Browsing by Author "Koffi, D."
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Item Analysis of strain distribution, migratory potential, and invasion history of fall armyworm populations in northern Sub-Saharan Africa(Nature Publishing Group, 2018) Nagoshi, R.N.; Goergen, G.; Tounou, K.A.; Agboka, K.; Koffi, D.; Meagher, R.L.Fall 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. © 2018 The Author(sItem Assessment of Bacillus thuringiensis and emamectin benzoate on the fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) severity on maize under farmers’ fields in Ghana(Springer, 2021) Koffi, D.; Kyerematen, R.; Osae, M.; Amouzou, K.; Eziah, V.Y.The introduction of fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) into Ghana is a threat to maize production. This study determined the severity of this pest on maize production subjected to Bacillus thuringiensis (Bt), emamectin benzoate (Eb) sprayed and unsprayed farms under farmers’ practices in Ghana. At least one farm per treatment was selected in each Agro-Ecological Zone (AEZ) for data collection throughout the maize phenology during three production seasons. Percent damaged plants and ears were determined, the proportion of feeding damage on leaves and ears was scored, and yields measured on each farm. Ear damage was most severe in the Guinea Savannah Agroecological Zone with a correspondingly lower yield. The highest yield was recorded from the Tropical Rain Forest zone. The damage levels decreased when plants aged, but the scoring of damage level on attacked ears was greater than that on leaves. Maize plant damage was highest with corresponding lowest yields on unsprayed farms compared to sprayed farms which recorded similar results for both insecticides. Bt and Eb based insecticides (applied at 50g/15L H2O/ha and 75mL H2O/ha, respectively) are efective on FAW larvae and are therefore recommended for FAW management in Ghana.Item Comparative molecular analyses of invasive fall armyworm in Togo reveal strong similarities to populations from the eastern United States and the Greater Antilles(Public Library of Science, 2017) Nagoshi, R.N.; Koffi, D.; Agboka, K.; Tounou, K.A.; Banerjee, R.; Jurat-Fuentes, J.L.; Meagher, R.L.The fall armyworm (Spodoptera frugiperda, J.E. Smith) is a noctuid moth that is a major and ubiquitous agricultural pest in the Western Hemisphere. Infestations have recently been identified in several locations in Africa, indicating its establishment in the Eastern Hemisphere where it poses an immediate and significant economic threat. Genetic methods were used to characterize noctuid specimens infesting multiple cornfields in the African nation of Togo that were tentatively identified as fall armyworm by morphological criteria. Species identification was confirmed by DNA barcoding and the specimens were found to be primarily of the subgroup that preferentially infests corn and sorghum in the Western Hemisphere. The mitochondrial haplotype configuration was most similar to that found in the Caribbean region and the eastern coast of the United States, identifying these populations as the likely originating source of the Togo infestations. A genetic marker linked with resistance to the Cry1Fa toxin from Bacillus thuringiensis (Bt) expressed in transgenic corn and common in Puerto Rico fall armyworm populations was not found in the Togo collections. These observations demonstrate the usefulness of genetic surveys to characterize fall armyworm populations from Africa. © 2017, Public Library of Science. All rights reserved. This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.Item Comparison of pheromone trap design and lures for Spodoptera frugiperda in Togo and genetic characterization of moths caught(Entomologia Experimentalis et Applicata, 2018-11-29) Koffi, D.; Meagher, R.L.J.; Agboka, K.; Tounou, A.K.; Agbevohia, K.A.; Amouze, T.R.; Adjevi, K.M.; Nagoshi, R.N.Fall armyworm, Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), is a pest of grain and vegetable crops endemic to the Western Hemisphere that has recently become widespread in sub- Saharan Africa and has appeared in India. An important tool formonitoring S. frugiperda in the USA is pheromone trapping, which would be of value for use with African populations. Field experiments were conducted in Togo (West Africa) to compare capture of male fall armyworm using three commercially available pheromone lures and three trap designs. The objectives were to identify optimum trap 9 lure combinations with respect to sensitivity, specificity, and cost. Almost 400 moths were captured during the experiment. Differences were found in the number of S. frugiperda moths captured in the various trap designs and with the three pheromone lures, and in the number of non-target moths captured with each lure. The merits of each trap 9 lure combination are discussed with respect to use in Africa. A nearly equal number of COI-CS (161) and COI-RS (158) moths was captured with no differences found in COI marker proportions among traps or lures. However, the diagnostic rice strain marker Tpi was rarely found. Overall, the genetic characterization of the pheromone trap collections indicated a consistent distribution of genetic markers from 2016 to 2017, suggesting a population at or near equilibrium.Item The fall armyworm strain associated with most rice, millet, and pasture infestations in the Western Hemisphere is rare or absent in Ghana and Togo(PLOS, 2021) Nagoshi, R.N.; Koffi, D.; Agboka, K.; Adjevi, A.K.M.; Meagher, R.L.; Goergen, G.The 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 eco nomic 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 exam ined 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 Rstrain, 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.Item Maize Infestation of Fall Armyworm (Lepidoptera: Noctuidae) Within Agro-Ecological Zones of Togo and Ghana in West Africa 3 Yr After Its Invasion(Environmental Entomology, 2020-04-29) Koffi, D.; Agboka, K.; Adenka, D.K.; Osae, M.; Tounou, A.K.; Adjevi, M.K.A.; Fening, K.O.; Meagher, R.L.J.The fall armyworm Spodoptera frugiperda (J. E. Smith) invaded several West African countries in 2016 causing severe injury to maize plants and economic damage. This study assesses variations in the occurrence of this species in different Agro-Ecological Zones (AEZs) in Togo and Ghana during the 3 yr following its discovery. The surveys were conducted on 120 farms in Togo and 94 farms in Ghana by collecting larvae from 200 maize plants per hectare. Infestation levels were 68.46% in 2016, 55.82% in 2017, and 17.76% in 2018. The number of larvae recorded per hectare and infestation levels were higher in Togo than in Ghana. The lowest number of collected larvae and infestation levels of S. frugiperda were in 2018, compared to the other 2 yr. Larvae per hectare and the infestation level varied regionally inside the two countries. The southern part of Togo (AEZ five) contained higher numbers of larvae and higher infestation levels during the 2 yr following the invasion of the pest. We concluded that infestation levels of S. frugiperda are much lower in 2018 than the two previous years and it is therefore necessary to determine the factors that affect the population dynamics of S. frugiperda in the field, which is a perquisite for developing management interventions.