Virginia Tech program supports biocontrol of the destructive fall armyworm in Nepal and Bangladesh

The Feed the Future Innovation Lab for Integrated Pest Management (IPM Innovation Lab) – a U.S. Agency for International Development (USAID)-funded organization housed at Virginia Tech – is implementing augmentative biocontrol in Nepal and Bangladesh to help manage the spread of fall armyworm (FAW), Spodoptera frugiperda. Thus far, the program has successfully trained numerous scientists and technicians across both countries on the process of mass-rearing and releasing FAW’s natural enemies.

In 2018, farmers in Asia could look at a leaf curled around an ear of corn and practically see through it. Translucent “windowpane” leaves, along with frass and round holes on the ear of corn itself, are signature marks showing that the invasive fall armyworm (FAW) pest has attacked and reached a field of one of the most important staple food crops in the world.

While the FAW attacks hundreds of plant species, the pest prefers to feed on maize, in which over 200 million people are dependent for food security every day. The FAW adapts to new environments quickly, is resilient to harsh conditions, can fly up to 100 miles in one night, and rapidly pushes out native insects. By 2023, the pest has reached more than 70 countries worldwide and has cost billions of dollars in crop losses.

At the time of FAW’s arrival in Asia in 2018, the IPM Innovation Lab had already started developing an augmentative biocontrol protocol – or the release of additional numbers of a natural enemy when too few are present to control a pest effectively – against FAW in Africa, where the fall armyworm had already begun causing USD$6 billion in losses annually. Given the extremely replicable approach, the IPM Innovation Lab began surveying for natural enemies in Asia through its two associate awards, the Feed the Future Nepal Integrated Pest Management (FTFNIPM) program – implemented locally by International Development Enterprises (iDE) – and the Feed the Future Bangladesh Integrated Pest Management Activity (IPMA), a collaborative project with CIMMYT.

“The fall armyworm is a very resilient pest, so it requires a long-term, sustainable solution to mitigate it,” said Muni Muniappan, director of the IPM Innovation Lab. “Biocontrol of FAW is a valuable approach for many smallholder farmers who often cannot afford high-quality pesticides or who lack protective equipment to apply them. Biocontrol harnesses what nature is already doing for us – it increases the natural enemies already attacking FAW, and then, through targeted release, reaches the areas most impacted by the pest.”

Over the last several years, FTFNIPM has scouted numerous FAW natural enemies in Nepal, including egg parasitoids Telenomus remus and Trichogramma chilonis; egg larval parasitoid Chelonus formosanus; larval parasitoids Charops bicolor and Cotesia spp.; and pupal parasitoid Brachymeria sp. In Bangladesh, IPMA has scouted egg parasitoids Telenomus remus, Trichogramma chilonis and Trichogramma pretiosum, and larval parasitoids Bracon hebetor, Cotesia sp. and Campoletis chloridae.

Currently, FTFNIPM is supporting the production of Telenomus remus and Trichogramma chilonis in Nepal and IPMA is supporting the production of Telenomus remus, Trichogramma pretiosum, Trichogramma chilonis and Bracon hebetor in Bangladesh. The programs are harnessing a “satellite” approach, which involves institutes such as the National Entomology Research Centre in Nepal and the Bangladesh Agricultural Research Institute to serve as nucleus centres that produce FAW parasitoids and subsequently provide training and technical support for universities and provincial laboratories to replicate the process.

Both FTFNIPM and IPMA develop “IPM Packages,” or suites of IPM strategies farmers can choose from based on their needs and conditions – the packages are also informed by farmer surveys, which assess constraints that limit the capacity of women, youth and marginalized groups to applying IPM strategies. For the IPM Package developed for maize, the programs have established a series of simple approaches farmers can apply both before and after FAW has reached their fields, including biocontrol. Corn seeds, the maize IPM Package recommends, should be treated with a systemic insecticide, which protects the crop up to four weeks from feeding by caterpillar pests, before sowing and setting up pheromone traps in the field. Immediately after first observing FAW moths in the pheromone traps, egg parasitoids reared in a lab can be released into the field. FAW moths will lay eggs on the systemic insecticide-treated plants and the caterpillars that emerge out of those eggs will die when they feed on the leaves. The egg parasitoids will continue to multiply in the field without interruption. By the time the systemic insecticide effect ends, there will be a substantial population of the parasitoid built up in the field. Young FAW caterpillars that continue to emerge will feed on the maize leaf surface, causing insignificant damage, also known as giving the leaves a “windowpane” effect. However, when the caterpillars reach about an inch in length, they become cannibalistic and eat one another, leaving only one caterpillar on the plant. This caterpillar will feed on the leaves at night and hide in the whorl during the day, which does cause significant damage. For this FAW attack, the IPM Innovation Lab programs recommend treating just the affected maize whorls with neem, which forces the caterpillar out of the whorl, exposing it to the larval parasitoid Bracon hebetor and others.

“Biocontrol, in combination with other environmentally sound techniques, is an important tool that will help us fight the fall armyworm, a pest that has the ability to wreak havoc across Asia for years to come,” said Madhab Chandra Das, IPMA Chief of Party. “It’s vital to remember just how essential maize is to the food security of communities across the continent. Asia’s millions of small-scale farmers, many of whom own less than an acre of land, have been disproportionately impacted by the FAW’s invasion given their limited access to technology and that they have less land to depend on.”

In this piloting phase, FTFNIPM and IPMA are in the process of involving provincial government labs, cooperatives, universities, and private entrepreneurs to reach farmers with the biocontrol solution concept. In Nepal specifically, FTFNIPM conducted a study of 17 districts in seven provinces to assess the FAW’s spread in farmers’ fields – while FAW damage has significantly decreased since it first arrived five years ago, overall infestation of FAW is still 19 percent in the districts and continues to significantly impact food security.

The IPM Innovation Lab programs are working diligently to train emerging scientists, including a focus on training women scientists, on the FAW biocontrol technique. In addition, the programs collaborate with a FAW taskforce to prepare communities for FAW spread and conduct national workshops to increase awareness of the pest’s status, biology, management, and methods for engaging the private sector in its management. In Nepal, FTFNIPM supports research assistantships focused on FAW biocontrol to Master’s- and Bachelor’s-level agriculture students at Agriculture and Forestry University (AFU) and Far-Western University (FWU). In Bangladesh, IPMA trained both faculty and students at Patuakhali Science & Technology and Khulna Universities on rearing parasitoids and establishing a parasitoid-rearing laboratory.

“We’ve now helped conduct numerous trainings for scientists and stakeholders on FAW awareness as well as management, and it’s important to emphasize that a collaborative effort such as this will help sustain the management of the FAW pest over time,” said Lalit Sah, iDE Agriculture Program Lead. “We look forward to continuing to build capacity throughout Nepal and across Asia on biocontrol efforts so that it builds a foundation not only for managing FAW, but other caterpillar pests. IPM Innovation Lab support in Nepal and Bangladesh has contributed to the long-term viability of agriculture while reducing reliance on chemical pesticides and minimizing impact on the environment.”

In the coming weeks, five scientists from Nepal and two scientists from Bangladesh are undergoing training on rearing of natural enemies of FAW at the National Bureau of Agricultural Insect Resources at Bengaluru, India. Both programs also conduct exposure visits for Bangladesh and Nepal entrepreneurs, scientists, and extension staff to India to observe production and use of pheromone lures, biopesticides, and biocontrol on the ground.

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