The most promising options for the management of FAW by African smallholders are presented below, building on experiences from the Americas and latest research available in Africa, reflecting IPM strategies. These can be tested out in FFS as appropriate.
Seeds and varieties
Seed treatment might prevent early damage of the seedlings after germination.
Longer-term solutions of resistant or tolerant maize varieties might have potential, but are several years off.
FAO recognizes that crop improvement through innovative technologies, including both conventional breeding and modern biotechnologies, is an essential approach to achieving sustainable increases in crop productivity and thus contributes to food security. Scientific evidence has shown that modern biotechnologies offer potential options to improving such aspects as the yield and quality, resource use efficiency, resistance to biotic and abioticstresses, and the nutritional value of the crops.
FAO is also aware of the public perception and concerns about the potential risks to human health and the environment associated with genetically modified organisms (GMOs). FAO underlines the need to carefully evaluate the potential benefits and possible risks associated with the application of modern technologies. FAO emphasizes that the responsibility for formulating policies and making decisions regarding these technologies rests with the Member Governments themselves. The responsibility for formulating policies and making decisions regarding GMOs lies with the individual Governments. So FAO does not interfere in the policies or decisions, including those related to GMOs, of its Member Governments and so it has no position regarding the development, testing or commercial release of GMOs in any specific country. On request, FAO provides legal and technical advice to governments on areas such as the development of national biotechnology strategies and the development of biosafety frameworks.
Regarding the potential use of GM (genetically modified) maize to control the FAW in Africa, FAO considers that it is yet too early to draw conclusions. Bt maize has been demonstrated to decrease damage from FAW, but FAW populations in the Americas have evolved resistance to some Bt maize varieties.
Nevertheless, more work still needs to be done including conducting trials and collecting data. It must be kept in mind that the Bt maize grown currently in some parts of Africa is used primarily for controlling the maize stem borer insect and not FAW.
Maize has been genetically engineered by incorporating genes from the bacterium Bacillus thuringiensis (Bt) that produce insecticidal proteins that kill important crop pests. The use of Bt maize has resulted in some cases in reduced insecticide use, pest suppression, conservation of beneficial natural enemies and higher farmer profits. However, such benefits may be short-lived. Insect populations are able to adapt to Bt proteins through the evolution of resistance. Despite efforts to delay the selection for resistance, many cases of field resistance evolution among maize pests have been demonstrated in Bt maize, including in the Fall Armyworm (Spodoptera frugiperda) in the Americas, and in South Africa in the maize stem borer (Busseola fusca).
While transgenic maize has provided some transitory benefits to commercial maize farmers, the context for the vast majority of African maize farmers is quite different. Over 98 percent of maize farmers in Africa are smallholders, growing maize on less than 2 ha of land and typically saving seed to plant the next crop. The use of purchased inputs, including seed, is low.
Given the cost of transgenic maize seed, the lack of adequate supply channels, and lack of economic incentives for smallholders to grow such maize (due to the low and volatile prices received), there is currently a low probability that the technology would be used in a sustainable manner by smallholder maize farmers in Africa. Even for commercial maize farmers in Africa, the longterm benefits of transgenic maize were put into doubt when, within two years of deployment, maize stem borers began to show resistance to Bt maize in South Africa.
Crop management
Management of FAW in maize fields begins with prevention.
Planting dates: avoid late planting, and avoid staggered planting (i.e. planting of fields at different dates in the same area), as this would continue to provide the favoured food of FAW locally (i.e. young maize plants). This is one of the most important recommendations for smallholders. In line with this, in January 2018 some FFS farmers in Kenya reported significant yield losses to FAW on late-planted maize plots, compared to adjacent plots which were planted earlier. See also the FFS Field Study in section B.4.4 on “Effects of planting dates on fall armyworm infestation and yield loss”.
Good soil health and adequate moisture are critical: they are essential to grow healthy plants, which can better withstand pest infestation and damage. Also, unbalanced inorganic fertilization of maize (especially excessive nitrogen use) can increase oviposition by female FAW. See the Box in this section, and the FFS Field Study in section B.4.5 on “Effects of nitrogen fertilization rates and manure on levels of fall armyworm infestation and yield loss”. See references in Bibliography for training material proposing FFS activities on soil health.
The efficacy of managing crop residues to break the life cycle of FAW generations is not well established by research. This practice is also time-consuming; it also runs counter other recommendations to maintain soil cover to improve soil health for sustainable production.
Plant diversity
Diversity on farm reduces Fall Armyworm infestation and supports natural enemies
Another very important aspect of prevention of FAW infestations is by maintaining plant diversity on farms.
Even if many female moths are flying about, if she doesn’t lay her egg masses on maize plants, or if very young larvae don’t move onto maize plants, then the maize won’t be infested by FAW.
FAW moths prefer maize to lay her eggs. In large monocultures of maize, she just flies about, laying her eggs in a sea of maize.
When maize is intercropped with other crops or there are other plants nearby that she doesn’t like, she is more likely to move on, skipping maize plants that may be mixed in with the plants she doesn’t like.
This is the first step in good FAW management – reduce oviposition on maize plants! Farmers in Central America have noticed that when they plant maize together with other crops such as beans and squash (their traditional “milpa” systems), they have less pest attacks.
Agroecologists have documented that polycrops may be effective because of four main reasons or mechanisms:
One possible explanation is that a diversity of plants in the same field confuses FAW, and it is difficult for it to find its preferred host plant (maize), eating less or laying fewer eggs.
- Another reason is that the female FAW moth doesn’t “like” certain plants because of the chemicals they emit. These volatile compounds are the “push” effect in push-pull systems, which “push” pest species away from certain plants while they are “pulled” to others because the plant chemicals make them more attractive (see section A.3.3.2 on Push-pull). So planting maize near other plants that “push” FAW moths away is the first step in preventing FAW infestation.
- A third possible explanation is that polycropping may provide natural enemies (parasitoids and predators) with resources such as nectar; water; or a place to hide, and those natural enemies will control FAW.
- A fourth rationale for the intercropping is that it increases soil organic matter, and in the case of legumes it increases Nitrogen, which improves plant health, making it more able to compensate for FAW damage
We know that especially plants that bear flowers for a long period of time, such as many “weeds” or some medicinal or plants used as condiments, do provide nectar to parasitoids and predators of FAW. In Mesoamerica, plants such as Tagetes lucida, Coriandrum, Sonchus olerace, Ruta and onions, attract beneficial insects.
Suggested experiments on plant diversity on your farm
- Try using different maize varieties and/or intercropping maize with other crops (for instance with cassava, which is not a host plant of the FAW)
- Observe which plants growing near or in your maize fields are attracting natural enemies, and how you can manage them to reduce FAW populations, without interfering with maize growth.
- Consider stimulating the growth of “weedy” plants in certain rows in between the crop, or to grow them around the plot.
Trees are also important for pest management. Trees allow birds to perch, and many birds prey over larvae including FAW. In Africa, many farmers are growing maize in agroforestry systems (MIAF). It could be important to document if the MIAF plots have less FAW attacks than maize grow in a monocrop.