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A Guide to Biological Control of Fall Armyworm in Africa Using Egg Parasitoids
Abstract and Figures
Biological control using egg parasitoids particularly from the genus Trichogramma and Telenomus remus is part of the IPM approach presently underway to control FAW in North and South America. The approach involves mass rearing and release of these egg parasitoids to control FAW. This guide is primarily intended for biological control practitioners at universities, research institutes and commercial laboratories particularly involved in managing FAW and other lepidopteran pests. The information in this document is also intended to assist those who are relatively new at rearing FAW, rice meal moth, and the parasitoid wasps and to those who wish to improve existing rearing systems. The document covers virtually all aspects of information on the rearing techniques of each species such as colony establishment, stock culture maintenance, diet preparation, mass rearing, storage, quality control and field release. Each section is interrelated, contains step-by-step procedures, and is supported by colour pictures.
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... In Africa, it was detected for the first time in Sao Tome, Nigeria in 2016, and spread to most other countries on the continent within a short period (Omit et al., 2021). This pest has since posed a major threat to the food security, income and livelihood of farmers (Jia et al., 2024;Tefera et al., 2019). It has the biological traits of a large reproductive capacity, several generations per year, absence of diapause, the ability to fly and a wide host range that have favoured its rapid spread and success. ...
... For example , Houngbo et al. (2020) reported that S. frugiperda has the potential to cause maize yield losses of 8.3-20.6 million metric tons per year in 12 of Africa's maize-producing countries. In addition, maize yield losses of 5%-100% have been reported in many African countries (Ogunfunmilayo et al., 2021;Sisay et al., 2019;Wondimu et al., 2021;Zereabruk & Weldu, 2024), and in Ethiopia, S. frugiperda has been identified to attack maize and sorghum since 2017 (Dessie et al., 2024;Kebede & Shimalis, 2018;Tefera et al., 2019). Despite the production potential and the importance of maize and sorghum in Ethiopia (CSA, 2022;Engida et al., 2021), the increasing magnitude of damage due to S. frugiperda is threatening their productivity (Hailu et al., 2023;Tefera et al., 2019). ...
... In addition, maize yield losses of 5%-100% have been reported in many African countries (Ogunfunmilayo et al., 2021;Sisay et al., 2019;Wondimu et al., 2021;Zereabruk & Weldu, 2024), and in Ethiopia, S. frugiperda has been identified to attack maize and sorghum since 2017 (Dessie et al., 2024;Kebede & Shimalis, 2018;Tefera et al., 2019). Despite the production potential and the importance of maize and sorghum in Ethiopia (CSA, 2022;Engida et al., 2021), the increasing magnitude of damage due to S. frugiperda is threatening their productivity (Hailu et al., 2023;Tefera et al., 2019). Convincingly, the increasing impacts prompted the development of more advanced pest management strategies to address this risk in the changing climate (Abdel-Rahman et al., 2023;Hailu et al., 2023;Zanzana et al., 2024). ...
The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is among the key invasive pests attacking maize and sorghum, the staple cereals in many countries in Africa. The determination of habitat suitability of invasive species via correlative model is among the priority tasks that provide basic information for achieving sustainable plant protection.
In this study, we developed a species distribution model of S. frugiperda and identified the key influencing environmental factors under current and future climatic conditions in Ethiopia via the MaxEnt program.
The results showed that the area under the curve (AUC) of the simulated model was 0.856 (±0.010), confirming the good predictive ability of the model. The isothermality and precipitation of the driest month are the most dominant bioclimatic variables with a percentage contribution of 39.4% and 11.6%, respectively, in the model. The percentages of very highly suitable, highly suitable, moderately suitable, low‐suitable, and unsuitable areas were 21.24%, 21.17%, 28.22%, 16.34% and 13.03%, respectively, of the total Ethiopian land mass. From the present to the 2070s, the areas of highly suitable and very highly suitable habitats for S. frugiperda will increase due to global warming.
This study noted that the pest was a major threat to maize and sorghum in Ethiopia. Hence, due emphasis should be given to strengthening monitoring and management in a suitable range, which would lessen economic losses due to invasion and ensure agricultural safety.
... To reduce pest-related losses and the risk of hazardous chemicals, several International Research Organizations in Africa have actively conducted research to develop effective IPM strategies for FAW management. They have also made various training materials available, including handouts and guides (FAO, 2018;Prasanna et al., 2018;Tefera et al., 2019;Ahissou et al., 2021;Kasoma et al., 2021). Researchers have implemented a range of community-based educational programs to encourage African farmers to adopt FAW IPM technologies. ...
... Antigua Gpo2 mir-1 CP, antibiosis, etc Kasoma et al. (2020) Antigua 2D -118 Nonpreference Kasoma et al. (2020) T-FAWCC (C5) Nonpreference & antibiosis Widstrom et al. (1992); Singh et al. (2022) Mp704 Antibiosis and Antixenosis due to 33-kD cysteine proteinase; mir1-Cysteine proteinase (mir1-CP); higher content of crude fiber, hemicellulose, and cellulose in whorls laboratories and effective in managing FAW population (Figueiredo et al., 2002;Gutierrez-Martinez et al., 2012;Tefera et al., 2019). Abbas (2023) reported a total of 17 predators of FAW in Africa, which include seven coleopterans from the Coccinellidae family (Coleomegilla maculata, Cycloreda sanguinea, Cheilomenes sulphurea, Coccinella transvirsalis, Harmonia octomaculata, Eriopis sp., and Hippodamia sp.), two coleopterans from the Carabidae family (Callida sp. and Calosoma granulatus), one coleopteran from the Lampyridae family (Hematochares obscuripennis), three dermapterans from the Forficulidae family (Diaperasticus crythrocephalus, Forficula senegalensis, and Doru sp.), one hemipteran from the Geocoridae family (Geocoris sp.), one hemipteran from the Pentatomidae family (Podisus sp.), one hymenopteran from the Formicidae family (Pheidole megacephala), and one lepidopteran from the Erebidae family (Perprius modiulipes). ...
The fall armyworm (FAW), Spodoptera frugiperda, is a polyphagous pest native to the American continent that was first detected in Africa in 2016, where it has since become a major constraint to agriculture. This species severely damages staple crops like maize, sorghum, and rice, threatening food security and the livelihoods of millions of smallholder farmers. Maize, the most vulnerable crop in sub-Saharan Africa, suffers significant annual losses due to the destructive impact of FAW, which affects agricultural productivity and overall rural economies. The pest displays complex biological and ecological patterns that are highly dependent on environmental factors, host plant availability, and natural enemy diversity, making control efforts challenging. This review explores the traits driving FAW's invasive success in Africa, summarizing key findings on its biology and ecology while outlining current management strategies. It underscores the importance of Integrated Pest Management (IPM), which includes cultural practices, biological control, mechanical/physical methods, host plant resistance, and judicious application of chemicals. Regular crop monitoring and surveillance principles are also discussed as prevention and early detection measures to mitigate FAW damage. Future directions emphasize the need for collaboration among stakeholders, including international research organizations, to effectively control FAW invasion. Given the economic risks of the FAW outbreak in Africa, adopting IPM solutions is crucial for reducing pesticide reliance and ensuring stable agricultural production. This review offers valuable insights into achieving this goal. KEYWORDS fall armyworm, integrated pest management, food security, crop loss, host plant resistance Frontiers in Agronomy
... Key strategies include refining rearing methods for mass production, enhancing delivery systems within rice fields, and exploring potential genetic modifications to increase their effectiveness against FAW. Numerous reports have highlighted the potential of biological control for managing FAW (Tefera et al., 2019;Ballal et al., 2021;Abbas et al., 2022;Wyckhuys et al., 2024). Moreover, enhancing biological control through effective management practices has proven to be an efficient strategy for controlling FAW (Mensah et al., 2024). ...
Rice (Oryza sativa L.), a primary staple food for billions of people worldwide, faces a growing threat from the invasive fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), in Asia. Given the predominance of small-scale farmers in Asian rice production, which accounts for over two-thirds of global rice output, the region is highly vulnerable to FAW infestations. The FAW’s rapid reproduction, extensive dispersal capabilities, and remarkable adaptability pose significant risks, with the potential for substantial yield losses comparable to those observed in other crops. Recent reports highlight a concerning host shift of the corn-specialized FAW strain towards rice cultivation in Asia. Beyond direct yield losses, FAW infestations can lead to the excessive use of pesticides, posing serious threats to human health and environment safety. Effective and sustainable FAW management in rice is crucial for ensuring long-term agricultural sustainability. Control strategies encompass a diverse range of approaches, including cultural techniques, biological methods, chemical interventions, and habitat manipulation. The absence of rice varieties resistant to FAW underscores the urgent need for accelerated development through genetic engineering. Cultural control practices, such as staggered planting, deep tillage, crop rotation with non-host species, and improved field sanitation, can effectively reduce FAW populations. While promising, methods like trap cropping and push-pull strategies require further field validation in rice systems. Biological control measures utilize natural predators, such as big-eyed bugs and ground beetles, and parasitoids like Telenomus remus and Campoletis sonorensis. Additionally, entomopathogenic agents like Metarhizium rileyi, Bacillus thuringiensis (Bt), and Beauveria bassiana offer environmentally sustainable alternatives to chemical insecticides. While synthetic insecticides remain an essential component of FAW management, the increasing prevalence of pesticide resistance and associated economic losses necessitate a shift towards eco-friendly solutions. The growing resistance of FAW to multiple insecticide classes underscores the urgent need for robust resistance management strategies. This review emphasizes the critical role of integrated pest management (IPM) in combating FAW in Asia, advocating for a balanced approach that prioritises biological control, effective cultural practices, judicious use of insecticides, and sustainable agricultural methods to mitigate FAW damage and ensure long-term rice security for the region.
... This may be through the actions of variant biochemical molecules/enzymes that also work in compensatory mechanisms during heat stress . Telenomus remus is usually stored under low-temperature environments (10 ± 1°C) to extend its shelf-life and provide opportunities to accumulate sufficient numbers before their eventual release into the targeted environments (Rathee & Ram, 2018;Tefera et al., 2019). Our overall thermal tolerance polygons showed insignificant cold tolerance changes following short-term and long-term acclimation pretreatment, meaning that cold storage of the parasitoids may not negatively influence their ecological performance. ...
The fall armyworm, Spodoptera frugiperda J.E. Smith, is a significant global agricultural pest known for its rapid invasion and devastating impact on crops. While pesticides may be effective for controlling the pest in the short-term, they cause several socioeconomic and ecological costs that highlight the need for more sustainable management strategies. Telenomus remus (Nixon) is a promising egg parasitoid for its biological control. For the parasitoid to provide effective ecosystem services, it should be able to survive and coexist within the same ecological niches as its host. However, there is limited information regarding the potential responses of T. remus to thermal changes. In the context of the changing climate environments, it is key to understand the para-sitoid's overall environmental fitness in relation to its host. We investigated the effects of short-term (2 h) and long-term (6 h) acclimation pretreatment of T. remus adults and S. frugiperda eggs to high and low temperatures (18°C and 32°C, respectively) in comparison with the control (28°C). Telenomus remus thermal fitness (critical thermal maxima [CT max ], heat knockdown time and critical thermal minima [CT min ]), parasit-ism rates, and adult emergence were determined. Pretreated S. frugiperda eggs were assessed for hatchability under the control conditions. Acclimation at low (18°C) and high (32°C) temperatures significantly reduced and increased heat tolerance, respectively. Both temperatures, however, reduced cold tolerance. The parasitoid thermal tolerance polygons following acclimation pretreatment, showed significant heat-but not cold-tolerance gains. Fall armyworm eggs short-term acclimated to 32°C had significantly higher (p < 0.05) but comparable hatchability to the control treatment. Similarly, parasitism and adult emergence rates were significantly lower (p < 0.001) following long-term acclimation of host eggs and the parasitoid to 32°C. These findings suggest that high temperatures may decouple the T. remus-fall armyworm ecological relationship, threatening its success in warming regions. The findings provide valuable insights into the potential environmental resilience and suitability of T. remus as a biological control agent across different climates or geographies.
... Les traitements témoins ont été T0 (Témoin absolu) avec des plants de maïs sans application d'insecticide ni de piège à phéromone et T1 (Témoin relatif) constitué de pieds traités un insecticide binaire à double action à base d'Acétamipride à 25 g/l et Indoxacarbe 30 g/l recommandé dans la lutte contre les insectes; T2 : phéromone à la dose de 12 pièges/ha ; T3 : phéromone à la dose de 8 pièges/ha ; T4 : phéromone à la dose de 16 pièges/ha (Figure1). Ces doses ont été définies sur la base qui guide proposé par les travaux de Tefera et al. (2019). Au total, 50 plants ont été évalués pour chaque traitements. ...
Maize is the most important raw material for animal and human nutrition in Côte d'Ivoire. The fall armyworm (CLA) is one of the pests that cause significant losses ranging from 50 to 100%. The aim of this study was to contribute to the development of an effective control method for the fall armyworm (Spodoptera frugiperda) in maize crops in Côte d'Ivoire using sex pheromones. The use of insecticides against Spodoptera frugiperda has been proposed as a control method. This bioefficacy study of a pheromone ‘Spodoptera frugiperda Lure’ (SFL) was made up of Z-7-dodecenyl acetate, Z-11-hexadecenyl acetate and Z-9-tetradecenyl acetate in Ferkessédougou. The effect of the SFL was compared to plots treated (T1) with a dual-action binary insecticide based on Acetamiprid 25 g/l and Indoxacarb 30 g/l recommended for insect control and to untreated plots without pheromones (T0). The SFLs were placed on the 14th day after sowing in the plots at densities of 8 (T2); 12 (T3); and 16 (T4) traps/ha. Plots treated with insecticide received one application each week. The infestation rate data showed that at the densities of 8, 12 and 16 traps/ha, the values recorded were low at 27%, 12% and 10% respectively, compared with 42% for the control plots. The ‘Spodoptera frugiperda Lure’ tested provided effective protection for maize fields against the armyworm
... Moreover, it plays a significant role as a primary source of income for resourcelimited farmers in many developing nations. In sub-Saharan Africa (SSA), where maize cultivation spans over 36 million hectares each year, a substantial portion of the local population relies on this crop for their food security and livelihood (Tefera et al. 2019). ...
The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), causes significant damage to maize, threatening the food security and livelihood of millions of smallholder farmers in sub-Saharan Africa (SSA). Crop diversification has been recommended as an ecologically sustainable FAW control option. However, limited information is available on the impacts of companion plants and their control mechanisms against FAW in SSA, being a relatively new pest to the region. Building upon our earlier laboratory study, which elucidated how edible companion intercrops effectively reduce FAW infestation, we conducted field experiments in Kenya to assess the effectiveness of intercropping maize with beans, groundnut, cassava and sweet potato under realistic field conditions. Growing maize with these intercrops consistently resulted in fewer FAW eggs, larvae and lower plant infestation compared to maize monoculture except with cassava. Additionally, maize under these intercrops experienced low FAW damage and higher crop yield compared to maize monoculture. Maize growth stages significantly influenced the population of FAW eggs and larvae, with a peak observed between vegetative stages V4 and V10. Furthermore, intercropped maize plots exhibited a higher presence of FAW predators, such as lady beetles and earwigs. Correlation analysis revealed a significant correlation between temperature, relative humidity, and the population of FAW life stages and natural enemies at the experimental sites. Therefore, intercropping maize with beans, sweet potato, and groundnuts can be incorporated into an integrated FAW management strategy to sustainably control the pest in real farming conditions. These findings are particularly relevant for small-scale farmers in Africa and beyond, who cannot afford expensive FAW control using insecticides.
The fall armyworm, Spodoptera frugiperda (J.E. Smith) is a destructive pest that affects more than 80 different crops. Originally found in North and South America, it was first discovered in Ethiopia in 2017. To control this pest, farmers often rely on heavy pesticide use. However, this approach can lead to unintended consequences such as the development of resistance in the pest, the emergence of secondary pests, and a decline in natural enemy populations. To address these challenges, there is a growing interest in developing agroecological pest management solutions, such as crop diversity. One approach is the use of intercropping systems, where different crops are grown together. The study included four treatments: maize-cowpea, maize-haricot bean, maize-mung bean and maize monocrop. The highest number of fall armyworm male adults was trapped during the rainy season compared to the dry period. Infestation levels reached as high as 89.5% in sole maize plots but were reduced to 67% in intercropped plots. Similarly, the average damage scale, which rose to 7% in sole maize systems, decreased to 5% in maize-bean intercropping systems. The study also observed a greater abundance of natural enemies in intercropped plots, including predators such as ladybirds (16.04%), lacewings (17.46%), ants (29.44%) and earwig (11.83%). Among parasitoids, Cotesia congregate (Say) (15.54%) and Palexorista zonata (Curran) (12.67%) were the most prevalent in the intercropped systems. By creating a more diverse and balanced ecosystem, farmers can enhance natural pest control and reduce their reliance on pesticides. Based on these findings, intercropping systems are of paramount importance in managing fall armyworms in maize-producing areas of Ethiopia.
Except Antarctica, maize, Zea mays L.
(Poaceae), is one of the most adaptable crops, with a
greater tolerance for a variety of agro-climatic
circumstances. Because of its great genetic yield
potential among cereals and ranking third in
importance globally behind wheat and rice, maize is
regarded as the “Queen of Cereals” by everyone. More
than 100,000 hectares of maize are planted in 70
countries, including 53 developing nations [Bueno et
al.,2011]. In India, maize is grown for a variety of uses,
including food processing, animal and poultry feed,
human consumption, and the extraction of starch,
dextrose, corn syrup, and corn oil. With a composition
of roughly 72% carbohydrate, 10% protein, and 4% fat,
maize has an energy density of 365 kcal/100 g.
Numerous entities target the crop among them these
three insect pests have caused significant problems in
India up until recently: the shoot fly (Atherigona spp.),
pink stem borer (Sesamia inferens Walker), and spotted
stem borer (Chilo partellus Swinhoe). Besides these, in
May 2018, the invasive pest known as fall armyworm
(Spodoptera frugiperda) had spread quickly throughout
every Indian maize-growing ecology except for
Himachal Pradesh and Jammu and Kashmir casting a
shadow on maize production
Spodoptera frugiperda, are polyphagous agricultural pests that began in America and were ultimately discovered in West Africa in 2016.The larval stage of the pest's life cycle causes the most damage. It impacts 353 different crop types and leads to a 70% loss in crop yield, hurting the economy. Studies have shown that these pests do well in temperatures above 10°C, but moth wings become deformed when the temperature goes above 30°C.The cultural method is the most effective pest control approach, making up 56% of pest management efforts. The push and pull technique, meanwhile, controls 82.6% of larvae per plant. Research has found that Azadirachta indica (neem) seed powder can reduce larval mortality by 70%, while L. javanica and N. tobacum decrease larval toxicity by 66%. Spinosad causes over 90% of larval deaths, while a mixture of sawdust and chlorpyrifos controls 20% of the pests. This detailed review covers all types of biological control methods, including parasitoids, nematodes, predators, viruses, entomopathogenic fungi, biopesticide bacteria, as well as cultural, chemical, physical, and botanical controls. It focuses on how effective these methods are against the Fall Armyworm (FAW).
The fall armyworm, Spodoptera frugiperda, a moth originating from tropical and subtropical America, has recently become a serious pest of cereals in sub-Saharan Africa. Biological control offers an economically and environmentally safer alternative to synthetic insecticides that are being used for the management of this pest. Consequently, various biological control options are being considered, including the introduction of Telenomus remus, the main egg parasitoid of S. frugiperda in the Americas, where it is already used in augmentative biological control programmes. During surveys in South, West, and East Africa, parasitized egg masses of S. frugiperda were collected, and the emerged parasitoids were identified through morphological observations and molecular analyses as T. remus. The presence of T. remus in Africa in at least five countries provides a great opportunity to develop augmentative biological control methods and register the parasitoid against S. frugiperda. Surveys should be carried out throughout Africa to assess the present distribution of T. remus on the continent, and the parasitoid could be re-distributed in the regions where it is absent, following national and international regulations. Classical biological control should focus on the importation of larval parasitoids from the Americas.
Surveys of fall army worm Spodoptera frugiperda (J. S. Smith) on maize and sorghum in Niger revealed the occurrence of egg parasitoids (Trichogrammatoidea sp., Trichogramma sp., and Telenomus sp.), egg-larval parasitoids (Chelonus sp.), and larval parasitoids (Cotesia sp., and Charops sp.).
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.
Fall armyworm, Spodopterafrugiperda , is a crop pest native to the Americas, which has invaded and spread throughout sub-Saharan Africa within two years. Recent estimates of 20–50% maize yield loss in Africa suggest severe impact on livelihoods. Fall armyworm is still infilling its potential range in Africa and could spread to other continents. In order to understand fall armyworm’s year-round, global, potential distribution, we used evidence of the effects of temperature and precipitation on fall armyworm life-history, combined with data on native and African distributions to construct Species Distribution Models (SDMs). We also investigated the strength of trade and transportation pathways that could carry fall armyworm beyond Africa. Up till now, fall armyworm has only invaded areas that have a climate similar to the native distribution, validating the use of climatic SDMs. The strongest climatic limits on fall armyworm’s year-round distribution are the coldest annual temperature and the amount of rain in the wet season. Much of sub-Saharan Africa can host year-round fall armyworm populations, but the likelihoods of colonising North Africa and seasonal migrations into Europe are hard to predict. South and Southeast Asia and Australia have climate conditions that would permit fall armyworm to invade. Current trade and transportation routes reveal Australia, China, India, Indonesia, Malaysia, Philippines and Thailand face high threat of fall armyworm invasions originating from Africa.
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.
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.
The fall armyworm (FAW) Spodoptera frugiperda (J. E. Smith) is a species native to the Americas. This polyphagous lepidopteran pest was first reported in Nigeria and the Democratic Republic of São Tomé and Principe in 2016, but its presence in eastern Africa has not been confirmed via molecular characterisation. In this study, FAW specimens from western and central Uganda were identified based on the partial mtDNA COI gene sequences, with mtDNA COI haplotypes matching those identified in Nigeria and São Tomé. In this study, we sequence an additional partial mtDNA Cyt b gene and also the partial mtDNA COIII gene in Ugandan FAW samples. We detected identical mitochondrial DNA haplotypes for both the mtDNA Cyt b and COI partial genes, while combining the mtDNA COI/Cyt b haplotypes and mtDNA COIII haplotypes enabled a new maternal lineage in the Ugandan corn-preferred FAW samples to be identified. Our results suggested that the African incursions of S. frugiperda involved at least three maternal lineages. Recent full genome, phylogenetic and microsatellite analyses provided evidence to support S. frugiperda as likely consisted of two sympatric sister species known as the corn-preferred and rice-preferred strains. In our Ugandan FAW populations, we identified the presence of mtDNA haplotypes representative of both sister species. It is not known if both FAW sister species were originally introduced together or separately, and whether they have since spread as a single population. Further analyses of additional specimens originally collected from São Tomé, Nigeria and throughout Africa would be required to clarify this issue. Importantly, our finding showed that the genetic diversity of the African corn-preferred FAW species is higher than previously reported. This potentially contributed to the success of FAW establishment in Africa. Furthermore, with the additional maternal lineages detected, there is likely an increase in paternal lineages, thereby increasing the diversity of the African FAW population. Knowledge of the FAW genetic diversity will be needed to assess the risks of introducing Bt-resistance traits and to understand the FAW incursion pathways into the Old World and its potential onward spread. The agricultural implications of the presence of two evolutionary divergent FAW lineages (the corn and the rice lineage) in the African continent are further considered and discussed.
Maize is a major staple food for over 300 million people in sub‐Saharan Africa. Sustainable productivity of this primary crop has been recently threatened by Fall armyworm (FAW), Spodoptera frugiperda invasion. Due to lack of environmentally safe management strategies, immediate responses by growers and governments to tackle FAW are based on rampant use of pesticides. Looking for efficient biopesticides, twenty entomopathogenic fungal isolates (14 Metarhizium anisopliae and 6 Beauveria bassiana) were screened for their efficacy against eggs and second instar larvae of FAW. A single discriminating concentration of 1 × 108 conidia ml−1 and four replicates per treatment were used in all experiments. Isolates were assessed for their ability to cause mortality of FAW second instar larvae, eggs and the neonate larvae that emerged from treated eggs. Among the isolates tested, only B. bassiana ICIPE 676 caused moderate mortality of 30% to second instar larvae. Metarhizium anisopliae ICIPE 78, ICIPE 40 and ICIPE 20 caused egg mortalities of 87.0%, 83.0% and 79.5%, respectively, and M. anisopliae ICIPE 41 and ICIPE 7 outperformed all the others by causing 96.5% and 93.7% mortality to the neonate larvae, respectively. The cumulated mortality of eggs and neonates was highest with M. anisopliae ICIPE 41 (97.5%), followed by M. anisopliae ICIPE 7, 655, 40, 20 and 78 with total mortality of 96.0%, 95.0%, 93.5%, 93.0% and 92.0%, respectively. These isolates with high cumulated mortality (≥92%), especially ICIPE 78 and 7, which are already commercialized for spider mites and ticks control respectively, would be good candidates for development as biopesticides for management of FAW in Africa if further evidence of their efficacy is obtained in the field.
