Armyworm war needs new tactic
Africa should turn to lower risk solutions to fight the pest which is endangering food security and livelihoods
THE CATERPILLARS of the fall armyworm (Spodoptera frugiperda), an invasive moth, can potentially feed on more than 350 species of plants. In the Americas it’s known as a serious pest.
It destroys crops of maize, rice, sorghum, sugar cane, peanuts, soybean and non-food crops such as cotton. In maize, fall armyworm feeds on the developing leaves and then the grains, damaging the plant and reducing yield.
It was found only in the Americas. But in 2016 it appeared in West Africa and is in more than 40 countries in tropical and southern Africa. It has also recently been reported in India.
Research mapping environmental suitability shows that large areas of Asia are suitable for fall armyworm, including parts of India and China, the world’s second-largest maize producer.
The pest presents a threat to food security and its impact on maize alone could devastate the livelihoods of tens of millions of farmers. Estimates suggest that the potential yield loss due to fall armyworm in 12 countries would be huge. The data show that between 4 million and 18 million tons annually out of an expected production of 39 million tons could be lost.
The economic cost is estimated to be from $1 billion (R14bn) to $4.6bn a year.
To protect their food supplies, African countries are putting in place large-scale emergency measures. Many of these focus on the widespread distribution and use of pesticides. But this isn’t the ideal solution for a number of reasons. First, some pesticides are harmful and toxic. Second, pesticides put many smallholder farmers at risk – many aren’t familiar with the products and might lack the protective equipment to prepare and apply them safely.
There are other lower risk alternatives. One of these is biopesticides – naturally occurring substances or organisms that kill pests. In a recently published study we show that biopesticides present safe, low-risk options which can serve as viable alternatives.
Biopesticide products to control fall armyworm are commercially available in the Americas and are used by farmers in North and South America. Some African countries are also moving in this direction. For example, South Africa has provisionally registered several biopesticide products for use against the fall armyworm, and biopesticide trials are under way in many other countries.
Our study assessed more than 50 biopesticide active ingredients which have been registered in fall armyworm’s native range in the Americas as well as in some African countries. We reviewed the literature and regulatory documents with the aim of answering five key questions: Is the biopesticide effective against fall armyworm? Is it of low risk to human health and the environment? Is it sustainable? Is it practical for use by small-holder farmers? Is the biopesticide available?
We identified 23 active ingredients that we recommended for further consideration. We also identified eight active ingredients that should be brought to market. These include products containing neem plant extracts and Bacillus thuringiensis, two of the most widely used biopesticides globally. This includes fast-tracking product registration, as well as reviewing and updating information materials and recommendations for farmers, as well as taking into account availability.
More needs to be done if biopesticides are going to replace chemical pesticides. For example, in the medium-term, governments will have to assist farmers by subsidising biopesticides, an approach being adopted by Ghana. They could consider local production of biopesticides, working in partnership with the private sector.
There are a host of challenges too. Few biopesticide products are registered for use in African countries. And most of those registered aren’t widely available or affordable, particularly for smallholder farmers. While some farmers might be willing to pay a premium for a lower risk product, many smallholders have such small margins that they will seek to minimise production costs. So older, off-patent and cheaper pesticides might be preferred, despite the dangers.
With greater support from governments, research, the private sector and NGOs, a market for lower risk products could be developed, which would lower prices. Ultimately, biopesticides present an opportunity to lower not just the economic cost of controlling fall armyworm, but also the cost to the environment and human health.
Such an approach should fit into a broader drive to control fall armyworm by using a more integrated approach that combines a variety of agricultural practices. Known as integrated crop management, the approach involves combining a range of practices with an emphasis on those regarded as “low risk” compared to conventional chemical pesticides.
This could include closely monitoring the crop, intercropping, manual removal, biological control, insect-resistant varieties and traditional methods such as applying ash. | The Conversation
Dr Melanie Bateman, lecturer in ICM Master’s programme on jointly organised by CABI, University of Neuchâtel, Switzerland. Roger Day, programme executive at CABI, also contributed to this article.