Dr. Yubak Dhoj GC

Over the past few years, Nepal's agriculture sector has been hit by several new crop pests and pathogens. Among those feature migratory pests, which periodically make their appearance in the country, as well as invasive pests. The latter comprise organisms that are entirely new to Nepal, often originate from far-off parts of the world and invade new territories through pathways such as intercountry trade of agricultural goods and commodities, international travel or tourism.
Climate change can also facilitate the arrival of new species for example by shifting their long-distance movement patterns. Extreme weather events such as extended droughts and heightened temperatures also disrupt natural pest control processes in farmers' fields and thus make the crop more susceptible to (invasive or native) pest attack.

Fall Armyworms
At present, one of the most prominent pests is the fall armyworm (scientific name Spodoptera frugiperda). This night-flying moth originates from the Americas, where it migrates over large distances and annually affects maize, rice and sugarcane production in countries such as the USA, Brazil or Mexico. Its larvae are especially voracious and can damage young plantlets, cause extensive leaf-feeding within the maize whorl or lead to spoiling of the maize cobs. In 2016, this pest made its unwelcome arrival in western Africa and has since colonized most of the continent.
By 2018, this pest had been recorded in India's Karnataka province, as if it had put on its proverbial 'seven-league boots' to cross the Arabian Sea and make its unwelcome arrival in southern Asia. It wasn't for long since it showed up in Nepal and neighbouring countries such as Bangladesh, China or Bhutan.
"Fall armyworm has hit Nepal's maize crop particularly hard," says Sahadev Humagain, National Program Coordinator on Fall Armyworm management, Kathmandu, Nepal. "This invasive pest is currently found in 40% of maize fields, where it is causing yield losses of 6-7% on average. As such, it has augmented the cost of farmers' crop protection activities by the estimated US $40."
Over the past two years, this tiny moth has colonized most of eastern Asia and is inflicting losses in a range of gramineous crops – from Myanmar's Ayeyarwady delta to the uplands of Papua New Guinea. Eradication of this pest is entirely unfeasible and pest-induced losses likely will be felt for decennia; its impacts on Nepal's agriculture cannot be disregarded. In Nepal, maize is grown on a little less than one million hectares and is widely cultivated as food, feed and fodder crop.
Maize-growing constitutes a central feature of the daily lives of hundreds of thousands of Nepali farmers. Aside from causing important yield losses, the fall armyworm will negatively impact rural livelihoods in multiple ways.
For example, in southern China, maize farmers have largely reverted to synthetic pesticides to tackle fall armyworm outbreaks. Since 2019, local pesticide application frequencies have increased three-fold. The repeated application of those toxic chemicals isn't only costly (especially for resource-poor smallholder farmers), but also carries clear risks for farmer health and the environment.
"Fall armyworm however isn't the only pest that's causing headaches to Nepali farmers," says Yubak Dhoj GC, Senior Plant Protection Officer at the FAO Regional Office for Asia and the Pacific in Bangkok, Thailand. "Several other invasive pests have recently made their appearance, while many native herbivores are reaching increasingly higher infestation levels".
Like the fall armyworm, the tomato pinworm Tuta absoluta also has near-antipodal origins and made its first appearance in Nepal in 2016; its related losses in local tomato production are expected to total the US $50 million per year. Another pest that made its way across the globe is the potato tuber moth Phtorimaea opercullela, which first appeared in Nepal in the late 1960s but is attaining progressively higher infestation levels – likely aided by global warming and agricultural intensification. Climate change possibly may also be at play in orienting locust swarms towards Nepal.

Locust Outbreak
Throughout history, outbreaks of the desert locust Schistocerca gregaria (or Salaha in the Nepali language) have frequently been recorded from neighbouring India. However, it wasn't until 1962 (and thereafter in 1996) that Nepal also experienced an invasion by these devastating crop pests. Last year, swarms with millions of desert locusts once again covered Nepali skies - causing important losses in approx. 1000 hectares of maize grown in Surkhet and Pyuthan including several other parts. As with fall armyworm, synthetic pesticides are routinely used to tackle all the above six-footed foes.
“By looking for quick fixes and easy solutions, we tend to forget that chemical toxins are not the only available tool in farmers’ plant protection arsenal”, says Kris A.G. Wyckhuys – a private plant protection consultant based in Hanoi (Vietnam). “By diversifying their cropping systems, incorporating organic matter in the soil, using disease-free planting material or adopting proper crop spacing, a lot of trouble can already be avoided.
Also, on a healthy farm, there are hundreds of beneficial organisms that consume pests and thus prevent crop losses”. “Ants, earwigs, ground beetles or social wasps: they abound on Nepal’s farmland and all have fall armyworm caterpillars for breakfast” he asserts jovially.
Back in 1997, the Food and Agriculture Organization (FAO) of the United Nations launched its Farmer Field School (FFS) programme in Nepal. With generous funding from Norway and different UN agencies, FFS programmes trained tens of thousands of Nepali farmers through a novel 'learning-by-doing approach. Wide-eyed and with a sense of wonder, farmers discovered the various beneficial organisms that live on their farms, observed how they preyed upon key crop pests and came to value the related ecological processes. As such, Nepali farmers gained confidence in non-chemical crop protection tactics and were able to lower their pesticide use by 65% (without any yield loss, thus reaping net income gains of 20-40%).

Food Demand
In light of the crippling impacts of COVID-19 in every activity of life, the FAO, Regional Office, Bangkok, Ministry of Agriculture and Livestock Development and FAO Country Office Nepal can rollout the Fall Armyworm activities in Nepal. In this endeavour, the supports from federal, provincial and local level institutions at various technical capacitation is praiseworthy.
Considering the growing demands of food, the events are launched following all the safety measures and protocols. Farmers can keep the low pest infestation, using varieties of tactic focusing on nature-based solutions. These learnings will be crucial for the sustainable management of transboundary plant pest not only in Nepal but also in the region.
Now, nearly 25 years later, it is most advisable to blow new life into these FFS training modules and seek to modernize them e.g., with cellphone, video and other digital technologies. No doubt; FFS’ observation-based learning approaches will optimally equip Nepal’s farmers to tackle the unceasing stream of new crop pests.
In the meantime, we need to recognize that Nepali farmers don’t find themselves alone in their battle with these six-footed opponents. These so-called ‘transboundary pests’ are best addressed hand-in-hand with Governments, other Asian countries and international collaborators.

(GC is Senior Agriculture Officer, FAO, Regional Office, Bangkok)