The fall armyworm (FAW), or Spodoptera frugiperda, is an invasive caterpillar from the Americas that devours crops and is, therefore, the latest threat to the agricultural sector. Spreading fast through India, the pest is causing extensive damage to crops, thus affecting the livelihoods of many. The Indian Council of Agricultural Research (ICAR) centre in Meghalaya, in July 2019, came out with a 50-page compendium on FAW, which provides complete information on it—where it is born, how it devastated crops in Africa, its life cycle, and how to tackle it.
Predominantly infecting maize, FAW has the potential to spread to many other crops such as rice, sorghum, sugarcane, cotton, and vegetable crops. According to the ICAR compendium, the FAW egg mass cannot be easily distinguished from those of 2 other related worm (and moth) species associated with maize. The eggs of the FAW are laid in a mass inside the whorls or on the lower surface of leaves or on the stem. The female moth lays more than 1,000 eggs in single or in multiple clusters on maize or other host plants. It is, therefore, essential to prevent its infestation in the early stages. For this, awareness on the management of this pest has to be created among farmers and other stakeholders.
Rapid Spread
The fact that the FAW has assumed epidemic proportions in a span of three years is a matter of grave concern. From the tropical and subtropical parts of the Americas, the insect spread to Africa in 2016 through imported produce. In India, it was first traced in July 2018 in Karnataka. Since then, the pest has spread rapidly to almost all of South India and Central India (Maharashtra, Chhattisgarh), and the north-east region. Reportedly, FAWs have destroyed crop worth ` 18.4 crore in Mizoram since March 2019. In Chhattisgarh, the FAWs are rapidly devouring paddy, chickpea, jowar, and groundnut. Though it is not known as to how much of the farm area has been affected, it is clearly spreading into newer regions. The dry spell and humid conditions have helpled in their spread.
Control
The FAW is polyphagous, meaning it can feed on the leaves, stems, and flowers of as many as 186 plant species. Its early emergence in crop life cycle, voracious feeding habit, large-scale aggressive behaviour, high reproduction, fast migration, and irreparable nature of crop damage, all make it a key pest.
Another issue is pesticide use against the pest. As they reproduce quickly, they adapt to chemicals very fast; therefore, pesticides are initially effective but after a few days, do not have any significant effect. Meanwhile, farmers continue to use them, which means that there is an overuse of pesticides and the toxins’ possible entry into the food chain, even as they do not kill the pests.
FAWs feed on one another. But this does not reduce their growth and spread: as there is less competition due to their consuming one another, it leads to their faster growth. Though birds, other insects, and mice can be used to eat them up, these animals damage crops and that becomes a problem. Potential use of biological agents is seen as an option.
The FAW, therefore, presents a significant challenge to smallholder farmers by substantially increasing their cost of production, reducing productivity and farmers’ income. The following methods have been advised to tackle the growing menace of the worm by the ICAR compendium and others.
* The Union Ministry of Agriculture and Farmers’ Welfare has recommended three chemicals for the control of this pest—Spinetoram 11.7 per cent SC, Chlorantraniliprol 18.5 per cent SC, and Thiomethoxam.
* Deep ploughing of the fields is recommended so as to expose more soil to the sun.
* Simultaneous planting, wherein all fields are planted over a period of a week or less, must be preferred over staggered sowing over a period of several weeks. If an entire village carries out sowing within a short span of time, the growth of crops would be uniform and so would be the distribution of the pest, thereby significantly reducing the extent of crop damage.
* The ICAR compendium calls for timely sowing: maize should not be sown until at least 50 mm of rainfall is recorded during the season.
* Only treated maize seeds (seeds treated with fungicides) must be sowed in order to protect them from soil-borne pathogens.
* The compendium advises avoiding staggered sowings and inter-cropping of maize with pulses that are grown in a particular region, like the red gram which is commonly grown in some regions.
* Desmodium grass cultivated alongside maize crops can be a distraction for the worm, thus causing lesser harm to maize.
* Growing ornamental crops as an inter-crop can help in the build-up of natural enemies.
* Hand-picking and destruction of egg masses and neonate larvae in mass by crushing or immersing in kerosene water would help.
* Releasing bio-control agents like Trichograma Pretiosum and spraying entomopathogenic fungi like Nomoruea Rileyi for the natural reduction of pest populations can be helpful.
* Application of ‘poison bait’ inside the whorl of maize is an effective way of controlling the FAW. Poison bait is prepared by combining a mixture of 10 kg of rice and 2 kg of jaggery in 2–3 litres of water and allowing it to ferment for a day. To this fermented product, 100 gm of Thiodicarb, an insecticide, is added, along with sand and limestone powder in a ratio of 9:1. The final product is then applied inside the whorl.
* Application of dry sand into the whorl of affected maize plants would help.
* Pheromone lures can be used to trap male FAWs, thus disturbing their mating cycle and preventing their breeding. When left in plastic baskets hooked to sticks and placed at various locations in the maize or sorghum fields, these lures attract male FAWs, who mistake the pheromones for female FAWs. The males drop into the baskets and get trapped. The ICAR compendium has asked farmers to establish five pheromone traps in the infested areas and those that may be infested, both in crop season and in off season. Farmers and other stakeholders have been asked to scout for FAW following a ‘W’ path in the field just as maize seedlings begin growing.
Entities, such as the South Asia Biotechnology Centre (SABC), are involved in creating awareness among the farmers for the effective management of the FAW. They have urged the government to exempt pesticides, pheromone traps and lures, safety kits, masks, and gloves from GST, which is currently at 18 per cent.
Project Saffal
The SABC has launched an ambitious and multi-year project [Safeguarding Agriculture and Farmers against Fall Armyworm in India (SAFFAL)] in Mumbai. The project is supported by FMC India, a global leader in sustainable crop protection. The project aims at developing a suite of techniques, good agricultural practices, and control measures along with educational material for various stakeholders to enhance farmers’ preparedness to tackle the menace of the fall armyworm. It has been launched in Maharashtra and is to be expanded to other states: Gujarat, Chhattisgarh, Rajasthan, and Tamil Nadu.
Meet on Tackling FAW
Over 100 stakeholders from 8 nations of South Asia and South-east Asia met at the International Crops Research Institute for Semi-Arid Tropics (ICRISAT) to discuss the challenges posed by the worm and ways to counteract it. The 3-day workshop, ‘Fall Armyworm Management in Asia’, was jointly organised by the US Agency for International Development, the International Maize and Wheat Improvement Centre, and India, Sri Lanka, Myanmar, Bangladesh.