New Study Reveals Natural Enemies of Fall Armyworm in Both Asia and Africa
By Sara Hendery
The fall armyworm (Spodoptera frugiperda) is a resilient pest that has wreaked havoc throughout Africa and Asia in recent years, despite persistent efforts to mitigate its spread.
Native to the Americas, the fall armyworm reached Africa in 2016 and Asia in 2018, attacking maize and hundreds of other vital plant species. In 2017, it was assessed that the economic value of fall armyworm damage in 12 countries in Africa could be between $2.5 billion and $6.3 billion. The pest’s resilience to harsh conditions and chemical pesticides—especially amid the current COVID-19 pandemic, which has limited agricultural labor and production efforts—is setting unprecedented challenges for farmers in the developing world.
In 2018, the Feed the Future Innovation Lab for Integrated Pest Management initiated a biological control approach to combat the fall armyworm, searching for natural enemies that could safely and economically prevent the pest from spreading further. The team found two natural enemies—parasitoid wasps in the genera Telenomus and Trichogramma—in East Africa, which showed up to 70 percent parasitism of fall armyworm eggs. New research recently published in the Indian Journal of Entomology reveals that the IPM Innovation Lab, in collaboration with a host of global institutions, has now found natural enemies of the fall armyworm in Asia as well.
The study confirms the occurrence of egg parasitoids Trichogramma mwanzai and Telenomus remus in East Africa and reports the presence of egg parasitoids Trichogramma chilonis and Telenomus remus in Nepal. Institutions including FAO, the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in Niger, the National Biological Control Centre in Tanzania, the Nepal Agricultural Research Council, the International Centre of Insect Physiology and Ecology (icipe), the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service, and the Kenya Agricultural and Livestock Research Organization were involved in surveying and identifying the natural enemies in maize fields.
The study also offers an inventory of natural enemies of the fall armyworm found predominately in the Americas.
The discovery of natural enemies in both Africa and Asia—and, in particular, one of the species in both places—has important implications not only for suppressing the fall armyworm but also for south-south and cross-continental technology transfer of their mass-production.
“These natural enemies do not occur in abundant populations early enough in the season to successfully suppress the fall armyworm on a large scale,” says Muni Muniappan, Ph.D., director of the IPM Innovation Lab and a co-author of the study, “which is why we will mass-produce them in the lab for an inoculative, augmentative biocontrol approach. There is a lot of value in research that is cross-cutting over multiple regions. With many countries experiencing food insecurity as a result of this pest, the sharing of ideas, knowledge, and resources will increase the chance of fighting it more quickly, economically, and sustainably.”
Trichogramma species can be successfully reared on an alternative host, the rice meal moth Corcyra cephalonica, which cuts mass-production costs in half. Research is ongoing to assess whether Telenomus can be effectively reared on the alternative host as well.
The IPM Innovation Lab, which is housed at Virginia Tech and funded by the U.S. Agency for International Development, has already conducted trainings on augmentative biocontrol using the natural enemies at ICRISAT-Niger and icipe-Kenya with participants from around the world, including scientists from Bangladesh, Benin, Burkina Faso, Cambodia, Cameroon, Cape Verde, Cote d’Ivoire, Democratic Republic of Congo, Ethiopia, Ghana, Kenya, Mali, Nepal, Niger, Senegal, South Sudan, Sudan, Tanzania, Togo, and Vietnam.
The study emphasizes that, now that the natural enemies have been found in Asia and Africa, the next step is establishing “satellite centers” in each country where the natural enemies can be mass-produced and subsequently released into the fields to feed on the fall armyworm. Mass production is underway in East Africa and is currently being replicated in Nepal.
As the COVID-19 pandemic persists, curbing crop threats in the developing world and tackling food insecurity risks is more imperative than ever. As seen with other human disease outbreaks like malaria, which is one of the leading causes of death in Sub-Saharan Africa, reduced labor activity caused by the disease results in major crop losses.
“Summer maize production in Nepal is being affected by the fall armyworm as well as the COVID-19 pandemic,” says Ajaya Bajracharya, a senior scientist at the National Agricultural Research Council in Nepal and a co-author of the study. “Movement of agricultural technicians into the field is being restricted, resulting in a lack of appropriate knowledge among farmers to manage the pest. The need for this sustainable fall armyworm management technology is being felt urgently in Nepal.”
Indian Journal of Entomology
Sara Hendery is the communications coordinator for the Feed the Future Innovation Lab for Integrated Pest Management at Virginia Tech. She holds an MFA in nonfiction from Columbia College Chicago. Email: firstname.lastname@example.org.