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Fall armyworm (Spodoptera frugiperda) management by smallholders



The fall armyworm (FAW) (Spodoptera frugiperda) is a crop pest species that has become global, having spread from its native American distribution to Africa and Asia since 2016. Its rapid spread, plus concerns about potential yield losses, have led to the search for sustainable management options. While most farmers affected by FAW in America have large-scale farm operations, the overwhelming majority of farmers in Africa and Asia are smallholders. This dramatically different context means that different management approaches must be sought. Large-scale producers with high-productivity, access to international market prices, risk-transfer mechanisms and the benefits of government subsidies are able to use technologies unavailable to smallholder farmers without access to those conditions. This review examines these differences and surveys the literature for accessible management options for smallholders, largely based on locally available solutions using ecological knowledge. Innovative digital solutions may also play a role in helping farmers learn about these solutions, and share them locally.
Fall armyworm (Spodoptera frugiperda) management by smallholders
Allan J. Hruska
Address: Food and Agriculture Organization of the United Nations, Viale delle Terme di Caracalla, Rome 00153, Italy
AJH: 0000-0003-0984-3816.
Correspondence: Allan J. Hruska. Email:
Received: 3 April 2019
Accepted: 1 July 2019
doi: 10.1079/PAVSNNR201914043
The electronic version of this article is the definitive one. It is located here:
© CAB International 2019 (Online ISSN 1749-8848)
The fall armyworm (FAW) (Spodoptera frugiperda) is a crop pest species that has become global,
having spread from its native American distribution to Africa and Asia since 2016. Its rapid spread,
plus concerns about potential yield losses, have led to the search for sustainable management
options. While most farmers affected by FAW in America have large-scale farm operations, the
overwhelming majority of farmers in Africa and Asia are smallholders. This dramatically different
context means that different management approaches must be sought. Large-scale producers with
high-productivity, access to international market prices, risk-transfer mechanisms and the benefits of
government subsidies are able to use technologies unavailable to smallholder farmers without access
to those conditions. This review examines these differences and surveys the literature for accessible
management options for smallholders, largely based on locally available solutions using ecological
knowledge. Innovative digital solutions may also play a role in helping farmers learn about these
solutions, and share them locally.
Keywords: Africa, Agriculture, Americas, Asia, Fall armyworm (FAW), Infestations, Maize, Pests, Smallholders
Review Methodology: We reviewed all the literature relevant to FAW management by smallholder maize producers.
The Rapid Spread of Fall Armyworm
The fall armyworm (FAW) (Spodoptera frugiperda), has
been a consistently important insect pest for a number of
crop species, especially maize, in the Americas for
centuries [1]. In the last few years, FAW has become an
invasive species in Africa, the Near East and Asia. FAW was
first reported in early 2016 in mainland West Africa
(Nigeria, Togo, Benin) and on the island of São Tomé
(São Tomé and Príncipe) [2]. It rapidly spread across
sub-Saharan Africa during 2016 and 2017 and by late 2018,
had been confirmed by virtually every country in
sub-Saharan Africa [3]. It was confirmed in Yemen and
India by July 2018 [4] and by early 2019, had been
confirmed in an additional five Asian countries, including
China [3].
FAW prefers maize, but it is also common on sorghum,
rice and millets, and is sporadically important on a vast
array of additional crops and plants, including cotton and
vegetables. It is reported to infest 186 host plant species in
North and Central America [5], while Montezano et al.[6]
have reported 353 host plant species based on a literature
review and additional surveys in Brazil, from 76 plant
families, principally Poaceae, Asteraceae and Fabaceae.
FAW is native to tropical and subtropical regions of the
Americas and migrates north and south annually, following
maize plantings in temperate zones [7]. FAW is not able to
enter diapause and is killed by low temperatures [1, 8]. In its
native range, it is established year-round where winter
temperatures rarely fall below 10 °C [810]. Adult females
are relatively short-lived (1319 days at 26.8 °C) but highly
fecund, with around 1000 eggs being laid per female, in
clusters of 100300, usually on leaf surfaces [11]. The first
and second instars scrape leaves, leaving a windowing
damage, while later instars leave ragged holes in young
leaves emerging from the plant whorl. In a trial examining
larval dispersal of S.frugiperda, Pannuti et al. [12] reported
finding over 90% of recovered larvae within a 1.1 m radius
CAB Reviews 2019 14, No. 043
of a maize plant 14 days after being infested with an egg
mass. Larvae are cannibalistic at high larval densities [13],
resulting in typically one later instar larva per maize plant.
FAW Management in America
In the USA, Brazil and Argentina, FAW is routinely
controlled via the use of genetically modified maize,
which incorporate genes that express for the production
of toxins lethal to FAW. The adoption of this technology
has now surpassed 85% of the maize area planted in those
three countries [14]. The use of this technology and of
effective pesticides is supported by the access that the
farmers have to relatively stable international markets for
their maize, which is primarily used for animal feed, ethanol
production, or processed to extract high fructose syrup,
coupled with subsidies and risk transfer mechanisms
(e.g. insurance).
Globally, the vast majority of maize farmers are
smallholders, whose context is very different from that of
large-scale commercial farmers. These differences include
economic, ecological and cultural factors. The vast majority
of smallholder maize farmers do not have access to high and
stable prices for their maize, subsidies, or risk-transfer
mechanisms, severely limiting their access to expensive
control technologies. They also produce in much more
diverse landscapes and cropping systems, and have different
production goals.
FAW in Africa and Asia
FAW quickly and naturally spread across sub-Saharan Africa
and Asia upon its arrival, and now routinely infests millions
of hectares of maize across Africa and Asia. Although
FAW is capable of feeding on many crop species, the
crop most affected in Africa and Asia has been maize.
However, in drier areas, such as in the Sahel, FAW has
been consistently reported from crops other than maize;
e.g. sorghum, millets, wheat and teff. The infestation levels
vary dramatically, but the average infestation level across
the continent is about 30% of plants infested with FAW [3].
Most maize farmers across the continent are now aware of
the pest: 99% of maize farmers in Ethiopia were aware of
FAW as were 100% of maize farmers in Kenya [15].
Maize is grown on approximately 37 million hectares
annually in sub-Saharan Africa [16], the vast majority
(approximately 95% of the area) in smallholdings, usually
<2 ha. These small plots form a heterogeneous patchwork
of often polyculture plots, mixed in a landscape of trees and
shrubs across much of Africa. Most maize grown in Africa is
white maize, produced for family consumption, unlike the
yellow maize grown by commercial producers globally.
Asia produces about 32% of the maize globally [3]. China
is the second largest maize producer in the world, growing
maize on over 40 million ha. Like Africa, most maize
farmers are smallholders. Unlike Africa, in Asia, most maize
is yellow maize, produced as animal feed.
Smallholder Maize Producers
Smallholder maize farmers in sub-Saharan Africa typically
grow their small plots of maize using almost exclusively
family labour; they plant saved seed, use few purchased
inputs, and their production is mostly for household
consumption [1719] If they have excess maize, they
typically receive low prices from local intermediaries for
their production; e.g. US$0.02/kg [FAO, in press]. Low
produce price was perceived to be a risk among 100% of
farmers surveyed in Ghana [18].
The low prices severely limit their ability or interest
in using higher rates of purchased inputs. The concept of
economic injury level and economic threshold was
developed to determine the break-even point between
the direct costs of pest damage and the value of the
production protected or savedby taking the management
actions [20]. Typically, the calculation seeks a pest
population level at which action should be taken to avoid
economic losses. Pedigo et al. [21] defined Economic Injury
level (ElL) as EIL = C/VIDK, where the EIL is expressed
in number of injury equivalents per production unit
(e.g. insects/ha), C = cost of the management activity per
unit of production (e.g. US$/ha), V = market value per unit
of the produce (e.g. US$/kg), I = injury units per insect per
production unit [e.g. proportion defoliated (insect/ha) and
D = damage per unit injury [e.g. (kg reduction/ha)/
proportion defoliated] and K = proportionate reduction
of the insect population from the action.
Economic equilibrium (optimal expenditures) is reached
when C = VIDK. For smallholder maize producers in Africa
facing FAW, typical values for VIDK are: (US$0.05/kg)
(1400 kg/ha) (15% yield reduction) (75% effectiveness) =
US$7.88/ha. Thus, to be economically rational, a farmer
should not spend more than US$7.88/ha to manage FAW
under these conditions. The low prices received by the
farmers and the low productivity of production result in
very limited options for smallholder maize farmers to
manage FAW in their maize. A recent paper by Baudron
et al. [22] estimated 12% yield reduction from FAW
infestation in maize in Eastern Zimbabwe.
Given this economic context, it is not surprising that
most smallholder maize farmers in Africa, before the arrival
of FAW, had used few purchased inputs. Most had used no
pesticides. Muhammad et al. [23] conducted 350 household
surveys of maize-producing families in Makueni and
Machakos, Kenya and found that 0.5% had used herbicides
and 2% had used insecticides. Household surveys carried
out from 2010 to 2012 by the World Bank demonstrated
that across six countries (Ethiopia, Malawi, Niger, Nigeria,
Tanzania and Uganda) 16% of farmers used agrochemicals
across all crops. This group included countries with
significant agricultural input subsidy programmes. In
2 CAB Reviews
countries without input subsidy programmes, the use of
pesticides was very low (Malawi, 3%, Niger, 8% and Uganda,
11%). The use of these inputs in maize is probably even
lower, given the use of production for self-consumption
and the low prices received for any market sales [24].
FAO [25] carried out household surveys in Namibia in
August 2017. Interviews of 592 households in 301 villages
demonstrated that only 1.7% of households used pesticides.
This low proportion is in line with the 2013/2014 Namibia
Census of Agriculture which found that only roughly
13 000 out of approximately 150 000 agricultural house-
holds in the communal sub-sector use pesticides of any
sort, including herbicides, fungicides, insecticides and
traditional products [26].
During 2016 and 2017, many governments, some with
donor support, provided pesticides free of charge to
farmers for FAW control or applied them with government
employees. For example, in Zambia in 2017, nearly
102 000 litres of pesticides valued at 18 million Zambian
Kwacha (US$1.97 million) were distributed, and a further
3 million Kwacha (US$330 000) was spent on sprayers and
personal protective equipment such as gumboots and
respirators [27]. In Ethiopia, the government distributed
271 779 litres of pesticides for FAW in 2017 and
167 896 litres in 2018 [28].
Not surprisingly, the use of pesticide among smallholder
maize farmers increased dramatically in those countries
with such policies and programmes. This was documented
in a report for CABI by Rwomushana et al. [27], which said:
53% of farmers in Ghana and 43% of farmers in Zambia
used pesticides (in 2018). However, when compared with
2017 data, farmers were generally using fewer synthetic
chemicals (72% in 2017 for Ghana, and 62% in 2017 in
Zambia)The marked reduction in pesticide use in Zambia
for the control of FAW compared to the previous year may
be due to reduced purchase and distribution of pesticides
by the governmentThe current survey (2018) also
established that in Zambia, twice as many farmers were
using traditional methods such as applying ash, urea or sand
on larvae, while only 27% of farmers handpicked egg masses
compared to 36% in 2017. The increase in farmers
deploying a wider range of control methods may also be
attributed in part to the lack of pesticide distribution as well
as Zambian smallholder farmerstraditional non-chemical
approaches to maize cultivation. A third of farmers
interviewed did not apply any control measure, compared
to 23% in the 2017 survey[27]. Many donors and
governments began to scale back the distribution of
pesticides from 2017 to 2018, as exemplified by the 38%
reduction in pesticide distribution by the Ethiopian
government during that period [28].
Most smallholder maize farmers in Africa traditionally
use cultural controls, including the destruction of crop
residues, manipulation of planting dates, use of locally
available substances and tillage methods [29]. The majority
of smallholder farmers in Africa practice intercropping
[30]. As free pesticide distribution diminishes, due to lack of
government funds and donor fatigue, smallholders will be
faced with managing FAW in their fields within the context
of their production systems. This review examines
the agroecological basis of sustainable integrated pest
management for smallholder maize farmers and suggests
a research agenda to fill knowledge gaps and validate
promising practices over a wide range of ecosystems.
Since the arrival of FAW in Africa, some research has
begun on management practices accessible by smallholders.
Although some practices have been tried, there are still
many more potential effective, accessible practices based
on the agroecology of FAW in Africa and Asia that need
to be explored. This review presents a survey of the
agroecology of FAW that leads to management of land-
scapes and cropping systems to take advantage of locally
available practices that are immediately accessible to
smallholders, but which require further research and
validation over the wide range of cropping systems and
environments across Africa.
Impact of FAW Infestation on Maize Yield
The direct foliar damage from FAW feeding on maize is
alarming to many farmers who have never seen this type of
damage before. This alarm is often shared by politicians,
leading to the urgent response of pesticide procurement
and use. But the foliar damage caused by FAW in many
cases does not result in dramatic yield reduction. The maize
plant is quite capable, under good moisture and nutrition
conditions, to compensate for a level of foliar damage that
may appear alarming to farmers first seeing the damage.
The response of maize plants to foliar damage at different
stages of plant growth has been well studied in other parts
of the world. Dozens of careful, controlled studies on the
yield loss caused by FAW have been carried out in the
Americas (notably, the USA, Brazil and Mexico).
In the USA, many maize farmers have subsidized crop
insurance for their maize crops; specifically against hail,
which can have a devastating effect on maize yields at
certain moments. Crop insurance in the USA started in the
1880s when private insurance companies first sold policies
to protect farmers against the effects of hail storms. In
2016, farmers spent US$981 million on crop-hail insurance
to protect US$36 billion worth of crops [31]. Due to the
large area covered and the importance of this insurance
programme, the National Crop Insurance Service (NCIS)
has reviewed and prepared corn loss instructionsfor the
private insurance companies that provide coverage to
The US Department of Agriculture published the results
of NCIS research in the Corn Loss Adjustment Standards
Handbook (FCIC 25080) in 2013. The results from the
research show that even 70% defoliation at the 12-leaf stage
is estimated to cause a 15% yield reduction. A 25%
defoliation never causes more than 9% yield reduction
and may cause less than a 5% yield reduction when the
Allan J. Hruska 3
damage occurs before the 18-leaf stage. These results are
very significant for FAW damage, as rarely does the
defoliation from FAW exceed 50%, and more typically is
closer to 25%. At these levels of infestation, farmers with
little experience with FAW and unaccustomed to observing
significant foliar damage to their maize are likely to
overestimate the impact of FAW damage on their maize
yield. In some cases, however, FAW does directly infest
cobs. This direct damage has a much greater impact of
grain yield and grain quality than does the indirect foliar
The results demonstrate the capacity of maize plants to
compensate for low-level artificial defoliation across
growth stages and the capacity of maize plants to
compensate for higher levels of defoliation when it
occurs at certain growth stages. These results were
subject to further testing recently by Thomison et al.
[32], who carried out field studies in three different
locations in the midwestern United States, conducting
artificial defoliations at two levels (50% and 100%) and at
three stages of maize growth, then measuring the yield
reduction from each treatment and comparing their results
with the NCIS chart. In all cases, the field trials had lower
yield losses than the NCIS chart and in most cases,
significantly lower. In none of the cases did artificial
defoliation at the 50% level, even when conducted up to
three times, result in more than 24% yield loss.
These studies of the impact of artificial defoliation on
yield clearly demonstrate maizes ability to compensate for
foliar damage. While the defoliation caused by FAW looks
dramatic, especially to farmers unaccustomed to seeing
such foliar damage in their fields, its impact on maize yield is
likely to be significantly lower than what farmers would
In addition to artificial defoliation studies, the yield loss
due to FAW infestation has also been extensively studied in
field trials conducted in the Americas. The maize yield
response to FAW infestation in the American state of
Indiana was studied by Cruz and Turpin [33]. They
artificially infested maize plants with FAW larvae at 810
leaf stage, measured FAW feeding damage and yield in trials
over 2 years. In the first year, they recorded a 15% yield
reduction from 98% of plants infested versus 0% infestation.
The same study showed no significant yield reduction of
31% of plants infested. In the second year, an 18% yield
reduction was recorded with 100% of plants infested. Cruz
et al. [34] examined the impact of 100% of plants infested
(manually infested) with FAW at mid-whorl stage on maize
yield in Brazil on three different maize varieties. Yield
reductions due to FAW were measured at 58%, 29% and
21% compared to uninfected controls. The yield impact of
FAW and southwestern corn borer [Diatraea grandiosela]
was examined over 2 years by Williams and Davis [35],
used artificial infestation of larvae, resulting in almost 100%
of plants infested. FAW infestation resulted in 13% yield
reduction, while D. grandiosela infestation resulted in a 57%
yield reduction.
Hruska and Gladstone [36] studied the response of
maize yield to different levels of plant infestation during
three periods of vegetative maize growth in irrigated maize
under hydric stress in Nicaragua. Chemical insecticides
were applied and protected the plants from FAW and the
neotropical cornstalk borer (Diatraea lineolata). Yields from
treatments which had infestation during just one period
(approximately 15 days) did not differ from complete
protection. The treatment that had maximum infestation
during three periods yielded 34% less than the treatment
that had complete protection. Hruska and Gould [37]
reported on four field trials in Nicaragua of FAW and
Diatraea lineolata infestation and their impact on maize
yield. In the four studies, the yield reduction from
maximum FAW and D. lineolata infestations resulted in
yield reductions of 25%, 17%, 25% and 43%. The differences
were explained based on different infestation pressures and
environmental (rainfall) conditions.
FAW Economic Thresholds and the Need for
Validation in Africa and Asia
Based on the results of field trials on FAW impact on yield
and the economics of maize production and protection,
recommendations have been made regarding management
decisions for FAW in maize in the USA. For example,
Purdue University in Indiana recommends: The application
of an insecticide is usually not economical for control of the
fall armyworm. However, it may be necessary if the
infestation is extremely severe and/or the plants are
under stress. In such cases, if 75% of the plants exhibit
whorl feeding damage and larvae are less than 11/4 inches
(31 mm) long, and the plants are under stress, treatment
may be advisable[38].
Growing conditions of maize in Africa and Asia are quite
different from conditions in the Americas. The ability of the
maize plant to compensate for foliar damage depends on
the genetics, nutrition and water availability of the plant.
Maize varieties, plant density and other agronomic practices
will also influence the relationship between FAW infesta-
tion and yield. Experimental field studies are urgently
needed to validate the results from the Americas. In
addition, African and Asian smallholder farmers may have
different decision-making processes than American maize
farmers. To date, there is only one published paper that
measured maize yield loss due to FAW in Africa, reporting
a 12% reduction [22].
During the first years of infestation, the only estimates of
infestation levels and yield losses were available from
farmersestimates. Such estimates are fraught, due to the
inexperience of farmers with FAW. Without the experi-
ence of observing damage to their maize and then
harvesting the maize, farmers in Africa do not have the
practical experience to guide their estimates of yield loss. In
addition, farmers may sense that overestimates of damage
or yield loss may result in benefits from government
4 CAB Reviews
programmes or foreign donations, creating an incentive to
overestimate damage and yield loss.
Smallholder Maize Integrated Pest Management
Maize integrated pest management programmes in a
number of countries, including the USA, Brazil and
Argentina, incorporate new technologies, such as the
latest generation of chemical insecticides and genetically
modified hybrid varieties. The access to these technologies
is made possible by the economics of producing for
international markets that seek maize for use as animal
feed, ethanol production and as a source of sweeteners.
These same technologies are typically not accessible by
smallholder maize farmers, due to the low and unstable
prices and lack of access to risk transfer mechanisms.
Smallholder maize farmers are very constrained in their
access to integrated pest management options and must
often depend on locally available, low-cost options.
Before the arrival of FAW and the free provision of
pesticides to smallholder maize farmers in Africa and Asia,
the overwhelming majority did not use pesticides in their
maize but have instead used cultural control methods to
deter or kill insect pests. The practices of intercropping
maize with common beans, handpicking and killing insects,
and the application of tobacco extracts, wood ash and soils
to plants is common among these farmers [30]. The
economic constraints on smallholder maize producers
mean that their sustainable integrated pest management
will be largely dependent on agroecological approaches.
Those will rely heavily on knowledge and experience of
FAW in the local cropping systems and the conditions that
lead to the prevention of high levels of FAW damage. They
will also rely on adequate manipulation of the ecosystem to
maximize the effectiveness of naturally occurring enemies,
coupled with the use of locally available, low-cost tactics,
such as mechanical control and the use of local substances
to deter or kill FAW.
Due to the typically small plot size of maize production in
Africa and Asia, the direct, mechanical control (squashing
egg masses and handpicking small larvae) is feasible. Good
experiences have been reported with this technique
in Kenya (
events/detail-events/en/c/1113777/) and Ethiopia (2018),
where 337 000 ha of infested FAW fields were mechani-
cally controlled in 2017 and 402 000 ha in 2018 with
satisfaction expressed.
Good management of FAW begins with preventing
infestation and the impact of larval feeding. Late-planted
maize is often infested with high levels of FAW as the moths
seek vegetative maize. Thus, staggered planting of maize in
a landscape should be avoided. The ability of maize to
compensate for foliar damage is largely influenced by
adequate moisture and nutrition. Many smallholders grow
maize under unfavourable conditions for both and as a
result, suffer greater yield loss than if the maize had
adequate nutrition and moisture. Increased plant diversity,
especially intercropping, has been shown to suppress
herbivore populations, increase natural enemy populations
and reduce crop damage [39]. Garcia Gonzalez et al. [40]
found that fields intercropping pumpkin with maize had
lower FAW infestations than fields of just maize. Baudron
et al. [22] however, found significantly greater FAW damage
in maize fields intercropped with pumpkins. Van Huis [41]
showed in Nicaragua that intercropping maize with beans
reduced the percentage of maize plants infested by
S. frugiperda by 20% to 30%. Hailu et al. [42] demonstrated
that intercropping common beans or groundnut with maize
has reduced FAW oviposition by 30% in maize in Uganda.
One use of plant diversity is the push-pullsystem that
uses two types of plants: one which emits volatile chemicals
that repel pest insects, such as desmodium, Desmodium
uncinatum Jacq.(Leguminaceae) (push); and planting an
attractive trap plant, such as Napier grass, Pennisetum
purpureum Schumach (Poaceae) (pull), as a border crop
around this intercropped field. Moths are repelled from the
main crop by the repellent plant and are simultaneously
attracted to the trap plant [43]. The use of desmodium and
Napier grass in maize systems has recently been shown to
be effective in reducing FAW infestations and plant damage
caused by FAW [44]. Reductions are reported to be 82.7%
in the average number of larvae per plant and 86.7% in plant
damage per plot in climate-adapted push-pull compared to
maize monocrop plots.
Role of Natural Enemies
Many studies have shown that FAW is attracted by a large
array of natural enemies and their combined level of
mortality can be quite high. Luginbill [1] stated in 1928: As
has been previously mentioned, the abundance or scarcity
of natural enemies to a large extent determines whether or
not fall army worms become abundant enough during a
season to cause destruction to a crop. Local outbreaks are
often controlled by natural enemies alone.
In Nicaragua, 15 parasitoid species, one species of a
nematode parasite, three entomopathogen species and a
large number of predator species have been found on
S. frugiperda in maize. Important parasites are: the
braconids (up to 30% parasitism of the collected larvae,
mainly Aleiodes (=Rogas) laphygmae and Chelonus insularis);
the tachinids (up to 60% parasitism in maize and up to 100%
in weeds, mainly Lespesia archippivora); and mermithids (up
to 30% parasitism, Hexamermis sp) [41]. Pair and Gross [45]
found 73% FAW pupal mortality mainly due to predators.
In Honduras, Wheeler et al. [46] reported that 42% of
FAWs were killed by a complex of parasitoids, Chelonus
insularis (Cresson) (Hymenoptera; Braconidae) being the
most common.
Castro et al. [47] found up to 71% natural parasitism of
FAW larvae by an endoparasitic nematode (Mermithidae).
In Brazil, Varella et al. [48] conducted careful life table
Allan J. Hruska 5
analyses of FAW mortality, at both egg and early larval
stages over 3 years. They found that total egg mortality
ranged from 73% to 81% and the greatest egg mortality was
due to unviability, dislodgement and predation. At the early
larval stage, >95% of early larvae died from predation,
drowning and dislodgment by rainfall. They note the special
importance of rainfall and predation in early larval
mortality. Hoballah et al. [49] studied natural mortality of
FAW in Veracruz, Mexico over 2 years and found that early
larvae suffered 34% and 80% natural mortality during the
2 years.
In Ethiopia, Sisay et al. [50] examined parasitism of FAW
and found Cotesia icipe was the dominant larval parasitoid
with parasitism ranging from 33.8% to 45.3%, while in
Kenya, the tachinid fly, Palexorista zonata, was the primary
parasitoid with 12.5% parasitism. Many of these parasoi-
toids are very sensitive to chemical insecticides used in
commercial maize fields, as demonstrated by Meagher et al.
[51] in Florida, where they found that natural parasitism
levels of FAW larvae ranged from 1% in a commercial sweet
corn field to 92% in an unsprayed field on an agricultural
experiment station in Palm Beach County.
Perfecto [52] found that experimental reduction in ant
(Pheidole radowszkoskii and Solenopsis geminata) populations
in maize fields in Nicaragua resulted in significantly greater
FAW larval populations per plant and greater foliar damage
to maize caused by FAW. Perfecto [53] also showed that
application to the soil at planting of carbofuran resulted in
significantly reduced ant foraging and increased population
levels of FAW. Ants are often common in maize cropping
systems in Africa. Myrmicaria natalensis is a common ant in
Africa agriculture, and has been observed predating on
FAW in Malawi (personal observation). This species has
previously been observed attacking Heliothis armigera [54].
For smallholder farmers in Mesoamerica, the combi-
nation of the use of plant-diverse cropping systems and the
levels of control by natural enemies maintains FAW
populations at levels low enough levels for smallholders in
Central America [55].
Although many natural control organisms of FAW
appear to be already present, field surveys need to be
conducted to determine their distribution across the new
environments. Important gaps between the natural enemy
complexes in the natural FAW distribution and the
complexes present in the new range could be studied for
possible classical biological control programmes.
Enhancing populations of natural enemies through
landscape management
Plant diversity has also been shown to increase FAW
natural enemy populations harbouring and increasing the
activity of natural enemies [56, 57]. In Nicaragua, van Huis
[41] demonstrated that weeds increased parasitism of
FAW: 35 and 42 days after plant emergence, parasitism
by the tachinid Lespesia archippivora on larvae from weeds
was 10% to 20% higher than on larvae from maize; at 42
days, 54% of the maize larvae and 75% of the weed larvae
were parasitized by L. archippivora. Perfecto and Sediles [58]
showed that maize intercropped with beans led to a 28%
decrease in FAW infestation. They attributed this to the
lower populations of ants in maize monocultures.
Degri et al. [59] studied the effect of intercropping pearl
millet with groundnut on stem borer infestation of millet in
Nigeria and found up to 48% reduction in the per cent of
plants infested with stem borer and a 58% reduction in the
number of borers per plant. This reduction was attributed
to the increased levels of natural enemies found in the
intercropped fields. Midega et al. [57] found that in the
push-pull system there is an increased abundance, diversity
and activity of predatory arthropods, contributing to
reducing pest populations. Cañas and ONeil [60] tested a
traditional practice in Honduras of spraying sugar water in
maize fields and found that the sugar-treated maize had
higher numbers of natural enemies, 35% less FAW leaf
damage and 18% lower plant infestation rates than maize
treated with water alone.
The observations that ants can be important predators of
FAW in maize fields, coupled with the observation that
these predatory ants are attracted to certain protein-based
substances, has led farmers to experiment with the use of
fish soup and kitchen grease to increase ant populations and
decrease FAW larval populations [61].
Importance and Use of Entomopathogens
Gardner and Fuxa [62] reviewed the pathogens naturally
found on FAW in the USA and noted that the S. frugiperda
nucleopolyhedrovirus (SfMNPV) is commonly found
naturally and frequently causes epizootics in FAW. They
found up to 38% mortality in FAW attacking sorghum in the
state of Georgia. Other important pathogens of FAW
include fungi, bacteria and nematodes. Some of these
pathogens have already been observed killing FAW larvae in
Africa, sometimes at high levels (personal observation).
FAW was first reported in Yemen in August 2018 and in the
first reports of FAW in maize, cadavers of FAW were found
infected with fungi. Similarly, fungi have been reported
killing FAW soon after its arrival in India [63].
Due to their effectiveness and low mammalian toxicity,
interest in using entomopathogens as bio-pesticides
against FAW has increased. A number of commercial
bio-pesticides are registered and available for FAW in many
countries, including fungi and bacteria, and more recently
SfNPV (Andermatt & AgBiTech). Some of these pathogens
(Bacillus thuringiensis) have also been produced at low
cost, in local production (Cuba, Brazil). Local production
of Trichogramma has been successful in a number
of countries (Brazil, Egypt, etc.) for FAW and other
lepidopteran crop pest species.
In addition, at a very local level, some farmers have
multiplied pathogens by infecting larvae with the pathogens
6 CAB Reviews
and then harvesting them, processing them artisanally and
applying them. Some smallholders in Central America
simply collect dead larvae from their fields, grind them,
strain them and apply a solution of the extract into maize
plants infested with FAW (personal observation).
Vega [64] reviewed 85 published papers reporting fungal
entomopathogens as endophytes and their potential
for biological control. Of the 38 plant species studied,
maize was the most common. In a number of cases, the
endophytic fungus Beauveria bassiana demonstrated an
effect on Lepidoptera species tested. Entomopathogenic
fungi are widespread in agricultural fields and help suppress
crop pests. These natural enemies may be hindered by
certain agronomic practices associated with conventional
agriculture including the use of pesticides.
The entomopathogenic communities have been shown
to be affected by the cropping systems.
A significantly higher occurrence of insect pathogenic
fungi in soils from arable fields of organically managed farms
versus conventionally managed farms in Norway was found
by Klingen et al. [65]. Clifton et al. [66] reported similar
results in Iowa, in the USA, where in 1 year of the survey,
soil from organic fields and accompanying margins had
significantly more entomopathogenic fungi than conven-
tional fields and accompanying margins. Regression analysis
revealed that the percentage of silt and the application of
organic fertilizer were positively correlated with entomo-
pathogenic fungi abundance; but nitrogen concentration,
tillage, conventional fields and margins of conventional
fields were negatively correlated with entomopathogenic
fungi abundance.
Use of Locally Available Substances Toxic to FAW
Many smallholder farmers around the world use locally
available substances to try to control FAW. These include
local botanical extracts, soil, sand, wood ash, lime, oils
and soaps.
In addition to botanical extracts, some of which have
been demonstrated to be effective, other substances are
reported by farmers to be useful in killing FAW larvae.
With the exception of botanical extracts, the effectiveness
of the other substances has been little tested and virtually
no published results are in the scientific literature. These
substances (wood ash, soil, sand, detergents, oils, salt, lime,
urine and others) beg scientific testing, elucidation of the
mechanism of action and an exploration of the robustness
of results over space and time.
Among these substances, the effectiveness of botanical
extracts on FAW have been studied. Neem seed powder
was shown to be effective in killing FAW larvae, always
causing mortality of over 70% in laboratory studies [67].
Silva et al. [68] confirmed this result, finding neem toxicity
to FAW larvae and calculating the LC [48] values for neem
seed cake and leaves at 0.13% and 0.25% respectively. Souza
et al. [69] demonstrated that plant oils from Corymbia
citriodora, Eucalyptus urograndis and Eucalyptus urograndis
had positive significant effects of protecting maize from
FAW larvae. An aqueous seed extract from Carica papaya
was found to produce significant mortality of FAW larvae,
similar to that of the chemical insecticide malathion [70].
Salinas-Sanchez et al. [71] found that hexane, acetone
and ethanol extracts of Tagetes erecta caused 48%, 60% and
72% mortality respectively of FAW larvae. Lizarazo et al.
[72] tested three local plants in Colombia against FAW
larvae and found that one of them (Polygonum hydro-
piperoides) produced larval mortality as high as a commer-
cial insecticide (chlorpyrifos). Delgado Cáceres and Gaona
Mena [73] achieved 82% mortality of FAW larvae with
Polygonum hydropiperoides extracts at 50 g/100 ml water.
Franco et al. [74] demonstrated 100% FAW larval mortality
with water extracts of seed of Carica papaya at 10%
concentration. Plant oils from turmeric, clove, palmarosa
and neem were shown to have significant positive effects
of protecting maize from first and second instar FAW
larvae [75].
Stevenson et al. [76] reviewed the current status of
research and use of botanically active substances in Africa
and found great potential for their use in pest management
in Africa. Anjarwalla et al. [77] collected a good deal of
information on 18 pesticidal plants, much of it of use to
smallholder farmers in southern and eastern Africa.
Use of Soil for FAW Control
Smallholder maize farmers around the world may place soil
into infested whorls of maize plants out of desperation, but
a look into soil and FAW control analysis reveals a
fascinating agroecology, basis of functionality and potential
for use. Soil may kill FAW larvae directly, via abrasiveness
or absorption of wax from insect cuticles, causing larval
Diatomaceous earth has long been used for insect
control, especially for stored grain pests [78] and many
commercial products are available. It is considered one of
the safest and effective naturally occurring insecticides [79].
Diatomaceous earth adheres to the insect body and
damages the protective waxy layer of the insect cuticle by
absorption, and to a lesser degree by abrasion. Loss of
water from insect body results in death [79]. Constanski
et al. [80] studied the effects of several inert powders,
including diatomaceous earth and bentonite on FAW.
Benotite caused 93% FAW mortality, diatomaceous earth
caused 47% mortality.
In addition to the direct physical properties of soil
particles, soil often contains a rich ecosystem of micro-
organisms, some of which may kill FAW larvae. A number
of studies have looked at these entomopathogenic com-
munities. Valicente and Barreto [81] found that 75% of
1448 soil samples in ten Brazilian states, 75% contained
Bacillus thuringiensis. Ramirez-Rodriguez and Sánchez-Peña
[82] isolated the fungal entomopathogen Beauveria bassiana
Allan J. Hruska 7
from the soil in Mexico and found that it caused 98%
mortality of FAW larvae. Williams et al. [83] sampled soil
from maize fields in southern Mexico, Guatemala and Belize
and found that 29% of the samples contained SfMNPV
occlusion bodies/polyhedra in high levels. Williams et al.
[83] sampled soil from maize fields in southern Mexico,
Guatemala and Belize and found that 29% of the samples
contained SfMNPV occlusion bodies/polyhedra in levels
high enough to produce mortality in early instar FAW
Knowledge Gaps
Research on host plant resistance, including genetically
modified plants, and chemical control is advancing in the
private sector and international research institutes. Most of
these new technologies are not accessible by smallholder
farmers. Large knowledge gaps exist for the use of
biological control, plant chemical ecology and the use of
locally available substances to deter or kill FAW. Very little
research is being carried out on the use of these methods
by smallholders.
The research and experiences from the Americas
demonstrate that FAW has a complex agroecology that
can be used to sustainably manage FAW. Smallholders in
Central America and Mexico have been sustainably mana-
ging FAW for thousands of years. Many smallholders still
use the traditional mixed cropping systems (milpa), where
maize, common beans and a cucurbit are grown together in
polycultures. The experiences and the research from this
context are especially informative for smallholders in Africa
and Asia. Experiences and research from large-scale
commercial maize farms in the Americas are probably
less useful for smallholders.
Experienced farmers do not panic if FAW infests their
maize. They understand that the population levels are not
great and that they do not cause much damage or yield loss.
They also go to the fields often to observe and mechanically
control FAW. They have a basic understanding that many of
the FAW eggs and larvae are naturally killed in the fields by
rain, due to desiccation, or the direct action of natural
enemies. Farmers sometimes try to attract natural enemies
(e.g. by spraying sugar water) and when they need to, they
use locally available substances that have shown to be
effective in the past (use of local botanical extracts, soil, ash,
lime, salt, oils, soaps and urine).
These elements of smallholder maize integrated pest
management need to be carefully studied across the
ecosystems of Africa and Asia, to better understand
under what conditions they work best, understand their
mechanisms and to begin to develop recommendations that
can be up-scaled. Many farmers are already trying some of
these innovations in their fields. For example, the use of fish
soup to attract ants to fields has been reported from
Malawi. Researchers should work with farmer innovators in
their fields to test and measure the results of these
practices under different conditions. Special attention
should be paid to the costs, both economic and labour
time of different approaches, to ensure that the tactics are
accessible by smallholders. This type of co-creation is part
of Farmer Field Schools, which are a natural crucible for
doing farmer-led and researcher-aided research.
In addition to co-creation with farmers, researchers
should pay special attention to conducting controlled
yield-loss studies as a response to different levels of FAW
infestation at different periods of maize growth. These data
should be gathered from a number of ecosystems across
the continent so that better decisions can be made by
farmers and resource allocators. Farmer Field Schools have
been shown to be an excellent medium for smallholder
farmer innovation and co-creation [84].
Digital Technologies
A promising innovation that is being developed by FAO and
partners is the use of digital technologies that have the
potential of delivering FAW advice, based on local
conditions and creating communities of farmers to share
experiences locally. FAO has developed the Fall
Armyworm Monitoring and Early Warning System [3].
These tools are able to help farmers correctly identify and
monitor populations of FAW while providing them with
off-line, free advice based on local conditions delivered
from satellite data. This scalable technology shows huge
potential in delivering up-to-date information and advice to
farmers in their pockets.
FAW continues to spread into new territory, moving
further east and north in Asia, as well as north from
sub-Saharan Africa. The vast majority of farmers in the new
territories are smallholders. These farmers have limitations
and special contexts which define their options for
management of FAW. Fortunately, there is a vast literature
and knowledge about the ecology of FAW systems,
including chemical ecology and natural biological control,
which can be harnessed and tested in the new environ-
ments and landscapes of FAW in Africa and Asia. This
review has examined this extensive literature and reviews
the FAW management options for smallholders, largely
based on locally available solutions using agroecological
The author would like to thank the following reviewers of
this text, for their comments and suggestions: Mona Chaya,
Senior Coordinator for Food Chain Crises, FAO; Joyce
Mulila-Mitti, Plant Production and Protection Officer for
8 CAB Reviews
Southern Africa FAO; Keith Cressman, Senior Locust
Forecasting Officer FAO; Makiko Taguchi, Agricultural
Officer, FAO; Hans Dreyer, Director, Plant Production
and Protection Division of the Agriculture and Consumer
Protection Department, FAO; and three anonymous
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Allan J. Hruska 11
... In contrast, the low maize yield recorded per plot without any FAW control treatments was not consistent with the severity of FAW on maize leaves and cobs since the highest maize yield was achieved in 2018 which was characterized by the highest foliar and cob damage. In other words, lower damage does not necessary translate into higher yield as previously mentioned in other studies due to the involvement of additional variables such as attacked leaf and phenological stages, agronomic practices and ecological conditions (Hruska, 2019;Baudron et al., 2019). However, what might be some of the reasons here ? ...
... It has been already reported that under good moisture and fertilization conditions, maize can tolerate and recover from FAW damage depending on the plant stages attacked (Gross et al., 1982;Lima et al., 2010;Thomison et al., 2016;Hruska, 2019;Van den Berg et al., 2021). Indeed, seedling and vegetative crops have been shown to recover from defoliation, over a short period of time, particularly if the crop is rapidly growing like our planted maize variety. ...
... In sub-Saharn Africa, the development and use of biopesticides for the management of S. frugiperda is still in its infancy (Bateman et al., 2021). Less than 1% of the farm households use botanical insecticides to control FAW (Ndolo et al., 2019), although onfarm use of some of pesticidal plants is quite common to many African smallholder farmers (Stevenson et al., 2017;Hruska, 2019). In most African countries, with the exception of South Africa and Kenya, there is still a small number of identified biopesticide active ingredient registered for use and very few of them are registered against FAW . ...
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Fall armyworm (FAW), Spodoptera frugiperda, is a major pest of maize worldwide. Since its first report in West Africa in 2016, FAW has quickly spread causing severe outbreaks and crop losses. Chemical control remains the primary management option despite its adverse effects and its increasing inefficiency but safer and more effective alternatives exist. Here, we investigated the effectiveness of two bioinsecticides, a microbial and a botanical ones, in reducing the damage caused by FAW larvae to maize leaves and cobs, and their effects on yield. This was compared to that of two chemicals commonly used against FAW, deltamethrin- and a binary lambda-cyhalothrin and acetamiprid-based insecticides. A field trial was conducted in 2018 and 2019 in northwestern Senegal using a randomized complete block design. Without treatment, 1–25% of the total leaf area and 3–44% of the maize cobs were damaged by FAW. Despite different levels of damage between the two years, the same pattern was revealed with insecticide applications. Although deltamethrin insecticide may, in some years, reduce defoliation and cob damage, the effect of chemical insecticides, if any, was not reproducible, and maize yield was not improved. In contrast, azadirachtin and Bacillus thuringiensis formulations significantly reduced FAW damage on leaves. The proportion of damaged cobs could also be reduced by a factor of between 2 and 7.5 and the total maize yield was at least doubled. The scope of our results is discussed in the context of S. frugiperda control, particularly in Integrated Pest Management programmes and farmers’ practices.
... Given the level of infestation, the presence of the FAW in Africa is irreversible, and therefore, the smallholder farmers must learn how to manage this insect pest (Hruska, 2019). In response to this threat, one of the first reactions of farmers is the use of neurotoxic insecticides that are often not efficient and pose environmental hazard (Togola et al., 2018). ...
... In the Americas, producers and researchers have long studied FAW and their experiences are being used to develop sustainable management options appropriate for large-scale farmer systems (Meagher et al., 2022;Sparks, 1986). For example, in the United States, Brazil and Argentina, FAW was commonly controlled by the application of effective pesticides and the use of genetically modified corn (Bt corn), which incorporated genes to produce lethal toxins against FAW (Hruska, 2019). Farming systems as well as agroecological and socio-economic conditions (such as farm size, yields and access to institutional support services) did not allow African farmers to explore these options (Tambo et al., 2019). ...
... Unfortunately, these armyworm, 96.4% in Burkina Faso,85.3% in Gabon,65.2% In parallel, a number of literatures explore the control strategies used by farmers in some parts of Africa and their perception towards such management practices against FAW (Ahissou et al., 2022;Ansah et al., 2021;Caniço et al., 2021;Chimweta et al., 2020;Houngbo et al., 2020;Hruska, 2019;Kansiime et al., 2019;Kasoma et al., 2021;Kassie et al., 2020;Kumela et al., 2019;Tambo et al., 2019Tambo et al., , 2021Tambo et al., , 2022Tambo, Kansiime et al., 2020). Although research has already been undertaken in Africa, information on indigenous practices is lacking in some African countries, especially in Frenchspeaking countries, such as DR Congo, Gabon, Senegal etc., yet farmers in these countries have been facing the FAW invasion since 2016 and indigenous knowledge, perceptions and management practices might be different depending on the situation in each country. ...
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The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is currently an important pest of maize crops worldwide not only because of its dispersal ability but also because of its polyphagous feeding behaviour. Lack of sufficient information on the management of the fall armyworm attacks remains a crucial problem for maize smallholder farmers in Africa. In this study, 420 farmers were surveyed in central and west Africa using individual interviews to assess farmers' knowledges and perceptions of the fall armyworm damages and the management practices used. Most farmers (99.4%) were shown to recognize the fall armyworm and 92.5% claimed to already have damages in their fields. The fall armyworm seems not to be a new pest as most farmers identified it in different countries from 2015 to 2019. Apart from maize as the preferred crop of S. frugiperda, several alternative host plants including Napier grass, sorghum, onion, and cabbage were identified by the farmers. Although cultural and mechanical control methods are used by several farmers, the synthetic pesticide market is still preferred by almost half of the farmers (44.28%) who still use them. To control fall armyworm, 96.4% in Burkina Faso, 85.3% in Gabon, 65.2% in Benin and 25% in DR Congo reported using insecticides, against 5.9% in Senegal. Semiochemical-based method and biological control by promoting natural enemies of the fall armyworm are new concepts for farmers in DR Congo, Gabon and Benin. To avoid additional problems regarding health and resilience of agricultural systems, alternative methods such as push–pull approach, the development of biopesticides and resistant cultivars should form the basis of training given to farmers and should be popularized for sustainable control of the fall armyworm in central and west Africa.
... Given that maize is the most important staple crop for millions of people in the sub-Saharan Africa (SSA) region (12), large yield losses in maize caused by the invasion of FAW have further compounded the risks to food security in SSA. The invasion of FAW in Africa alarmed the governments of various countries, who then implemented a massive insecticide spray program to control FAW in maize fields (7,11,13,14). However, dependence on chemical insecticides poses risks to human and environmental health and results in the development of insecticide resistance (15,16). ...
... As is common in most SSA countries, Ethiopian maize farmers are predominantly smallholder farmers who depend on cultural methods for the control of insect pests (7,14,17). According to a review by Harrison et al. (18) of native FAW infestation in the Americas, there are various cultural and agroecological practices, such as sustainable soil fertility management practices, tillage techniques, and cropping systems, which can help to manage FAW infestation. ...
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The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a polyphagous pest native to the Americas. It attacks several crops but in particular causes significant damage to maize, which is a staple crop in Africa. Organic soil amendments have an impact on the physical, chemical, and biological properties of soil, which enhance plant resistance to or tolerance of insect pests and also promote a diverse population of natural enemies of the pest. However, the practices followed for the management of crop residue and animal manure affect their use as organic soil amendments. A field experiment was conducted to evaluate the effect of maize residue and cattle manure incorporation into soil on FAW in the Mana and Omo Nada districts of the Jimma zone, southwest Ethiopia, during the 2018/19 cropping season. Treatment involved three factors: five different levels of maize residue retention (0%, 25%, 50%, 75%, and 100%), different cattle manure storage systems (control, open, steel roof, and grass roof), and two different districts (Mana and Omo Nada). These variables were organized in a randomized complete block design and replicated three times. The infestation and damage ratings were collected from 30 days after planting at 20-day intervals. The results indicated that maize plots with retained crop residue had a significant reduction in FAW infestation compared with plots without maize residue (control) in both study districts. Furthermore, manure-fertilized plants had a lower percentage of FAW infestation when compared with maize plots without cattle manure in both study districts. The lowest severity of FAW infestation was recorded in a plot with 100% of residue incorporated and treated with cattle manure stored under a grass roof in the Mana district. Therefore, conventional tillage with 100% maize residue incorporation and the application of cattle manure stored under a grass roof showed the best result for reducing FAW infestation in maize. However, further studies are important to determine the effect of treatments over seasons and locations on FAW infestation and maize yields. KEYWORDS: crop residue, fall armyworm, manure, maize, pest management
... It is an economically important insect pest and poses major threat to food security due to its rapid spread and ability to cause substantial distortion to multiple crops. FAW causes maize yield reduction of up to 70%, when maize plants are attacked during early stages (Hruska 2019). FAW attacks all stages of maize crop from seedling emergence to ear development (Sisay et al. 2019). ...
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Background Bacillus thuringiensis ( Bt ) is known as the most successful microbial insecticide worldwide used against lepidopteran insect pests in agriculture. Native Bacillus isolate VKK5 showing insecticidal activity against Spodoptera frugiperda (FAW) (J.E. Smith) (Lepidoptera: Noctuidae) was characterized as B. thuringiensis (BtVKK5) on a morphological and molecular basis. Recent research has shown that Bt can be established as an endophytic organism for controlling insect pests. The present work aimed at assessing the colonization of BtVKK5 as an endophyte in five maize cultivars by seed treatment (ST), soil drenching (SD), foliar application (FA) and combination of all methods (ST + SD + FA) and its bioefficacy against neonates of FAW. Results Establishment of inoculated BtVKK5 as endophytes in five maize cultivars, viz. Pusa HQPM7 Improved, Pusa Jawahar Hybrid Maize 1, Pusa Vivek Hybrid 27 Improved (PVH27I), Pusa HQPM5 Improved and DMRH 1301, was confirmed by re-isolating from the leaves of the plant on ampicillin-selected agar plates. Estimation of colony-forming units per gram of leaf showed that there was a significant difference in colonization of the Bt strain among maize cultivars by different inoculation methods. The colonies were further substantiated by the amplification of cry1A and cry1E genes. Bioefficacy studies showed the highest mortality (50%) in the ST + FA + SD inoculation method, followed by ST (40%) in PVH27I. Moreover, growth inhibition was observed in survived larvae on inoculated plants vis-a-vis control. Conclusion Establishment of Bt strain as an endophyte in maize plants, complemented with insecticidal activity, could possibly lead to an innovative approach to the management of S. frugiperda and other borers.
... Before the invasion of FAW, farmers relied on locally available and low-cost options, including indigenous management practices. These included mechanical control (crushing egg masses and handpicking small larvae) and cultural control (intercropping maize with common edible legumes such as beans, and the application of tobacco extracts, wood ash and soils) 20 to control similar pests such as stemborers Busseola fusca (Fuller) and Chilo partellus (Swinhoe) 21 . These indigenous pest management practices have been extended to FAW and constitute essential components of IPM. ...
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Before the invasion of the fall armyworm (FAW) Spodoptera frugiperda into Africa, smallholder farmers had been using indigenous practices such as applying fish soup onto plants to manage stemborer pests. Although farmers have since begun adapting this practice against FAW, no attempt had been made to evaluate the practice scientifically. Therefore, we assessed the efficacy of applying fish soup to maize plants that were artificially infested with FAW under semi-field conditions. Our results showed that foliar damage is inversely correlated with the concentration of a fish soup + sugar solution, with the highest (100%) concentration resulting in the lowest foliar damage and the highest plant recovery. A concentration of fish soup + sugar solution of at least 25.9% was required to achieve the lowest foliar damage of 17.8% and peak plant recovery of 73.6%. Fish soup + sugar solutions attracted a wide range of insects, including potential natural enemies (predators and parasitoids) of FAW in a dose-dependent manner. Maize plants treated with fish soup + sugar showed higher chlorophyll content and better growth than the control did. Proximate and chemical analysis showed that fish soup contains essential plant growth nutrients (e.g. nitrogen, phosphorus and calcium). Through GC-MS analyses, we identified 76 volatile organic compounds in fish soup, of which 16 have been reported as insect attractants, highlighting their potential ecological significance. Therefore, the indigenous pest management practices for FAW, such as the use of fish soup, deserve particular attention. These practices could contribute to food security and improved livelihoods of vulnerable communities. Further field validation studies, economic analyses, product development and optimisation are required.
... A similar situation was reported in Ethiopia, where the main problems affecting management efforts are lack of financial and equipment resources [36]. Depending on the context, smallholders may have limitations that will define their pest management options [37]. Maize remains the crop that receives the most insecticide sprays. ...
... Early instar larvae after hatching start feeding on the epidermis of leaves and in later days their presence can be witnessed by the presence of holes in the leaves. FAW attack during the initial stages of the crop results in seventy percent of yield losses in Maize (Ayala et al, 2013, Hruska et al, 2019. The later instar larvae bore into the central shoot of the Maize plant and start damaging the inner whorls. ...
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Invasive pest fall armyworm Spodoptera frugiperda has recorded for the first time on Maize during the year 2018 in southern parts of India. Since then, chemicals with varied mode of action were employed to bring down the pest load. Usage of chemicals impacts the environmental conditions and beneficial organisms. To combat with these challenges, bicontrol agents such as Beauveria bassiana, Metarhizium anisopliae, Metarhizium reliyi, Bacillus thuringiensis and parasitoids were employed against Fall armyworm. Metarhizium reliyi was outstanding in decreasing larval population (1.68 cadavers), which was also evident from the percent reduction in leaf and plant damage (12.6% and 13.1%). The next better results were obtained from the Beauveria bassiana in diminishing the larvae (1.50 cadavers) along with leaf and plant damage (13.2% and 16.0 %) respectively. Application of entomopathogens as foliar spray in Maize crop helps in management of fall armyworm and makes a best component in Integrated pest control. There was no significant variations in the performance of the parasitoids in the initial stages of the crop growth period. Parasitoids though might not have immediate effect in standing crop, its multiplication may occur in environment in later stages which might complement in next season.
In the last 6 years, the fall armyworm (FAW) has spread to the Middle East, Asia and the Pacific, as well as most nations in Africa. This case focuses on sub-Saharan Africa, where more than 300 million people depend on maize, as a staple crop, and the preferred host plant of FAW. Synthetic pesticides against FAW are not always used safely or effectively. Here we assess work on the current state of knowledge on biopesticides for FAW in Africa, document information gaps, including compatibility with other recommended management practices, and list biopesticides that are a priority for research, development and promotion. The case incorporates two earlier assessments, one from 2018 on the status of biopesticide options against FAW, and one from 2020 that led to recommendations for field trials for eight active ingredients – Bacillus thuringiensis subsp. kurstaki , Beauveria bassiana , Dysphania ambrosioides , ethyl palmitate, eugenol, garlic extract, Metarhizium anisopliae and Steinernema spp. Field trials for some of these pesticides have now been carried out but other trials are still ongoing. The team also recommended bioassays to determine the effectiveness of four active ingredients against FAW – GS-omega/kappa-Hx-tx-Hv1a, canola oil, capsaicin and D-limonene. Information © CAB International 2023
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Fall Army Worm (Spodoptera frugiperda), with the traits of devastating, voracious, polyphagous nature had recently imposed a global threat. Possessing these traits, this pest constituted a threat to global food security by ambushing more than several host plant species. To tackle this pest, insecticide management approaches was used initially. Later, with a better comprehension of the dynamic biology of the pest, such as their long migration capability, their ability to develop resistance against insecticide and the adverse effects of pesticides on human and the environment, an alternative strategy which is environmentally safe i.e., biological control approaches that is effective and low-risk is laid emphasis. A rich diversity of microbial populations which have the ability to infect the pest to a certain degree in nature remains untapped, and if so, identification of high virulence and productive strains within the population is lacking hitherto. This review focused on the information regarding the scenario of the occurring pest and its damaging nature to the host plants and microbial agents with their surplus potentialities along with the mode of interactions with the insect pest and self-perpetuating nature and their boon of disarming nature. The details of each microbe viz., fungi, bacteria and viruses that possess the traits of controlling the pest naturally are briefed with an insight into molecular information, present findings, constraint and future prospects.
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Fall armyworm (FAW, Spodoptera frugiperda J.E. Smith) is an invasive lepidopteran pest established in most of sub-Saharan Africa since 2016. Although the immediate reaction of governments has been to invest in chemical pesticides, control methods based on agronomic management would be more affordable to resource-constrained smallholders and minimize risks for health and the environment. However, little is known about the most effective agronomic practices that could control FAW under typical African smallholder conditions. In addition, the impact of FAW damage on yield in Africa has been reported as very large, but these estimates are mainly based on farmers’ perceptions, and not on rigorous field scouting methods. Thus, the objectives of this study were to understand the factors influencing FAW damage in African smallholder maize fields and quantify its impact on yield, using two districts of Eastern Zimbabwe as cases. A total of 791 smallholder maize plots were scouted for FAW damage and the head of the corresponding farming household interviewed. Grain yield was later determined in about 20% of these fields. FAW damage was found to be significantly reduced by frequent weeding operations and by minimum- and zero-tillage. Conversely, pumpkin intercropping was found to significantly increase FAW damage. FAW damage was also found to be higher for some maize varieties, although these varieties may not be the lowest yielding. If the incidence of plants with FAW damage symptoms recorded in this research (32–48%, depending on the estimate used) is commensurate with what other studies conducted on the continent found, our best estimate of the impact of FAW damage on yield (11.57%) is much lower than what these studies reported. Although our study presents limitations, losses due to FAW damage in Africa could have been over-estimated. The threat that FAW represents for African smallholders, although very real, should not divert attention away from other pressing challenges they face.
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The fall armyworm, Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae), is the most important noctuid pest in the Americas and has recently become an invasive pest in Africa. A detailed record of S. frugiperda’s host plants is essential to better understand the biology and ecology of this pest, conduct future studies, and develop Integrated Pest Management programmes. In this study, we collected and systematically arranged the fragmented bibliographic information on S. frugiperda feeding records. Furthermore, we registered new records of host plants for S. frugiperda based on eight years of surveys in Brazil. The literature review and surveys resulted in a total of 353 S. frugiperda larval host plant records belonging to 76 plant families, principally Poaceae (106), Asteraceae (31) and Fabaceae (31). The literature search revealed 274 (77 % of total) bibliographic records, while 82 (23 %) are new records from surveys in Brazil. The new comprehensive and updated host plant list will improve our understanding of pest biology and management, as well as facilitate future studies on this pest.
Technical Report
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This Evidence Note provides new evidence on the distribution and impact of fall armyworm in Africa, summarises research and development on control methods, and makes recommendations for sustainable management of the pest.
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Core Ideas Recommending complex maize pest management options for small‐scale African farmers. Determining effective and environmentally friendly fall armyworm management for smallholder farmers. Evaluating effects of edible legume and maize intercropping on fall armyworm. Maize ( Zea mays L.) production in Africa is constrained by several biotic and abiotic factors. The recent occurrence of fall armyworm (FAW), Spodoptera frugiperda (JE Smith) a new invasive pest in Africa, has escalated the problem. Push–pull technology (PPT), proven to be effective for stemborers ( Chilo partellus Swinhoe and Busseola fusca Fuller) and the parasitic weed striga ( Striga hermontica Delile) management in Africa has been shown to provide good control of FAW. This study investigated if intercropping maize with edible legumes can also reduce the abundance of FAW. Six treatments including (i) climate‐smart PPT, (ii) conventional PPT, (iii) maize intercropped with bean ( Phaseolus vulgaris L.), (iv) maize intercropped with soybean [ Glycine max (L.) Merr.], (v) maize intercropped with groundnut [ Vigna unguiculata (L.) Walp.] and, (vi) mono‐cropped maize were evaluated on farm in six districts of Uganda in the 2017 short rains season. Data collected included FAW, stemborer, and striga infestation symptoms, and severity of infestation. Climate‐smart PPT performed best in reducing stemborer, FAW, and striga infestation followed by conventional PPT over all the phenological stages of maize. Intercropping of maize with leguminous crops also provided significant reduction of stemborer and FAW compared to mono‐cropped maize, especially in the early growth phases of the maize up to tasseling. However, intercropping of maize with edible legumes was not very effective for striga management as compared to PPT. Hence in addition to PPT, intercropping of maize with edible legumes could also be an alternative FAW management option when integrated with other sustainable management measures.
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The fall armyworm (FAW), Spodoptera frugiperda, is a major pest of maize in North and South America. It was first reported from Africa in 2016 and currently established as a major invasive pest of maize. A survey was conducted to explore for natural enemies of the fall armyworm in Ethiopia, Kenya and Tanzania in 2017. Smallholder maize farms were randomly selected and surveyed in the three countries. Five different species of parasitoids were recovered from fall armyworm eggs and larvae, including four within the Hymenoptera and one Dipteran. These species are new associations with FAW and were never reported before from Africa, North and South America. In Ethiopia, Cotesia icipe was the dominant larval parasitoid with parasitism ranging from 33.8% to 45.3%, while in Kenya, the tachinid fly, Palexorista zonata, was the primary parasitoid with 12.5% parasitism. Charops ater and Coccygidium luteum were the most common parasitoids in Kenya and Tanzania with parasitism ranging from 6 to 12%, and 4 to 8.3%, respectively. Although fall armyworm has rapidly spread throughout these three countries, we were encouraged to see a reasonable level of biological control in place. This study is of paramount importance in designing a biological control program for fall armyworm, either through conservation of native natural enemies or augmentative release.
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Fungal entomopathogens have been proposed as environmentally friendly alternatives to chemical control. Unfortunately, their effectiveness continues to be limited by their susceptibility to ultraviolet (UV) light and low moisture. A relatively recent development, the use of fungal entomopathogens as endophytes, might overcome the traditional obstacles impeding the widespread adoption of fungal entomopathogens and also provide a novel alternative for management of insect pests and plant pathogens. In addition, some fungal entomopathogens could also function as biofertilizers. Eighty-five papers covering 109 individual fungal entomopathogen studies involving 12 species in six genera are reviewed. Thirty-eight plant species in 19 families were studied, with maize, common bean, and tomato being the most investigated. Of the 85 papers, 39 (46%) examined the effects of fungal entomopathogen endophytism on 33 insect species in 17 families and eight orders. Thirty-four (40%) examined plant response to endophytism, corresponding to 20 plant species. Various inoculation techniques (e.g., foliar sprays, soil drenching, seed soaking, injections, etc.) are effective in introducing fungal entomopathogens as endophytes, but colonization appears to be localized and ephemeral. The field of insect pathology will not substantially profit from dozens of additional studies attempting to introduce fungal entomopathogens into a wider array of plants, without attempting to understand the mechanisms underlying endophytism, the responses of the plant to such endophytism, and the consequent responses of insect pests and plant pathogens. This review presents several areas that should receive focused attention to increase the probability of success for making this technology an effective alternative to chemical control.
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Fall armyworm, Spodoptera frugiperda (J E Smith), an economically important pest native to tropical and sub-tropical America has recently invaded Africa, causing substantial damage to maize and other crops. We evaluated functionality of a companion cropping system, ‘climate-adapted push-pull’, developed for control of cereal stemborers in drier agro-ecologies, as an added tool for the management of fall armyworm. The technology comprises intercropping maize with drought-tolerant greenleaf desmodium, Desmodium intortum (Mill.) Urb., and planting Brachiaria cv Mulato II as a border crop around this intercrop. Protection to maize is provided by semiochemicals that are emitted by the intercrop that repel (push) stemborer moths while those released by the border crop attract (pull) them. 250 farmers who had adopted the technology in drier areas of Kenya, Uganda and Tanzania were randomly selected for the study during the long rainy season (March-August) of 2017. Each farmer had a set of two plots, a climate-adapted push–pull and a maize monocrop. Data were collected in each plot on the number of fall armyworm larvae on maize, percentage of maize plants damaged by the larvae and maize grain yields. Similarly, farmers' perceptions of the impact of the technology on the pest were assessed using a semi-structured questionnaire. Reductions of 82.7% in average number of larvae per plant and 86.7% in plant damage per plot were observed in climate-adapted push-pull compared to maize monocrop plots. Similarly, maize grain yields were significantly higher, 2.7 times, in the climate-adapted push-pull plots. Farmers rated the technology significantly superior in reducing fall armyworm infestation and plant damage rates. These results demonstrate that the technology is effective in controlling fall armyworm with concomitant maize grain yield increases, and represent the first documentation of a technology that can be immediately deployed for management of the pest in East Africa and beyond.
The experiment was performed at the Laboratory of the Division of Entomology, Department of Plant Protection, Faculty of Agricultural Sciences (FCA) of the National University of Asunción (UNA), in the city of San Lorenzo, under controlled conditions of temperature of 25 + 2°C, relative humidity 70 + 10% and 12 hours photoperiod. The aim of the study was to evaluate the insecticidal effect of ka'atái extract (Polygonum hydropiperoides Michx), at different doses for control of armyworm (Spodoptera frugiperda Smith), assuming that the higher the dose correspond higher mortality of larvae. The design used was completely randomized, with six (6) treatments and five (5) repetitions, applied to first instar larvae, being fed corn husks. We performed an analysis of variance (ANOVA) and Tukey subjected to the 5% probability of error. Assessments were made for 7 consecutive days after application. The results demonstrated that T6 treatment dose (ka'atái 50%) was the most effective, having a 82% of control.
Corn (Zea mays) is one of the world's main agricultural crops, and Spodoptera frugiperda (J. E. Smith) is its most important pest. In order to find natural controlling alternatives, this study aimed to determine the effect of plant oils on the feeding preference of first- and second-instar caterpillars. The experimental design was completely randomized in a 6 x 5 factorial combination (turmeric, clove, palmarosa, tea tree, common juniper, and neem oils) at five concentrations (0, 25, 50, 100, and 200 μL mL⁻¹), plus a control consisting of acetone 100.0%, with five replicates per treatment. Twenty-five-day-old corn leaf sections received the corresponding treatments in addition to the control and were deposited along orthogonal axes in an arena arranged in Petri dishes. Ten 1st instar caterpillars were released at the center of the plates, and results were obtained after 8h and 24h from the release, based on the number of caterpillars found on each treatment. For 1st instar caterpillars, the best results were observed for clove and palmarosa, which negatively influenced caterpillar feeding activity in both evaluation periods, followed by turmeric oil, which showed the same effectiveness in the last period only. For second-instar caterpillars, the best effects were observed for neem, turmeric, palmarosa, and clove oil in the first evaluation period. Furthermore, the effectiveness of the first three oils was maintained in the second evaluation period. These results emphasize the potential capability of plant oils when used in management programs against this pest, in which the oils of turmeric, clove and palmarosa showing the best controlling potential of this pest from the lowest concentration corresponding to 25 μL mL⁻¹.