The fall armyworm strain associated with most rice, millet, and pasture infestations in the Western Hemisphere is rare or absent in Ghana and Togo

Open Access Journal; Published online: 21 June 2021The moth pest fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is now present throughout much of the Eastern Hemisphere where it poses a significant economic threat to a number of crops. Native to the Western Hemisphere, fall armyworm is one of the primary pests of corn in the Americas and periodically causes significant economic damage to sorghum, millet, cotton, rice, and forage grasses. This broad host range is in part the result of two populations historically designated as host strains (C-strain and R-strain) that differ in their host plant preferences. Reports of infestations in Africa have to date mostly been limited to the C-strain preferred crops of corn and sorghum, with little evidence of an R-strain presence. However, this could reflect a bias in monitoring intensity, with the R-strain perhaps being more prevalent in other crop systems that have not been as routinely examined for the pest. Because knowledge of whether and to what extent both strains are present is critical to assessments of crops at immediate risk, we analyzed specimens obtained from a systematic survey of pasture grass and rice fields, habitats typically preferred by the R-strain, done contemporaneously with collections from corn fields in Ghana and Togo. Substantial larval infestations were only observed in corn, while pheromone trap capture numbers were high only in corn and rice habitats. Little to no fall armyworm were found in the pasture setting. Comparisons with a meta-analysis of studies from South America identified differences in the pattern of strain-specific markers typically found in fall armyworm collected from rice habitats between the two hemispheres. Genetic tests of specimens from rice and corn area traps failed to show evidence of differential mating between strains. These results are consistent with the R-strain being rare or even absent in Africa and, at least for the Ghana-Togo area, this R-strain lack does not appear to be due to limitations in pest monitoring. The implications of these results to the crops at risk in Africa and the accuracy of existing molecular markers of strain identity are discussed

Analysis of strain distribution, migratory potential, and invasion history of fall armyworm populations in northern sub-Saharan Africa

Open Access Journal; Published online: 27 Feb 2018Fall armyworm (Spodoptera frugiperda J.E. Smith) is a noctuid moth pest endemic throughout the Western Hemisphere that has recently become widespread in sub-Saharan Africa. There is a strong expectation of significant damage to African maize crop yield and a high likelihood of further dispersal, putting the rest of the Eastern Hemisphere at risk. Specimens from multiple locations in six countries spanning the northern portion of the infested region were analyzed for genetic markers. The similarity of haplotypes between the African collections was consistent with a common origin, but significant differences in the relative frequency of the haplotypes indicated limitations in migration. The mitochondrial marker frequently used to identify two host strains appears to be compromised, making uncertain previous reports that both strains are present in Africa. This more extensive study confirmed initial indications based on Togo populations that Florida and the Greater Antilles are the likely source of at least a subset of the African infestation and further suggest an entry point in western Africa. The origin of a second subgroup is less clear as it was rarely found in the collections and has a haplotype that has not yet been observed in the Western Hemisphere

Natural enemies of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in Ghana

Open Access JournalThe fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is an invasive insect pest attacking maize in Ghana and sub-Saharan Africa countries. Biological control will need to be an important management strategy, and a first step was to identify potential natural enemies. Sampling was conducted in different localities of the 10 regions of Ghana from May to Nov 2017. A total of 1,062 larvae were collected from 106 maize farms, and the presence of natural enemies was recorded in 18 (17.0%) farms. Among natural enemies recorded, 7 species were parasitoids: Chelonus bifoveolatus Szpligeti, Coccygidium luteum (Brull), Cotesia icipe Fernandez, Meteoridea testacea (Granger), and Bracon sp. (all Hymenoptera: Braconidae), Anatrichus erinaceus Loew (Diptera: Chloropidae), and an undetermined tachinid fly (Diptera: Tachinidae). The parasitism rate was 3.58%. Three predator species were collected: Pheidole megacephala (F.) (Hymenoptera: Formicidae), Haematochares obscuripennis Stål, and Peprius nodulipes (Signoret) (both Heteroptera: Reduviidae). The 2 most abundant parasitoids were C. bifoveolatus and C. luteum with a relative abundance of 29.0% and 23.7%, respectively, and a parasitism rate of 1.04% and 0.85%, respectively. However, C. bifoveolatus was the most dispersed parasitoid, found in 6.6% of the inspected sites within all the agroecological zones of Ghana. This species is a good candidate as a biological control agent for fall armyworm in Africa. The predator that was most abundant (46.0%) and dispersed (3.8% of the farms) was P. megacephala. El cogollero, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), es una plaga de insectos invasora que ataca el maíz en Ghana y los países de África subsahariana. El control biológico deberá ser una estrategia de manejo importante, y un primer paso es identificar los enemigos naturales potenciales. Se realizó el muestreo en diferentes localidades de las 10 regiones de Ghana desde mayo hasta noviembre del 2017. Se recolectó un total de 1.062 larvas de 106 granjas de maíz, y se registró la presencia de enemigos naturales en 18 granjas (17.0%). Entre los enemigos naturales registrados, 7 especies fueron parasitoides: Chelonus bifoveolatus Szpligeti, Coccygidium luteum (Brull), Cotesia icipe Fernandez, Meteoridea testacea (Granger) y Bracon sp. (todos los Hymenoptera: Braconidae), Anatrichus erinaceus Loew (Diptera: Chloropidae) y una mosca taquinida indeterminada (Diptera: Tachinidae). La tasa de parasitismo fue del 3.58%. Se recolectaron tres especies de depredadores: Pheidole megacephala (F.) (Hymenoptera: Formicidae), Haematochares obscuripennis Stål y Peprius nodulipes (Signoret) (ambos Heteroptera: Reduviidae). Los 2 parasitoides más abundantes fueron C. bifoveolatus y C. luteum con una abundancia relativa del 29.0% y 23.7%, respectivamente, y una tasa de parasitismo del 1.04% y 0.85%, respectivamente. Sin embargo, C. bifoveotus fue el parasitoide más disperso, encontrado en el 6.6% de los sitios inspeccionados dentro de todas las zonas agroecológicas de Ghana. Esta especie es un buen candidato como agente de control biológico para el cogollero en África. El depredador que fue más abundante (46.0%) y disperso (3.8% de las granjas) fue P. megacephala

Improvement of Rice Production under Drought Conditions in West Africa: Application of QTLs in Breeding for Drought Resistance

Rice plays a paramount role in food and nutrition security in many West African countries. Despite the doubling of production during the last decade, rice consumption has grown faster, creating a deficit between the demand and supply. Although the West African sub-region remains the main rice-producing centre on the continent, production is severely hampered by biotic and abiotic stresses. Drought is one of the factors that most severely reduce grain yields of rice. Systems of production need to be established in order to mitigate yield loss as a result of drought. This review discusses the effects of drought on rice production in West Africa and its mitigation with an emphasis on the improvement of tolerance to drought stress. Yield stability can be achieved by developing drought-tolerant varieties through several processes encompassing profiling of known QTLs and identification of new ones, marker-assisted selection, genomic selection, and extensive multi-locational yield trials. We suggest a comprehensive strategy for breeding drought-tolerant rice varieties in West Africa

Genetic studies of fall armyworm indicate a new introduction into Africa and identify limits to its migratory behavior

Open Access Journal; Published online: 04 Feb 2022The fall armyworm, Spodoptera frugiperda (J.E. Smith) is native to the Americas and a major pest of corn and several other crops of economic importance. The species has characteristics that make it of particular concern as an invasive pest, including broad host range, long-distance migration behavior, and a propensity for field-evolved pesticide resistance. The discovery of fall armyworm in western Africa in 2016 was followed by what was apparently a remarkably rapid spread throughout sub-Saharan Africa by 2018, causing economic damage estimated in the tens of billions USD and threatening the food security of the continent. Understanding the history of the fall armyworm invasion of Africa and the genetic composition of the African populations is critical to assessing the risk posed to different crop types, the development of effective mitigation strategies, and to make Africa less vulnerable to future invasions of migratory moth pests. This paper tested and expanded on previous studies by combining data from 22 sub-Saharan nations during the period from 2016 to 2019. The results support initial descriptions of the fall armyworm invasion, including the near absence of the strain that prefers rice, millet, and pasture grasses, while providing additional evidence that the magnitude and extent of FAW natural migration on the continent is more limited than expected. The results also show that a second entry of fall armyworm likely occurred in western Africa from a source different than that of the original introduction. These findings indicate that western Africa continues to be at high risk of future introductions of FAW, which could complicate mitigation efforts

The LabTogo-Project

A joint project between West African Science Service Center on Climate Change and Adapted Land Use (WASCAL), the University of Lomé and the German Biomass Research Center (Deutsches Biomasseforschungszentrum; DBFZ) was initiated in 2020. The project aims at evaluating alternative and regenerative energy sources for rural areas and creating the basis for successful implementation. In three different work packages, therefore, biomass potentials should be quantified, technologies should be examined with regard to their suitability and - in the case of biogas application - a research structure, pilot biogas laboratory, should be created that is necessary to enable the sustainable implementation of technologies

Harnessing data science to improve integrated management of invasive pest species across Africa: an application to Fall armyworm (Spodoptera frugiperda) (J.E. Smith) (Lepidoptera: Noctuidae)

Open Access Journal; Published online: 11 Feb 2022After five years of its first report on the African continent, Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) is considered a major threat to maize, sorghum, and millet production in sub-Saharan Africa. Despite the rigorous work already conducted to reduce FAW prevalence, the dynamics and invasion mechanisms of FAW in Africa are still poorly understood. This study applied interdisciplinary tools, analytics, and algorithms on a FAW dataset with a spatial lens to provide insights and project the intensity of FAW infestation across Africa. The data collected between January 2018 and December 2020 in selected locations were matched with the monthly average data of the climatic and environmental variables. The multilevel analytics aimed to identify the key factors that influence the dynamics of spatial and temporal pest density and occurrence at a 2 km x 2 km grid resolution. The seasonal variations of the identified factors and dynamics were used to calibrate rule-based analytics employed to simulate the monthly densities and occurrence of the FAW for the years 2018, 2019, and 2020. Three FAW density level classes were inferred, i.e., low (0–10 FAW moth per trap), moderate (11–30 FAW moth per trap), and high (>30 FAW moth per trap). Results show that monthly density projections were sensitive to the type of FAW host vegetation and the seasonal variability of climatic factors. Moreover, the diversity in the climate patterns and cropping systems across the African sub-regions are considered the main drivers of FAW abundance and variation. An optimum overall accuracy of 53% was obtained across the three years and at a continental scale, however, a gradual increase in prediction accuracy was observed among the years, with 2020 predictions providing accuracies greater than 70%. Apart from the low amount of data in 2018 and 2019, the average level of accuracy obtained could also be explained by the non-inclusion of data related to certain key factors such as the influence of natural enemies (predators, parasitoids, and pathogens) into the analysis. Further detailed data on the occurrence and efficiency of FAW natural enemies in the region may help to complete the tri-trophic interactions between the host plants, pests, and beneficial organisms. Nevertheless, the tool developed in this study provides a framework for field monitoring of FAW in Africa that may be a basis for a future decision support system (DSS)

Maize stemborers distribution, their natural enemies and farmers’ perception on climate change and stemborers in southern Togo

Objective: The objectives of this study were to (i) assess the importance of the different stemborer species and their associated natural enemies on maize, and (ii) evaluate cereal producers’ perception on the effect of the current climate variability, on the maize stem and ear borers and their mitigation strategies to alleviate the impact of climate change on their cropping system. Methodology and results: Surveys were conducted in 2012 during the long cropping season lasting from March to July and the short one from September to October in southern Togo, to determine geographic distribution, relative importance of lepidopterous stemborers and their parasitism by natural enemies on maize. A questionnaire was introduced to evaluate cereal farmers’ perception of climate change and its effects on maize stem and ear borers. Of the total borer species recovered, the most abundant was Sesamia calamistis Hampson (Lepidoptera: Noctuidae) (76.02%), followed by Busseola fusca Füller (Lepidoptera: Noctuidae) (21.71%) and then Eldana saccharina Walker (Lepidoptera: Pyralidae) (2.27%). The borers’ abundance was affected by the agroecological zones and cropping seasons. Eldana saccharina was found in Zio and Yoto in coastal zone whereas B. fusca was recorded only in Yoto. Sesamia calamistis was the only species found in all the surveyed agroecological zones (III, IV and V). Fields were infested by all borer species at 34.4% and 83.3% in the long and short cropping seasons respectively. The percentage of infested plants ranged from 0 to 72% in the first cropping season, and 33 to 95% in the second cropping season. The borer densities varied from 0 to 3 larvae per plant in the long cropping season and 1 to 8 larvae per plant in the short cropping season. The egg parasitoid Telenomus busseolae Gahan (Hymenoptera: Scelionidae) was identified as the most important with a high natural parasitism rate of 82% on S. calamistis. The main larval parasitoid recorded was Sturmiopsis parasitica Curan (Diptera: Tachnidae) with mean parasitism ranged of between 0 and 8%. Beauveria bassiana (Bals.) Vuill. (Deuteromycotina: Hyphomycetes) infection rate vary from 0 to 5%.of borers’ larvae. Data on farmer’s perception showed that all producers recognized stem and ear borers and their damages. However, they perceive climate change effects differently by high temperatures, rains irregularity, floods, strong winds and to a lesser extent the proliferation of new pests such as termites (Isoptera), Zonocerus variegatus (L) (Orthoptera: Pyrgomorphidae) and Cicadulina spp. (Hemiptera: Cicadellidae). Adaptation strategies practiced by farmers are the choice of early maturing crop varieties, the spacing of sowing period and the crop diversification. Conclusion and application of funding: From these results, we conclude that S. calamistis, E. saccharina, and B. fusca and their associated natural enemies are present in all agroecological zones of southern Togo. These findings could serve as baseline data for further studies. Key words: Climate change, ear borers, incidence, maize, parasitism, severity, stem borers

Interactions variations climatiques – insectes ravageurs et perception des producteurs de cereales au sud Togo

La présente étude se propose d'établir les données de base relatives aux facteurs déterminants responsables de la structuration des espèces et procéder à des analyses qui permettront de déterminer la distribution des insectes ravageurs du maïs avec les prévisions actuelles des changements climatiques. De façon générale, le foreur de tige Sesamia calamistis a été l’espèce la plus rencontrée dans toutes les zones prospectées avec une abondance de 76,02% suivi de Busseola fusca (21,7%) et de Eldana saccharina (2,3%). Les projections d’une hausse des températures au Togo entraineraient de légères augmentations annuelles d’au moins + 0,23 des générations de S. calamistis et de E. saccharina. De plus l’analyse de la perception des agriculteurs indique l’apparition de «nouveaux» ravageurs tels que les termites, le criquet puant Zonocerus variegatus et une recrudescence des ravageurs de stock.Mots clés: Changements climatiques, Sesamia calamistis, maïs, générations, termitesEnglish Title: Climate variations-insect pests interactions and perception of cereal producers in southern TogoEnglish AbstractThe present study seeks to establish baseline data on the determinants responsible for the structuring of species and conduct analyzes that will determine the distribution of insect pests of maize under projected climate change. In general, stem borer Sesamia calamistis was the most important species found in all surveyed areas with an abundance of 76.02% followed by Busseola fusca (21.7%) and Eldana saccharina (2.3%). The result showed that projected increasing temperatures in Togo will probably lead to slight annual increases of at least +0.23 in number of S. calamistis and E. Saccharina generations. Further analysis of the perception of farmers indicates the proliferation of "new" pests such as termites, Zonocerus variegatus and an increase in storage insect pests.Keywords: Climate change, Sesamia calamistis, maize, generations, termite

Effects of plant extracts and oil emulsions on the maize cob borer Mussidia nigrivenella (Lepidoptera: pyralidae) in laboratory and field experiments

Aqueous extracts of Tephrosia vogelii and Hyptis suaveolens, and of oils of Azadirachta indica and Jatropha curcas, as well as the pesticide Furadan 5G were evaluated for their insecticidal activity against the maize cob borer Mussidia nigrivenella Ragonot in laboratory and field experiments. In general, treated plants had a strong deterrent effect on ovipositing M. nigrivenella. The oviposition deterrence index was highest with neem oil at both concentrations, J. curcas at 5% and H. suaveolens at 20%. In addition, neem and Jatropha oils adversely affected egg hatch; it decreased with an increase in concentrations of oil emulsions and varied between 3 and 25.5% for neem and 6 and 16% for J. curcas. The lethal concentration 50 values calculated were 1.3 and 0.8%, respectively, for neem and J. curcas. By contrast, larval survival was not affected by the oil treatments. In the field, Furadan, neem and J. curcas oils significantly reduced the number of M. nigrivenella larvae by 16–49.2%, while aqueous extracts of T. vogelii and H. suaveolens were similar to the emulsified water control. The treatments did not significantly influence cob weight, and only neem oil at both concentrations and Furadan significantly reduced cob damage and consequently grain losses. These results showed that oil emulsions of A. indica and J. curcas oils act not only as an oviposition deterrent but also as ovicides. The prospects for possible inclusion of botanicals into integrated M. nigrivenella control in maize cropping systems are discussed