When fall armyworm first arrived on the African continent in 2016, the potential loss of crops was estimated to potentially cost farmers over USD 13 billion per year throughout Sub-Saharan Africa, threatening the livelihoods of millions.
Native to the Americas, fall armyworm has over the last few years rapidly spread across Africa, the Near East, Asia and the Pacific.
In response, the Food and Agriculture Organization of the United Nations (FAO) has called for urgent action to prevent the pest from devastating global food security and the livelihoods of hundreds of millions.
In November 2019, FAO launched a three-year program — Global Action for Fall Armyworm Control — to ensure a strong, coordinated approach at country, regional and global levels. The program aims to mobilize USD 500 million over 2020–22 to take radical, direct and coordinated measures to strengthen prevention and sustainable pest-control capacities globally.
On 16 July 2020, FAO hosted a webinar to share knowledge concerning the use of agroecological approaches to manage fall armyworm, highlighting experience from parts of Africa, South America and South Asia. Speakers included Rhett Harrison, landscape ecologist and conservation biologist with ICRAF; N. Bakhtavatsalam, director in charge of the National Bureau of Agricultural Insect Resources at the Indian Council of Agricultural Research in Bangalore, and Seirian Sumner, behaviour ecologist at University College London. The webinar was moderated by Buyung Hadi, integrated pest management officer with FAO.
Global Action Chief Technical Advisor Elisabetta Tagliati opened the session, describing the negative impact of fall armyworm and FAO’s commitment to fight the pest.
‘Global coordination for capacity development in sustainable management of fall armyworm is a key goal of Global Action and agroecological approaches are among the first options that can be leveraged to achieve these goals,’ she said.
Tagliati explained that although agroecological approaches form an essential part of farming practices in many countries, these approaches possess weaknesses — such as lack of scientific validation — and exist in diverse variations, with some lacking efficacy in managing fall armyworm.
She concluded by emphasising that scientific validation was needed of which practices were best for adoption by farmers.
Rhett Harrison explained that agroecological approaches provide farmers with an inexpensive alternative to managing pests.
‘These approaches offer culturally appropriate, low-cost, pest-control strategies that can be readily integrated into existing efforts to improve smallholders’ incomes and resilience through sustainable intensification,’ he said. ‘Such approaches should therefore be promoted as a core component of integrated pest-management programs for fall armyworm in combination with crop breeding for pest resistance, classical biological control and selective use of safe pesticides.’
Harrison noted that agroecological approaches were diverse and did not disrupt ecosystem services, rather, they tended to maximize benefits for a farmer. However, their suitability needs to be carefully assessed across various environmental and socio-economic conditions.
He also challenged policy makers and farmers to readjust from the standard way of doing agriculture, which ignores biodiversity. He emphasized that biodiversity encourages increases in natural enemies that are important in the control of fall armyworm. He cited an example of ants as natural enemies that harvested over 90% of fall armyworm pupae in farmers fields in Nicaragua.
He discouraged resorting to the indiscriminate use of industrial insecticides because most them have either been banned in some countries owing to the danger they pose to human health as well as the environment. Harrison instead called for the use of nature-based solutions to encourage populations of natural enemies.
The use of agroecological approaches in the management of fall armyworm is important in improving food production systems because they trigger three essential elements of integrated soil fertility to support healthy plants for food production: 1) management of healthy plants; 2) enhancing biodiversity; and 3) specific cultural interventions, such as insect hotels and bat boxes.
Using ‘Push Pull’ to manage fall armyworm
Images from a Push-Pull experiment carried out in a maize field in India. Photo: National Bureau of Agricultural Insect Resources
Bakhtavatsalam noted that since the pest’s detection in 2018, farmers in India immediately begun to experience massive crop losses. During the first year, plant damage was 70 percent. Through various interventions involving habitat manipulation, conservation biological control and Pull and Push technology, damage was reduced to 20–30 percent. He noted that Push Pull is an agroecological approach that has been noted for its efficacy in Zambia and many other African countries.
‘In India, farmers are using Push Pull strategies for management of fall armyworm in maize,’ he said. ‘A Push Pull strategy is a method of growing fodder legumes, such as Desmodium species, as an intercrop to repel adult moths from oviposition. Napier grass is used as a border crop to attract adult moths.’
He explained that the advantage of such a strategy led to increased forage, improved soil health, reduced soil erosion, conservation of biodiversity and increased income.
Bakhtavatsalam also noted that the majority of experiments conducted across Asia involving maize monocrop fields were found to have more fall armyworm damage compared to maize intercropped.
‘Evaluations showed the mean percent plant damage by fall armyworm was below 18 and 33 for monocrop plots,’ he said. ‘Results confirmed the role of intercropping legumes with maize in reducing damage and higher yield performance.’
Maybe wasps?
Researchers are optimistic that wasps could be effective controllers against fall armyworm. Photo: Seirian Sumner
Seirian Sumner was quick to dismiss the general view of wasps as fearsome, gruesome and gangsters of the insect world and that avoiding these insects only sounded logical. After all, some people find a wasp sting lethal.
Sumner gave an illustration of a survey that showed why people had a preference for bees to wasps in regard to being useful to their everyday life when in fact they offer much more.
‘We conducted a survey of 750 people that showed that many hate wasps simply due to lack of understanding of what they do,’ she said. ‘However, wasps perform important roles in our ecosystems as they provide support directly and indirectly to the quality of human life in adverse biodiversity techniques. These services include but are not limited to, pest control, pollination, indicators of habitat quality and devastation.
‘In the management of fall armyworm, wasps have showed their effectiveness through hunting hidden lepidopteran prey due to their ability to burrow down and pull out concealed prey.’
She explained that experiments conducted in Brazil and Zambia indicated that the presence of social wasps results in less plant damage by fall armyworm.
Sumner argued that adopting wasps as biocontrol agents for pest management would also tackle a number of Sustainable Development Goals, such as Zero Hunger, Good Health and Wellbeing, Clean Water and Sanitation, Life on Land and Climate.
A concern was raised from a listener on whether agroecological approaches would work on a larger field compared to a small one. Harrison replied that agroecological approaches are not a single approach and, hence, a suitable approach for each field must be decided as part of an integrated pest-management strategy. For example, cover crops and no-till agriculture is widely practised by commercial farmers in the US.
Another listener asked how one could host a wasp safely for the purpose of pest control. Seirian explained that wasps can easily be relocated to a safe zone to avoid human and insect conflict within a field. She recommended that people should improve their understanding of the importance of wasps to appreciate their role in supporting human life, in a similar manner to studies on bees living around humans. She advised that learning husbandry roles for wasps would enable humans to benefit from them.
Bakhtavatsalam added that adoption of agroecological approaches by farmers can be easily done once scientific validation of their efficacy in reducing the impact of fall armyworm is confirmed by researchers.
In closing the webinar, Harrison called for more funding to conduct research in the use of agroecological approaches to manage pests. He noted that the specific environments where farmers are located need to be better understood so as to identify the best approach for managing pests. He further emphasised the need to educate farmers against resorting to spraying with pesticides as a first option but rather as a last resort, to avoid killing natural enemies that help control the pest.
This story was originally published by The World Agroforestry Center.
