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Rodney N Nagoshi - One of the best experts on this subject based on the ideXlab platform.
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genetic characterization of fall armyworm infesting south africa and india indicate recent introduction from a common source population
PLOS ONE, 2019Co-Authors: Rodney N Nagoshi, Isabel Dhanani, H M Mahadevaswamy, Rethinaswamy Asokan, Chicknayakanahalli M Kalleshwaraswamy, Robert L MeagherAbstract:The invasion of the Western Hemisphere native fall armyworm (Spodoptera frugiperda; J. E. Smith) (Lepidoptera: Noctuidae) into the Eastern Hemisphere has been notable for the rapidity and geographical breadth of new detections. In the year following the first discovery in western sub-Saharan Africa in 2016, infestations have been documented in most sub-Saharan maize growing regions and has now expanded beyond Africa with populations recently reported in India. These observations could indicate a remarkable capacity for rapid establishment and long-distance dissemination. However, while fall armyworm does exhibit extended migration in North America where it annually traverses thousands of kilometers, this behavior is known to be dependent on highly favorable wind patterns and so can’t be assumed to occur in all locations. An alternative possibility is that the species has long been present in Africa, and perhaps the rest of the Hemisphere, but was undetected until the enhanced monitoring that resulted after its initial discovery. Determining whether the fall armyworm in the Eastern Hemisphere is newly arrived or long pre-existing is important for assessing the risks of significant economic impacts, as the former indicates a change in pest composition while the latter does not. This study examined this issue by comparing collections from two geographically distant locations, South Africa and India. Sequence comparisons were used to quantify differences between the South Africa and India collections, assess the likelihood of their sharing a common source population, and their possible relationship with previously characterized fall armyworm from other regions of Africa. The results indicate genetic homogeneity between the South African and Indian fall armyworm populations tested and substantial similarities between these and collections from Eastern Africa. The implications of these findings on fall armyworm population behavior and composition are discussed.
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evidence that a major subpopulation of fall armyworm found in the western Hemisphere is rare or absent in africa which may limit the range of crops at risk of infestation
PLOS ONE, 2019Co-Authors: Rodney N NagoshiAbstract:The introduction and establishment of fall armyworm (Spodoptera frugiperda) in Africa presents a major threat to agriculture in that continent and potentially to the entire Eastern Hemisphere. The species is subdivided into two subpopulations called the R-strain and C-strain that differ in their distribution on different plant hosts. This means that the scope of the economic risk posed by invasive fall armyworm is influenced by whether one or both strains are present. Multiple studies have found mitochondrial markers diagnostic of the two strains throughout Africa but there is substantial disagreement with a nuclear strain marker that makes conclusions about strain composition uncertain. In this study the issue of whether both strains are present in Africa was tested by an assay that can detect strain-biased mating behaviors. Western Hemisphere fall armyworm consistently showed evidence of strain-specific assortative mating in the field that was not found in surveys from multiple locations in Africa. The absence of strain mating biases and the disagreements between the strain diagnostic genetic markers indicates that the R-strain is rare (<1% of the population) or absent in Africa. Instead, it appears that the African fall armyworm populations are dominated by two groups, the C-strain and the descendants of interstrain hybrids. These results suggest that plant hosts associated with the R-strain may not be at high risk of fall armyworm infestation in Africa.
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evidence that a major subpopulation of fall armyworm found in the western Hemisphere is rare or absent in africa which may limit the range of crops at risk of infestation
bioRxiv, 2018Co-Authors: Rodney N NagoshiAbstract:The introduction and establishment of fall armyworm (Spodoptera frugiperda) in Africa presents a major threat to agriculture in that continent and potentially to the entire Eastern Hemisphere. The species is subdivided into two subpopulations called the R-strain and C-strain that differ in their distribution on different plant hosts. This means that the scope of the economic risk posed by invasive fall armyworm is influenced by whether one or both strains are present. Multiple studies have found mitochondrial markers diagnostic of the two strains throughout Africa but there is substantial disagreement with a nuclear strain marker that makes conclusions about strain composition uncertain. In this study the issue of whether both strains are present in Africa was tested by an assay that can detect strain-biased mating behaviors. Western Hemisphere fall armyworm consistently showed evidence of strain-specific assortative mating in the field that was not found in surveys from multiple locations in Africa. The absence of strain mating biases and the disagreements between the strain diagnostic genetic markers indicates that the R-strain is rare (
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analysis of strain distribution migratory potential and invasion history of fall armyworm populations in northern sub saharan africa
Scientific Reports, 2018Co-Authors: Rodney N Nagoshi, Georg Goergen, Kodjo Agbeko Tounou, Komi Agboka, Djima Koffi, Robert L MeagherAbstract: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.
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comparative molecular analyses of invasive fall armyworm in togo reveal strong similarities to populations from the Eastern united states and the greater antilles
PLOS ONE, 2017Co-Authors: Rodney N Nagoshi, Kodjo Agbeko Tounou, Komi Agboka, Djima Koffi, Rahul Banerjee, Juan Luis Juratfuentes, Robert L MeagherAbstract: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.
R. W. Schneider - One of the best experts on this subject based on the ideXlab platform.
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from select agent to an established pathogen the response to phakopsora pachyrhizi soybean rust in north america
Phytopathology, 2015Co-Authors: Heather Y Kelly, James J. Marois, David L. Wright, Scott A. Isard, R. W. Schneider, Nicholas S Dufault, David R Walker, Loren J Giesler, Glen L HartmanAbstract:The pathogen causing soybean rust, Phakopsora pachyrhizi, was first described in Japan in 1902. The disease was important in the Eastern Hemisphere for many decades before the fungus was reported in Hawaii in 1994, which was followed by reports from countries in Africa and South America. In 2004, P. pachyrhizi was confirmed in Louisiana, making it the first report in the continental United States. Based on yield losses from countries in Asia, Africa, and South America, it was clear that this pathogen could have a major economic impact on the yield of 30 million ha of soybean in the United States. The response by agencies within the United States Department of Agriculture, industry, soybean check-off boards, and universities was immediate and complex. The impacts of some of these activities are detailed in this review. The net result has been that the once dreaded disease, which caused substantial losses in other parts of the world, is now better understood and effectively managed in the United States. The disease continues to be monitored yearly for changes in spatial and temporal distribution so that soybean growers can continue to benefit by knowing where soybean rust is occurring during the growing season.
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first report of soybean rust caused by phakopsora pachyrhizi in the continental united states
Plant Disease, 2005Co-Authors: R. W. Schneider, J. R. Hernández, Mary E. Palm, J. M. Mckemy, Laurene Levy, Clayton A. Hollier, H. K. Whitam, R DevriespatersonAbstract:Asian soybean rust, caused by Phakopsora pachyrhizi Sydow, has been known to occur in the Eastern Hemisphere for nearly a century. More recently, it was reported from Hawaii in 1994, Eastern and so...
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First Report of Soybean Rust Caused by Phakopsora pachyrhizi in the Continental United States.
Plant disease, 2005Co-Authors: R. W. Schneider, J. R. Hernández, Mary E. Palm, J. M. Mckemy, Laurene Levy, Clayton A. Hollier, H. K. Whitam, R. Devries-patersonAbstract:Asian soybean rust, caused by Phakopsora pachyrhizi Sydow, has been known to occur in the Eastern Hemisphere for nearly a century. More recently, it was reported from Hawaii in 1994, Eastern and southern Africa from 1996-1998, Nigeria in 2001, and Brazil and Paraguay in 2002. Aerobiological models suggested that urediniospores of the pathogen would be disseminated on wind currents to the continental United States in association with tropical storms if the disease became established north of the equator during hurricane season (U.S. Soybean Rust Detection and Aerobiological Modeling online publication at www.aphis.usda.gov/ppq/ ep/soybean_rust/). Since soybean rust was observed at approximately 5°N latitude in South America before several hurricanes impacted the continental United States in September 2004, it seems likely that the introduction was associated with at least one of these tropical storms, especially hurricane Ivan. Symptoms of the disease were first observed on soybean (Glycine max (L.) Merr.)...
Robert P. Adams - One of the best experts on this subject based on the ideXlab platform.
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phylogenomic evidence for ancient recombination between plastid genomes of the cupressus juniperus xanthocyparis complex cupressaceae
BMC Evolutionary Biology, 2018Co-Authors: Robert P. Adams, Andan Zhu, Weishu Fan, Jeffrey P MowerAbstract:Phylogenetic relationships among Eastern Hemisphere cypresses, Western Hemisphere cypresses, junipers, and their closest relatives are controversial, and generic delimitations have been in flux for the past decade. To address relationships and attempt to produce a more robust classification, we sequenced 11 new plastid genomes (plastomes) from the five variously described genera in this complex (Callitropsis, Cupressus, Hesperocyparis, Juniperus, and Xanthocyparis) and compared them with additional plastomes from diverse members of Cupressaceae. Phylogenetic analysis of protein-coding genes recovered a topology in which Juniperus is sister to Cupressus, whereas a tree based on whole plastomes indicated that the Callitropsis-Hesperocyparis-Xanthocyparis (CaHX) clade is sister to Cupressus. A sliding window analysis of site-specific phylogenetic support identified a ~ 15 kb region, spanning the genes ycf1 and ycf2, which harbored an anomalous signal relative to the rest of the genome. After excluding these genes, trees based on the remainder of the genes and genome consistently recovered a topology grouping the CaHX clade and Cupressus with strong bootstrap support. In contrast, trees based on the ycf1 and ycf2 region strongly supported a sister relationship between Cupressus and Juniperus. These results demonstrate that standard phylogenomic analyses can result in strongly supported but conflicting trees. We suggest that the conflicting plastomic signals result from an ancient introgression event involving ycf1 and ycf2 that occurred in an ancestor of this species complex. The introgression event was facilitated by plastomic recombination in an ancestral heteroplasmic individual carrying distinct plastid haplotypes, offering further evidence that recombination occurs between plastomes. Finally, we provide strong support for previous proposals to recognize five genera in this species complex: Callitropsis, Cupressus, Hesperocyparis, Juniperus, and Xanthocyparis.
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phylogeny of juniperus using nrdna and four cpdna regions
Phytologia., 2013Co-Authors: Robert P. Adams, Andrea E SchwarzbachAbstract:The Phylogeny of Juniperus is presented based on nrDNA (ITS), petN-psbM, trnS-trnG, trnD-trnT, trnL-trnF sequencing (4411 bp) utilizing all currently recognized species. The major clades of the phylogenetic tree were congruent with the previously published phylogenetic tree of Mao et al. (2010) that had a subset of taxa of the current study. The lone species with serrate leaves in the Eastern Hemisphere, J. phoenicea, was found to be in a clade quite separated from the serrate junipers of North America. Juniperus phoenicea is referred to as 'pseudoserrate' to distinguish it from the semi-arid, serrate leaf junipers of the western Hemisphere. Section Sabina is the most derived group and has radiated into niches in both the Eastern and western Hemispheres with approx. 60 species. Published on-line: www.phytologia.org Phytologia 95(2): 179-187 (May 1, 2013).
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post pleistocene geographic variation in juniperus communis in north america
Phytologia., 2007Co-Authors: Robert P. Adams, Sanko NguyenAbstract:Plants of Juniperus communis L. var. communis, J. c. var. depressa Pursh, J. c. var. megistocarpa Fern. & St. John, J. c. var. saxatilis Pall. were sampled and DNA fingerprinting (RAPDs, Random Amplified Polymorphic DNAs) was performed. Based on 100 RAPD bands, J. communis var. communis and J. c. var. saxatilis from the Eastern Hemisphere were clearly separated from J. communis in North America. Populations referred to as var. saxatilis from the Pacific northwest did not show alliances with authentic var. saxatilis from Europe. However, plants with short, curved leaves, and having a white stomatal band about twice as wide as the green margins are allied with J. c. var. jackii Rehdr. Geographic variation in North American populations of J. communis revealed the southern Appalachian Mountains appear to have been a refugium during the late Pleistocene (Wisconsin). Plants from the isolated Mt. Charleston, Nevada were very differentiated, reflecting a long period of genetic isolation. The populations at Banff and Canmore, Alberta were somewhat intermediate between J. c. var. depressa and J. c. var. jackii from Queen Charlotte Island.
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pan arctic variation in juniperus communis historical biogeography based on dna fingerprinting
Biochemical Systematics and Ecology, 2003Co-Authors: Robert P. Adams, Kyle Hoegh, Ram N Pandey, Jerry W. Leverenz, N Dignard, T ThorfinnssonAbstract:Twelve populations of Juniperus communis L. were sampled from throughout the arctic, worldwide and DNA fingerprinting (RAPDs, Random Amplified Polymorphic DNAs) was performed. Based on 152 RAPD bands, all of the populations (J. communis var. depressa Pursh and J. communis var. megistocarpa Fern. and St. John) from the western Hemisphere formed one group and all of the populations of the Eastern Hemisphere (including Greenland and Iceland), formed another group that included J. communis var. communis and J. communis var. saxatilis Pall., except for the Kamchatka population that was quite dissimilar to any population examined. Most likely, the current sites of all of the populations were covered with ice or otherwise inhospitable, up to or during the late Pleistocene (ca. 12,000 BP). Therefore, these populations are recent in origin. The path of re-colonization appears to have been northward in North America. Greenland appears to have been colonized from Iceland plants, which in turn came from northern Europe. The Kamchatka population seems likely to have come from Japan.
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systematics of the one seeded juniperus of the Eastern Hemisphere based on leaf essential oils and random amplified polymorphic dnas rapds
Biochemical Systematics and Ecology, 2000Co-Authors: Robert P. AdamsAbstract:The compositions of the leaf essential oils of all the one seed/cone species of Juniperus (sect. Sabina) of the Eastern Hemisphere are reported and compared (J. convallium, J. convallium var. microsperma, J. indica, J. komarovii, J. pingii, J. pingii var. carinata, J. prezewalskii, J. pseudosabina, J. recurva, J. recurva var. coxii, J. saltuaria, J. squamata, J. squamata var. morrisonicola, J. tibetica, J. wallachiana). In addition, DNA fingerprinting by RAPDs was utilized. The combined terpenoid and DNA data supported the continued recognition of the aforementioned taxa as distinct species except for four varieties which were recognized at the specific level: Juniperus carinata (Y.K. Yu & L.K. Fu) R.P. Adams, stat. nov. (Syn.: J. pingii var. carinata); J. coxii A.B. Jacks. (Syn.: J. recurva var. coxii); Juniperus microsperma (Cheng & L.K. Fu) R.P. Adams, stat. nov. (Syn.: J. convallium var. microsperma); J. morrisonicola Hayata (Syn.: J. squamata var. morrisonicola).
Robert L Meagher - One of the best experts on this subject based on the ideXlab platform.
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genetic characterization of fall armyworm infesting south africa and india indicate recent introduction from a common source population
PLOS ONE, 2019Co-Authors: Rodney N Nagoshi, Isabel Dhanani, H M Mahadevaswamy, Rethinaswamy Asokan, Chicknayakanahalli M Kalleshwaraswamy, Robert L MeagherAbstract:The invasion of the Western Hemisphere native fall armyworm (Spodoptera frugiperda; J. E. Smith) (Lepidoptera: Noctuidae) into the Eastern Hemisphere has been notable for the rapidity and geographical breadth of new detections. In the year following the first discovery in western sub-Saharan Africa in 2016, infestations have been documented in most sub-Saharan maize growing regions and has now expanded beyond Africa with populations recently reported in India. These observations could indicate a remarkable capacity for rapid establishment and long-distance dissemination. However, while fall armyworm does exhibit extended migration in North America where it annually traverses thousands of kilometers, this behavior is known to be dependent on highly favorable wind patterns and so can’t be assumed to occur in all locations. An alternative possibility is that the species has long been present in Africa, and perhaps the rest of the Hemisphere, but was undetected until the enhanced monitoring that resulted after its initial discovery. Determining whether the fall armyworm in the Eastern Hemisphere is newly arrived or long pre-existing is important for assessing the risks of significant economic impacts, as the former indicates a change in pest composition while the latter does not. This study examined this issue by comparing collections from two geographically distant locations, South Africa and India. Sequence comparisons were used to quantify differences between the South Africa and India collections, assess the likelihood of their sharing a common source population, and their possible relationship with previously characterized fall armyworm from other regions of Africa. The results indicate genetic homogeneity between the South African and Indian fall armyworm populations tested and substantial similarities between these and collections from Eastern Africa. The implications of these findings on fall armyworm population behavior and composition are discussed.
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analysis of strain distribution migratory potential and invasion history of fall armyworm populations in northern sub saharan africa
Scientific Reports, 2018Co-Authors: Rodney N Nagoshi, Georg Goergen, Kodjo Agbeko Tounou, Komi Agboka, Djima Koffi, Robert L MeagherAbstract: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.
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comparative molecular analyses of invasive fall armyworm in togo reveal strong similarities to populations from the Eastern united states and the greater antilles
PLOS ONE, 2017Co-Authors: Rodney N Nagoshi, Kodjo Agbeko Tounou, Komi Agboka, Djima Koffi, Rahul Banerjee, Juan Luis Juratfuentes, Robert L MeagherAbstract: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.
R. Devries-paterson - One of the best experts on this subject based on the ideXlab platform.
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First Report of Soybean Rust Caused by Phakopsora pachyrhizi in the Continental United States.
Plant disease, 2005Co-Authors: R. W. Schneider, J. R. Hernández, Mary E. Palm, J. M. Mckemy, Laurene Levy, Clayton A. Hollier, H. K. Whitam, R. Devries-patersonAbstract:Asian soybean rust, caused by Phakopsora pachyrhizi Sydow, has been known to occur in the Eastern Hemisphere for nearly a century. More recently, it was reported from Hawaii in 1994, Eastern and southern Africa from 1996-1998, Nigeria in 2001, and Brazil and Paraguay in 2002. Aerobiological models suggested that urediniospores of the pathogen would be disseminated on wind currents to the continental United States in association with tropical storms if the disease became established north of the equator during hurricane season (U.S. Soybean Rust Detection and Aerobiological Modeling online publication at www.aphis.usda.gov/ppq/ ep/soybean_rust/). Since soybean rust was observed at approximately 5°N latitude in South America before several hurricanes impacted the continental United States in September 2004, it seems likely that the introduction was associated with at least one of these tropical storms, especially hurricane Ivan. Symptoms of the disease were first observed on soybean (Glycine max (L.) Merr.)...