The Experts below are selected from a list of 633 Experts worldwide ranked by ideXlab platform

Laurent Costet - One of the best experts on this subject based on the ideXlab platform.

  • Morphometric and molecular discrimination of the sugarcane aphid, Melanaphis sacchari, (Zehntner, 1897) and the sorghum aphid Melanaphis sorghi (Theobald, 1904).
    PloS one, 2021
    Co-Authors: Samuel Nibouche, Laurent Costet, Jocelyn R. Holt, Joëlle Sadeyen, Anne-sophie Zoogones, Raul F Medina, Paul Brown, Roger L Blackman
    Abstract:

    Melanaphis sacchari (Zehntner, 1897) and Melanaphis sorghi (Theobald, 1904) are major worldwide crop pests causing direct feeding damage on sorghum and transmitting viruses to sugarcane. It is common in the scientific literature to consider these two species as synonyms, referred to as the 'sugarcane aphid', although no formal study has validated this synonymy. In this study, based on the comparison of samples collected from their whole distribution area, we use both morphometric and molecular data to better characterize the discrimination between M. sacchari and M. sorghi. An unsupervised multivariate analysis of morphometric data clearly confirmed the separation of the two species. The best discriminating characters separating these species were length of the antenna processus terminalis relative to length of hind tibia, siphunculus or cauda. However, those criteria sometimes do not allow an unambiguous identification. Bayesian clustering based on microsatellite data delimited two clusters, which corresponded to the morphological species separation. The DNA sequencing of three nuclear and three mitochondrial regions revealed slight divergence between species. In particular, the COI barcode region proved to be uninformative for species separation because one haplotype is shared by both species. In contrast, one SNP located on the nuclear EF1-α gene was diagnostic for species separation. Based on morphological and molecular evidence, the invasive genotype damaging to sorghum in the US, Mexico and the Caribbean since 2013 is found to be M. sorghi.

  • differences in microbiota between two multilocus lineages of the sugarcane aphid Melanaphis sacchari in the continental united states
    Annals of The Entomological Society of America, 2020
    Co-Authors: Jocelyn R. Holt, Samuel Nibouche, Laurent Costet, Scott J Armstrong, Alex Styer, Jennifer A White, Antonino Malacrino, Josephine B Antwi, Jason A Wulff, G. C. Peterson
    Abstract:

    The sugarcane aphid (SCA), Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), has been considered an invasive pest of sugarcane in the continental United States since 1977. Then, in 2013, SCA abruptly became a serious pest of U.S. sorghum and is now a sorghum pest in 22 states across the continental United States. Changes in insect-associated microbial community composition are known to influence host-plant range in aphids. In this study, we assessed whether changes in microbiota composition may explain the SCA outbreak in U.S. sorghum. We characterized the SCA bacterial microbiota on sugarcane and grain sorghum in four U.S. states, using a metabarcoding approach. In addition, we used taxon-specific polymerase chain reaction (PCR) primers to screen for bacteria commonly reported in aphid species. As anticipated, all SCA harbored the primary aphid endosymbiont Buchnera aphidicola, an obligate mutualistic bacterial symbiont. Interestingly, none of the secondary symbionts, facultative bacteria typically associated with aphids (e.g., Arsenophonus, Hamiltonella, Regiella) were present in either the metabarcoding data or PCR screens (with the exception of Rickettsiella and Serratia, which were detected by metabarcoding at low abundances <1%). However, our metabarcoding detected bacteria not previously identified in aphids (Arcobacter, Bifidobacterium, Citrobacter). Lastly, we found microbial host-associated differentiation in aphids that seems to correspond to genetically distinct aphid lineages that prefer to feed on grain sorghum (MLL-F) versus sugarcane (MLL-D).Graphical abstract

  • Invasion of sorghum in the Americas by a new sugarcane aphid (Melanaphis sacchari) superclone
    PloS one, 2018
    Co-Authors: Samuel Nibouche, Alana L Jacobson, Laurent Costet, Jocelyn R. Holt, Joëlle Sadeyen, J. Scott Armstrong, G. C. Peterson, Adrian Pekarcik, N.w. Mclaren, Raúl Medina
    Abstract:

    In the United States (US), the sugarcane aphid (SCA) Melanaphis sacchari (Zehnter) (Hemiptera: Aphididae) was introduced in the 1970s, however at that time it was only considered a pest of sugarcane. In 2013, a massive outbreak of M. sacchari occured on sorghum, resulting in significant economic damage to sorghum grown in North America including the US, Mexico, and Puerto Rico. The aim of the present study was to determine if the SCA pest emergence in American sorghum resulted from the introduction of new genotypes. To this end we used microsatellite markers and COI sequencing to compare the genetic diversity of SCA populations collected in the Americas after the 2013 SCA outbreak on sorghum (during 2013–2017) to older samples collected before the pest outbreak (during 2007–2009). Our results show that the SCA outbreak in the Americas and the Caribbean observed since 2013 belong to populations exhibiting low genetic diversity and consisting of a dominant clonal lineage, MLL-F, which colonizes Sorghum spp. and sugarcane. The comparison of MLL-F specimens collected post-2013 with specimens collected in Louisiana in 2007 revealed that both populations are genetically distinct, according to COI sequencing and microsatellite data analyses. Our result suggest that MLL-F is a new invasive genotype introduced into the Americas that has spread rapidly across sorghum growing regions in the US, Mexico, Honduras and the Caribbean. The origin of this introduction is either Africa or Asia, with Asia being the most probable source.

  • Morphometric and Molecular Delineation of Melanaphis sacchari and Melanaphis sorghi
    2018
    Co-Authors: Samuel Nibouche, Raúl Medina, Jocelyn R. Holt, Joëlle Sadeyen, Anne-sophie Zoogones, Sandro Moretti, Laurent Costet
    Abstract:

    The Sugarcane Aphid, Melanaphis sacchari, is a major worldwide crop pest causing direct feeding damage on sorghum and transmitting viruses to sugarcane. In the US, Mexico and Caribbean, an invasive genotype of Sugarcane Aphid has become a major pest of sorghum since 2013. The taxonomic status of M. sacchari varies among authors. Some consider that the species M. sorghi is a synonym of M. sacchari, while others consider them as distinct species according to morphological differentiations. In this study, based on the comparison of samples collected from the whole distribution area, we use both morphometric and molecular data to confirm that M. sacchari and M. sorghi are distinct species. The invasive genotype recently introduced in the Americas is found to be M. sorghi.

  • Costet L. Low genetic diversity in Melanaphis sacchari aphid populations at the worldwide scale
    2016
    Co-Authors: Samuel Nibouche, Benjamin Fartek, Bernard Reynaud, Stelly Mississipi, Laurent Costet
    Abstract:

    Numerous studies have examined the genetic diversity and genetic structure of invading species, with contrasting results concerning the relative roles of genetic diversity and phenotypic plasticity in the success of introduced populations. Increasing evidence shows that asexual lineages of aphids are able to occupy a wide geographical and ecological range of habitats despite low genetic diversity. The anholocyclic aphid Melanaphis sacchari is a pest of sugarcane and sorghum which originated in the old world, was introduced into the Americas, and is now distributed worldwide. Our purpose was to assess the genetic diversity and structuring of populations of this species according to host and locality. We used 10 microsatellite markers to genotype 1333 individuals (57 samples, 42 localities, 15 countries) collected mainly on sugarcane or sorghum. Five multilocus lineages (MLL) were defined, grouping multilocus genotypes (MLG) differing by only a few mutations or scoring errors. Analysis of a 658 bp sequence of mitochondrial COI gene on 96 individuals revealed five haplotypes, with a mean divergence of only 0.19 %. The distribution of MLL appeared to be strongly influenced b

Samuel Nibouche - One of the best experts on this subject based on the ideXlab platform.

  • Morphometric and molecular discrimination of the sugarcane aphid, Melanaphis sacchari, (Zehntner, 1897) and the sorghum aphid Melanaphis sorghi (Theobald, 1904).
    PloS one, 2021
    Co-Authors: Samuel Nibouche, Laurent Costet, Jocelyn R. Holt, Joëlle Sadeyen, Anne-sophie Zoogones, Raul F Medina, Paul Brown, Roger L Blackman
    Abstract:

    Melanaphis sacchari (Zehntner, 1897) and Melanaphis sorghi (Theobald, 1904) are major worldwide crop pests causing direct feeding damage on sorghum and transmitting viruses to sugarcane. It is common in the scientific literature to consider these two species as synonyms, referred to as the 'sugarcane aphid', although no formal study has validated this synonymy. In this study, based on the comparison of samples collected from their whole distribution area, we use both morphometric and molecular data to better characterize the discrimination between M. sacchari and M. sorghi. An unsupervised multivariate analysis of morphometric data clearly confirmed the separation of the two species. The best discriminating characters separating these species were length of the antenna processus terminalis relative to length of hind tibia, siphunculus or cauda. However, those criteria sometimes do not allow an unambiguous identification. Bayesian clustering based on microsatellite data delimited two clusters, which corresponded to the morphological species separation. The DNA sequencing of three nuclear and three mitochondrial regions revealed slight divergence between species. In particular, the COI barcode region proved to be uninformative for species separation because one haplotype is shared by both species. In contrast, one SNP located on the nuclear EF1-α gene was diagnostic for species separation. Based on morphological and molecular evidence, the invasive genotype damaging to sorghum in the US, Mexico and the Caribbean since 2013 is found to be M. sorghi.

  • differences in microbiota between two multilocus lineages of the sugarcane aphid Melanaphis sacchari in the continental united states
    Annals of The Entomological Society of America, 2020
    Co-Authors: Jocelyn R. Holt, Samuel Nibouche, Laurent Costet, Scott J Armstrong, Alex Styer, Jennifer A White, Antonino Malacrino, Josephine B Antwi, Jason A Wulff, G. C. Peterson
    Abstract:

    The sugarcane aphid (SCA), Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), has been considered an invasive pest of sugarcane in the continental United States since 1977. Then, in 2013, SCA abruptly became a serious pest of U.S. sorghum and is now a sorghum pest in 22 states across the continental United States. Changes in insect-associated microbial community composition are known to influence host-plant range in aphids. In this study, we assessed whether changes in microbiota composition may explain the SCA outbreak in U.S. sorghum. We characterized the SCA bacterial microbiota on sugarcane and grain sorghum in four U.S. states, using a metabarcoding approach. In addition, we used taxon-specific polymerase chain reaction (PCR) primers to screen for bacteria commonly reported in aphid species. As anticipated, all SCA harbored the primary aphid endosymbiont Buchnera aphidicola, an obligate mutualistic bacterial symbiont. Interestingly, none of the secondary symbionts, facultative bacteria typically associated with aphids (e.g., Arsenophonus, Hamiltonella, Regiella) were present in either the metabarcoding data or PCR screens (with the exception of Rickettsiella and Serratia, which were detected by metabarcoding at low abundances <1%). However, our metabarcoding detected bacteria not previously identified in aphids (Arcobacter, Bifidobacterium, Citrobacter). Lastly, we found microbial host-associated differentiation in aphids that seems to correspond to genetically distinct aphid lineages that prefer to feed on grain sorghum (MLL-F) versus sugarcane (MLL-D).Graphical abstract

  • Invasion of sorghum in the Americas by a new sugarcane aphid (Melanaphis sacchari) superclone
    PloS one, 2018
    Co-Authors: Samuel Nibouche, Alana L Jacobson, Laurent Costet, Jocelyn R. Holt, Joëlle Sadeyen, J. Scott Armstrong, G. C. Peterson, Adrian Pekarcik, N.w. Mclaren, Raúl Medina
    Abstract:

    In the United States (US), the sugarcane aphid (SCA) Melanaphis sacchari (Zehnter) (Hemiptera: Aphididae) was introduced in the 1970s, however at that time it was only considered a pest of sugarcane. In 2013, a massive outbreak of M. sacchari occured on sorghum, resulting in significant economic damage to sorghum grown in North America including the US, Mexico, and Puerto Rico. The aim of the present study was to determine if the SCA pest emergence in American sorghum resulted from the introduction of new genotypes. To this end we used microsatellite markers and COI sequencing to compare the genetic diversity of SCA populations collected in the Americas after the 2013 SCA outbreak on sorghum (during 2013–2017) to older samples collected before the pest outbreak (during 2007–2009). Our results show that the SCA outbreak in the Americas and the Caribbean observed since 2013 belong to populations exhibiting low genetic diversity and consisting of a dominant clonal lineage, MLL-F, which colonizes Sorghum spp. and sugarcane. The comparison of MLL-F specimens collected post-2013 with specimens collected in Louisiana in 2007 revealed that both populations are genetically distinct, according to COI sequencing and microsatellite data analyses. Our result suggest that MLL-F is a new invasive genotype introduced into the Americas that has spread rapidly across sorghum growing regions in the US, Mexico, Honduras and the Caribbean. The origin of this introduction is either Africa or Asia, with Asia being the most probable source.

  • Morphometric and Molecular Delineation of Melanaphis sacchari and Melanaphis sorghi
    2018
    Co-Authors: Samuel Nibouche, Raúl Medina, Jocelyn R. Holt, Joëlle Sadeyen, Anne-sophie Zoogones, Sandro Moretti, Laurent Costet
    Abstract:

    The Sugarcane Aphid, Melanaphis sacchari, is a major worldwide crop pest causing direct feeding damage on sorghum and transmitting viruses to sugarcane. In the US, Mexico and Caribbean, an invasive genotype of Sugarcane Aphid has become a major pest of sorghum since 2013. The taxonomic status of M. sacchari varies among authors. Some consider that the species M. sorghi is a synonym of M. sacchari, while others consider them as distinct species according to morphological differentiations. In this study, based on the comparison of samples collected from the whole distribution area, we use both morphometric and molecular data to confirm that M. sacchari and M. sorghi are distinct species. The invasive genotype recently introduced in the Americas is found to be M. sorghi.

  • Costet L. Low genetic diversity in Melanaphis sacchari aphid populations at the worldwide scale
    2016
    Co-Authors: Samuel Nibouche, Benjamin Fartek, Bernard Reynaud, Stelly Mississipi, Laurent Costet
    Abstract:

    Numerous studies have examined the genetic diversity and genetic structure of invading species, with contrasting results concerning the relative roles of genetic diversity and phenotypic plasticity in the success of introduced populations. Increasing evidence shows that asexual lineages of aphids are able to occupy a wide geographical and ecological range of habitats despite low genetic diversity. The anholocyclic aphid Melanaphis sacchari is a pest of sugarcane and sorghum which originated in the old world, was introduced into the Americas, and is now distributed worldwide. Our purpose was to assess the genetic diversity and structuring of populations of this species according to host and locality. We used 10 microsatellite markers to genotype 1333 individuals (57 samples, 42 localities, 15 countries) collected mainly on sugarcane or sorghum. Five multilocus lineages (MLL) were defined, grouping multilocus genotypes (MLG) differing by only a few mutations or scoring errors. Analysis of a 658 bp sequence of mitochondrial COI gene on 96 individuals revealed five haplotypes, with a mean divergence of only 0.19 %. The distribution of MLL appeared to be strongly influenced b

Benjamin Fartek - One of the best experts on this subject based on the ideXlab platform.

  • Costet L. Low genetic diversity in Melanaphis sacchari aphid populations at the worldwide scale
    2016
    Co-Authors: Samuel Nibouche, Benjamin Fartek, Bernard Reynaud, Stelly Mississipi, Laurent Costet
    Abstract:

    Numerous studies have examined the genetic diversity and genetic structure of invading species, with contrasting results concerning the relative roles of genetic diversity and phenotypic plasticity in the success of introduced populations. Increasing evidence shows that asexual lineages of aphids are able to occupy a wide geographical and ecological range of habitats despite low genetic diversity. The anholocyclic aphid Melanaphis sacchari is a pest of sugarcane and sorghum which originated in the old world, was introduced into the Americas, and is now distributed worldwide. Our purpose was to assess the genetic diversity and structuring of populations of this species according to host and locality. We used 10 microsatellite markers to genotype 1333 individuals (57 samples, 42 localities, 15 countries) collected mainly on sugarcane or sorghum. Five multilocus lineages (MLL) were defined, grouping multilocus genotypes (MLG) differing by only a few mutations or scoring errors. Analysis of a 658 bp sequence of mitochondrial COI gene on 96 individuals revealed five haplotypes, with a mean divergence of only 0.19 %. The distribution of MLL appeared to be strongly influenced b

  • Host Plant Specialization in the Sugarcane Aphid Melanaphis sacchari
    PLOS ONE, 2015
    Co-Authors: Samuel Nibouche, Benjamin Fartek, Bernard Reynaud, Stelly Mississipi, Hélène Delatte, Laurent Costet
    Abstract:

    Most aphids are highly specialized on one or two related plant species and generalist species often include sympatric populations adapted to different host plants. Our aim was to test the hypothesis of the existence of host specialized lineages of the aphid Melanaphis sacchari in Reunion Island. To this end, we investigated the genetic diversity of the aphid and its association with host plants by analyzing the effect of wild sorghum Sorghum bicolor subsp. verticilliflorum or sugarcane as host plants on the genetic structuring of populations and by performing laboratory host transfer experiments to detect trade-offs in host use. Genotyping of 31 samples with 10 microsatellite loci enabled identification of 13 multilocus genotypes (MLG). Three of these, Ms11, Ms16 and Ms15, were the most frequent ones. The genetic structure of the populations was linked to the host plants. Ms11 and Ms16 were significantly more frequently observed on sugarcane, while Ms15 was almost exclusively collected in colonies on wild sorghum. Laboratory transfer experiments demonstrated the existence of fitness trade-offs. An Ms11 isofemale lineage performed better on sugarcane than on sorghum, whereas an Ms15 lineage developed very poorly on sugarcane, and two Ms16 lineages showed no significant difference in performances between both hosts. Both field and laboratory results support the existence of host plant specialization in M. sacchari in Reunion Island, despite low genetic differentiation. This study illustrates the ability of asexual aphid lineages to rapidly undergo adaptive changes including shifting from one host plant to another.

  • Low Genetic Diversity in Melanaphis sacchari Aphid Populations at the Worldwide Scale
    PloS one, 2014
    Co-Authors: Samuel Nibouche, Benjamin Fartek, Bernard Reynaud, Stelly Mississipi, Hélène Delatte, Laurent Costet
    Abstract:

    Numerous studies have examined the genetic diversity and genetic structure of invading species, with contrasting results concerning the relative roles of genetic diversity and phenotypic plasticity in the success of introduced populations. Increasing evidence shows that asexual lineages of aphids are able to occupy a wide geographical and ecological range of habitats despite low genetic diversity. The anholocyclic aphid Melanaphis sacchari is a pest of sugarcane and sorghum which originated in the old world, was introduced into the Americas, and is now distributed worldwide. Our purpose was to assess the genetic diversity and structuring of populations of this species according to host and locality. We used 10 microsatellite markers to genotype 1333 individuals (57 samples, 42 localities, 15 countries) collected mainly on sugarcane or sorghum. Five multilocus lineages (MLL) were defined, grouping multilocus genotypes (MLG) differing by only a few mutations or scoring errors. Analysis of a 658 bp sequence of mitochondrial COI gene on 96 individuals revealed five haplotypes, with a mean divergence of only 0.19 %. The distribution of MLL appeared to be strongly influenced by geography but not by host plant. Each of the five MLL grouped individuals from (A) Africa, (B) Australia, (C) South America, the Caribbean and the Indian Ocean including East Africa, (D) USA, and (E) China. The MLL A and C, with a wide geographic distribution, matched the definition of superclone. Among aphids, M. sacchari has one of the lowest known rates of genetic diversity for such a wide geographical distribution.

  • Genotypic variability of sugarcane resistance to the aphid Melanaphis sacchari, vector of the Sugarcane yellow leaf virus
    Plant Breeding, 2014
    Co-Authors: Benjamin Fartek, Samuel Nibouche, Bernard Reynaud, Toulassi Atiama-nurbel, Laurent Costet
    Abstract:

    The objective of this study was to analyse the genotypic variability of sugarcane resistance to the main aphid vector of the Sugarcane yellow leaf virus (ScYLV) (Polerovirus, Luteoviridae), Melanaphis sacchari. We assessed the incidence of aphids in a field trial comparing 181 sugarcane cultivars. Based on the percentage of infested leaves, aphid incidence was scored every two weeks during three cropping seasons. Analysis of variance revealed highly significant genotype, and genotype 9 year variance, and high broad sense heritability. Using semivariograms, we showed that the alpha lattice design used in the field trial was able to cope with spatial correlation issues caused by the patchy nature of aphid infestations. Twenty-two aphid resistant cultivars were identified. A laboratory study of the development of M. sacchari on four of these 22 resistant cultivars confirmed the resistant status of three of them. We observed modest positive phenotypic and genetic correlations between the aphid incidence and the incidence of ScYLV. The 22 cultivars resistant to M. sacchari showed twofold lower mean virus incidence than the remaining 159 cultivars. (Resume d'auteur)

  • Genotypic variability of sugarcane resistance to the aphid #Melanaphis sacchari,# vector of the #Sugarcane yellow leaf virus#
    Plant Breeding, 2014
    Co-Authors: Benjamin Fartek, Samuel Nibouche, Bernard Reynaud, Toulassi Atiama-nurbel, Laurent Costet
    Abstract:

    The objective of this study was to analyse the genotypic variability of sugarcane resistance to the main aphid vector of the Sugarcane yellow leaf virus (ScYLV) (Polerovirus, Luteoviridae), Melanaphis sacchari. We assessed the incidence of aphids in a field trial comparing 181 sugarcane cultivars. Based on the percentage of infested leaves, aphid incidence was scored every two weeks during three cropping seasons. Analysis of variance revealed highly significant genotype, and genotype 9 year variance, and high broad sense heritability. Using semivariograms, we showed that the alpha lattice design used in the field trial was able to cope with spatial correlation issues caused by the patchy nature of aphid infestations. Twenty-two aphid resistant cultivars were identified. A laboratory study of the development of M. sacchari on four of these 22 resistant cultivars confirmed the resistant status of three of them. We observed modest positive phenotypic and genetic correlations between the aphid incidence and the incidence of ScYLV. The 22 cultivars resistant to M. sacchari showed twofold lower mean virus incidence than the remaining 159 cultivars. (Résumé d'auteur)

Bernard Reynaud - One of the best experts on this subject based on the ideXlab platform.

  • Costet L. Low genetic diversity in Melanaphis sacchari aphid populations at the worldwide scale
    2016
    Co-Authors: Samuel Nibouche, Benjamin Fartek, Bernard Reynaud, Stelly Mississipi, Laurent Costet
    Abstract:

    Numerous studies have examined the genetic diversity and genetic structure of invading species, with contrasting results concerning the relative roles of genetic diversity and phenotypic plasticity in the success of introduced populations. Increasing evidence shows that asexual lineages of aphids are able to occupy a wide geographical and ecological range of habitats despite low genetic diversity. The anholocyclic aphid Melanaphis sacchari is a pest of sugarcane and sorghum which originated in the old world, was introduced into the Americas, and is now distributed worldwide. Our purpose was to assess the genetic diversity and structuring of populations of this species according to host and locality. We used 10 microsatellite markers to genotype 1333 individuals (57 samples, 42 localities, 15 countries) collected mainly on sugarcane or sorghum. Five multilocus lineages (MLL) were defined, grouping multilocus genotypes (MLG) differing by only a few mutations or scoring errors. Analysis of a 658 bp sequence of mitochondrial COI gene on 96 individuals revealed five haplotypes, with a mean divergence of only 0.19 %. The distribution of MLL appeared to be strongly influenced b

  • Host Plant Specialization in the Sugarcane Aphid Melanaphis sacchari
    PLOS ONE, 2015
    Co-Authors: Samuel Nibouche, Benjamin Fartek, Bernard Reynaud, Stelly Mississipi, Hélène Delatte, Laurent Costet
    Abstract:

    Most aphids are highly specialized on one or two related plant species and generalist species often include sympatric populations adapted to different host plants. Our aim was to test the hypothesis of the existence of host specialized lineages of the aphid Melanaphis sacchari in Reunion Island. To this end, we investigated the genetic diversity of the aphid and its association with host plants by analyzing the effect of wild sorghum Sorghum bicolor subsp. verticilliflorum or sugarcane as host plants on the genetic structuring of populations and by performing laboratory host transfer experiments to detect trade-offs in host use. Genotyping of 31 samples with 10 microsatellite loci enabled identification of 13 multilocus genotypes (MLG). Three of these, Ms11, Ms16 and Ms15, were the most frequent ones. The genetic structure of the populations was linked to the host plants. Ms11 and Ms16 were significantly more frequently observed on sugarcane, while Ms15 was almost exclusively collected in colonies on wild sorghum. Laboratory transfer experiments demonstrated the existence of fitness trade-offs. An Ms11 isofemale lineage performed better on sugarcane than on sorghum, whereas an Ms15 lineage developed very poorly on sugarcane, and two Ms16 lineages showed no significant difference in performances between both hosts. Both field and laboratory results support the existence of host plant specialization in M. sacchari in Reunion Island, despite low genetic differentiation. This study illustrates the ability of asexual aphid lineages to rapidly undergo adaptive changes including shifting from one host plant to another.

  • Low Genetic Diversity in Melanaphis sacchari Aphid Populations at the Worldwide Scale
    PloS one, 2014
    Co-Authors: Samuel Nibouche, Benjamin Fartek, Bernard Reynaud, Stelly Mississipi, Hélène Delatte, Laurent Costet
    Abstract:

    Numerous studies have examined the genetic diversity and genetic structure of invading species, with contrasting results concerning the relative roles of genetic diversity and phenotypic plasticity in the success of introduced populations. Increasing evidence shows that asexual lineages of aphids are able to occupy a wide geographical and ecological range of habitats despite low genetic diversity. The anholocyclic aphid Melanaphis sacchari is a pest of sugarcane and sorghum which originated in the old world, was introduced into the Americas, and is now distributed worldwide. Our purpose was to assess the genetic diversity and structuring of populations of this species according to host and locality. We used 10 microsatellite markers to genotype 1333 individuals (57 samples, 42 localities, 15 countries) collected mainly on sugarcane or sorghum. Five multilocus lineages (MLL) were defined, grouping multilocus genotypes (MLG) differing by only a few mutations or scoring errors. Analysis of a 658 bp sequence of mitochondrial COI gene on 96 individuals revealed five haplotypes, with a mean divergence of only 0.19 %. The distribution of MLL appeared to be strongly influenced by geography but not by host plant. Each of the five MLL grouped individuals from (A) Africa, (B) Australia, (C) South America, the Caribbean and the Indian Ocean including East Africa, (D) USA, and (E) China. The MLL A and C, with a wide geographic distribution, matched the definition of superclone. Among aphids, M. sacchari has one of the lowest known rates of genetic diversity for such a wide geographical distribution.

  • Genotypic variability of sugarcane resistance to the aphid Melanaphis sacchari, vector of the Sugarcane yellow leaf virus
    Plant Breeding, 2014
    Co-Authors: Benjamin Fartek, Samuel Nibouche, Bernard Reynaud, Toulassi Atiama-nurbel, Laurent Costet
    Abstract:

    The objective of this study was to analyse the genotypic variability of sugarcane resistance to the main aphid vector of the Sugarcane yellow leaf virus (ScYLV) (Polerovirus, Luteoviridae), Melanaphis sacchari. We assessed the incidence of aphids in a field trial comparing 181 sugarcane cultivars. Based on the percentage of infested leaves, aphid incidence was scored every two weeks during three cropping seasons. Analysis of variance revealed highly significant genotype, and genotype 9 year variance, and high broad sense heritability. Using semivariograms, we showed that the alpha lattice design used in the field trial was able to cope with spatial correlation issues caused by the patchy nature of aphid infestations. Twenty-two aphid resistant cultivars were identified. A laboratory study of the development of M. sacchari on four of these 22 resistant cultivars confirmed the resistant status of three of them. We observed modest positive phenotypic and genetic correlations between the aphid incidence and the incidence of ScYLV. The 22 cultivars resistant to M. sacchari showed twofold lower mean virus incidence than the remaining 159 cultivars. (Resume d'auteur)

  • Genotypic variability of sugarcane resistance to the aphid #Melanaphis sacchari,# vector of the #Sugarcane yellow leaf virus#
    Plant Breeding, 2014
    Co-Authors: Benjamin Fartek, Samuel Nibouche, Bernard Reynaud, Toulassi Atiama-nurbel, Laurent Costet
    Abstract:

    The objective of this study was to analyse the genotypic variability of sugarcane resistance to the main aphid vector of the Sugarcane yellow leaf virus (ScYLV) (Polerovirus, Luteoviridae), Melanaphis sacchari. We assessed the incidence of aphids in a field trial comparing 181 sugarcane cultivars. Based on the percentage of infested leaves, aphid incidence was scored every two weeks during three cropping seasons. Analysis of variance revealed highly significant genotype, and genotype 9 year variance, and high broad sense heritability. Using semivariograms, we showed that the alpha lattice design used in the field trial was able to cope with spatial correlation issues caused by the patchy nature of aphid infestations. Twenty-two aphid resistant cultivars were identified. A laboratory study of the development of M. sacchari on four of these 22 resistant cultivars confirmed the resistant status of three of them. We observed modest positive phenotypic and genetic correlations between the aphid incidence and the incidence of ScYLV. The 22 cultivars resistant to M. sacchari showed twofold lower mean virus incidence than the remaining 159 cultivars. (Résumé d'auteur)

T. E. Reagan - One of the best experts on this subject based on the ideXlab platform.

  • Life Cycle and Larval Morphology of Diomus Terminatus (Coleoptera: Coccinellidae) and its Potential as a Biological Control Agent of Melanaphis sacchari (Hemiptera: Aphididae)
    Annals of the Entomological Society of America, 2009
    Co-Authors: W. Akbar, Christopher E. Carlton, T. E. Reagan
    Abstract:

    ABSTRACT The life cycle, morphology, and potential of Diomus terminatus Say (Coleoptera: Coccinellidae) to control the sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), were examined in the laboratory. The morphologies of first and fourth instars are described and illustrated, with emphasis on characters of first instar that differ from those of later instars. Dramatic differences exist in the relative size and abundance of specialized setae between early and late instars. Field-collected late instars of D. terminatus were successfully reared to adult stage at 26°C by using M. sacchari feeding on small pieces of sugarcane {Saccharum, spp.) leaves. The eggs laid on the sugarcane leaves hatched in 4.5 ± 0.1 d. Larval and pupal stages lasted an average of 6.8 ± 0.6 and 4.9 ± 0.2 d, respectively. D. terminatus required 12.1 ± 0.6 d from egg hatch to adult emergence. The adult longevity test with single adults in petri dishes revealed that D. terminatus remained alive for 26 ± 1.9 d when ...

  • Temporal Increase and Spatial Distribution of Sugarcane Yellow Leaf and Infestations of the Aphid Vector, Melanaphis sacchari.
    Plant disease, 2008
    Co-Authors: C. D. Mcallister, Jeffrey W. Hoy, T. E. Reagan
    Abstract:

    Yellow leaf, caused by Sugarcane yellow leaf virus (ScYLV), is a potentially important disease of sugarcane first found in Louisiana during 1996. A survey during 2002 determined that ScYLV infection was present in all sugarcane-production areas of Louisiana. Virus was detected in 48% of 42 fields, and incidence averaged 15% in these fields. Disease progress curves determined in four fields during two growing seasons indicated that the greatest temporal increase of virus infection occurred during late spring and early summer and coincided with the initial infestation and increase of the virus vector, the sugarcane aphid (Melanaphis sacchari). Aphid infestations in the experimental fields during 2002 and 2003 ranged from 1.2 to 33.0 and 1.0 to 4.2 aphids per leaf, respectively. Final disease incidences of 2.9, 5.2, and 5.2% were recorded in three fields planted with virus-free seed-cane. Distribution of ScYLV infections and aphids evaluated with spatial autocorrelation analysis indicated that ScYLV and its aphid vector both exhibited a predominantly random spatial distribution, with occasional aggregation. The low incidence and rates of disease increase observed, despite the widespread occurrence of potential vectors, suggest that inoculum pressure remains low in Louisiana. Therefore, it may be possible to keep yellow leaf at low levels by planting virus-free seed-cane.