per night. That explains how such a tiny insect can colonize an entire continent in a short time.”

While FAO decided to take an active role in coordinating partners’ activities and plans to provide sustainable solutions to the FAW challenge, a series of awareness workshops organized by IITA, CIMMYT, and USAID were conducted in various western, eastern, and southern African countries. It soon became clear that there is no single solution to control the new pest, which called for an Integrated Pest Management approach. At IITA, efforts currently include biological control using natural enemies and developing biopesticides, advocacy and awareness raising, the development of an App for early detection of FAW by farmers as well as breeding for resistance in support of efforts led by CIMMYT.


In 2018, the outcry from farmers was less vibrant than the two preceding years, so one can wonder why? “FAW is still with us but is less pervasive as initially conditions for outbreaks were particularly conducive. Today moth populations are still important, but farmers no longer panic when their maize is damaged and have learned from past seasons how to minimize damage.” However, both Kumar and Georg agree on one thing, “The fall armyworm is bound to stay and become a lasting threat in the newly invaded regions. We need to use an integrated pest management strategy. Pesticide application is one of them, but it is not sustainable. Not all farmers can afford pesticides since they are expensive and if used excessively, they induce pesticide resistance, destroy the environment, kill beneficial insects, and make our food unsafe since overuse leads to pesticide residue in food. Pesticides should be used only when necessary, we should look at environmentally compatible options like biocontrol—the use of natural enemies,” Georg advises.