Fall armyworm in Nepal: The importance of early, targeted intervention

By Sara Hendery

In June 2019, the invasive and destructive fall armyworm (Spodoptera frugiperda) reached Nepal. But, due to early warnings, workshops, and trainings delivered by the IPM Innovation Lab and collaborators, the country was prepared a year ahead of time.

Fall armyworm (FAW) is foe to many. While the pest tends to favor maize, a staple food crop around the world, it attacks over 300 plant species. It is also resistant to many control options, and adults can migrate up to 100 kilometers in a single night. 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.

Given increased globalization and extreme weather events resulting from climate change, the spread of invasive species into new regions has intensified dramatically in recent years, causing major impacts on food security. The IPM Innovation Lab, housed at Virginia Tech and funded by the U.S. Agency for International Development (USAID), had been tracking, mapping, and managing the spread of several other invasive species at the time FAW invaded Africa and Asia. In Nepal specifically, the program assisted farmers in management of Tuta absoluta, a ravenous tomato pest.

Advance Preparation

A year before the FAW pest reached Nepal, the IPM Innovation Lab arranged for a collaborating Nepali scientist to attend an FAW workshop in Addis Ababa, Ethiopia. The program also conducted a workshop on monitoring and management of FAW in Kathmandu, the capital of Nepal, for policymakers, scientists, entrepreneurs, and representatives of value-chain projects. In early 2019, the IPM Innovation Lab co-sponsored another FAW management workshop with participation from international organizations such as the Centre for Agriculture and Bioscience International, the International Maize and Wheat Improvement Center, the International Crops Research Institute for the Semi-Arid Tropics, USAID, and private companies and local organizations.

″One of the many benefits of tracking invasive species is predicting when they will arrive,″ says Muni Muniappan, Ph.D., director of the IPM Innovation Lab. ″Early detection of pests not only gives us a better understanding of where they’re headed, but gives us time to develop sound solutions that work for every kind of farmer. We wanted to be sure that we found a solution that small-scale farmers could afford, that was culturally acceptable, and something that could be used long term.″

Of the several technologies recommended for management of FAW in these workshops, augmentative biological control—or laboratory rearing and field release of local and effective parasitoids of FAW—was emphasized as a leading strategy for addressing the pest, as it was both effective and helpful in reducing reliance on chemical pesticides. Given limited access to protective equipment in Nepal, the application of chemical pesticides frequently leads to bodily exposure.

Putting Biological Control Into Action

Feed the Future Nepal Integrated Pest Management (FTFNIPM), implemented locally by iDE (International Development Enterprises), is an IPM Innovation Lab associate award granted by the USAID Mission in Nepal that has spearheaded the advancement of FAW biocontrol. Given the additional advantages of early local human and institutional capacity building, Nepal was an important place to execute such a strategy.

In collaboration with the Nepal Agricultural Research Council entomology laboratories at Khumaltar and Rampur, FTFNIPM and the IPM Innovation Lab collected the egg parasitoids Trichogramma chilonis and Telenomus remus locally from eggs of FAW and mass-reared them for eventual field releases. These laboratories were identified as nucleus centers for rearing the natural enemies of FAW in Nepal, and satellite laboratories were identified involving public and private institutions in the provinces. This model was set up for the nucleus centers to develop technologies for mass-production of these and other natural enemies and provide training and backstopping.

In May 2022, the teams conducted a three-day workshop on mass-rearing and release of the parasitoids T. chilonis and T. remus to train scientists and technicians from local agricultural universities, provincial laboratories, cooperatives, and NGOs at Nepal’s National Maize Research Program entomology center at Rampur.

″This training was very timely and was mostly focused on practical aspects of mass-rearing and releasing the FAW parasitoids,″ says Komal Pradhan, chief of party of FTFNIPM. ″This will help in promoting and developing the supply chain of FAW parasitoids to the farmers at the local level through satellite centers in different districts of USAID’s Feed the Future Zone of Influence.″

Recently, FTFNIPM and the IPM Innovation Lab conducted a survey for FAW natural enemies in Nepal and found a total of eight parasitoids from eggs, larvae, and pupae of FAW, which have been sent to international specialists for confirmation of their identity.

Learning Along the Way

An important finding during this survey was a simple change in perspective. FAW is cannibalistic, and thus it will eat other fall armyworms on the maize plant leaves until it gets to where it really wants to be: inside the whorl of the plant where tender leaves are. Damage to the leaf blades by early instars is superficial, but damage to the whorl is important to avoid. The FTFNIPM team observed that, if chemical pesticides are going to be sprayed, it would only be necessary to place a small amount of chemicals in the whorl of the plant. By not spraying the entire plant, small-scale farmers in Africa and Asia could protect themselves from any potentially harmful chemical exposure and avoid spraying and killing any natural enemies of the pest on the plant.

″As we continue to combat this pest, we will learn more and more about safer and sustainable ways to address it,″ Muniappan says. ″It’s important that we adapt our earlier habits so that we can offer farmers affordable, safe, and easy tactics to grow their food. We look forward to learning even more in Nepal from our own research and from collaborating scientists about productive ways of managing this pest.″