Not just maize: Africa’s fall armyworm crisis threatens sorghum, other crops, too
By Sara Hendery
Scientists from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in Niger say that 99 percent of the media and research coverage on the fall armyworm focuses on the invasive pest’s deadly threat to maize.
And deservedly so: The fall armyworm (Spodoptera frugiperda) is indeed a major problem for maize—more than 40 nations in Africa, where hundreds of millions of people depend on maize, are rushing to find a solution to the pest that can travel long distances and reproduce in large numbers.
However, management methods solely addressing the fall armyworm’s damage on one crop could leave communities that rely on additional drought-resistant crops, like sorghum, at a disadvantage.
“The fall armyworm is polyphagous, which means it feeds on various foods,” says Muni Muniappan, Ph.D., director of the Feed the Future Innovation Lab for Integrated Pest Management. “We saw serious damage on the sorghum fields we visited during our last trip to Niger and damage on millet, as well, the nation’s staple crop. Not only is a diversified diet important for food-insecure nations, but it’s very common for a community of people not to eat a certain food simply because it doesn’t look or taste like their preference, which means we can’t just look to save one crop in this crisis. A one-track, one-crop solution for a multi-track pest could be very dangerous.”
Sorghum ranks as the fifth most important cereal crop in the world, but it is the second most important cereal in Africa. Its value is insurmountable to Sahelian countries that have a dry, hot climate. In Niger, maize can typically only be grown during the short and singular rainy season, or under irrigation, on which Sahelian countries cannot consistently depend. Protein- and fiber-rich, sorghum is a nutritious food and is also a vital source of income given its many uses as fodder, for fermentation, industrial purposes, syrups, biofuel, and more.
Malick Ba, Ph.D., principal scientist at ICRISAT in Niger, says that sorghum is the fall armyworm’s second host preference, and local reports of the pest on the valuable crop in the Sahelian region have been unending.
“Fall armyworm damage on sorghum has been reported in Burkina Faso, Mali, Northern Nigeria, Niger, Chad and elsewhere,” says Ba. “Infestation in the whorl of sorghum can reduce grain yields by 55 percent to 85 percent. Putting all the control efforts on maize would even worsen the situation on sorghum and other host plants. It is largely understood in the scientific community that research on fall armyworm should have a holistic, integrated approach going forward, to include all targeted crops.”
Every year, Africa loses almost half of crop yields due to pests; given the recent urgency to mitigate the fall armyworm problem, pesticides have been the primary management method thus far, but the use of chemicals continues to be expensive and over-reliance on them can lead to resistance developing in fall armyworm populations. Muniappan said such downsides further solidify the case for an integrated approach to managing the fall armyworm. In addition to botanicals, biopesticides, and other forms of control, the IPM Innovation Lab will soon implement biological control in several African nations to weaken the spread of the pest.
The team has already found two local egg parasitoids and four local larval parasitoids with collaboration from ICRISAT and the International Centre of Insect Physiology and Ecology (ICIPE), optimistic that a multitude of approaches for a multitude of threatened crops will be a more effective way for smallholder farmers to address the fall armyworm issue and begin to regain control of their farms.
“Given the circumstances of farmers,” Ba says, “who live on very little land, are often less educated, and have limited resources, emphasis for pest control should be put on methods that are accessible, which includes the use of local natural enemies, like parasitoids and predators.”
Not only will the IPM Innovation Lab’s implementation of biological control benefit all fall armyworm-vulnerable crops, but the method itself is also easily transferable from region to region. The team and collaborators at the Feed the Future Innovation Lab for Collaborative Research on Sorghum and Millet have already sent technicians from Niger to Egypt and technicians from Kenya to Niger to learn the technique of mass-multiplying and releasing parasitoids. In Niger and Kenya, colonies of the natural enemies are now being developed.
Niger has on record some of the highest malnutrition and mortality rates in the world—last year, more than 1.5 million people in the nation were affected by food insecurity. Still, possible, practical solutions exist that could spread from region to region, crop to crop. During the IPM Innovation Lab’s recent trip to Niger, farmers worked above the orange, dusty desert floor in the immense heat of the day; when asked where exactly they had seen the fall armyworm on the farms this year, one of them waved their hand in one slow swoop across the land to suggest, simply, everywhere.