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FAO has received various indications that the following highly hazardous pesticides have been used or recommended for use to control Fall Armyworm in African countries:

In addition, the use of pyrethroids and neonicotinoids has been reported to control Fall Armyworm. It should be noted that resistance development though the use of pyrethroids is a concern for public health in malaria – affected countries. And that the use of neonicotinoids such as imidacloprid pose risks to pollinators where present.

This list is not intended to be an exhaustive list of HHPs in use in the African countries. It is the result of a first assessment of the pesticides that have been reported to be in use or recommended for use on Fall Armyworm and assessed against the FAO/WHO JMPM criteria. It is very likely that other HHPs are currently in use. Some African countries have prohibited the use of these and other pesticides due to the conditions of use.

The options for mitigating risks of highly hazardous pesticides range from ending, restricting or changing formulations or uses. Selection of the most appropriate option will vary from case to case and depend on risk levels and needs, but also on policies and adequacy of institutional infrastructure for pesticide management.

FAO recommends an Integrated Pest Management approach with the use of low-risk pesticides as the last resort. Within the group of low-risk pesticides, bio pesticides are considered to be the best option. However, if there are temporary constraints to the use of biopesticides, low-risk pesticides, e.g. products falling under WHO hazard classes III and U, can be considered.

The use of highly hazardous pesticides (HHPs) to control Fall Armyworm (FAW) has been reported in several African countries. Under the conditions of use prevailing in these countries, HHPs pose great concerns for human health and the environment.

It should be noted that:

• FAO has been mandated by the Council in 2006 and again in 2013 to assist member countries in reducing risks posed by highly hazardous pesticides

• The International Code of Conduct on Pesticide Management under article 7.5 stipulates that Prohibition of the importation, distribution, sale and purchase of highly hazardous pesticides may be considered if, based on risk assessment, risk mitigation measures or good marketing practices are insufficient to ensure that the product can be handled without unacceptable risk to humans and the environment

• The fourth session of the International Conference on Chemicals Management (ICCM4) in 2015 called for concerted action to address highly hazardous pesticides (resolution SAICM/ICCM.4/15)

• FAO and WHO have issued the Guidelines on Highly Hazardous Pesticides in 2017 to provide criteria for the identification of highly hazardous pesticides and guidance on risk mitigation.

Definition:

Highly hazardous pesticides (HHPs) are pesticides that are acknowledged to present particularly high levels of acute or chronic hazards to health or environment according to internationally accepted classification systems such as the World Health Organization (WHO) or the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) or their listing in relevant binding international agreements or conventions. In addition, pesticides that appear to cause severe or irreversible harm to health or the environment under conditions of use in a country may be considered to be and treated as highly hazardous (Code of Conduct).

Criteria:

The FAO/WHO Joint Meeting on Pesticide Management (JMPM) has defined eight criteria to identify highly hazardous pesticides:

1. Pesticide formulations that meet the criteria of Classes Ia or Ib of the WHO Recommended Classification of Pesticides by Hazard;
2. Pesticide active ingredients and their formulations that meet the criteria of carcinogenicity Categories 1A and 1B of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS);
3. Pesticide active ingredients and their formulations that meet the criteria of mutagenicity Categories 1A and 1B of the GHS;
4. Pesticide active ingredients and their formulations that meet the criteria of reproductive toxicity Categories 1A and 1B of the GHS;
5. Pesticide active ingredients listed by the Stockholm Convention in its Annexes A and B, and those meeting all the criteria in paragraph 1 of Annex D of the Convention;
6. Pesticide active ingredients and formulations listed by the Rotterdam Convention in its Annex III;
7. Pesticides listed under the Montreal Protocol;
8. Pesticide active ingredients and formulations that have shown a high incidence of severe or irreversible adverse effects on human health or the environment.

For criteria 1-7 there are reference lists and related guidance can be found in the Annex 1 of the FAO/ WHO Guidelines on Highly Hazardous Pesticides (HHPs). Assessment as to whether an active ingredient of a formulation would fall under Criterion 8 is more complex as this depends on the actual situation in individual countries.

For the selection of pesticides to control Fall Armyworm, criterion 8 is however particularly relevant due to the constraints that many countries face in controlling conditions of use. Some African countries have already taken the appropriate measures to phase out highly hazardous pesticides.

FAO Environmental and Social Risk Management requires that all pesticide use in FAO field activities be considered and cleared by FAO’s Plant Production and Protection Division (AGP).

Some pesticides are more toxic than others.

In technical terms, pesticides that have a high acute or chronic toxicity, or hazard to the environment are called highly hazardous pesticides.6 Under the current prevailing condition of use in African countries, it is advisable to primarily avoid the use of highly hazardous pesticides. Fortunately, only a relatively small share of the products available on the market is highly hazardous and therefore farmers can learn to recognise them, and avoid their use.

Pesticide labels provide important information to recognise the toxicity of a product. This includes instructions for use, content including active ingredients, requirements for personal protective equipment, re-entry intervals, and first aid statements.

Farmers should look for:

Active ingredient – Products are sold with different commercial names, but the important information on the label is the actual chemical that provides the pesticidal action (the poison). This is called active ingredient.

Toxicity Colour code – Some countries have adopted a colour-coded toxicity label on pesticide containers.

Pesticides labelled with red and yellow should always be avoided, unless proper conditions of use can be ensured.

Hazard pictograms – Visuals warning about specific high hazard (toxicity) levels to human health and the environment.

Pictograms commonly-used on pesticide-labels under the Globally Harmonized System of Classification and Labelling of Chemicals indicate:

There is a common misconception among farmers that pesticide toxicity determines its efficacy (“the more toxic, the better”). However, important factors that influence pesticide performance are: choosing the right product for the pest, the time and mode of application, water quality, temperature, and more importantly the stage of the target pest (for instance, some insecticides will only be effective on very young larvae).

What are pesticides?

Pesticides are substances used to kill or repel insects, diseases, plants, animals (rats, mice…) and other living organisms which are invasive, harmful and cause damage and therefore are considered to be pests.Pesticides are however also toxic to people and non-target organisms, and pollute the environment. Their handling, use and disposal always require special care.

Pesticide toxicity\

There are two types of toxicity: acute and chronic toxicity.Acute toxicity of a pesticide refers to the product’s ability to cause harm to a person or an animal from a single exposure event, generally of short duration. Acute effects generally appear promptly, or within 24-48 hours of exposure.To better understand acute poisoning, farmers can think of the effects of the bite of a venomous snake. People and animal develop a quick reaction after the bite (exposure to the poison). The effects can be reversible, or lead to death depending on the strength of the poison.These effects are similar to those of other types of poisoning and to other illnesses, and include:

• Headache
• Fatigue
• Nausea
• Vomiting
• Sweating
• Irritation
• Swelling
• Affect metabolism
• Respiratory difficulties
• Seizures
• Dizziness
• Increased heart rate
• Unconsciousness
• Pain
• Stomach cramps
• Trembling
• Death

Antidotes can be effective if administrated promptly.

Chronic toxicity refers to harmful effects that occur from small doses repeated over a period of time. The main problem with chronic symptoms is that it can take time for them to become apparent, and then, when you do notice them, it is too late to do anything about them.

Pesticides with chronic hazard might cause cancer, immune suppression, damage to kidneys, brain and other organs, diminished intelligence, reduced fertility or damage to the unborn child (baby in the mother’s womb).

Chronic toxicity of pesticides concerns farmers and pesticide applicators working directly with the chemicals, but also the community and the general public potentially exposed to pesticide containers and pesticide residues on or in food products, water, and the air.

To better understand chronic toxicity, farmers can think of the effects of smoking over time.

Pesticide exposure

When people or animals come in contact with a pesticide they are exposed to their toxicity. There are three main exposure routes:

• eye and skin contact
• inhalation
• ingestion

You can be poisoned no matter which way pesticides enter your body. The dermal and inhalation routes of pesticide entry are likely to be the most important routes of pesticide applicator exposure. Farmers might breathe pesticide in, splash them on their skin, or expose themselves to pesticide drift.

There are also practices and behaviours that can increase the likelihood of exposure such as smoking, eating and drinking in the field, or applying chemicals against the wind.

Children and pregnant women are particularly susceptible to adverse effects from exposure to pesticides.

In addition to conservation biological control (relying on and protecting the natural enemies which are locally present, as explained above), other approaches include for instance classical biological control(importing natural enemies from elsewhere and establishing them in farmers fields) and augmentative biological control (supplementing the numbers of naturally-occurring natural enemies with releases of natural enemies reared in labs or collected in the field; they can be released in large quantities – these are called inundative releases, or beginning with small quantities– these are called inoculative releases).

In Latin America Trichogramma spp., in particular T. pretiosum and T. atopovirilia, are commonly mass-reared on alternative hosts in local mass production units, and commercialized for inundative field releases against the FAW. Release rates totalling circa 100 000 wasps/ha performed in 3 introductions spaced each by 3 days, is a recommended release scheme. In Brazil, control levels are reported as good in conjunction with the use of pheromone traps to monitor thresholds. However a number of constraints such as production technique, susceptibility to weather conditions, threshold adjustment for interventions, transportation to release site, the need for repetitive releases, compatibility with other interventions etc. are limiting a wide application.

As explained above, a number of parasitoids of FAW have already been identified in Africa. Before introductions of the FAW co-evolved parasitoids from the Americas are contemplated, or complex rearing and release efforts of local NEs envisaged, a thorough inventory work and impact assessment of the native guild of natural enemies is necessary.

Biopesticides

Biopesticides can be instrumental as part of an IPM approach against the FAW. The term biopesticide comes from”bio”, a root word derived from Greek which means “life” while “pesticide” includes all substances or mixture of substances that are intended to suppress pests and prevent the damage or loss that they cause. Biopesticide is a generic term generally applied to a substance derived from nature, such as a microorganism or botanical or semiochemical, that may be formulated and applied in a manner similar to a conventional chemical pesticide and that is normally used for short-term pest control.2 Thus, biopesticides are “living formulations” that are derived from natural materials originating from plants, animals (including parasitoids and predators), or microorganisms, are often cultured to increase amounts in order to exploit their characteristics of controlling pests.

• Broadly, biopesticides may belong to several classes:
• Microbial pesticides or microorganisms – including bacteria, algae, protozoa viruses or fungi
• Pheromones and other semiochemicals; these are chemicals produced by plants and animals (and synthetic analogues of such substances) that influence the behaviour of individuals of the same or other species
• Plant extracts and botanicals and
• Invertebrate Biological Control Agents, or macrobials – including insects, mites and nematodes that are natural enemies, antagonists or competitors of a pest. This class is sometimes not considered as a “biopesticide” per se.

Compared to broad spectrum conventional pesticides, biopesticides are usually more target-specific and inherently less toxic, and this limits their impact on non-target species, such as other insects, birds and mammals. They usually are biodegradable in the natural environment, thus reducing exposure and environmental pollution as well as reducing chances of pests developing resistance to them.

Microbial biopesticides are particularly relevant for the management of FAW. In this category of biopesticides, the active ingredient is typically the microorganisms themselves or the spores that they produce which are pathogenic to the target pest. For a description of the naturally occurring entomopathogens of FAW, see section A.3.5.1. on Biological control. They may be bacteria, fungi, algae, viruses or protozoans that suppress the target pests, either by producing toxic metabolites that are relatively specific to the target insect pest or closely related species, causing disease and are thus entomopathogenic.

Promotion of biopesticides to manage the Fall Armyworm

Biopesticides, such as those based on the bacteria Bacillus thuringiensis (Bt), fungi (such as Beauveria bassiana) and Baculoviruses have proven to be effective in the management of FAW.

Biopesticides – like any other pesticide – should be registered in the country before use. FAO has developed Guidelines3 on the registration of microbial, botanical and semiochemical substances for both plant protection and public health uses.

Some of the biopesticides that have been registered to control FAW

Other biopesticides registered for control of Lepidoptera are currently being tested for Fall Armyworm. In addition, certain botanical pesticides, such as those based on neem have also shown positive results.

Some of these naturally occurring diseases have been harnessed to produce commercial biopesticide products, such as Bt spray; but their availability in Africa is currently limited.

Substantial success has been recorded worldwide in using specific entomopathogens to control lepidoperan pests such as stem borers, a number of armyworm species as well as Helicoverpa.

Key limitations in the use of biopesticides in general include their delayed knockdown effect on pests compared to synthetic pesticides which is more immediate; lack of awareness of their existence; lack of standard recommendations for their use; improper storage conditions impacting the product efficacy; most of them usually have a short life; process of their official registration is often costly and time consuming; and the slow development of research in this area.

Furthermore, utilization of microbial pesticides in IPM of FAW requires scientific studies such as systematic surveys and larval collections and rearing, investigations on their properties as well as modes of action on the targeted insect pest and pathogenicity. The starting point for the scientific studies is local identification of their existence and impact.

Participants in FFS can conduct their own pilot exploration of locally available microbial pesticides which can be incorporated as one of the key tools for the IPM of FAW. It is recommended that trainers develop collaboration with national research centres for further support in the characterization of microbes that will be encountered.

Farmers should be aware that most biological pesticides do not kill pests immediately; but they reduce feeding, which is essential, while insects/larvae die normally in a few days time.

Botanical pesticides for Fall Armyworm management

The use of plant-derived pesticides (commonly called “botanicals”) in pest management is a cultural practice of most African farmers. It could provide a potential arsenal against the Fall armyworm in Africa.

The mode of action of botanical pesticides is broad and ranges from: repellency, knock-down, larvicidal to anti-feedant, moulting inhibitors and growth regulation.

They have a broad-spectrum activity with generally little or no mammalian toxicity; however some botanical pesticides are highly toxic not only for pests but also for natural enemies and for mammals including humans, for instance tobacco extracts. Pyrethroids will also affect natural enemies.

Farmers generally extract bioactive compounds as a concoction after grinding plant materials using water. Essential oils from bioactive rich plants and powdered forms are also used to some extent.

There are comparative advantages associated with the use of botanicals:

• X they are biodegradable and do not accumulate in the environment
• X generally less harmful to farmers and consumers (though there are some exceptions); and
• X they often are less toxic to natural enemies (predators and parasitoids), hence not disrupting ecosystem services delivered by these natural enemies.

Several plants extracts have been reported to have insecticidal properties against stemborers in cereals. These include Neem, Azadirachta indica; Persian Lilac, Melia azadirach; Pyrethrum, Tanacetum cinerariifolium; Acacia, Acacia sp; Fish-poison Bean, Tephrosia vogelii; Wild marigold, Tagetes minuta; wild sage, Lantana camara; West African peppar, Piper guineense; Jatropha, Jatropha curcas; Chillies, Capsicum spp; onion, Allium sativum, Allium cepa; Lemon grass, Cymbopogon citratus; Tobacco, Nicotina spp; Chysanthemum, Chrysanthemum sp; Wild Sunflower, Tithonia diversifolia. etc. (Ogendo et al., 2013; Mugisha-Kamatenesi et al., 2008; Stevenson et al., 2009, 2017).

Preliminary evidence indicates that seeds or leaves of plants of the Meliaceae family (Azadirachta indica, i.e. neem and Melia) and Asteraceae family (Pyrethrum) and other plants such as Tephrosia vogelii orThevetia neriifolia are showing effecacy in the management of armyworms.

This needs to be investigated in further detail against FAW. Potent botanical pesticides need to be further researched. It is critical to further research promising plants, their plant parts (leaf, stem, root or seeds), to optimize extraction methods and to evaluate their efficacy (mortality and repellence).

The capacities of smallholders should be strengthened through to promote preparation, utilization, testing, and adoption of botanical pesticides for FAW management as appropriate.

It is also important to assess the compatibility of botanical pesticides with other pest management options such as pheromones and entomopathogens, in order to optimize low-cost and effective pest management strategies for FAW.

Integration of botanical pesticides with management options such as Push-pull/ intercropping; pheromones, and less toxic synthetic pesticides as a last resort, is critical to achieve effective management of FAW.

Note that trainers and farmers should not assume that botanical pesticides are always harmless to humans and animals. Some can be highly toxic (such as tobacco leaf extract, containing nicotine). Farmers should rely on traditional knowledge about plant toxicity, and take precautions to reduce risks when preparing and using local botanicals especially in first instances.

See special topic on preparation of botanical pesticides in section B.6.10.

Botanicals are one category of biopesticides and as such, like any other pesticide, their registration in the country should be promoted. For more information on how to deal with botanical registration issues, please refer to the FAO “Guidelines4 on the registration of microbial, botanical and semiochemical substances for both plant protection and public health uses”.

In this category you find natural enemies that kill one or several individuals of FAW during their life time either as larvae or adults. In this case, eggs, caterpillars, pupae or adult FAW are considered as preys. Usually predators are non-selective or generalists, thus they feed opportunistically on more than one host species, sometimes even on their own kind. The following insects belong to generalist predators:

Earwigs (Dermaptera: Forficulidae, Carcinophoridae)

Two species are currently recognized to play a significant role as FAW egg predator in maize crops: Doru luteipes (Scudder) and Euborellia annulipes (Lucas).

Ladybird beetles (Coleoptera: Coccinellidae)

Both adults and larvae of ladybugs feed on various phytophagous insects such as mites, aphids, scales, mealybugs, eggs and young larvae of Lepidoptera including the Fall Armyworm. Coleomegilla maculata DeGeer, Cycloneda sanguinea (Linnaeus), Hippodamia convergens Guérin MenevilIe, Eriopis connexa Mulsant, Olla v-nigrum Mulsant, Harmonia axyridis (Pallas) and Neda conjugata (Mulsant) are species commonly found in maize fields in the Americas.

Ground beetles (Coleoptera: Carabidae)

Many carabid beetle species occurring in maize cropping are known for their predatory habits both as larvae or adults. Calosoma granulatum Perty has been observed to feed on young FAW caterpillars.

Assassin and flower bugs (Hemiptera: Reduviidae, Pentatomidae, Geocoridae, Nabidae, Anthocoridae)

There are several species of bugs that have been observed to feed on immatures of the FAW. The best known of this category belong to the genera Zelus (Reduviidae), Podisus (Pentatomidae), Nabis (Nabidae), Geocoris (Lygaeidae), Orius and Anthocoris (Anthocoridae).

Eusocial, solitary and other predatory wasps (Hymenoptera: Vespoidea) Spiders (Arachnida: Araneae)

Ants (Hymenoptera: Formicidae)

Ants are often among the most important predators of FAW larvae and pupae. Perfecto (1980) studied the interactions among ants, FAW and pesticides in maize systems in Nicaragua. She found that ants are very important predators of FAW in maize in Nicaragua and that pesticides dramatically reduced the presence and effectiveness of ants a natural biological control of FAW. She placed FAW pupae in the soil in maize fields and found that 92 percent of the pupae were removed within 4 days in fields without insecticide treatments, compared with only 4 percent in fields with insecticidal treatments.

Ants have already been seen attacking and killing FAW larvae in maize fields in Africa.

Some farmers have begun trying to apply lard or fish soup on their maize plants, to see if they can attract ants to their maize fields, so that they will then eat the FAW larvae present.

Birds and bats

Birds and bats have been observed to prey on FAW larvae. Studies in Central America have demonstrated significant impacts of birds on infestation levels of the FAW. Presence of trees or bird perches in or near fields will help attract birds who can prey on the FAW and help control their population.

Despite their importance as natural antagonists, a thorough assessment for predatory wasps, ants and spiders is often neglected because of the difficulty to establish a methodology to accurately assess their impact.

In Africa, though generalist predators such as ladybug beetles, earwigs, predatory bugs, eusocial- solitary- and other predatory wasps, ants and spiders are regularly observed in maize fields, a list of these natural enemies is yet not available.

It is expected that for these major functional groups, forthcoming assessments will reveal many parallels between the pest’s area of origin and the newly invaded continent.

How to favour the presence of natural enemies in fields?

Farmers can take many actions to protect and favour populations of natural enemies in their fields (this is called “conservation biological control”). Measures include avoiding overuse of synthetic insectides that can have detrimental effects on natural enemies; ensuring diverse boundaries around fields including open flowers and shrubs as habitat or food for natural enemies; trees or bird perches in or near fields; if pesticides are considered necessary, selecting products that are compatible with biological control such as Bt and botanicals based formulations, and more.

Entomopathogens

Pathogens (microorganisms that can cause disease) are everywhere. In agriculture, plant pathogens (e.g. fungi, bacteria, viruses, nematodes) affect plants, reducing yield or quality. Also very important, but less perceived by farmers, are entomopathogens – those pathogens that affect insects (‘entomo-‘).

The Fall Armyworm is naturally affected by several different types of pathogens:

• Viruses, in particular Nuclear Polyhedrosis Virus (NPVs) such as the Spodoptera Frugiperda Multicapsid Nucleopolyhedrovirus (SfMNPV)
• Fungi, in particular

1.  Metarhizium anisopliaey 
2. Metarhizium rileyi
3.  Beauveria bassian

• Bacteria, such as the Bacillus surigensis(Bt)

•  Protozoa

•  Nematodes

The host-specificity of these pathogens is quite high, usually restricted to a few closely-related insect species. These pathogens do not affect other groups of insects (natural enemies), plants, animals or humans.

FAW larvae naturally killed by viruses and fungi are easily identified in the field. Virus-killed larvae become soft and many hang from leaves, eventually oozing viroid particles and fluids (photo 2). Fungal- killed larvae turn rigid and appear “frozen” on the leaves, eventually turning white or light green, as the fungal spores mature (photo 1). These are the two most common groups of entomopathogens naturally killing FAW larvae in the field.

Farmers can learn to recognize these ‘farmer-friendly’ pathogens in the field. They can also multiply them locally. Farmers in the Americas sometimes collect the dead and dying larvae, full of viroid particles of fungal spores (the infective stages of the pathogens), grind them up in kitchen blenders. Then they strain the larval body parts out, mix the concentrated filtrate of virus or fungus with water, and spray them back out into the field, especially directly into maize plants currently infested with FAW.

Entomopathogens can play a very important role in natural regulation of FAW populations in the field. Farmers should learn how to identify the different organisms, understand their biology and ecology, and begin to experiment with them! They are truly farmers’ friends!

Naturally-occurring bio-control agents

The Fall Armyworm has many naturally-occurring ‘natural enemies’ or ‘farmers’ friends’. These biological control agents are organisms that feed on FAW.

In the Americas, and probably in Africa, these natural enemies can be active during all development phases of FAW, i.e. in the egg, larval, pupal and adult stage. Natural enemies have the potential to substantially reduce the FAW populations and hence the damage caused by FAW.

Their impact however depends on a number of factors including the diversity of organisms being active, their life-style, local presence, numerical and timely abundance, host specificity, agronomic practices, pest management methods etc.

A major challenge is to create conditions to exploit the potential of these beneficial organisms to their full extend. Broad spectrum pesticides kill many of the farmers’ friends. It is important that farmers recognize the pest in all its development stages, its associated natural antagonists, identity possible gaps to be filled in local natural enemy guilds and at the same time sustain their action by adequate management measures in an IPM context.

Biological control should be understood as an integral component of IPM and an important part of mutually compatible pest-suppressing methods aimed at generating higher profits whilst preserving the environment and human health.

Biological control agents (BCAs) include the following: 1) predatory insects and mites, which eat their prey; 2) parasitoids, which are insects with a free living adult stage and a larval stage that is parasitic on another insect; and 3) parasites and microbial pathogens, such as nematodes, fungi, bacteria, viruses and protozoa, which cause lethal infections.

Parasitoids of the FAW

Parasitoids are organisms whose adults lay eggs inside or attached to a single host organism. For their development, the resultant larvae feed on the tissues of the host until they are fully grown and pupate. The larvae of parasitoids always kill their host as the outcome of their development.

The majority of parasitoids known to be associated with the FAW are wasps, and less frequently flies. Species that have undergone an adaptation process to the FAW display a narrow host range.

Such co-evolved parasitoids can exert a strong impact on populations of the FAW and are thus good candidates for use in biological control programmes.

During inventories in the Western Hemisphere, about 150 different parasitoid species were found to be associated with the FAW in various crops.

The following are some of the most common parasitoids known to be well adapted to the FAW in the Americas:

Telenomus remus Nixon (Hymenoptera: Platygastridae)

• –  Identification: minute wasp of about 0.6 mm size with black shiny body. The wings are transparent and have reduced venation. Female antennae have 11 segments whereby the last 5 are enlarged forming a club. Males have 12 antennal segments of equal size.
• –  Behaviour: The species behaves as an egg parasitoid, i.e. females T. remus are attracted to FAW egg masses where they oviposit. Offspring of the parasitoid develop within eggs of FAW of which they then emerge as adults.
• –  Life cycle: over their lifetime females are able to parasitize some 120-130 FAW eggs. The development of immatures takes about 10 days at 280C and thus about 40 generations are produced per year.
• –  Importance: T. remus is reported to be highly effective in several South American countries with parasitism rates above 80 percent depending information sources.

Chelonus insularis Cresson (Hymenoptera: Braconidae)

• Identification: parasitoid of about 5 mm size characterized by a carapace-like abdomen. A white band medially divided can be observed at the base of the abdomen. Wings bear numerous veins. Antennae of both sexes are filiform and have 16 segments or more.
• –  Behaviour: C. insularis is an ovo-larval parasitoid. Females oviposit in eggs of FAW but larvae start their development in later instars of the caterpillar. When mature, parasitoid larvae exit their host and build a silken cocoon to pupate.
• –  Life cycle: each female can parasitize about 600 FAW eggs. At 28-300C the parasitoid is able to develop within 20-22 days and females can live for about 12 days.
• –  Importance: C. insularis is the most common among FAW parasitoids in the Caribbean as well as in Central and South America.

Cotesia marginiventris Cresson (Hymenoptera: Braconidae)

• –  Identification: Male and female average 3 mm in length. While the head and thorax of adults are black, the abdomen is tan. The antennae are long segmented and slighter shorter than the body length. Females can be recognized by a very short ovipositor at the tip of the abdomen.
• –  Behaviour: C. marginiventris is a solitary larval parasitoid of noctuids. On the FAW, Cotesia adult females attack preferably 1st and 2nd caterpillar instars, on which a single egg is usually laid. Shortly before pupation the full grown parasitoid larva leaves its host and spins a white cocoon of 4 mm size, of which an adult wasp will emerge a few days later.
• –  Life cycle: The parasitoid needs 12 days to develop from egg to adult at 300C. In total, 200 to 300 offspring are produced per female. Adults have a lifespan of 22 to 30 days.– Importance: C. marginiventris is less sensitive than other parasitoids in environments sprayed with chemical insecticides. It is adapted to subtropical and warm temperate areas. Attracted to host volatiles, it can persist at low FAW population densities using alternate hosts, thus it is a better competitor than Chelonus insularis.

Trichogramma spp. (Hymenoptera: Trichogrammatidae)

•  Identification: There are numerous species of the genus Trichogramma known to develop inside the eggs of the FAW and of many other Lepidoptera. Typically Trichogramma spp. are tiny wasps less than 0.5 mm long. Adults are mostly orange, brown or even black. Antennae are short, clubbed in females and hairy in males.
• –  Behaviour: Adult females lay their eggs inside FAW eggs. Along with the larval development they gradually turn darker and are almost black when the parasitoids pupate. Adults emerge by chewing an exit hole on the FAW egg.
• –  Life cycle: The parasitoid completes its development in about 8 days at 280C. Females can parasitize up to 120 moth eggs and live for 6-7 days.
• –  Importance: In Latin America Trichogramma spp., in particular T. pretiosum and T. atopovirilia, are commonly mass-reared on alternative hosts in local mass production units and commercialized for inundative field releases.

Fly parasitoids: Archytas, Winthemia and Lespesia (Diptera: Tachinidae)

• –  Identification: Several fly species of the family Tachinidae are able to develop on FAW caterpillars. Attacks by such parasitoids can be detected either when small maggots are visible in presence of FAW caterpillars, or tiny white eggs are observed on their skin. Alternatively fly pupae can be found nearby dead FAW larvae.
• –  Behaviour: For species that lay directly several eggs on the skin of their host, parasitism starts immediately upon penetration of the maggot into its host. Other species await pupation of FAW to intensify their host feeding and complete their development. Despite frequent superparasitism, only a single fly develops per caterpillar.
• –  Life cycle: larvae Lespesia archippivora (Riley) completes their development within 13 to 17 days. Fly females can lay up to 204 eggs during their life time.
• –  Importance: About one third of parasitoids inventoried from the Americas belong to the family Tachinidae. While these often target several species of Lepidoptera attacking maize including other noctuids, they are also found on diverse host plants of the FAW.

In Africa, because of the relatively recent introduction of the FAW on the African continent, data on native natural enemies are still very scanty. First field data demonstrate that a few parasitoids species have already accepted eggs and caterpillars of the FAW as a host.

As these data are preliminary, it remains to be verified whether these natural enemies have shifted from African stemborers or earborers to the FAW, or if they represent new associations from other hosts.

The following parasitoids were recovered from the FAW in West, Central and East Africa:

A very important management option for smallholder farmers in Africa, based on the experience of smallholders in the Americas, is to visit their fields regularly, and crush egg masses and young larvae*(“use your fingers, not pesticides”). Farmers should visit fields twice a week during vegetative stage, especially in periods of heavy oviposition by FAW, and once a week or every 15 days in later stages.

Some smallholder farmers in the Americas report using ash, sand, sawdust or dirt into whorls to control FAW larvae. Ash, sand and sawdust may desiccate young larvae.

Dirt may contain entomopathogenic nematodes, Nucleo- polyhedrosis Virus (NPV), or bacteria (such as Bacillus sp.) that can kill FAW larvae.

Smallholder maize farmers in Central America and FFS farmers in Africa also report using lime, salt, oil and soapsas control tactics. Lime and ash are very alkaline.

They also use local botanicals (neem, hot pepper, local plants) and some farmers report success.

Other farmers recycle the naturally-occurring entomopathogens, by collecting the larvae killed by virus or fungi, grinding them, straining the body parts out (leaving just the fungal spores or viroid particles), mixing this filtrate with water and spraying it back into the whorls of infested plants (see also the following section on biological control).

Some FFS farmers report effectively pouring water in the maize whorl to drown the larvae.

Other farmers in Central America and FFS farmers in Africa use sugary sprays, oil or lard, ‘fish soup’ or other material to attract ants and wasps to the maize plants. The predatory ants are attracted to the lard, oil, bits of fish parts, or sugar; once on the maize plants, they also find and eat FAW larvae.

Finally, FFS farmers for instance in Benin, reported picking larvae to feed them to chicks for poultry production.

FAW are also edible for human consumption. In countries where insects are consumed, they can be a good complementary source of protein for local population.

Very little formal “scientific” studies have been carried out on these local controls, but many farmers including in Africa report success with them. They should be further tried by farmers under their local conditions.

* It is important however, that mechanical controls such as crushing egg masses and picking larvae do not interfere with children’s regular attendance at school.

Push-pull technology

Push-pull is a habitat management strategy developed and implemented to manage pests such as stem borers, striga weed and address soil degradation, which are major constraints in maize production in Africa. The technology entails using a repellent intercrop (Desmodium as a “push”) and an attractive trap plant (Napier/Brachiaria grass as a “pull”).

The Napier grass planted around the maize farm:

•  attracts stemborers and FAW to lay eggs on it;
• but it does not allow larvae to develop on it due to poor nutrition; so very few larvae survive. At the same time, Desmodium, planted as an intercrop:
•  emits volatiles that repels stemborers or FAW, and
•  secretes root exudates that induces premature germination of striga seeds and kills the germinating striga; so this depletes seed banks of striga in maize farms over time;
•  covers the ground surface between maize, thus smothering weeds
•  enriches the soil with nitrogen, preserves soil moisture and protects the soil from erosion

The Desmodium and Napier/Brachiaria grass grown in Push-pull farms also:

•  provide valuable biomass as fodder for livestock, which can translate into increases in dairy products like milk.

“Push-pull climate smart” (combination of Desmodium Greenleaf and Bracharia cv Mulato II):

•  is designed for dry and hot conditions to address the challenges posed by climate change
•  Brachiaria grass grows fast with less water, and has been found to tolerate dry conditions better than Napier grass.

Push–pull is an effective and efficient low-cost technology as it addresses some major constraints faced by smallholder farmers. The multiple benefits of this technology can result in an overall and significant improvement of farmer’s food security and livelihoods.

Observations on FAW (S. frugiperda) by at least 250 farmers who had adopted the climate-smart Push-pull technology in drier areas of Kenya, Uganda and Tanzania indicated reduction of FAW larvae per plant and subsequent reduction in plant damage. Further surveys on climate-smart Push-pull and monocropped maize farms indicated 82.7 percent reduction in average number of larvae per plant and 86.7 percent reduction in plant damage per plot in climate-adapted push-pull compared to maize monocrop plots.

Hence, Push-pull technology appears effective in controlling FAW, with associated maize grain yield increases under the conditions tested. This technology could be immediately deployed for management of the pest in East Africa and in areas with similar conditions. Further testing in other agroecological zones is needed (Midega et al. 2018).

The push-pull technology is a specific application illustrating the general principle of the role of plant diversity on insect populations. There may be other plants (including crop species) that can be used to ‘push’ or ‘pull’ FAW and its natural enemies.

Damaged plants can scare farmers. Never before have they seen this type of damage, where the insect eats through so much of the leaves. Farmers know about stem borers, but because they aren’t often seen (hidden in the stems), they don’t often scare farmers like this new pest, the Fall Armyworm.

The spectacular-looking damage is very photogenic. The combination of farmers’ nervousness, media alarmism, and politicians’ quick reaction to do something has led to some bad decisions, including the use of Highly Hazardous Pesticides. Some older pesticides, which have long been banned in other parts of the world due to demonstrated human health impacts, are still available and used in some African countries. Some of the older pesticides don’t work, because FAW has developed resistance to them.

Such panicky responses are likely when the farmers and others don’t understand the potential impact of FAW damage. The quick response to sight of significant-looking damage is to assume that it will cause dramatic yield reduction. But that’s not necessarily true. In fact, we know that in most cases FAW does NOT cause “total destruction”. In most cases the leaf damage does cause some yield reduction, but it is probably far less than what farmers without experience with the pest believe.

Maize has been selected by humans for thousands of years to yield well, even in face of damage to insects, pathogens and other threats. These eons of selection have resulted in maize plants that have considerable capacity to compensate for foliar damage.

The response of maize yield to FAW infestation has been studied in the field a number of times in the Americas. A review of these studies shows that while of concern, FAW damage in maize is not devastating.While a few of the studies show yield reductions due to FAW of over 50 percent, the majority of the field trials show yield reductions of less than 20 percent, even with high FAW infestation (up to 100 percent plants infested). Maize plants are able to compensate for foliar damage, especially if there is good plant nutrition and moisture. While FAW needs to be managed sustainably by farmers, it is not cause for panic.

In FFS, we can examine our maize’s ability to compensate for defoliation by conducting a Special Topics experiment (see section B.6.7). The experiment will look at the impact of defoliation of maize plants at different growth stages on grain yield.