Biocontrol of the Fall Armyworm: Long-term Resilience for Small-scale Farmers
The fall armyworm is destroying crops throughout Asia and Africa, intensifying the many burdens small-scale farmers are met with every day.
The Armyworm and Small-scale Farmers
In rural Ethiopia, farmer Birhanu Kinessa applies ash and chemicals to control pest attacks in his maize plot. Kinessa belongs to one of the 500 million smallholder households that produce a significant portion of the world’s food, despite often working on less than one acre of land. Small-scale farmers face limited access to productive agricultural technologies, deepening their vulnerability to crop losses from pests, disease, and drought, and increasing their risk of food insecurity.
A person holds a blade of grass with an armyworm crawling on it.
One recent pest in particular—the fall armyworm—is destroying critical food and cash crops throughout Asia and Africa, intensifying the many burdens small-scale farmers are met with every day.
Native to the Americas, it took just one year for the fall armyworm to spread throughout most of sub-Saharan Africa, where it has caused billions of dollars in crop losses. The pest has now reached Asia, where it continues its scourge. Maize, a major staple crop in both regions, is the pest’s preference, but it also dines on up to 300 other plant species including rice, sugarcane, and cotton. After the caterpillar finds its food, crops are left looking dilapidated and impossible to salvage.
Current reports suggest a quarter of land planted with maize in Ethiopia is infested with fall armyworm – small-scale farmers like Kinessa are in urgent need of sustainable management solutions that build resilience, not burdens, against the fall armyworm and all future crop threats.
Damage to an ear of corn from an armyworm.
The Feed the Future Innovation Lab for Integrated Pest Management has monitored the invasive pest's movement throughout Africa and Asia since it emerged in both continents in 2016 and 2018, respectively. Abating the fall armyworm’s spread follows the program’s quarter-of-a-century long tenure addressing other invasive species around the world including the tomato pest Tuta absoluta and the papaya mealybug.
At one of the program’s meetings in Tanzania last year, a group of 50+ farmers listed a variety of methods they’ve used to keep the fall armyworm at bay—ash and sand, hand-picking, chemicals, soapy water, even a homemade soup—but none seemed to be strong enough opponents against the fall armyworm.
“We’ve used these methods,” said one smallholder farmer at the meeting, “but the problem is the amount we need in order to protect the entire farm from the pest.”
The fall armyworm is formidable. It can fly 500 kilometers in its lifetime, feed at all crop stages, migrate quickly, and destroy an entire maize field in a single night.
The IPM Innovation Lab currently works in seven countries in Asia and Africa, and thus has weighed possible solutions for the pest’s menace throughout the regions. While pesticides have been the primary control in most countries, the fall armyworm has become resistant to many synthetic chemicals, which can be expensive for small-scale farmers. Protective equipment is often not available, increasing risk of exposure. Direct spraying can also be futile since the pest typically burrows inside of a plant’s whorl, out of sight and grasp.
Genetically modified maize could be a solution, but since the fall armyworm is polyphagous and attacks more than just maize, host plant resistance might not comprehensively curb the pest’s spread or do so in a timely manner. Choice of crop variety also varies between cultures and regions.
“Due to the fall armyworm’s resilience,” IPM Innovation Lab Director Muni Muniappan cautioned at the Tanzania meeting, “An integrated management solution is necessary. It is also important not to ignore the nuances of the developing world by applying solutions that may be specific to the New World.”
Three men collect armyworms on a farm to protect their crops.
A Sustainable Approach
While a variety of tactics for managing the fall armyworm exist, the IPM Innovation Lab implements a biological control approach, a long-term strategy that is inexpensive, socially acceptable, and safe for the environment.
After finding seven potential parasitoids, or natural enemies, of fall armyworm eggs and larvae, the program landed on two for release against the fall armyworm—Trichogramma spp. and Telenomus remus—both known to be effective in suppressing populations of fall armyworm in Central and South America.
In IPM Innovation Lab trials in Kenya, T. remus showed 69.3 percent parasitism of fall armyworm eggs, while in Tanzania, Trichogramma showed parasitism of over 60 percent of fall armyworm eggs. The program developed a mass-rearing technique for both natural enemies using a rice moth, which is an alternative host, cutting costs in half.
In the case of the fall armyworm, and other enduring pests, money matters. In 2017, Ethiopia spent $4.6 million in insecticide purchases and equipment for tracking and tracing pest infestations, increasing insecticide use by nearly 38 percent. Such urgent and high investment can divert other critical resources for development.
T. remus and Trichogramma are two tiny wasps naturally found in both Asia and Africa. Since the wasps are local to both regions, there is no risk of introducing another invasive species. This is critical in a time when developing countries have the most to lose from invasive species spread, which is increasingly becoming more rampant with globalization and climate change.
The two natural enemies search for and lay their eggs on fall armyworm egg masses, killing the pest before it reaches larval stage, which is its most destructive. Releasing these natural enemies will not only protect maize from the fall armyworm, but in fact all critical food crops that are attacked by similar caterpillar pests.
A biocontrol strategy calls for partnership between cooperatives, the private sector, research centers, and other groups in Asia and Africa for long-term implementation. The IPM Innovation Lab collaborates with a number of institutions such as the International Centre of Insect Physiology and Ecology (icipe) and the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) to train scientists on the mass rearing technique and release the natural enemies in the field. Scientists from Niger, Bangladesh, Cambodia, Ethiopia, Kenya, Nepal, Tanzania, and Vietnam have already been trained and the program is currently setting up nucleus and satellite parasitoid rearing centers for release of the natural enemies throughout East Africa and Nepal.
In addition to initiating field release and evaluation of the efficacy of Trichogramma and T. remus, the IPM Innovation Lab has also conducted fall armyworm awareness and management workshops throughout Asia and Africa. Once the pest arrives, it cannot be eradicated, so sustainable management solutions are urgent. It is expected that its global impact will relentlessly continue and exacerbate the already capricious food security and livelihood conditions of smallholder farmers around the world.
The IPM Innovation Lab’s biological control approach will help small-scale farmers address more than crop pests. Reduced reliance on synthetic chemicals, which can be harmful to human, animal, and environmental health, will have an especially positive impact on valuable agricultural resources, like water. In the coming years, small-scale farmers will also continue to be disproportionately affected by a changing climate, which will continuously require more resources. If reducing the burdens of small-scale farmers is critical to increasing food security, a self-perpetuating approach like biological control against the fall armyworm is one step closer to getting there.
The Chicago Council is pleased to present the blog series, "Breaking Ground," to explore how food systems innovation and agricultural research and development can empower farmers and feed the world. This post is part of a special subsection of this series, "Field Notes," which features voices from Feed the Future Innovation Labs and CGIAR centers.